Introducing: Journal News

The research being conducted and the media for sharing findings change through time. In the past decade, these changes have been particularly rapid, as the technology available for measuring the world and for publishing papers have each gone through multiple step changes. The journal is adapting to these changes in service of our research community. This Journal News section of the blog is intended to communicate these adaptations to maintain a leading quality outlet for your work.

All changes at the Journal of Biogeography will reflect our commitment to continually (1) keep pace with and lead advances in the discipline, (2) deliver a constructive, productive process for publishing your biogeographical studies, (3) enhance value to the community, such as replication and reuse of your work, and (4) add value to you by widely disseminating your research to a global audience.

To attain these goals, we made several changes at the journal since September 2019:
Cover Image: published for free to highlight research in each issue
Editors’ Choice: will be ‘full access’ for two years at no cost to the author
– Social media: new team to increase visibility and achieve broader reach
– Updated our statement of the journal’s scope

Other improvements are in the works. Watch for announcements in the coming months.


Introducing: Featured Researchers

The Journal of Biogeography aims to support early career researchers by highlighting their recently published journal articles and providing a space where the community can get to know the authors behind the works and learn from their publication experiences. In our featured posts, researchers dive into the motivations, challenges, and highlights behind their recent papers, and give us a sense of the broader scientific interests that drive their biogeographic research. This is where we also get a sneak peek into novel and interesting research that is yet to come!

Based on the information provided when manuscripts are submitted, the editorial team will routinely contact authors each month to invite a contribution from those who are both (1) early career researchers, i.e. up to and including postdocs, and (2) corresponding author on their upcoming publication in Journal of Biogeography. However, we also welcome contributions from other early career researchers who may be first or middle authors on these papers; if the study has multiple authors, we very much welcome a single submission from the cadre of early career co-authors involved.

To keep the process simple for all involved, we invite contributions to follow a standard format (see below). Responses need not be given to all prompts, but there should be a critical mass of responses to be informative; responses to prompts that are answered should be concise; thus the experience is streamlined, personalized, and easy.

We encourage a tone and standard suitable for social media and that conveys the excitement and intrigue of being a biogeographer.  Previous submissions can provide a guide for your own individualized entries.  The social media editors are happy to provide feedback and assistance in revising content before posting.  The senior editorial team approves all posts.

If you have any questions or would like to submit your own contribution, please contact one of our social media editors: Dr. Leanne Phelps and Dr. Joshua Thia using the journal’s gmail address, jbiogeography@gmail.com. To help you get started, the questionnaire is provided below. Check out recent contributions for examples and ideas!


Questionnaire format:


Links to social media and/or personal website(s)


Current academic life stage (Honours, Masters, PhD, Postdoc?) 

Major research themes and interests

Current study species/system? What makes it interesting (/cool!)? (100 words)

Recent paper in Journal of Biogeography (citation)

Describe the motivation behind this recent paper (100–150 words)

Describe the key methodologies in this recent paper, highlighting anything particularly novel or ingenious and how this provides new insights (100–150 words)

Describe any unexpected outcomes of this research, or any challenges you and your coauthors experienced and overcame along the way (100–150 words)

Describe the major result of this recent paper and its contribution toward the field (100–150 words)

What is the next step in this research? (100 words)

If you could study any organism on Earth, what would it be and why?

Is there anything else you would like to tell us about yourself or your featured research? (Any hidden gems the above questions might have missed?)

If available, please provide three or more visually appealing photos (with captions) that relate to your work, so we can feature you on our social media platforms.


Introducing: Highlighted Papers

Every month, each new issue of the Journal of Biogeography (JBI) includes at least two highlighted articles—the Editors’ Choice and the paper associated with the cover image—and periodically we highlight a topic with a series of papers as part of a special issue. Our intention on the blog is to communicate additional aspects of these, and other papers published in JBI, from slightly different perspectives.

Every published paper has a story behind it that complements and enriches our understanding of the published science. Very rarely, the parallel narrative might provide as radical a reframing of the entirety of our scientific work as did Thomas Kuhn’s “The Structure of Scientific Revolutions”, Bruno Latour’s study of “Laboratory Life”, and the feminist critique of science by Evelyn Fox Keller, Sandra Harding, Helen Longino, and others. On occasion it may cause us to rethink the history of the discipline and its modern consequences—as in recent works on decolonialization of biogeography—or likewise to consider current approaches and what they may mean for the future. Oftentimes the parallel narrative is simply a personal perspective on how we stumbled upon a particular question, co-opted a tool for a different job, ran into unexpected difficulties or found something easier than anticipated, visited wonderful places, worked with fascinating organisms and systems, became aware of related challenges, saw something on the side that sparked our curiosity for the next study, and so on.

Irrespective of what your story is, these pages are intended to provide a small window onto that complimentary narrative that details the human endeavor of biogeography. The idea is to try to demystify how the polished published biogeographical story emerges from at times complicated studies of a complex world. No matter what our career stage, each study comes with its challenges, the solutions merit acknowledgement (and can potentially help others), and each publication is an achievement to be celebrated. In recognizing these commonalities, we hope the diversity of routes and strategies for publishing become a little more transparent and a little more accessible to all.

The format for highlighting papers is flexible (within a limit of ~750 words [+/- 250]), but we provide a few optional prompts below to get you started and make sure some key information is available.


Format & some optional prompts:

Title for blog post

Author name, title, institutional details

Links to social media and/or personal website(s)

Citation including URL for recent paper in Journal of Biogeography 

Describe the motivation behind this recent paper.What’re the major research themes and interests it addresses? — What makes it interesting/cool/important? What surprised you / the team while designing, conducting, completing the study? What knotty problem did you have to overcome? — Reflecting on the whole process, beyond the published research, what were other important outcomes from the project? Where do you / the team go from here? Is there anything else you would like to tell us (any hidden gems the prompts might have missed)?Two to three visually appealing photos/images (with captions) that relate to the work and this narrative is possible.

ECR feature: Himalayan wolves with Geraldine Werhahn

Geraldine Werhahn is a research associate at Oxford University. She is a conversation biologist who uses a multidisciplinary approach to study the ecology and evolution of carnivores in the Himalayas and the Tibetan Plateau. Geraldine shares her recent work on the taxonomy and adaptive evolution of the Himalayan wolf.

Geraldine in the Himalayas, collecting wolf scat for population genetic analyses (Photo credit: Naresh Kusi).

Personal links. Twitter | Instagram

Institute. Wildlife Conservation Research Unit (WildCRU), Department of Zoology, Oxford University, UK

Academic life stage. Research associate.

Research themes and interests. My research focuses on the conservation and ecology of carnivores in the high-altitude ecosystems of the Himalayas and the Tibetan Plateau of Asia. My work is driven by the need to maintain healthy carnivore populations and conserving ecosystem integrity. I take a multidisciplinary research approach (from genetics, to ecology, to social science) to understand my study system and develop science-based conservation strategies.

Current study system. My current study system is the Himalayan wolves and coexisting carnivores in the high altitudes of Asia. These high-altitude ecosystems are vast wilderness regions, also sometimes called the third pole, where the harsh climate and low oxygen levels shape a unique fauna and flora. The Himalayan wolf is found in habitats above 4000 m elevation and is unique to the Himalayas and the Tibetan Plateau. As a top predator alongside the Snow leopard it plays an important role in ecosystem function, warranting its conservation.

A Himalayan wolf pup in the Transhimalayas of Nepal (Photo credit: Geraldine Werhahn).

A herd of Kiang (Equus kiang) in the Transhimalayas of Nepal. These wild equines share their habitat with the Himalayan wolf (Photo credit: Geraldine Werhahn).

