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. Thejournal 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.
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, firstname.lastname@example.org. To help you get started, the questionnaire is provided below. Check out recent contributions for examples and ideas!
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.
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.
Anthropogenic disturbances affect the structure of metacommunities
Above: Examples of Brazilian Neotropical Savanna stream sampled in our study.
The current conditions of any ecosystem are the result of both ancient and contemporary processes, such as geological shifts, ecological conditions in adjacent ecosystems and changes in land use and occupation. Local biodiversity, especially, is a reflection of all of these processes. In our work we seek to understand how two ecological processes could explain the organization of aquatic invertebrate metacommunities, that is, a set of local communities that interact with each other by the dispersal of some of its constituent species. The processes in question are the presence of species that were able to disperse and establish themselves in these places and environmental filtering, when local conditions restrict or allow organisms to live there, depending on the traits of the organism in question.
Our object of study, the aquatic macroinvertebrates, have long been used in biomonitoring programs because the structure and composition of their communities tend to reflect very closely the ecological health of the ecosystems in which they are found. You can imagine what kind of information their metacommunities can give! However, this is easier said than done, because it is not so simple to monitor the movement of aquatic insects, which have an aquatic immature phase, and a winged adult with a short life span. In order to circumvent that, we decided to see how the attributes of these organisms, such as those related to life history and dispersion skills, could explain the structure of local sets of metacommunities. We calculated the distances (Figure 1) between streams in physical terms, as in the normal distance between one another, and also considered distances in terms of obstacles to dispersion, such as topographical differences, anthropogenic land uses and local ecological conditions (as predicted by environmental filtering theory). We then tested whether these distances are able to explain the dissimilarities between the aquatic macroinvertebrate communities. Basically, we put ourselves in the place of the dispersing organisms: “If I were an insect, would I prefer to fly longer, but through a less difficult terrain, or would I prefer to spend a little more energy, and try to arrive faster?”
EDITORS’ CHOICE: (Free to read online for a year.) Firmiano, KR, Cañedo‐Argüelles, M, Gutiérrez‐Cánovas, C, et al. Land use and local environment affect macroinvertebrate metacommunity organization in Neotropical stream networks. J Biogeogr. 2021; 48: xxx– xxx. https://doi.org/10.1111/jbi.14020
And bingo! We found that environmental filtering had big importance for the structure of aquatic invertebrate metacommunities, as similar places had similar biota. In addition, we found that the dispersing organisms can “perceive” changes in the terrestrial landscape, and such changes can encourage or inhibit the dispersion from one stream to another, if there are many obstacles in the way, which in our study area were changes in landscape due to anthropogenic land use and occupation. In short, we found that environmental conditions, both in local and regional scales, are the most important aspects for the structure of aquatic invertebrate metacommunities.
Figure 1:Details of the four distance metrics used in our study. For simplicity only one pairwise comparison is shown (distances between sites A and B). Environmental distance: dissimilarity between two sites was based on a set of local water quality and physical habitat variables. Network distance: least-cost path between each pair of sites along the network drainage. Only one pathway exists between a given pair of sites. For the resistance distances, raster grids were converted to electrical networks (represented by Resistance* box) where each pixel represents a cell (illustrated by black dots), with a given resistance value, and adjacent pixels are connected by resistors. Topographic distance: pairwise resistances considering that elevation gradients would affect dispersal (elevation-weighted distance). High elevation is represented by high resistance (dark gray pixel), and flat terrain is represented by low resistance (light gray pixel). Land use distance: pairwise resistances considering that land use configuration, such as urbanized areas or human altered open areas, would act as barriers to dispersal (land use-weighted distance). The different colors of the pixels indicate different degrees of land use, ranging from weak human impact to strong human impact when moving from green, yellow, orange, to red pixels.
It is important to say that these results are part of a much bigger project focusing in understanding the effects of anthropogenic alterations, both in local and regional scales, in the freshwater ecosystem in the Brazilian Neotropical Savanna (see examples of Brazilian Neotropical Savanna streams, above). This ecosystem, a hotspot of biodiversity, is highly threatened by the expansion of agrobusiness and mining in Brazil, and recently, by the active dismantling of national mechanisms for environmental protection by the current government. The data and discoveries unraveled by this and other studies in this region are invaluable for understanding its processes and for conservation efforts.
Nowadays, we are still looking to understand how human-made alterations are changing the freshwater ecosystems in this precious biome. Kele is currently working in Instituto Guaicuy, a NGO working for the benefit of the population affected by disaster resulting from the tailing dam rupture in Brumadinho city (Brazil) in 2019. She’s focusing on understanding how this disaster impacted the aquatic environment, and how it is affecting freshwater fauna and flora in the Paraopeba river basin. Marden is working as a postdoctoral fellow in the Laboratório de Ecologia de Bentos, in the Federal University of Minas Gerais, focusing his efforts in thermodynamic ecological indicators and invasive species.
Written by: Kele R. Firmiano (1) & Marden S. Linares (2)
(1) Biomonitoring senior analyst, Instituto Guaicuy. (2) Post-Doc researcher, Universidade Federal de Minas Gerais, Instituto de Ciências Biológicas, Departamento de Genética, Ecologia e Evolução, Laboratório de Ecologia de Bentos.
Evan Whiting is a PhD candidate at the University of Minnesota. He is a herpetologist interested in understanding the diversification and biogeography of reptiles. Evan shares his recent work on latitudinal and environmental clines (or lack thereof) across and within different snake and lizard clades in continental North America.
Evan Whiting enjoying a hike in Florida, looking for lizards and other wildlife.
Major research themes. Palaeontology, Herpetology, Ecomorphology, Biogeography, Systematics
Current study system. I’m currently studying squamate reptiles (lizards and snakes), one of the most diverse groups of modern vertebrate animals (>11,000 recognized species). I’ve always been fascinated by squamates and other reptiles, which have an incredible evolutionary history and wide range of different ecologies. Squamates are ectothermic (‘cold-blooded’), so their body temperature and metabolism depend on external conditions in their habitat, like heat from sunlight and shade from trees. Thus, squamates are useful barometers for the climate and environment, so understanding their past and present distributions can tell us a lot about their ecosystems, as well as how they may respond to climate change.
Green Anole (Anolis carolinensis), one of the most widespread species of anoles in continental North America.