Recent paper in Journal of Biogeography. Werhahn et al. (2020) Himalayan wolf distribution and admixture based on multiple genetic markers. Journal of Biogeography. 47(6): 1272–1285. https://doi.org/10.1111/jbi.13824

Motivation for this recent paper. The motivation for this research was to investigate the genetics and ecology of the Himalayan wolf to inform its pending taxonomic classification and advance its conservation. Prior to our work, little research had been conducted on the Himalayan wolf. Most data were derived from captive animals at zoological gardens, or from museum collections, and a range of different names were used for this one wolf lineage across different publications. We focused especially on the evolutionary history, foraging ecology, and distribution of the Himalayan wolf. We wanted to determine if the Himalayan wolf was a distinct lineage that occurs alongside the Holarctic grey wolf, and to explore its phylogeny in relation to contemporary canids from around the globe. For conservation purposes, we also investigated whether hybridization occurs between the Himalayan wolf, the grey wolf, and domestic dogs.

Key methodologies. We developed a conservation genetics toolkit specifically tailored for non-invasive scat sampling of the Himalayan wolf. Our work was conducted in close collaboration with our genetics partner, the RZSS WildGenes lab in Edinburgh. We worked with non-invasive samples obtained from scat. Thereby we could cover many packs and individuals without interfering with the animals. Our methods allowed us to identify wolf individuals and determine their phylogenetic relationship with other canids. We also searched for genetic differences at functional genes known to be involved in adaptation to low environmental oxygen levels. Such genetic adaptations to low oxygen have been described for Tibetan mastiff dogs (the typical dog breed of the Tibetan Plateau) and human populations on the Plateau. So, we were interested to investigate if such adaptations might be important in the ecology of the Himalayan wolf. We analysed 280 wolf scat samples collected from the Tibetan Plateau in western China, and the Central Asian mountains in Kyrgyzstan and Tajikistan, and we included canid reference sequences from around the globe to build the phylogenies based on mitochondrial DNA sequences.

Major results. The Himalayan wolf forms a genetic clade that is distinct from other canids based on the tested mitochondrial and nuclear markers. We found consistent differentiation and unique alleles in the Himalayan wolf samples at functional genes known to be involved in adaptation to low oxygen levels (the hypoxia pathway).  

The distinctness of the Himalayan wolf may be related to the uplifting of the Himalayas and the Tibetan Plateau that produced a unique ecological niche in the high altitudes to be filled. Our preliminary research suggests that hybridisation is limited between the Himalayan wolf and the Holarctic grey wolf.

We hypothesise that the Himalayan wolf has a fitness benefit over the Holarctic grey wolf in the high altitudes due to its hypoxia adaptation. Our paper concludes that the Himalayan wolf merits taxonomic recognition and designation as an Evolutionary Significant Unit (ESU). Establishing the Himalayan wolf as an ESU will allow for the much-needed conservation to advance on the ground while the taxonomy is being conclusively decided on.

Geraldine observing a young wolf family from afar (Photo credit: Naresh Kusi).

Major challenges. Finding elusive carnivores like wolves in remote and harsh high-altitude habitats is challenging. Wolves inhabit large territories and leave few signs, usually in form of scats at characteristic landscape features, such as ridgelines and crossing points. Hence as researchers trying to find wolves in such vast landscapes we had to learn to read and navigate the valleys and mountains like a wolf pack does. With enough territory covered our team managed to collect substantial data of multiple wolf packs across the different study regions. We could provide a first estimation of the distribution range based on our landscape scale data and found that the Himalayan wolf is more widely distributed than previously thought: this wolf is found across the Himalayas and the Tibetan Plateau, which present a continuous high-altitude ecosystem. The distribution appears to be influenced by elevation, presumably in connection to its genetic adaptation to cope with the low oxygen levels in these high altitudes.

Pack mules, used for transporting scientific gear and equipment, grazing in the evening light on fresh grasses (a welcome nutritious forage for them after the long exhaustive weeks of expedition). Buddhist stupas in the background are characteristic landmarks of worship of the region (Photo credit: Geraldine Werhahn).

Net steps. Our team is now working on piloting conservation action in close collaboration with Himalayan mountain communities to mitigate human-carnivore conflict. The goal is to facilitate a long-term sustainable coexistence of humans and carnivores in these vast, pristine high-altitude habitats. We continue to monitor wolf populations in our study area and are collecting more ecological and behavioural data.

An important question is how many Himalayan wolves exist in wild populations today. Our study provides a first estimate of the population range. But a thorough understanding of their distribution on regional level is required to advance conservation of this species because hunting pressure seems high due to human-wildlife conflict and illegal wildlife trade.

If you could study any organism on Earth, what would it be? It would be canids, especially wolves, followed by snails. I have a profound interest for canids due to their complex social behaviour, their role in trophic cascades and importance in ecosystem functioning, their intelligence, and skilful adaptation to live in remarkably diverse habitats from urban spaces to high mountains and deserts. I would also be interested to study snails, for their immense diversity and occurrence in very diverse habitats and because I find the aesthetics of their “houses” fascinating. They are remarkable in their capability to seemingly disappear when conditions are unfavourable and then reappear in large numbers when conditions improve.

An adult Himalayan wolf watching over the valley below. Looking for his mates or potential prey? (Photo credit: Geraldine Werhahn)

Anything else? This research would not have been possible without a dedicated team that has become my family on the long expeditions. We discovered many new insights around other mammals besides the wolves, birds and plants during these expeditions. For example, my team rediscovered the charismatic wild yak for Nepal during one of our expeditions. This was breaking news for the country of Nepal and eventually our team’s photograph of the wild yak ended up on the Nepalese 5-rupee bill.

Three new initiatives at JBI

In addition to providing a choice venue for publishing the full range of biogeographical research, the Journal of Biogeography (JBI) has also long supported our scientific community in other ways too, e.g. organizing workshops for early career researchers (ECRs) to demistify the publishing process, funding symposia and special issues, providing travel grants to meetings, and supporting conference events. More recently we introduced this Journal of Biogeography blog and more social media to increase the reach of your research. We now add three major new initiatives to support ECRs and beyond, which will be rolled out in the coming six months.

First, we are delighted to announce a new Editorial Academy. The aim of the academy is to help early career biogeographers who are interested in scientific publishing to learn more about the process and to gain experience with the guidance and support of an experienced mentor. There will be multiple positions, each gaining first hand experience as an Associate Editor (with reduced workload) at JBI while working alongside one of the senior editorial team (Michael Dawson, Rosemary Gillespie, Holger Kreft, Richard Ladle, Christine Meynard, Jon Sadler). This partnership will give insight into the way a journal operates, illuminate the sometimes challenging decisions to be made by the editorial team, and allow the academy member to explore their potential to become a full-fledged member of the editorial board. We hope it also provides insight more broadly, beyond the academy, into the qualities of successful publishing as we increasingly build bridges between the editorial team and community of authors; in our view, these are ultimately one and the same. The more transparent and inclusive the process, the more rapid — i.e. fewer rounds of review — and straightforward it will be for all to support publication of creative and high quality biogeographic research. More information on this opportunity and guidelines on how to apply are available on this blog and at the journal’s website.

Second, we will soon open a call for proposals for one or more Global Colloquia.  The event may be stand-alone, or may be staged in association with a larger meeting, it may be in-person or virtual. The topic may be on any aspect of biogeography.  A goal of the colloquium should be to publish a synthesis paper and/or a series of papers that represent the range of topics discussed. We intend these colloquia to become a regular activity that helps biogeographers develop, exchange, and explore ideas that advance biogeography through consolidation of fragmentary knowledge, synthesis across disciplines, and innovation.  This call is not solely for ECRs, but we encourage proposals by and/or including ECRs, as well as biogeographers from our global audience. More information on this opportunity and guidelines on how to apply will be available in a month or two.