Motivation behind this paper. Most modern terrestrial vertebrate animal groups, including squamates, follow a latitudinal diversity gradient, with a greater number of species at lower latitudes. Studies addressing these gradients have typically focused on explaining broader patterns and larger groups, rather than breaking them down into their constituent clades, which might not all follow the same biogeographic and environmental patterns. We wanted to compare the latitudinal gradients of different types of North American lizards and snakes on a clade-by-clade basis. We wanted to determine if they are all driven by the same environmental factors (temperature, moisture/precipitation, topography), and assess how the geographic distributions of different squamate clades relate to the major North American biomes.
Prairie Rattlesnake (Crotalus viridis), a viperid snake widely distributed throughout the Great Plains region of North America.
Key methodologies. To study the latitudinal diversity gradients of lizards and snakes, we first used GIS software to build an equal-area grid system (100 × 100 km cells) spanning all of continental North America, from Canada to Panama. Our grid includes data for 10 climatic and topographic variables, as well as species richness data compiled from the geographic ranges of over 1,000 modern squamate species. Using the data from our new grid, we then constructed latitudinal diversity gradients and multiple linear regression models for each lizard and snake clade in our study to test for potential relationships between species richness and different climatic and topographic variables. We also documented squamate diversity across all major North American biomes and investigated whether species richness is strongly associated with biome area or biome variety, which we used as a proxy for habitat heterogeneity.
Major results. We found that lizards and snakes both exhibited strong latitudinal diversity gradients overall, although the snake gradient was substantially stronger than the lizard gradient. When we broke these larger gradients down, we found that many of the individual clades in our study did not follow strong latitudinal diversity gradients. Additionally, our multiple linear regression models demonstrated that not all the individual lizard and snake clades followed the same environmental patterns as squamates overall, although species richness was strongly positively correlated with temperature variables for most clades. We also found that lizards were generally more strongly associated with habitat heterogeneity than snakes, with a few exceptions. Our statistical results and grid-based species richness maps show that different squamate clades follow different latitudinal and environmental patterns, thereby demonstrating the importance of deconstructing latitudinal diversity gradients to evaluate their underlying structures and environmental drivers.
Southern Watersnake (Nerodia fasciata), a natricine colubrid snake native to the southeastern United States.
Challenges and unexpected outcomes. This was a completely new type of research project for me, so learning how to assemble the GIS data and code/conduct all of my analyses in R was admittedly quite challenging and outside of my comfort zone (i.e., bones and fossils). I certainly learned a lot though, particularly during the very helpful and constructive revision process. One of the most unexpected outcomes we found was that our regression models were not heavily influenced by underlying spatial structure in the species richness data, indicating that climate and topography are very strong predictors of squamate species richness. Another somewhat surprising outcome we found was that most of the individual lizard and snake clades in our study did not exhibit particularly strong latitudinal gradients, despite squamates overall displaying a very strong latitudinal diversity gradient.
Next steps? Our research complements and opens the doors for additional questions, such as how quickly different squamate clades respond to environmental perturbations and the geologic antiquity of modern biogeographic patterns. We know from previous studies that many of the modern latitudinal diversity gradients we observe for groups like mammals did not exist in the deep past, but we do not know if this was also the case for ancient lizards and snakes. This necessitates further systematic work on fossils from different regions and time intervals in order to improve our understanding of squamate evolution and distributions, which translates to lots of exciting future research opportunities and discoveries!
If you could study any organism on Earth, what would it be? I would like to continue studying reptiles, as they are my favorite animals and there is still so much that we do not know about them. I’m especially excited about studying fossil reptiles, which offer a unique opportunity to travel back in time and address questions about evolution, ecology, and biogeography in the deep past.
Green Iguana (Iguana iguana), a common iguanian lizard native to the Neotropics.
Victor Noguerales is a postdoc at the Instituto de Productos Naturales y Agrobiología in the Canary Islands – Spain. He is a phylogeographer interested in elucidating the mechanisms generating biological diversity, from populations to communities. Here, Victor shares his work on spatial hypotheses testing the processes promoting the genetic structure in a halophilic grasshopper.
Víctor Noguerales after completing a soil sampling campaign in Troodos mountain range, Cyprus (Photo credit: Emmanouil Meramveliotakis).
Institute. Instituto de Productos Naturales y Agrobiología (IPNA-CSIC) – Tenerife, Canary Islands, Spain.
Academic life stage. Postdoctoral researcher
Major research themes. I am interested in studying the mechanisms shaping spatial patterns of genetic variation at different biological levels of organization, from populations to communities. To deal with this question, I harness the power of genomic data, which I integrate into a multidisciplinary framework. In this sense, my research aims to decipher how geography, landscape structure and climate, along with their spatio-temporal dynamics, determine (i) gene flow patterns among populations (population genetics), (ii) diversification among lineages and species (phylogeography and phylogenetics) and (iii) composition and assembly of ecological communities (metabarcoding and community ecology). Broadly speaking, I am trying to provide some insights into our understanding of how biological diversity arises and responds to changing abiotic and biotic factors over space and time.
Current study system. I am fascinated by arthropods as they are highly diverse, exhibit a tremendous ecological and morphological diversity, and, in general, are poorly known fractions of biodiversity. During recent years, I have been studying grasshoppers with a special emphasis on taxa distributed in montane and halophilic (i.e., environments with high salt concentrations) habitats and whose evolutionary histories are often determined by intricate phenomena of geographic isolation and hybridization. Most recently, I am turning my attention to study soil arthropod communities (e.g., mites, springtails and beetles), which I use as study models to understand processes structuring spatial biodiversity patterns across forest habitats of Mediterranean islands.
Female and male of the saltmarsh band-winged grasshopper (Mioscirtus wagneri) on the typical salt crust covering the hypersaline lagoons during summer period (Photo credit: Pedro J. Cordero).