Third, in October 2020, we will invite submissions of manuscripts by Early Career Researchers for consideration for publication and JBI Awards for Innovation.  This opportunity is modeled after the early career awards first introduced when our current editor-in-chief was on the senior editorial team at Frontiers of Biogeography, and subsequently mirrored by Ecography, and is intended to provide a premium venue for emerging and innovative synthetic biogeography. Our general thinking here is that there is so much good biogeography out there that one award per year is insufficient, and it’s not always well aligned with your publication schedules, so we’ll provide more opportunities at the other end of the year. There will be awards in categories for several article types and all accepted manuscripts will be published free full access for one year. More information on this opportunity and guidelines on how to submit manuscripts will be released in October.

Our goal with each of these three JBI initiatives is to support and provide opportunity for the biogeography community to share the research about which you’re excited and that will advance and shape our discipline in the coming years.

In all these initiatives, following our updated vision and scope, which now includes an equity-diversity-inclusion statement, JBI aims to foster outstanding science that reflects the disciplinary, human, and geographic diversity of biogeography and biogeographers. Submissions will be welcomed from applicants of all ethnicities, races, colors, religions, sexes, sexual orientations, gender identities, national origins, disabilities, ages, or other individual status.

Invitation for applications: JBI Editorial Academy

The Journal of Biogeography is pleased to announce the first of three new opportunities for Early Career Researchers: the Journal of Biogeography’s Editorial Academy.

The Editorial Academy is aimed to help early career biogeographers who are interested to learn more about the publishing process to gain experience with the guidance and support of an experienced mentor.

Editorial Academy members will be partnered one-to-one with a chief editor of the journal.  Academy members will have the same role as a regular member of the Editorial Board, but will work closely with the relevant chief editor throughout the process.  This partnership will illuminate decisions by the editorial team, give insight into the way a journal operation runs, and allow the academy member to explore their potential to become a full-fledged member of the editorial board.  The partnership will convey appropriate procedures and consistent standards of the journal.

Appointments to the Academy are for two years.  The workload will be for 4 manuscripts per year.  Academy members may then be invited to be a continuing member of the editorial board with at least a half-load (6 manuscripts per year) for up to 2 years.  

To be considered for appointment to the Editorial Academy, please submit the following materials as a single PDF:

1. Your CV, including contact information

2. A one page statement explaining:
   – Your interest in and qualifications for the position
               Applicants should have 
                    .. ≥3 years of postdoctoral (or equivalent) experience.
                    .. published ≥6 papers (≥1/2 should be as first/corresponding/senior author)      – Your commitment to the discipline of biogeography
     – The role that being an Academy member will play in your development as a biogeographer
     – Your experience reviewing and, if appropriate, editing
     – Your philosophy on publishing, reviewing, and editing
     – Up to 8 keywords describing your disciplinary interests
     – The name of the chief editor(s) with whom you would prefer to be partnered.

Submit application: 01 July 2020
Decisions announced: 01 August 2020
Appointment begins: 01 September 2020 (negotiable)

Upload applications as a single PDF with the filename “LASTNAME_FIRSTNAME_EditorialAcademy.pdf” only to: https://www.dropbox.com/request/GJrhiiDZTpeM0OCtcVn5 *upload only*

Address enquiries (Subject line: “Enquiry: Editorial Academy”) to the Editor-in-Chief at mdawson@ucmerced.edu

JBI aims to foster inclusive science that reflects the disciplinary, human, and geographic diversity of biogeography and biogeographers. Submissions are welcomed from applicants of all ethnicities, races, colors, religions, sexes, sexual orientations, gender identities, national origins, disabilities, ages, or other individual status.

A deep dive on ecoregions

Ecoregions are central to global modeling of earth systems & development of conservation plans. There is great variability across taxonomic groups and regions of the world in how strongly ecoregions described community composition.

Two years ago, a team of us published a study entitled ‘A global test of ecoregions’ (Smith et al., 2018). In that paper, we set out with a relatively simple goal, to test whether or not maps of ecoregions, which are popular with both global modelers and conservation practitioners, are actually reflective of the distribution of unique groups of species around the globe? Or are they artifacts of a bygone era when we lacked the data on both the variability in environmental conditions and the distribution of species to properly assess biogeographic patterns?

Above. Our results show that we should expect ecoregions to be much more dissimilar from one another in the tropics than they are in the temperate zone.

EDITORS’ CHOICE: Smith, JR, Hendershot, JN, Nova, N, Daily, GC. (2020) The biogeography of ecoregions: Descriptive power across regions and taxa. J Biogeogr.; 47: 1413– 1426. https://onlinelibrary.wiley.com/doi/full/10.1111/jbi.13871

Over the course of that project we believed that we would find that ecoregions did not describe communities of species, but instead that species were distributed more or less individualistically across space. We were continually surprised at how wrong we were. We found compelling evidence that ecoregions described clusters of species across space much better than we would expect by chance alone. As we analyzed and discussed our results, we focused on this high level finding that ecoregions did in fact delineate unique communities of species.

It was not until we got comments back from our first round of revisions that we realized that maybe we missed the more interesting story. Our results showed that there was a large amount of variability, both across taxonomic groups and regions of the world, in how strongly ecoregions described community composition. In the short format of that original paper we were unable to dive into the nuance of these environmental and biological mechanisms, but are now thrilled that the Journal of Biogeography has given us the opportunity to do so in our new paper, “The biogeography of ecoregions: Descriptive power across regions and taxa” (Smith et al., 2020).

However, in this expanded format we were able to revisit some of the most famous biogeographers, and test decades or centuries old hypotheses that would never have been possible before the modern data renaissance. We could test if as Humboldt suggested, “associations of the same species of plants [in the tropics] are less consistently extensive, less numerous, than in temperate climates” (Humboldt & Bonpland, 1807). Or if, as Dan Janzen suggested, that “Mountain passes are higher in the tropics” (Janzen, 1967).

A tree line in the Colombian Andes showing sharp transitions between tree and shrub habitats (photo credit Christopher B. Anderson)

What we quickly realized was that climate played a dominant role in shaping how distinct the communities within neighboring ecoregions were from one another. Those ecoregions with higher mean temperatures and more stable temperatures across the year were more distinct from one another. Similarly, steep slopes led ecoregions to be more distinct from one another. Together, this leads us to believe that it is in fact Janzen, and not Humboldt, who was correct in hypothesizing that communities are more distinct from one another in tropical climates.

We were also able to test out more recent theories on how biological traits, such as body size and functional guild, led animals to be more restricted to specific ecoregions. We were able to add evidence to a growing body of literature suggesting that larger species that feed higher on the food chain are more likely to be found across a large number of ecoregions. Sadly, given the state of trait data available today we were only able to do this for four vertebrate taxa: birds, mammals, reptiles, and amphibians.

Despite the fact that we hoped to use this paper to follow up on questions posed by our initial piece, we find ourselves with just as many questions as we started with. How might we extend our findings to other taxonomic groups that we didn’t consider here, such as plant, fungi, and arthropods? How might climate change and land use change affect the robustness of ecoregion classification schemes moving forward? How can we incorporate data on the distribution of species a priori into ecoregional classification schemes (sensu Kreft & Jetz, 2010). We are incredibly excited to continue diving into these topics, along with all the readers of Journal of Biogeography.

Written by:
Jeffrey R. Smith, J. Nicholas Hendershot, Nicole Nova, & Gretchen C. Daily – Stanford University

Additional information:
@JeffreySmithJRS, @Appalachianary, @NicoleNovaBio, @CCBatStanford, @NatCapProject, @StanfordWoods

A beach in Northwestern Costa Rica showing sharp transitions between different types of ecosystems, with the beach quickly giving way to mangroves, which give way to upland shrublands (photo credit Jeffrey Smith)


Humboldt, A. von, & Bonpland, A. (1807). Essay on the Geography of Plants (S. T. Jackson, Ed.; S. Romanowski, Trans.; Reprint edition). University of Chicago Press.

Janzen, D. H. (1967). Why Mountain Passes are Higher in the Tropics. The American Naturalist, 101(919), 233–249. https://doi.org/10.1086/282487

Kreft, H., & Jetz, W. (2010). A framework for delineating biogeographical regions based on species distributions. Journal of Biogeography, 37(11), 2029–2053. https://doi.org/10.1111/j.1365-2699.2010.02375.x

Smith, J. R., Hendershot, J. N., Nova, N., & Daily, G. C. (2020). The biogeography of ecoregions: Descriptive power across regions and taxa. Journal of Biogeography, 47: 1– 14 https://doi.org/10.1111/jbi.13871

Smith, J. R., Letten, A. D., Ke, P.-J., Anderson, C. B., Hendershot, J. N., Dhami, M. K., Dlott, G. A., Grainger, T. N., Howard, M. E., Morrison, B. M. L., Routh, D., Juan, P. A. S., Mooney, H. A., Mordecai, E. A., Crowther, T. W., & Daily, G. C. (2018). A global test of ecoregions. Nature Ecology & Evolution, 2(12), 1889. https://doi.org/10.1038/s41559-018-0709-x

ECR feature: Chemical variations in fossil pollen with Florian Muthreich

Florian Muthreich is a PhD student in the Department of Biological Sciences at the University of Bergen, focusing on the application of chemical variations in fossil pollen to understand ecosystem dynamics. Florian’s work focuses on identifying Oak (Quercus) pollen in sediment cores – which is particularly difficult to differentiate with a light microscope – at species level.

Florian in the overgrown remains of an old monastery along the coast in Portugal.

Links: Research Gate | Google Scholar | Twitter | Lab Group

Institution: University of Bergen, Department of Biological Sciences

Current academic life stage: PhD

Research interests: I am interested in understanding the application of chemical variations in fossil pollen to understand ecosystem dynamics in sediment cores.

Current study system: I am currently studying the chemistry of pollen grains with the long term goal to use chemical methods to improve identification of pollen grains in sediment records. For most of my PhD I focused on Oak (Quercus) pollen, because oaks are an integral and important part of European and especially Mediterranean forests. One difficulty is that Quercus pollen is quite hard to differentiate using a light microscope. This means that past distributions of oaks are currently only studied on sub-genus or even genus level and chemical methods have the potential to improve our ability to discern Quercus pollen at the species level.

Recent paper in Journal of Biogeography: Muthreich, F., Zimmermann, B., Birks, H.J.B., Vila-Viçosa, C.M. and Seddon, A.W.R. 2020. Chemical variations in Quercus pollen as a tool for taxonomic identification: implications for long-term ecological and biogeographic research. Journal of Biogeography 47: 1298-1309. https://doi.org/10.1111/jbi.13817

Motivation for the paper: We wanted to explore the variability of pollen chemistry in fresh Quercus pollen using a large dataset sampled from a variety of environmental conditions. Other studies have utilised a large number of different species and showed the potential to differentiate pollen using their chemical composition, but often used a limited number of samples. We therefore aimed to collect pollen from a large number of different trees all over Portugal to see how this affects our ability to differentiate the species.

Key methodologies: We used fourier transformed infrared spectroscopy (FTIR) to record the chemical composition of the pollen. This is a fairly new and exciting method to analyse pollen and other studies showed great potential to separate pollen using their chemical composition. Analyses with FTIR produce large multivariate datasets, because FTIR records the absorbance of the sample over the entire infrared region. Different chemical compounds (lipids, protein, etc) have peaks at specific wavelengths and give differences in relative amounts of these compounds in the sample. Spectral datasets require multivariate methods for data analysis and we opted to use a variant of partial least squares regression (PLSR) to test the classification performance.

(left) Cork oak (Quercus suber) tree in a public park in Lisbon. (right) Mixed forest with cork oak (Quercus suber), kermes oak (Quercus coccifera) and Portuguese oak (Quercus faginea).

Unexpected challenges: We were quite surprised how variable the chemical composition of Querucs pollen was. Previous studies had shown that the lipid component was quite variable with climatic conditions (temperature, precipitation, etc), but we also found considerable variation in the composition of the grain wall of pollen. The pollen grain wall consists of sporopollenin, a polymer largely resistant to chemical degradation, which is the reason why pollen can be recovered from lake and bog sediments and used for past reconstructions. The exact structure of sporopollenin is unknown, but our results suggest that there is quite a bit of variability in sporopollenin chemistry within the same genus.

Major result and contribution to the field: We were able to show that identification using FTIR methods had similar performance to scanning electron microscopy (SEM), which is used to identify Quercus pollen into three sub genus sections. We were able to do the same with our FTIR methods and a relatively simple PLS model. At species level we had some success at separating the different Quercus species (~70% recall). Another result from our study was the amount of variability in the spectra we observed, both within and between species. The variability was not just contained to lipid content of the pollen, but also the sporopollenin content. This suggests a difference in grain wall chemistry between the three sub-genus sections of Quercus, and indicates that sporopollenin chemical composition varies between species.

What are the next steps? The next step for this research is to apply our FTIR methods to actual fossil pollen and see how it performs. There are several challenges to be addressed: i.) we aim to extract fossil pollen without any aggressive chemical treatment. ii.) we expect that most of the fresh components in pollen we relied on in our Quercus study (lipids, etc) are not present in fossil pollen. iii.) FTIR may not be ideal to resolve detailed chemical changes in sporopollenin (we are exploring other IR methods, such as Raman). These challenges are a great motivation for my future research.

If you could study any organism on Earth, what would it be and why?
I feel very fortunate to work on such an exciting project that is ambitious and trying to push the boundaries of pollen identification. Pollen are incredibly diverse and I have explored only a tiny fraction of what pollen has to offer. For now I am quite happy with what I am doing and want to apply our methods to additional pollen types, besides oaks.

Any other little gems you would like to share? Most pollen is yellow, but there are some species that have orange, red or even white coloured pollen. Quercus pollen is bright yellow. Most flavonoids absorb UV light and it is believed that flavonoids developed in pollen to protect the genetic material from the mutagenic UV-radiation. John Flenley, who we dedicated our article to, wrote about this in his article “Why is pollen yellow? And why are there so many species in the tropical rain forest?” (2011) in Journal of Biogeography: 38(5).

Valley in north eastern Portugal with olive trees Olea sp., cork oaks (Quercus suber) and Portuguese oaks (Quercus faginea)

Different evolutionary routes to becoming diversity hotspots

How to tease apart the evolutionary mechanisms underlying global biodiversity patterns.

A major question in evolution and ecology is why biodiversity is so unevenly distributed on Earth. This geographic pattern of global diversity has been extensively analyzed in plants and vertebrates, and has been suggested to be attributed to climatic and topographic variables. However, environmental factors can not directly change the regional richness of species in the absence of evolutionary processes such as speciation, extinction and dispersal. From an evolutionary perspective, high regional diversity may be the result of high net diversification (speciation minus extinction) rate, multiple immigration events from adjacent regions, and/or a long time available for the accumulation of species. However, the relative importance of these different evolutionary processes in shaping regional diversity patterns is poorly known.

Image: Alpine forest landscape in the Himalayas. Photo: Tianlong Cai.