Recent paper in JBI. Noguerales, V., Cordero, P.J., Knowles, L.L. & Ortego, J. (2020) Genomic insights into the origin of trans-Mediterranean disjunct distributions. J. Biogeogr. 2021;48:440–452. http://dx.doi.org/10.1111/jbi.14011
Motivation behind this paper. Previous research had investigated the factors underlying the phylogeographic structure of the saltmarsh band-winged grasshopper within the Iberian Peninsula. However, the questions concerning (i) the putative relict character of the western European populations and (ii) the tempo and mode of diversification throughout its entire Mediterranean distribution remained unexplored. Dispersal followed by vicariance promoted by the desiccation of the Mediterranean Sea during the Messinian Salinity Crisis (5.93-5.96 Ma) has been traditionally proposed as the driving factor behind the disjunct distribution that this and many other Mediterranean halophilic organisms currently exhibit. However, could more recent landscape change events have shaped similar distributional patterns? Whether to support or reject these hypotheses has long remained unclear given the paucity of empirical studies that have explicitly evaluated the relative importance of ancient versus contemporary landscape dynamics. That is, two motivations triggered the development of this study: we had a highly suitable study system for shedding light into this long-standing biogeographic paradigm, and we hoped to gain novel insights using a spatially-explicit perspective.
Halophilic vegetation in Peñahueca lagoon (Toledo, Spain) which constitutes the habitat of saltmarsh band-winged grasshopper (Mioscirtus wagneri; Photo credit: Pedro J. Cordero).
Key methodologies. This study combined methodological tools from landscape genetics (spatially explicit testing of biogeographical hypothesis) and phylogenomics (genealogical inference and divergence time estimation). Briefly, we constructed alternative scenarios of contemporary and historical population connectivity corresponding to the spatial configuration of emerged landmasses and climatically suitable areas during the present-day, Last Glacial Maximum (21 kya) and Messinian period (5.93-5.96 Ma). Then, we inferred gene flow for each hypothetical scenario by modeling individual movements over the landscape in a similar way to an electric circuit (i.e., circuit theory). Finally, the landscape scenario with the highest statistical support (i.e., the one best explaining the observed population genetic differentiation) was further assessed in the light of coalescent-based inferences of divergence times and phylogenomic relationships among populations. This multidisciplinary perspective combining genome-wide nuclear data and high-resolution spatial information arises as a powerful approach to provide key insights into our understanding of how local landscape dynamics ultimately shape biogeographic patterns.
Unexpected challenges. The saltmarsh band-winged grasshopper only inhabits scattered patches of a particular vegetation type associated with hypersaline lagoons that present a highly fragmented distribution at local and regional scales. Although it has specific ecological requirements, this grasshopper is not narrowly distributed but shows a transcontinental distribution range: from Iberia to northern Africa, the Middle East and beyond. This definitively sounds very appealing from a biogeographic point of view. Yet, sampling individuals and populations of this species across the Mediterranean is like looking for a needle in a haystack. So, probably the most challenging aspect of this study has been to collect enough samples from all the putative subspecies across its entire Mediterranean distribution range. Gathering all the samples took a long time (about seven years), but it was an amazing experience. Those steppe-like halophilic habitats are some of the most beautiful landscapes that I have ever contemplated!
(right) Male saltmarsh band-winged grasshopper (Mioscirtus wagneri); (left) Detail of the leaves of shrubby sea-blite (Suaeda vera), the host plant which the saltmarsh band-winged grasshopper (Mioscirtus wagneri) depends for feeding and shelter (Photos credit: Pedro J. Cordero).
Major results. Our analyses revealed that the genetic variation pattern of the species is the result of a post-Messinian colonization process followed by habitat fragmentation driven by Pleistocene climatic fluctuations. Of particular interest is the result demonstrating the permeability to gene flow of the Strait of Gibraltar, a phenomenon linked to the sea-level drops occurring during the Pleistocene cold stages. Such findings would highlight the capability of the species, despite its limited dispersal ability, to track and colonize suitable habitats during the last thousands of years. These results thus contradict prior hypotheses on the determining role of ancient range expansions during the Messinian Salinity Crisis (5.93-5.96 Ma) and long-term persistence in relict habitats in shaping the disjunct distribution of numerous steppe-like and halophilic Mediterranean organisms. Overall, this study stresses the power of bridging spatially explicit approaches and phylogenetics within the field of evolutionary biogeography to discern the relative role that different historical and contemporary landscape dynamics have played in promoting the observed biogeographic patterns.
A view of the Salicor lagoon (Ciudad Real, Spain) in early summer, showing the typical halophilic vegetation ring (Photo credit: Pedro J. Cordero).
Next steps for this research. The next steps revolve around our unexpected finding of the highly divergent lineages that present a parapatric distribution in Northern Africa. This finding opens the door to investigate the extent to which local adaptation followed by reinforcement and neutral processes linked to long-term isolation in cryptic refugia have synergistically determined that striking genetic differentiation pattern. The answer to this question would require a fine-scale sampling along the potential contact zones in Morocco and Tunisia, so we are planning further fieldwork in northern Africa, which I have wished for a long time!
If you could study any organism on Earth, what would it be? I feel lucky as I am studying the organisms that I most like on Earth. However, a different group of arthropods has lately attracted my attention: pseudoscorpions (Arachnida: Pseudoscorpiones). The first time I saw a pseudoscorpion in nature was just a couple of years ago while collecting soil mesofauna from leaf litter of golden oak forests (Quercus alnifolia) in Cyprus. And, honestly, I got impressed! They look so cool with their tiny pedipalps! Pseudoscorpions are an ancient lineage of arachnids whose origin dates back to the Devonian period. They are very small organisms (< 3-4 mm, at least the species I have spotted), so they easily go unnoticed. Despite their small body size and – apparently – reduced dispersal capability, they can actually move long-distances by attaching to other arthropods like flies and beetles, or even to some mammals, including bats. Amazing, isn’t it? I must admit that my knowledge about this group is still very limited, however, I wonder how much cryptic diversity they might hide and how their particular mode of dispersal affects their biogeographic patterns.
Juan David is a postdoc at the Museo Nacional de Ciencias Naturales in Spain. He is an ecologist interested in explaining how historical events shape current biodiversity patterns. Here, JD shares his recent research on how past and current processes impact beta diversity in Neotropical streams.
Juan David González-Trujillo is a postdoc researcher at the National Museum of Natural Sciences (Madrid, Spain).
Institute. Museo Nacional de Ciencias Naturales (Madrid, España)
Academic life stage. Postdoctoral researcher
Major research themes. My research interests are in the intersection between community ecology and historical biogeography. I am particularly interested in understanding how historical events have shaped current biodiversity patterns and how they allow us to forecast future changes.