FROM THE COVER: read the article on which this post is based …
Cai T, Shao S, Kennedy JD, et al. (2020) The role of evolutionary time, diversification rates and dispersal in determining the global diversity of a large radiation of passerine birds. J Biogeogr. 47:1612–1625. https://doi.org/10.1111/jbi.13823.

To examine the different routes to the build-up of global diversity patterns, we focused on the biodiversity hotpots in the Sino-Himalayan Mountains (Image 1) and oceanic islands of the Indo-Pacific and Indian Ocean regions using the large avian babbler radiation as a model system. The babblers include more than 450 species belonging to five families, with highly diverse morphological and ecological adaptations (Image 2). The group reaches its highest local diversity in the Sino-Himalayan Mountains, with 87 morphologically diverse species in a grid with the resolution of 0.5 geographical degrees, and in the Indo-Pacific and Indian Ocean islands, with ~100 morphologically similar species in the genus Zosterops. We were intrigued by such a high diversity of babblers in two different settings, i.e. a montane region and oceanic islands, and the underlying mechanisms shaping this pattern. We were interested to unravel the relative roles of diversification rates, evolutionary time and dispersal for the build-up of the babbler diversity.

Image 2: Representatives of the seven babbler families. Family Sylviidae: (1) Blackcap Sylvia atricapilla. Family Paradoxornithidae: (2) Fire-tailed Myzornis Myzornis pyrrhoura, (3) Fulvous Parrotbill Suthora fulvifrons, (4) Golden-breasted Fulvetta Lioparus chrysotis. Family Zosteropidae: (5) White-collared Yuhina Parayuhina diademata, (6) Chestnut-flanked White-eye Zosterops erythropleurus. Family Timaliidae: (7) Chestnut-capped Babbler Timalia pileata, (8) Streak-breasted Scimitar-babbler Pomatorhinus ruficollis. Family Pellorneidae: (9) Rusty-capped Fulvetta Schoeniparus dubius. Family Alcippeidae: (10) David’s Fulvetta Alcippe davidi. Family Leiothrichidae: (11) Black-headed Sibia Heterophasia desgodinsi, (12) Red-billed Leiothrix Leiothrix lutea. All photos: Per Alström..

Based on a near-complete time-calibrated phylogeny and a reconstructed evolutionary history, we found that babblers originated in the Sino-Himalayan Mountains, suggesting a long time for diversification and species accumulation within this region. We concluded that regional diversity of babblers could be well explained by the timing of the first colonization events, while differences in rates of speciation or immigration have had far weaker effects. Nonetheless, the rapid speciation of Zosterops, which we suggested was facilitated by repeated sea level fluctuations during the Pleistocene, has accounted for the babbler diversity on oceanic islands. Our findings support two different evolutionary scenarios: long-time accumulation of species in mainland montane regions and high speciation rate on oceanic islands.

Breeding habitats
Image 3: Views of main breeding habitats of Variegated Laughingthrush (Trochalopteron variegatum) in the Himalayas. ­(A) Rapid changes in vegetation landscapes within a very short geographic distance along elevational gradients. The mist conserves warm and humid climates in the valleys below snow-clad mountains. Three eggs of Variegated Laughingthrush are shown in the left bottom. (B) Alpine forest in the mountains at ~3000 m. Photos: Tianlong Cai.

The question why there are so many babblers in the Sino-Himalayan Mountains was addressed already in the 1980s by the father of Chinese ornithology, Tso-hsin Cheng. After analyzing distributions and morphological variation of the genus Garrulax, he postulated that the Hengduan Mountains in the Sino-Himalayas was the main diversity hotspot for the babblers because this region was the center of origin for the group due to the historically stable climate and long time for accumulation of diversity – in agreement with our findings. The Sino-Himalayan Mountains provide suitable habitats with a stable climate for diversification of babblers, leading to high regional diversity. Many of the deep valleys along the margins of the large highlands of the Sino-Himalayan Mountains would be places of atmospheric inversions, where cold air would sink down into the valleys at night, creating distinct mist zones that would maintain high humidity and cloud forests (see Image 3). In contrast, the Indo-Pacific and Indian Ocean islands underwent repeated contact-isolation circles due to the sea-level fluctuations during the Quaternary glacial cycles, which likely accelerated the speciation rate of the Zosterops group by vicariance, leaving a large number of geographically isolated and morphologically homogeneous descendants. Our study highlights how assessing differences in macroevolutionary history can help explain why biodiversity varies so much worldwide. Further studies based on analyzing functional traits of related species would help us to understand how species can coexist in these hotspots.

Written by:
Tianlong Cai and Shimiao Shao – Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China. 

Per Alström – Animal Ecology, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden

Additional information:
@TianlongCai; @AlstromPer;  https://katalog.uu.se/profile/?id=N99-636

ECR feature: Stephanie K. Adamczak

Stephanie is a PhD student at the University of California, Santa Cruz. She is a marine mammal ecologist with an interest in quantitative modelling approaches. Stephanie shares her recent work on trait evolution in pilot whales and the contrasts in ecogeographic rules between terrestrial and marine systems.

Stephanie conducting fieldwork off the coast of Long Island preparing to take photographs of humpback whales.

Personal links. Twitter | Webpage

Institute. University of California, Santa Cruz.

Academic life stage. PhD.

Major research themes and interests. I study the ecology and biology of marine mammals using quantitative modelling methods.  

Current study system. My current research examines harbor porpoise behaviour, reproductive success, and conservation using mathematical modelling. This modelling approach determines how human-induced disturbance alters harbor porpoise reproductive decisions, thereby influencing the population’s success. Although my current research differs from the work presented here and published in the Journal of Biogeography, the focus on better understanding the ecology and biology of marine mammals remains.

A pod of short-finned pilot whales travelling along Hudson Canyon in the Northwest Atlantic Ocean near New York. Drone imagery collected by Julia Stepanuk under National Marine Fisheries Service GA 21889 to L. Thorne.

Recent paper in Journal of Biogeography. Adamczak, SK, Pabst, DA, McLellan, WA, Thorne, LH. (2020) Do bigger bodies require bigger radiators? Insights into thermal ecology from closely related marine mammal species and implications for ecogeographic rules. Journal of Biogeography 47(5): 1193–1206. https://doi.org/10.1111/jbi.13796

Motivation for this paper. Ecogeographic rules, such as Bergmann’s rule and Allen’s rule, outline spatial variation in biological traits. Bergmann’s rule indicates that species in temperate climates will have larger bodies when compared to more tropical species. This is driven by thermoregulatory needs, as larger bodies typically have lower surface area to volume ratios which conserves more heat. Alternately, Allen’s rule states that species in temperate climates will have smaller appendages than more tropical species because smaller appendage surface area reduces heat loss. Although these rules have been well studied in terrestrial systems, little is known about how they impact the morphology of marine mammals. As a result, we set out to determine if these rules dictate morphological patterns observed in marine mammals as these animals already have very unique thermoregulatory adaptations. To test this, we compared the tropical short-finned pilot whale and the temperate long-finned pilot whale, two ecologically and phylogenetically similar species that occupy different thermal regimes.

Methodologies. To more accurately estimate surface area and volume of pilot whales, we employed a novel 3D modeling method to better account for the streamlined shape of marine mammals. After modelling surface area and volume for each individual, we compared the relationship of these two metrics between short- and long-finned pilot whales to examine differences in size and shape. We then compared overall surface area to volume ratios to directly test if pilot whales followed Bergmann’s rule. To test Allen’s rule we examined species-level differences in normalized appendage surface area (to account for differences in size between individuals) for the pectoral flippers, dorsal fin, and flukes individually and combined. This allowed us to determine the heat conservation/dissipation capacity of each appendage as well as the total thermoregulatory capacity of the combined appendages.

Example of the 3D model constructed with the program, Blender, used to estimate the surface area and volume of individual pilot whales in these analyses.

Major results. We expected the more temperate long-finned pilot whale to have a larger body size and lower surface to volume ratio when compared to short-finned pilot whales, as per Bergmann’s rule, and lower appendage surface area, as per Allen’s rule. Although Bergmann’s rule was upheld, Allen’s rule was reversed as we observed greater appendage surface area relative to body size in long-finned pilot whales when compared to short-finned pilot whales. This result was primarily driven by the very large pectoral flippers of long-finned pilot whales. My co-authors and I suggest that this reversal of Allen’s rule could be attributed to the use of appendages as heat dissipators in marine mammals. Marine mammal appendages act as thermal windows through which they can control heat loss and dissipate heat in times of thermal stress. It is possible that the large body size and effective insulation of long-finned pilot whales necessitates large thermal windows for effective heat dissipation when compared to short-finned pilot whales.

Unexpected outcomes. Our results suggest that Allen’s rule may not be applicable to marine mammals. We hypothesise that this may be a result of the different environmental pressures faced by marine mammals when compared to terrestrial mammals. Marine mammals are endotherms living in a highly conductive medium, and as such they are equipped with unique thermoregulatory adaptations such as thick blubber layers and large body size. These adaptations that offset the energetic costs of thermoregulation in the water may necessitate a greater need for rapid heat dissipation in times of thermoregulatory stress. Marine mammals have incredible control of the heat dissipated or conserved via their thermal windows, so we surmise that the improved capability to shut off or turn on thermal windows provides a unique advantage over terrestrial endotherms. We feel this research demonstrates that larger marine mammals inhabiting cold thermal regimes may need greater appendage surface area over which to rapidly dump heat, which contrasts the patterns seen in terrestrial species where larger, cold-climate species have small appendages to conserve heat.

Next steps? The next step in this research would definitely be to keep exploring biogeographical patterns in marine mammal species! Studies of Bergmann’s rule and Allen’s rule highlight the different evolutionary and environmental pressures faced by marine mammals when compared to terrestrial species, specifically when discussing thermoregulatory adaptations. Marine mammal thermoregulation is a fascinating field of study due to the unique adaptations of these animals, and as such, further analysis of Bergmann’s rule and Allen’s rule would highlight how these adaptations may lead to reversals or alterations to long-held ecological rules. Personally, I would love to see similar comparisons carried out in much larger marine mammal species occupying Arctic or Antarctic environments, as the patterns seen here may be even more prevalent in animals adapted for harsher environments.

If you could study any organism, what would it be? I find marine mammal species living in extreme, cold environments like Antarctica or the Arctic really interesting. The physiological adaptations that enable species like the Weddell seal or bowhead whale to persist in these environments fascinates me and I’d love to have the opportunity to study them some day.

Anything else you’d life to share? When I started this work as part of my Master’s thesis my intention was to examine the morphology of short- and long-finned pilot whales. It wasn’t until about half-way through my research that I realized I could apply my work to something broader and more interesting, such as biogeography. Thinking outside of the box can be extremely beneficial and lead you to some very interesting discoveries!

ECR feature: Jéssica Fenker

Jéssica Fenker is a PhD candidate at Australia National University. She is a herpetologist with a particular interest in adaptive radiations, species diversification, and savanna ecosystems. Jéssica shares her recent work, a multidisciplinary study, on characterising the biodiversity of lizards in the Cerrado, South America.

Jéssica Feneker posing with a goanna in Australia (left), and a false coral snake (Oxyrhopus trigeminus) during her fieldwork expedition in the Cerrado (right).

Personal link. Twitter | Website

Institution. Australian National University (ANU)

Academic life stage. PhD (finishing up)

Research themes and interests. Adaptation and
diversification of lizards (and sometimes snakes and amphisbaenians),
particularly savanna ecosystems, combining morphological, ecological and
genomic data across different geographic scales (from local communities to
intercontinental studies).

Current study system. Currently, I’m concluding my PhD
comparing patterns and processes of savanna reptile diversity across two
biogeographic realms – the Cerrado biome from South America and the Australian
Monsoonal Tropics of Australia. Cerrado is the most continuous and most diverse
savanna in South America, considered the second largest biome in the continent.
The also vast Australian Monsoonal Tropics has low population density and is
considered the most well conserved savanna in the world. Comparing these two
similar but evolutionarily independent systems, I expected to identify common
processes underpinning the high diversity of tropical savanna systems on
convergence and disparity in morphological traits, but also looking for region
specific spatial patterns of species richness, phylogeographic diversity and
endemism. I am also interested in how dispersal limitation, environment and
geographic barriers at the landscape scale can predict differences in
phylogeographic structure across co-distributed taxa.

Recent paper in Journal of Biogeography. Fenker J, Domingos
FMCB, Tedeschi LG, et al. (2020) Evolutionary history of Neotropical savannas
geographically concentrates species, phylogenetic and functional diversity of
lizards. Journal of Biogeography. 47(5): 1130–1142. https://doi.org/10.1111/jbi.13800

(left) The lizard, Norops (Anolis) meridionalis, one of the species featured in our analysis and present across Cerrado’s distribution (Photo: Jessica Fenker). (right) The lizard, Polychrus acutirostris, one of the species featured in our analysis and present across Cerrado’s distribution (Photo: Jessica Fenker).

Motivation for recent paper. Our motivation for this study was to map spatial patterns of diversity and endemism using an integrative approach, to highlight key areas for the past and future maintenance of biodiversity in the Cerrado. Previous studies have focused on a single metric (species composition), neglecting the fact that “species” within are often composed of multiple cryptic taxa that can co-occur and might be associated with different habitats. The Cerrado is a continent-size biome, with a complex landscape of alternating ancient plateaus and younger inter-plateau depressions. Still, studies debate its origin and process that affect the spatial distribution of species diversity, making our study pertinent for the region. The Cerrado is also a highly threatened savanna ecosystem, so understanding processes that shape diversity will help provide management tools and priorities for conservation.

A series of vistas from the Cerrado (Photos: Jéssica Fenker)

Key methodologies. In order to identify biodiversity
hotspots more robustly while integrating multiple factors, we used a
multi-dimensional approach, combining taxonomic, phylogenetic and functional
data to identify unique areas of richness and endemism within Cerrado. We
generated species distribution models using distribution records for all
Cerrado lizard species. These, combined with mitochondrial DNA phylogenies and
natural history data allowed us to map species richness, phylogenetic and
functional diversity, and phylogenetic and weighted endemism. Phylogenetic
endemism maps were then cross-referenced against protected areas to calculate the
amount of evolutionary history preserved within these areas. For me, the most
interesting aspect of this paper was the co-opting of previously published
phylogeographic studies to help refine species limits and prioritise regions
for conservation in Cerrado.

Major challenges. The biggest challenge was to gather and
synthethise all the relevant available information, especially with the
different genes, and the challenges of deciding how to delimit species. The
availability of sequencing data for Brazilian species has grown, although
characterising genetic variation within and among different taxa is still not a
common component of much biodiversity research. Nonetheless, we need more
genetic sequencing to improve diversity estimates, as many reptile groups are
known to actually belong to species complexes, and there is a need to surpass
the inadequate taxonomy.

Major results. We highlighted both climatically stable
plateau regions and environmentally heterogenous (less stable) valley areas as
hotspots of evolutionary diversity, being higher in taxonomic, phylogenetic,
and functional diversity. The central region of the Cerrado, a vast and
climatically stable plateau, stands out as important under all biodiversity
metrics. With the inclusion of evolutionary relationships in biodiversity
assessment, we detected four regional hotspots with high concentration of
spatially restricted evolutionary diversity. Protected areas cover only 10% of
the Cerrado area and hold only 11.64% of the summed phylogenetic endemism of
all lizards in the biome.