Current study system. I did my master’s and Ph.D. studies on freshwater biodiversity, focusing majorly on disentangling the community assembly process. However, I partially left that field after finishing my doctoral dissertation. The reason? As you may read in our JBI paper, we cannot understand present-day biodiversity without understanding each region’s historical background, ecosystem, or study system. So, I wanted to dig deeper into “the past of the present-day patterns“. That desire comes true as a postdoc researcher since I am currently exploring how climate shaped mammal’s food web structure during the Pleistocene. To do so, I train machine learning algorithms to retrodict paleo-communities’ trophic structures and then check the predictions against the fossil record.
Recent paper in JBI. González‐Trujillo, JD, Saito, VS, Petsch, DK, Muñoz, I, Sabater, S. Historical legacies and contemporary processes shape beta diversity in Neotropical montane streams. J. Biogeogr. 2021; 48:101–117. https://onlinelibrary.wiley.com/doi/10.1111/jbi.13986
Motivation behind this paper. Previous studies have revealed that species turnover may be partially or entirely shaped by historical drivers linked to past climatic (e.g., temperature oscillation) and geological (e.g., mountain uplift) events. However, the study of such interplay between ecological and evolutionary processes is biased towards terrestrial communities. In riverine ecosystems, for instance, research has focused on determining the effect of contemporary drivers, such as the network’s dendritic structure or the flow regime. Therefore, we wanted to fill such a gap by testing if past events have contributed to shaping present-day biodiversity in montane rivers. We chose montane rivers as they host high biodiversity and provide essential benefits to human societies, yet still are inadequately studied.
Key methodologies. Modeling the effect of historical legacies among contemporary drivers is quite challenging. Our paper used a path-length matrix, which recreated the basin’s evolutionary history during the Tertiary and Quaternary. To create such a matrix, we should recover information on the geologic and climatic events occurring during the Tertiary and Quaternary that contributed to shaping the current pools of species observed in the basin. We used the occurrence of such events (e.g., uplifts and glaciation events along the Andean chains) to sort study rivers based on their time of appearance and to model their historical relationships (figure below). The path-length matrix was included among other contemporary factors, as descriptors of insect and diatom species turnover among rivers. Additionally, to have a more comprehensive picture of the interplay between historical and contemporary forces, we assessed species turnover by quantifying different facets of beta diversity, such as taxonomic, functional, and phylogenetic. These facets are rather complementary. For example, while the functional facet provides insight into contemporary processes’ effect, the phylogenetic facet can reveal the signature of those processes at the evolutionary scale.
Cladogram representing the path length matrix modeling the evolutionary history of ecoregions in the Orinoco basin (right). On the left, a graphical illustration of the hypothetical reconstruction of the Orinoco basin.
Unexpected challenges. One of the major challenges was to describe the biological traits of insect species. In the Neotropics, such information is scarce and spare. Thus, we had to go through tons of published and unpublished literature, as well as observe the individuals in the field. The latter being the funniest activity, as I spent a lot of time under the water watching invertebrates using my beach googles! A more conceptual challenge was to choose between Balsega’s and Podani’s partitioning frameworks, as the pros and cons of both frameworks have been promoted and criticized in recent years. After going deeper into their computation, we decided to include both since they can be complementary to study the functional turnover causes and consequences. Our results showed that exploring both frameworks was the right choice. While the Baselga’s framework indicated that functional spaces are similar among the Orinoco basin, the Podani’s framework indicated that functional distances are closer between taxa belonging to rivers with similar evolutionary history. Such difference suggests that even if two communities share functional spaces, their functional dissimilarity may depend on which clades belong to each community. The implications of this phylogenetic constraint on functional diversity are worth further study in the future.
Major results. Our paper provides evidence supporting that past historical events have contributed to shaping the present-day diversity and distribution of benthic communities. Specifically, historical events seemed essential in separating lineages (and taxa) in different regions regardless of the long time available for dispersal (thousands or millions of years). Therefore, we stressed that knowing the historical background of a region is essential to better understand the mechanisms supporting (meta)community-level patterns. In the Neotropics, at least, the historical background of the tropical basins seems to be required to explain beta-diversity patterns, even when contrasting disparate communities such as diatoms and insects.
A ‘taster’ of rivers from the Orinoco basin. From left to right: Páramo, high-Andean, Alluvial fans.
Next steps for this research. The Andes are one of the greatest cradles of biodiversity in the world. A significant part of that biodiversity is due to historical events (e.g., historical isolation). Therefore, the next logical step is to expand our study area and explore the extent to which our results are generalizable along the Andean mountain chain. Besides, other tools may complement the assessment of species turnover. Including genetic information and phylogeographic methods, for instance, would be useful to disentangle historical legacies from contemporary processes. In this regard, I am currently exploring the phylogeographic patterns of several invertebrate species in a micro basin that crosses two ecoregions with distinct climatic histories.
If you could study any organism on Earth, what would it be? I want to study the ecology, genetics, and biogeography of non-biting midges (Chironomidae). Chironomidae is a widespread and mega-diverse family inhabiting all freshwater ecosystems. Biogeographers, such as Lars Brundin, have used non-biting midges to uncover dispersal paleo routes. Paleoecologists, such as Ian Walker, have used chironomid heads to reconstruct paleoclimates. Ecologists, such as August Thienneman, have found in Chironomidae a great bioindicator species for environmental pollution. Therefore, it seems to be a perfect group for performing studies in the intersection between community ecology and historical biogeography.
Anything else to add? During fieldwork, I met different people who are extraordinarily committed to nature conservation. It was amazing to talk with them, as they know a lot about nature and biodiversity. I was so surprised – and inspired – to find that they had a unique classification system of rivers and biodiversity. Some were empiric naturalists; they know where to find every fish species, its feeding behavior, preferred microhabitat, and even the mating period. Sadly, some of them are not with us anymore. The avarice for natural and mineral resources is threatening environmental leaders in Colombia. With their loss, cultural and historical legacies are also at risk.
A new species-based metric for island biogeography
Above: The response of the new metric ‘ecorichness’ to island area for terrestrial isopods of central Aegean islands. Size of dots is proportional to the number of habitats of each island.