Hotspot areas for conservation based on their high levels of phylogenetic endemism (PE). Heat colours represent priority areas.

Next steps. Creating new protected areas based on our identified regional hotspots will be important for future conservation. Ideally, this will combine sustainable land use and management with cultural and economic benefits to local communities. The challenge is to overcome Brazilian conservation policies, that often neglect non-forest ecosystems, and to conciliate conservation with human goals, as Cerrado has been dramatically converted to soy monoculture and cattle raising.

If you could study any organism on Earth, what would it be and why? I would definitely continue with squamate reptiles–they are not only the coolest organisms on Earth, but they are also excellent models to study biogeography, ecology and evolution. First, they use they habitat in a huge variety of ways, with different species being fossorial, terrestrial, aquatic and arboreal (and anything in between!). Second, as ectotherms they are particularly sensitive to climate variation in space and time. Finally, lizards in particular are relatively easy to sample in the wild, with high diversity and comparatively well-established knowledge of species’ distributions. I also love to do fieldwork, during day or night, and spot these amazing creatures.

Anything else you’d like the share? I’m a Brazilian student and have had the opportunity to develop my PhD in one of the best Australian universities with a supportive advisor (Professor Craig Moritz), and I consider myself really lucky to have this opportunity. Starting in June, I will join Professor Lacey Knowles’ laboratory at the University of Michigan, United States, as a post-doc working on conceptual issues related to the species delimitation process – an issue that was pertinent in all my PhD chapters. As a female and first-generation PhD candidate, I am involved in projects that promote equal gender opportunities in science, especially in South America where culturally ingrained masculine pride is normalised, and I aim to continue participating in projects that benefit Brazilian biodiversity.

The forgotten giants of the Western Indian Ocean reefs

Giant clams have long fascinated adventurers and naturalists. These large shallow-water molluscs certainly are among the most colourful, conspicuous and emblematic species of the Indo-Pacific coral reefs. They have been exploited for thousands of years for their flesh and shell. Giant clam conservation is also an increasingly concerning issue because of the vulnerability of giant clams to overharvesting. Surprisingly, up to recent years, giant clams have remained incompletely known and described, and their evolutionary history was poorly understood.

Image: C. Fauvelot (IRD) is doing a biopsy on a giant clam in Juan de Nova. Photo credit: T.B. Hoareau / TAAF-Iles Eparses research consortium.

FROM THE COVER: read the article on which this post is based …
Fauvelot, C, Zuccon, D, Borsa, P, et al. 2020. Phylogeographical patterns and a cryptic species provide new insights into Western Indian Ocean giant clams phylogenetic relationships and colonization history. J Biogeogr. 47:1086– 1105. https://doi.org/10.1111/jbi.13797

As Tridacna giant clams exclusively occur in coral reefs of the Indo-West Pacific (IWP), we believed that studying the mode and tempo of their speciation would provide us with clues on the evolutionary history of modern coral reef communities in the IWP. We addressed this objective by combining molecular phylogenies with the geographic distribution of Tridacna lineages across the IWP. With well-dated, albeit rare fossil records, we had a model of choice to link phylogenetic patterns to past geological events.

When we started our phylogeographic research in the late 2000s, little was known from the Indian Ocean although a robust phylogeography of Coral-Triangle and Pacific Tridacna lineages was already partly available. A distinctive T. maxima lineage and a newly rediscovered species (T. squamosina) had been reported from the Red Sea, but no phylogeographic information was then available from the western Indian Ocean (WIO). Hence our focus on Tridacna giant clams from that part of the tropical IWP.

During field work, several participants in this study – then working as separate teams – independently noticed giant clams initially identified as T. maxima but presenting somewhat distinctive features.

We noticed the sharply pointed triangular interstices between folds, and the remarkable emerald-green colour of the mantle edge.

Tridacna elongatissima from Etang Salé at Reunion Island. Photo credit: L. Bigot / Université de La Réunion.

Nucleotide sequences at the COI locus confirmed this giant clam was distinct from T. maxima, and from all other known Tridacna spp. then documented in public sequence databases. With an endemic species in the Red Sea (T. squamosina), two unverified rare species endemic to the Mascarene Basin (T. rosewateri and T. lorenzi), and now a new cryptic lineage in the WIO, we felt that we had an increasingly interesting subject to investigate. Our different teams merged efforts and datasets and pursued the phylogeographic work all together.

We managed to extract DNA from dried muscle tissue and ligament from the type material of T. rosewateri and from other specimens from the WIO region preserved in museum collections. Morphological and molecular analyses enabled us to identify the distinct Tridacna lineage present in the WIO as T. elongatissima, a long- forgotten species from Mozambique then synonymised with T. maxima, thereby adding a taxonomic hue to our primarily phylogeographic study. Meanwhile, T. lorenzi and T. rosewateri were found to be a single and same, distinct species. 

This newly resurrected WIO-endemic Tridacna elongatissima turned out to be the sister species of T. squamosina! These two species had evolved independently in, respectively, the WIO and the Red Sea (or perhaps an adjacent northwestern Indian Ocean refuge), revealing a geographic barrier between the two regions. The T. elongatissimaT. squamosina pair was itself sister to T. rosewateri, highlighting this part of the world as an hotspot of endemism for giant clams. Lineage diversification patterns within the widespread T. maxima mirrored those of T. elongatissima, T. rosewateri and T. squamosina with two unrelated lineages in the WIO, one of which was sister to a third lineage endemic to the Red Sea. Thus, the same geographic barriers and speciation processes may have acted repeatedly at different periods in the Pleistocene. 

We are aware, though, that no uniform explanation holds for the evolutionary history of species in the tropical IWP. At least we were able to refine our understanding of lineage diversification and endemism of Tridacna giant clams in the WIO and Red Sea region. Beyond the specific case of giant clams, our results emphasize the interest of sampling understudied regions of the tropical IWP, such as the WIO, to refine the evolutionary puzzle of this vast and complex geographic ensemble. Further investigations in the future may add to the story.

Written by:
Philippe Borsa and Cécile Fauvelot – Researchers – Institut de recherche pour le développement (IRD), UMR ENTROPIE, France.

Additional information:

ECR feature: Cavity-nesting pollinators and their antagonists with Antonia Mayr

Antonia V. Mayr is a Postdoc at the University of Würzburg department of Animal Ecology and Tropical Biology. Her research is based in tropical mountain ecology and focuses on questions about how climate and land use change affect species, and how functional and phylogenetic diversity relate to changes in ecosystem services. Antonia provides background information on her recent work, which examines cavity-nesting pollinators and their natural antagonists on Mt. Kilimanjaro, Tanzania, where a large elevational gradient gives rise to different climates and ecosystems on a relatively small spatial scale.

(left) Antonia while doing her favourite work – fieldwork! She was also called mama nyuki (mother of the bees in Kiswahili) by her Tanzanian field assistants. (right) Antonia’s fieldwork was much nicer with often very interested friends. Here, they are checking occupied nests to see if they already hatched. If yes, Antonia took them to the field station, if no, she placed them back in the bucket.

Links: Institutional webpage | Research Gate

Institution: University of Würzburg, Department of Animal Ecology and Tropical Biology

Current academic life stage: Postdoc

Research interests: My main research theme is tropical biology, especially tropical mountain ecology. Specifically, I am working on questions about how climate and land use changes affect species, but also functional and phylogenetic diversity and how this relates to changes in ecosystem services. I am fascinated by trophic interactions between plants, pollinators, predators and parasitoids and am very much interested in how to translate these findings into practical recommendations for conservation biology.