Habitat diversity, as an estimate of environmental heterogeneity, has been considered among the main factors shaping patterns of diversity in insular communities but its definition and measurement has not yet found a consensus among researchers. Area is the most commonly used predictor of species richness, in the absence of good information on habitat diversity. Despite controversies on how to best describe and measure habitats, their diversity should be a critical component of any robust theory of island ecology and biogeography, crucial for any synthesis of the factors shaping species diversity for a wide range of study systems. Thus far, most theories consider all species as ecologically equivalent. In real communities, though, each species covers a certain range of habitat specialization, from narrow specialists to wide generalists. The few island biogeography studies that incorporated ecological specialization, mostly used a crude binary classification of species into generalists and specialists. A step forward, therefore, will be to use a finer characterization of species’ position within the generalist-specialist continuum but this assumes a detailed knowledge of species’ habitat preferences and a meaningful classification of habitats in the study area.
In this study, we explored the effects of area and environmental heterogeneity on a metric that substitutes species richness with the standardized sum of species’ specialization range. We follow an approach that corresponds to the ‘fundamental Grinnelian specialization’ by replacing the occurrence of each species in the presence/absence matrix with the number of habitat types it exploits in the study system. Then, for a given island, we estimated the ‘ecorichness’ index by summing specialization range for the species occurring on it and standardizing for species richness.
EDITORS’ CHOICE: (Free to read online for a year.) Sfenthourakis, S, Triantis, KA, Proios, K, Rigal, F. The role of ecological specialization in shaping patterns of insular communities. J Biogeogr. 2020; 00: 1– 10. https://doi.org/10.1111/jbi.14012
We applied the metric to a real data set with terrestrial isopods from the Aegean islands (Greece), for which we had earlier made a detailed description of species’ habitat ranges. Based on our previous work and theoretical considerations, we expected small island communities to consist mainly of generalists while specialists should be added as area increases. Such an assumption would lead to a decreasing or a unimodal ‘ecorichness’ – area curve. No matter the pattern at the left part of the curve, the right part, corresponding to larger islands, should always show a decreasing trend. Furthermore, according to our predictions, the response of ‘ecorichness’ to area should be affected by the occurrence and strength of a ‘Small Island Effect’ (SIE), and should peak at an area threshold where the contribution of generalists is maximized, decreasing afterwards due to the increasing contribution of specialists with a small additive effect on ‘ecorichness’ values. It should be noted that the predictions of our approach are not based on actual ‘ecorichness’ values but on the pattern of its response to area (or other factors). Therefore, it should work with any measurement of habitat diversity and could be used in comparisons among different systems and taxa.
In agreement with our predictions, the relationship of ‘ecorichness’ with area (on a logarithmic scale) is expressed as a hump-shaped curve, ascending for small values of area and descending for areas larger than the Small Island Effect threshold. The ‘heightening’ of the left part of the ecorichness–area curve (i.e. increase of ‘ecorichness’ values for smaller islands) after the exclusion of the narrow specialist halophilous species, is also in accordance with original predictions that communities of small islands consist mostly, but not exclusively, of generalist species, while the contribution of specialists becomes important above the SIE threshold. Implications of our approach may shed light also on the debate about the presumed possibility of negative effects of very high habitat diversity on species richness. The ‘ecorichness’ approach supports a continuous increase or, at least, a stationary richness with increasing habitat diversity, given that real communities consist of a variable mixture of specialist and generalist species.
The habitat range distribution of terrestrial isopods on central Aegean islands. Porcellio flavomarginatus is a, not very narrow, specialist that exploits limestone-rich areas and rocky outcrops in dry Mediterranean habitats, while Armadillo officinalis is a generalist exploiting all Mediterranean-type ecosystems.
We believe that the ‘ecorichness’ approach can offer useful insights into processes shaping species−area, and species-habitat diversity relationships, through a quantification of the ‘ecological resource space’ used by species. Our approach falls within the general framework of a species-based theory of (island) biogeography and addresses aspects of community structure implicit in ‘assembly rules’ theory. It is important to explore more case studies since the scarcity of detailed data on species’ habitat ranges does not allow for a generalization of the present results, but we hope that our study will trigger the production of more such data in the near future. Also, we expect that a synthesis of ‘ecorichness’ with functional diversity metrics should offer important insights into processes shaping island communities. Finally, an even finer quantification of species’ habitat ranges should render an ‘ecorichness’ approach even more robust.
Written by: Spyros Sfenthourakis (1), Kostas A. Triantis (2), Konstantinos Proios (3), and Francois Rigal (4)
(1) Professor, Department of Biological Sciences, University of Cyprus, Lefkosia (Cyprus). (2) Associate Professor, Department of Biology, University of Athens, Athens (Greece). (3) PhD Student, Department of Biology, University of Athens, Athens (Greece). (4) Assistant Professor, Université de Pau et des Pays de l’Adour, Pau (France).
Tim is a postdoc at the University of British Columbia, Canada. He is an ecophysiologist interested in how plants respond to differences in climate. Here, he shares his recent research on how phylogeny and climate predict little variation in plant heat tolerance responses.
Author Timothy Perez, some bromeliads, aroids, and a rainbow eucalyptus tree at Fairchild Tropical Botanic Garden
Institute. University of Miami; University of British Columbia
Academic life stage. Postdoc
Major research themes. Plant physiological ecology, thermal ecology, climate change, evolution conservation biology
Recent paper in JBI. Perez, TM, Feeley, KJ. Weak phylogenetic and climatic signals in plant heat tolerance. J. Biogeogr. 2021; 48: 91– 100. https://doi.org/10.1111/jbi.13984
Motivation behind this paper. The motivation behind our paper was trying to understand if physiological tolerances influence patterns in species’ climatic distributions. More specifically, we wanted to know if hot climates act as environmental filters on community assembly. Physiological tolerances, like the heat tolerances of photosystem II (PSII) photochemistry, are thought to exert strong constraints on carbon assimilation, and by extension plant growth, survival and reproduction. Therefore, heat tolerances of PSII (hereafter heat tolerance) may reveal information about the kinds of species that can exist in hot climates. This information could be useful for predicting which species are most vulnerable to climate change and understanding how ecosystem processes may change in future climates.
Key methodologies. In our study, we took advantage of museum collections – specifically, the living plant collections of Fairchild Tropical Botanic Garden. Botanic gardens are great places to conduct ecophysiological research because plants with different ecologies and evolutionary histories are all growing together in a common garden-like environment. In other words, there is a lot of plant diversity, which can be harnessed to investigate different aspects of plant physiology. In our project, this common garden environment allowed us to sample many different species and understand how phylogenetic relatedness may influence variation in plant heat tolerance.
Sunrise over the botanical garden
Any challenges you and your co-authors faced along the way? Since I was working in a botanical garden, my study species were very easy to locate because the location of each plant (within the garden) that I wanted to sample had been mapped by garden curators. This is in contrast to most tropical fieldwork that requires hours of searching for your species of interest. This study was not my first campaign sampling plant traits or heat tolerances, which is another reason why data collection went fairly smoothly for this project. Luckily, there were no hurricanes during the sampling campaign, which have caused interruptions in my previous studies. I’m happy (and lucky!) that the project went as smoothly as it did.
Major results. Two important findings of our study were that species’ climatic distributions and heat tolerances are poorly coordinated, and that phylogeny explains little of the variation in plant heat tolerance. These results mean that hot climates are unlikely to influence patterns of community assembly based on heat tolerance alone, and that closely related species are not expected to exhibit similar tolerances. However, our results do point towards the importance of leaf thermoregulatory traits as a potential way forward for understanding variation in heat tolerance and how it may influence plant ecology. Thermoregulatory traits can cause leaves to experience different temperatures than ambient air temperatures. Therefore, leaf temperatures may be important for explaining variation in thermal tolerance and species’ distributions (see: https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2435.13658).
Species in the study were also sampled from the University of Miami’s Gifford Arboretum
Next steps in this research. Plant heat tolerances have been studied extensively, but we lack a coherent understanding of how variation in heat tolerance is linked to abiotic conditions. It is also unclear how heat tolerance integrates with carbon assimilation or aspects of plant productivity (see: https://onlinelibrary.wiley.com/doi/10.1111/pce.13990). I think these topics are important areas of future plant heat tolerance research.
If you could study any organisms on Earth, what would it be? I study plants because I think they are the coolest organisms on Earth! Plants dominate Earth’s biosphere, provide humans with essential ecosystem services, and are vital for mitigating climate change. There are endless practical reasons for why I study plants, including the fact that they are found just about everywhere, and the opportunities to study them are endless. However, I also just find plants and all of their strange forms and functions marvellously beautiful.
Gimo is a recently appointed research scientist at the National Museum in Bloemfontein, South Africa. He is an entomologist with interests in understanding the systematics and biogeography of dung beetles and related scarab beetles. Gimo shares his recent work on the contributions of different environmental factors in shaping diversity in the dung beetle genus, Sisyphus.
Gimo at the Musem of Comparative Zoology, Harvard University, USA-2017, working on Sisyphini collection (credit to Philip).
Institute. National Museum, Bloemfontein, South Africa
Academic life stage. I completed my PhD in Entomology 2019 from the University of Pretoria, South Africa and now hold a research appointment as Principal Museum Scientist at the National Museum, Bloemfontein, South Africa.
Major research themes. I am an entomologist with interests in the systematics and biogeography of dung beetles and related scarab beetles. I am cataloguing and describing the impressive biodiversity of Afrotropical dung beetles to address broader evolutionary questions, such as the role of geological uplift and climatic changes in the late Cenozoic in the diversification and possible extinction of scarab beetles in southern Africa.
Current study system. Dung beetles are a globally distributed insect taxon, but they exhibit their highest diversity in tropical forests and savannas. They feed on the microorganism rich liquid component of mammalian dung (and less commonly that of other vertebrates, as well as rotting fruit, fungi and carrion) and use more fibrous material to brood their larvae. They provide important ecosystem services, such as secondary seed dispersal, control of other insects or parasite suppression, dung and nutrient recycling in ecosystems and subsequent increasing of soil fertility.
Recent paper in JBI. Daniel, GM, Davis, ALV, Sole, CL, Scholtz, CH. Evolutionary history and eco‐climatic diversification in southern African dung beetle Sisyphus. J Biogeogr. 2020; 47: 2698– 2713. https://doi.org/10.1111/jbi.13974
(left) Image of habitus of Sisyphus (Sisyphus) oralensis (credit to Christian). (right)Circelium bacchus on the elephant poo at the Addo Elephant National Park, Eastern Cape, South Africa.
Motivation behind this paper. During my PhD studies I was working on the systematics of the southern African dung beetle genus, Sisyphus, which led to a monographic revision of the genus and the first molecular phylogeny of sisyphines. Current biogeographical patterns of dung beetles in southern Africa are thought to have been driven by orogenic, climatic, edaphic and vegetation changes during the late Cenozoic. However, no study has explicitly tested hypotheses on the relative contributions of these factors. Therefore, we used the genus Sisyphus as a model to understand dung beetle evolution in southern Africa.
Key methodologies. A dated molecular phylogeny of southern African Sisyphus was compared with a factor analysis of species distribution data that statistically defined groups of species according to current climatic distribution. We used these climatic clusters to estimate ancestral ranges using BioGeoBEARS. We then used Bayesian diversification models (compound Poisson process on mass extinction times) to test whether late Cenozoic uplift and climatic changes affected speciation and extinction rates of Sisyphus species. Furthermore, we implemented ecological niche modelling in MaxEnt to predict the habitat suitability of species under present climatic conditions.
Major results. Four species groups of Sisyphines (that were defined from factor analysis of current climatic distribution data) were found to be primarily restricted to the moist summer rainfall region in the northeast. Phylogeographic analyses and ecological niche modelling revealed that southern African dung beetle Sisyphus species are not homogenously distributed with respect to geography and climate. The taxonomic and eco-climatic diversification of sisyphines is coincident with geological uplift and changes in climate in east-central southern Africa. Therefore, the combination of phylogenetic methods, climatic data, and ecological niche modelling allowed us to infer that dung beetle evolution in southern Africa is primarily driven by the combination of both orogenic events and climatic shifts in the late Cenozoic.
Unexpected challenges. Sometimes the challenges are not so much to do with the actual research, for instance, when I was writing this paper, I had a problem with my right shoulder, so it was difficult and took me a long time to type, especially coding in R the ecological niche modelling analysis. After several months of physiotherapy my shoulder healed and I was finally able to finish the manuscript.
(left) Gimo in a field work in uMkhuze Game Reserve, KwaZulu-Natal, South Africa-2016, collecting dung beetles (credit to Jorge). (right) Gimo in his lab at the National Museum, working on the revision of Odontoloma (credit to Precious).