Current study system: Currently, I am studying cavity-nesting pollinators and their natural antagonists on Mt. Kilimanjaro, Tanzania. This is a very cool combination of study systems because the large elevational gradient of Mt. Kilimanjaro offers the possibility to study completely different climates and ecosystems on a relatively small spatial scale. Within few days, you can walk from the hot savanna through different mountain rainforests up to alpine ecosystems. Furthermore, the study of so-called trap nests enables us to investigate insects of different trophic levels, to collect data about functional and life-history traits and to study host-antagonist and food networks – which would be hardly possible to collect on this scale using only observational data.

A view of the Kilimanjaro summit from the field station in Nkweseko.

Recent paper in Journal of Biogeography: Mayr AV, Peters MK, Eardley CD, Renner ME, Röder J, Steffan-Dewenter I. 2020. Climate and food resources shape species richness and trophic interactions of cavity-nesting Hymenoptera. Journal of Biogeography 47: 854-865. https://doi.org/10.1111/jbi.13753

Motivation for the paper: Biologists have investigated the drivers of species richness for centuries. For insects, temperature, resource availability and top-down regulation as well as the impact of land use are considered to be important factors determining diversity. However, the relative importance of each of these factors is unknown. The steep climatic gradient and different land-use regimes at Mt. Kilimanjaro, together with the trap-nest system enabled us to simultaneously investigate the effects of temperature, resources, top-down control and land use on species richness of different trophic levels. With this paper, we hope to contribute to the discussion on drivers of insect species richness.

Key methodologies: We used trap nests, which are good bio-indicators for habitat quality and environmental changes, to collect and monitor cavity-nesting bees, wasps and their natural antagonists. To the best of our knowledge, this is the first trap-nest study in East Africa. We continuously monitored trap nests for 15 months, checking monthly for new nests and recently emerged insects. If you include the pre-experiment phase – in which we placed trap nests up to 4,240 m a.s.l and adapted the methodology – and the closing phase, our monitoring lasted 26 months in total. It is important to note that we hatched every nest on its respective study site. Normally, trap nests are collected, cut open and reared in the lab (in temperate regions during winter months) and/or brought back into nature after identification. In contrast, we did not take the nests to the research station before they hatched. The reason was that by working along an elevational gradient we would have changed the climatic conditions during the development of the inhabitants. This extra effort enabled us to collect year-round data about the occurrence of species, their development time and natural mortality, and link it to climate data.

(top left) A pair of trap nests with the first version of the roofs, field assistant Jumanne, and Antonia. (top middle) An extra bucket attached to wooden poles with occupied nests waiting for hatching. Antonia closed the nests with metal nets instead of plastic nets because some bee species were able to cut their way out of it with their strong mandibles. (top right) An edited version of our roofs – the double-folded metal shields allowed the air to pass through and the nests underneath did not heat up anymore in a way that many larvae died. (bottom) Trap nests serve as a model system to investigate cavity-nesting communities and trophic interactions in different trophic levels. The picture shows the three different functional host groups which are subject to this study: bees (Apidae, Colletidae and Megachilidae), caterpillar-hunting wasps (Eumeninae) and spider-hunting wasps (Pompilidae, Sphecidae and Crabronidae), their respective natural antagonists, food resources and type of top-down effects. The trophic level affiliation is indicated by the colours and the colourful circles in green, blue, violet and red show the groups for which we analysed species richness patterns in this study.

Unexpected challenges: The biggest unexpected challenge was that a well-established method does not work well in super-hot and dry ecosystems, like the savannah during dry season. We used reed internodes (which are the sections of a reed stem) to artificially imitate natural cavities for cavity-nesting Hymenoptera. Bees in particular willingly nested inside the provided reed internodes. However, in our pre-experiment, many bee larvae died because they were either grilled by the heat and aridity or they drowned in their melted food made out of pollen and nectar. Our solution was to use double-folded metal sheets instead of plastic as roofs, allowing the air to pass through.

It was also surprising that there was a clear line at the border of the national park, above which no reed internodes inside the trap nests were occupied. Apparently, the relative humidity in the lower montane rainforest was too high and the temperatures too low to enable the occurrence of cavity-nesting Hymenoptera. Another lesson to be learned was that basically every material is valuable. It seems trivial, but it was very helpful to use torx screws to attach the roofs and trap nests to the wooden poles, as torx screwdrivers are still uncommon in Tanzania. This saved our materials from being taken away.

(left) A cut open brood cell. Here, the host, a megachilid bee did not emerge, but died for an unknown reason. (right) Pinning of bees and wasps for later identification. (bottom) Nest in which the megachilid bee mum used duct tape instead of leaf discs to construct the broodcells of her offspring.

Major result and contribution to the field: With 38 bee and 43 stem-nesting wasp morphospecies and 49 morphospecies of natural antagonists, we observed a very high diversity in roughly 4,050 nests. Our data suggest that temperature is a major driving factor for species richness patterns in bees, wasps and their natural antagonists. Furthermore, we found more trophic interactions in the warmer climates of the mountain, i.e. lowland ecosystems. By systematically analysing different trophic levels, we found that the importance of food resources increased for natural antagonists at higher trophic levels. Thereby, our study contributes to the discussion about the drivers of biodiversity along elevational gradients and provides novel insights into the relative importance of temperature, resources, trophic level and biotic interactions for bees, wasps and their natural antagonists.

What are the next steps? The next steps with this trap-nest dataset will be first, to understand seasonal changes in occurrence of species of different trophic levels. This is important because insect communities vary seasonally with related changes in climate and resource availability, strength of competition or pressure by natural antagonists, but are not well investigated in tropical mountain ecosystems. The second step is to investigate microclimatic effects on survival rates in savannah ecosystems, because upper thermal limits will first be reached in the lowland savannahs. Hence, it is useful to investigate how species cope with higher temperatures in partially warmer microhabitats to forecast effects of climate change. The third step is to investigate if traits are affected by land use, because traits may respond earlier to land use changes than species. Therefore, changes in traits might forecast changes in species compositions with increasing land use. The final step is to investigate if temperature and land use have an effect on host-parasitoid networks, which might be even more sensitive to environmental changes than species-richness patterns because they depend on very specialized species interactions. 

If you could study any organism on Earth, what would it be and why? I was never totally restricted to one organism/group of organisms (before, I worked with ants). The better you get to know a group of organisms, the more fascinating they become. But I like diversity and enjoy not having only one model species. That is why I am very happy at the moment with bees and wasps, which show a high variety of forms and behaviour, e.g. in sociality and nesting. In addition, they inhabit very different ecosystems which not only makes fieldwork manifold, but offers the possibility to investigate adaptations to different environments, too.

Any other little gems you would like to share? Really impressive for me was the high diversity of nest-building behaviour. I was able to distinguish around 35 different types of nest closures – and this is only a study about cavity-nesting bees and wasps! What was outstanding for me, however, was that over time I discovered nests of leaf-cutter bees that used duct tape instead of leaves to build their broodcells and nest closures, with which I fixed broken trap nests. In the heat of the savannah, the duct tape stuck to my fingers so much that it was difficult for me to handle. How the bees cut the artificial pieces of leaves out of it without sticking to it is a complete mystery to me. Maybe bees are way more flexible and creative than we think they are…

(top) Diversity of nest closures, built out of soils, resins, plant leaves or fibres or secrets. (bottom) Antonia and her Tanzanian field assistants, who not only helped her to carry heavy luggage up the mountain, shoot trap nests high up the trees with a slingshot and check the trap nests, but they also contributed many creative and practical field solutions.