Next steps for this research. I would like to carry on with more studies using different diversification methods and other genera of scarabs as study models to test evolutionary hypotheses for the southern African fauna against the current findings. For instance, two projects on Odontoloma and Epirinus are running in my lab, the latter one is currently under review. Furthermore, my collaborators and I are working on a scarab beetle discovery project, in which we are planning to collect in very remote and unsampled areas like those in the Eastern Cape region in South Africa and Mabu forest (Google forest) in northern Mozambique. The aim is to document dung beetle species new to science and provide local ecological data that can be placed in a regional biogeographical context for conservation planning.
If you could study any organism on Earth, what would it be? Dung beetles, of course. I am passionate about these insects because of their great diversity worldwide, and most importantly, they have vital ecosystems functions that provide important and/or economically beneficial ecological services to humans. For example: secondary seed dispersal, biological control of other insects, organic material recycling and consequently increasing of soil fertility.
Anything else to add? My childhood was characterised by interaction with nature, including insect collection, especially beetles while grazing cow and goats on the Save River, Machanga (my homeland), a rural area in Central Mozambique. Although I was always “fighting” with my mother because she believed that I could contract a disease when collecting insects; I never gave up on my passion. I continued collecting beetles but hiding them from my parents. Due to this love for insects, years later, I was enrolled in a BSc degree in Biology back home. Two years later after my BSc, I was awarded a scholarship to pursue an MSc degree in Entomology in Brazil, which was focused on my childhood favourite insects (dung beetles). Afterward, I completed my PhD also working on dung beetles. I am a passionate entomologist intent on spending a lifetime pursuing my interests and inspiring local and disadvantaged communities – where my fierce ambition about a career in insect systematics has originated.
During the last 54 000 years, the range of red deer in Europe and the Ural Mountains changed in response to climate oscillations, generally decreasing in cooler periods and expanding in warmer periods, largely in agreement with the Expansion-Contraction model. However, these processes were asynchronous and differed in western and central regions when compared to eastern parts of Europe and the Ural Mountains.
Above: Red deer in the Białowieża Primeval Forest, Poland (Photo: Adam Wajrak)
The impact of climate changes on the distributions of red deer and other temperate mammal species is well recognized for the populations inhabiting western, south-western and southern Europe, but little is known about impacts of climate changes on mammal populations in eastern Europe. Our study, covering the whole continent and the Ural Mountains over 50 000 years, showed that the response of red deer to climate oscillations was different in western than in eastern Europe plus the Urals due to different environmental conditions in these areas. Easternmost Europe and the Urals were not covered by ice sheet during the Last Glacial Maximum (LGM) to such an extent as the western and central part of the continent. Consequently, much larger areas were available to terrestrial mammals, including red deer. Moreover, environmental niche modelling showed that during the LGM there were large areas suitable for red deer not only in western and southern Europe but also in eastern and south-eastern Europe in the vicinity of the Black Sea. We surmise that these areas were an important LGM refugium for temperate species such as red deer and the species recolonized eastern Europe from this region in postglacial times.
Cover paper: (read for free for a year) Niedziałkowska, M, Doan, K, Górny, M, et al. (2021) Winter temperature and forest cover have shaped red deer distribution in Europe and the Ural Mountains since the Late Pleistocene. J. Biogeogr. 48:147–159. https://doi.org/10.1111/jbi.13989
However, some of the results of the environmental niche modelling astonished us as they showed that some areas in the easternmost part of the continent and the Urals were not suitable for red deer during the last 50 000 years, although some red deer fossils dated to this time period were found there. The most probable explanation for this discrepancy is that, according to phylogenetic data, most of these red deer belonged to a more cold adapted red deer species: wapiti deer (Cervus canadensis).
Another interesting process took place during postglacial times. In western and central Europe red deer relatively quickly recolonized the area released by the glacier. However, recolonization was very different in the easternmost part of Europe, where clear disjunction appeared in the species range. Since the middle Holocene, red deer disappeared from the lower and middle Volga River region and later also in the Ufa region, to the west of the Ural Mountains. The last red deer were recorded in the Urals in the 19th century. The disappearance of the species in this part of the continent is probably related to climate and habitat changes. The contemporary easternmost border of red deer range in Europe runs parallel to the isoline of mean January temperature between −10 and −15°C, which is consistent with the 50 000 year-long climatic limits (mean January temperature below −10°C) of red deer found in this study.
Another explanation of the disappearance of red deer from eastern Europe and the Urals during the Holocene is west-east shift in range of wapiti deer, as was shown for other cold-adapted species such as the Siberian roe deer (Capreolus pygargus). Results of our study provide one more example that during at least the last 50 000 years the ranges of different species changed according to climatic oscillations not only in north-south but also west-east directions.
Future studies will enable checking of how other large mammal species have responded to climatic oscillations in eastern Europe during the last 50 000 years and how the geographical range of temperate mammals can change in the future due to present environmental changes.
Written by: Magdalena Niedziałkowska Associate Professor, Mammal Research Institute Polish Academy of Sciences in Białowieża, Poland
Integrating geology, geography and genomics to study the coupled evolution of life and Earth.
Geogenomics is an emerging field at the intersection of geology, geobiology, Earth system science, genomics, and higher-level biodiversity studies. Geogenomics employs genomic data to solve geologic problems or constrain geological hypotheses. Conversely, phylogenetics and phylogeography seek to use the geological record for understanding the diversification, spatial distribution, and origins of species and populations and for formulating diversification hypotheses. Progress in either direction relies upon reciprocal illumination between the disciplines. As is the case in most cross-disciplinary scientific pursuits, each field understands its own nuances and uncertainties but presume greater certainty in complementary fields, which is exacerbated on deep-time scales when uncertainty is high. Landscape (and seascape) genomics also integrates genetic and environmental/landscape variation but on finer, more recent timescales when uncertainty is usually lower and more mechanistic integration is possible. This presents an interesting conundrum that beckons a truly unified approach at the convergence of these two scales, where strengths of each can be combined to inform the hypothesis-space and leverage a synergistic understanding of the dynamic, sometimes deterministic and sometimes stochastic, world.
We are organising a special issue in Journal of Biogeography to summarize the foundations, current status, and to shape the future of integrative geological, geographic, and genomic research. We encourage multidisciplinary research teams and new ideas or approaches. This thematic issue intends to publish original and novel papers on the following research topics: geogenomics, geodiversity, biodiversity, geo-bio-informatics, phylogeography, geoecodynamics, biogeomorphology, landscape (& seascape) genetics and papers that intersect these fields in particular.
Contributions may be in any of the usual article formats at JBI. 1) Research Paper, 2) Methods and Tools, 3) Data, 4) Synthesis, 5) Perspective, 6) Commentary and 7) Correspondence.
Authors should indicate in the Cover Letter that the submission is directed to the Geogenomics Special Issue.
Accepted papers will be published online in Early View and later collated into the Special Issue.
All submissions are subject to peer review.
Papers will be full access for at least 2 months from the date of online publication.
Dr. Sherilyn Fritz – University of Nebraska – Lincoln Dr. Anna Papadopoulou – University of Cyprus Dr. Greer Dolby – Arizona State University Dr. Paul Baker – Duke University Dr. Camila Ribas – National Institute for Research in Amazonia
Arya Sidharthan is a PhD student at the Kerala University of Fisheries and Ocean Studies, India. She is a freshwater fish biologist, who uses molecular tools to study the ecology and evolution of fishes. Arya shares her recent work on unravelling the evolutionary history and cryptic diversity of mountain loaches in the Western Ghats.
It’s fun to be in the field early in the morning, when the mountain loaches are most active.
Institute. Kerala University of Fisheries and Ocean Studies (KUFOS), India
Academic life stage. PhD candidate
Major research themes. Molecular Ecology, Biogeography, Freshwater Fish
Current study system. My research focuses on the molecular ecology of hillstream/mountain loaches on the Indian subcontinent. By understanding the phylogenetics and biogeography of this fascinating group of freshwater fishes, my work helps unravel the processes that have led to the amazing biodiversity in the Western Ghats mountain ranges, which is a global hotspot for endemic freshwater fish. Using genetic data, I try to decipher when and where different loach lineages originated, how they diversified, and the physical, geographic and climatic factors that influenced their speciation.
Recent paper in JBI. Sidharthan, A., Raghavan, R., Anoop, V. K., Philip, S., & Dahanukar, N. (2020). Riddle on the riffle: Miocene diversification and biogeography of endemic mountain loaches in the Western Ghats Biodiversity Hotspot. Journal of Biogeography, 47(12), 2741-2754. (Link)
Motivation behind this recent paper. The endemic loaches of genus Bhavania from the Western Ghats are poorly studied with respect to their systematics, evolutionary history and biogeography. Their morphological similarity to sucker-loaches of Indo-China and Sunda Islands has fuelled speculations that this group originated in South East Asia, and colonized the Western Ghats during the Pleistocene – but this has not been tested using molecular techniques. Also, the apparent wide distribution of the genus in Western Ghats from 9° to 13°N latitudes (an approximate south-north distance of 450 km), and the fact that only two species are currently known, encouraged me to investigate the true diversity within this genus.
The mountain loach, Bhavania australis is a “cryptic species complex” endemic to the Western Ghats Biodiversity Hotspot in India. Latin Name: Bhavania australis. (Photo credit: Beta Mahatvaraj)
Key methodologies. We carried out a multigene phylogenetic analysis of Bhavania specimens collected throughout their distribution range, using mitochondrial and nuclear markers. Subsequently, several species delimitation methods including the Automated Barcode Gap Analysis, Poisson Tree Process and Generalized Mixed Yule-Coalescent Model were used to understand the actual species diversity within the genus. A Bayesian chronogram was constructed to estimate the time elapsed since the most recent common ancestor of the distinct lineages of Bhavania. Ancestral ranges of distinct lineages of Bhavania were reconstructed using the dispersal–extinction–cladogenesis model to understand the historic factors (physical, geographic and climatic) that led to the current distribution pattern.
Typical mountain loach habitat in the Western Ghats! But finding my “freshwater nemo” is the toughest part of the job.
Major results. Our study suggested that the endemic Western Ghats mountain loach genus Bhavania originated in the early Neogene and diversified/radiated into cryptic lineages during the Miocene. This refuted the previously long-standing theory that the group arrived in India during the Pleistocene. It is likely that the Bhavania loaches dispersed across the Western Ghats mountains, expanding their range, with the help of intensified monsoonal rains during Miocene climatic changes. The current distribution of Bhavania loach lineages has been further shaped by events in the Miocene such as aridification and drying up of riverine connections, formation of land barriers and fragmentation of streams. Our results highlighted the first evidence that Cauvery, one of the largest eastward flowing rivers of Western Ghats, has acted as an east–west pathway for dispersal and diversification of an endemic fish lineage in the Western Ghats.
Unexpected challenges. The southern part of the Western Ghats where I carried out my field work was hit by two extreme climatic events resulting in catastrophic floods for over 4 months in the years 2018 and 2019 (coinciding with my main sampling period) cutting off all my field sites and making them inaccessible for months. Working closely with local fishers, we then managed to collect samples during weeks when there was some respite from the rains, in the most challenging of conditions.
One of my sampling sites is just below these majestic waterfalls.
Next steps? Collaborating with colleagues from across South and South East Asia, we plan to investigate the family-wide (global) phylogeny of mountain loaches. This work will not only improve our understanding of the current-day diversity and distribution patterns of this group of fishes, but also provide broader context of their evolutionary and biogeographical history in Asia.
If you could study any organism on Earth, what would it be? Penguins – because I just love them! Not just because they are adorable, but because they dwell in one of the most extreme climates on the planet, and still manage to be the best swimmers. Ah, and of course there are various misconceptions about their life history too (Happened to read this interesting book “The unexpected truth about animals” by Lucy Cooke. You must read it too!!! One of the interesting penguin facts highlighted in Cooke’s book is that penguins are often regarded as gentle, monogamous birds, when in reality, they are often the complete opposite: aggressive and highly promiscuous!
Anything else to add? Studying freshwater biodiversity is monsoonal rivers, and particularly in tropical montane streams is challenging irrespective of gender due to the harsh and inaccessible terrain, and encounters with wild animals. But at the end of it, such studies give us a great satisfaction because of the way each study (however small) adds to the growing amount of knowledge required to conserve tropical freshwater biodiversity. In March 2020, I received an opportunity to present our work to the global conservation community at the Student Conference in Conservation Science at Cambridge. But Covid-19 dashed all my hopes. But now I am immensely happy that one of the world’s leading scientific journals has published and highlighted my work on their cover page, and through this blog!