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, email@example.com. 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.
The search for a yardstick to gauge geographic variation in a taxonomic context yielded answers to broader biogeographical questions
Above: Geographic variants in the Allen’s common moustached (Pteronotus fuscus). Left, cranium and mandible of a specimen from Paraguaná Peninsula (CVULA 8197). Center, cranium and mandible of a specimen from Venezuela south of the Orinoco River (CVULA 8155). Right above, wing of CVULA 8155. Right below, wing of another specimen from Paraguaná Peninsula (CVULA 8150).
Islands come in many sizes, ages, and kinds: from small to large; old to recent; isolated or part of archipelagos; continental or oceanic; and combinations thereof. On continents, there are also the so-called ecological islands—e.g. unconnected habitat patches, caves, and lakes—including ‘sky’ islands (mountainous areas surrounded by drastically different lowland environments) that also vary in size, age, and degree of isolation. Marine organisms, particularly those inhabiting isolated benthonic patches, have been postulated to be insular. The barriers that separate islands hamper gene flow thus are a major cause of speciation worldwide.
Since Darwin’s time, botanists and zoologist have been busy describing and cataloguing insular biodiversity, and islands have been fundamental as natural laboratories to study evolution. In the 1960’s, these efforts flourished in the form of the MacArthur-Wilson Equilibrium Theory of Island Biogeography, which postulated that the number of species on an island is related to its area, its distance from the mainland, and its balance between immigration and extinction. In the 1970’s, the ‘island rule’ was formulated, postulating that after colonizing islands animals become smaller if they were large and larger if they were small on the mainland; that is, it is predicted that they will converge to ‘optimal’ intermediate sizes thanks to the release from mainland predators and competitors failing to colonize the same islands.
I am a zoologist from Venezuela, a megadiverse country in northern South America. My interests include the taxonomy of Neotropical mammals, especially bats. In this and other animal groups, the degree of continuity and magnitude of geographic variation are of paramount importance to decide how many species and subspecies need to be recognized, or be included in conservation plans. One of the greatest complexities of taxonomic work involves deciding consistently how much geographic variation is sufficient to be formally reflected in scientific nomenclature. Thus taxonomists can be characterized as individuals who are perpetually searching for, refining, and applying morphological yardsticks to gauge geographic variation in their study organisms. I became interested in the island rule as part of this search.
Geographic variants in the Allen’s common moustached (Pteronotus fuscus). Above, typical specimen from the Venezuelan mainland. Below, specimen from Paraguaná Peninsula, in northwestern Venezuela.
Island rule studies caught my attention not only because they deal with geographic variation, but also because their fundamental metric, namely the size ratio between the members of the allopatric populations being compared, could be the yardstick that I needed. As I familiarized myself with the theme, I met a number of problems. First and foremost, despite the availability of information, no comprehensive study of the island rule existed for bats. Second, most island rule research was devoted to the comparison of island organisms with their mainland relatives, thus largely ignored within-mainland and inter-island size variation, which are relevant not only to taxonomy, but also as a frame of reference for the island rule itself. Third, bat taxonomists do not generally use body mass as a character to differentiate species; instead they use cranial and wing measurements because they are more constant. Body mass—in order to increase sample size, often inferred from diverse linear measurements—is the dependent variable generally used in island rule research. Thus most information found in island rule literature was inapplicable to taxonomy. To fill these gaps, I initiated the study on bats that has just been published in the Journal of Biogeography.
Editors’ choice / Cover article: (Free to read online for two years.) Molinari, J. (2023). A global assessment of the ‘island rule’ in bats based on functionally distinct measures of body size. Journal of Biogeography, 50. https://doi.org/10.1111/jbi.14624
The search for a morphological yardstick was successful. This is exemplified by the Allen’s common moustached bat (Pteronotus fuscus). Although allopatric populations of this species—or species complex—were known to differ substantially in cranial and wing dimensions (see figures above), now we can affirm that such morphometric variation is unusual, overall the greatest of the 251 bat species included in the study.
The results of the study transcended the initial goal of finding a yardstick to gauge geographic variation, and were amenable to address broader biogeographic questions. Thus I tested:
1) Whether bats follow the island rule, which has previously been concluded to be pervasive in mammals and other vertebrates. I found this not to be the case. The most likely explanation for this exception is that bats do not follow this rule owing to limitations imposed by flight and echolocation.
2) Whether on islands bat body sizes converge to intermediate supraspecific optima, as predicted by theoretical studies. I concluded that this is not the case and that instead sizes converge to species-specific optima, as the general pattern of geographic variation in bats—which appears to be dependent on ecological niches rather than on adaptive zones—would suggest.
3) Whether bats would be ranked in a similar order by skull size, by wing dimensions, and by body mass. Again, I also found this not to be the case. The most likely reason is that the three size measures are functionally distinct—being respectively most relevant to the feeding, movement, and physiological ecology of bats)—thus are subjected to different selective forces.
4) Whether a bias has existed to give formal taxonomic recognition with greater frequency to bats distributed across mainland-to-island ranges than to those distributed across island-to-island or within-mainland ranges. I concluded that this is the case. The explanation is that, owing to the long-standing fascination exerted by islands on evolutionary biologists, there has been a high level of interest in describing morphological differences between island species and their mainland counterparts.
Where do we go from here? In 2006, Mark Lomolino, a pioneer of island rule studies, and his collaborators, proposed a research agenda calling for the use of a comparative approach expanded to include a greater diversity of species, to test the island rule and other ecogeographic patterns and their exceptions. This agenda remains fully valid today. More ecogeographic studies of all kinds of organisms are needed that address ordinal and familial level variation across different kinds of geographic range.
Written by: Jesús Molinari Zoologist and ecologist at the Universidad de Los Andes, Venezuela
Long-term demographic processes of species leave behind traces in various forms, such as spatial genetic structure in extant populations and fossil remains in the ground. Combining these complementary sources of evidence from a dense sampling across the entire natural range of Swiss stone pine helped us to unravel the glacial history of this timberline species.
Above: Field site with a view: Swiss stone pine forest on Riederfurka above Aletsch glacier, with a historic monument in the foreground and geological monuments in the distance (photo: Felix Gugerli).
Imagine walking along the upper end of forest occurrence in the Alps or a similar high-elevation mountain system. Looking around, you will likely recognize certain imprints of former glacial activity, visible as remnant moraines and rocks showing glacier polish. These typical features of today’s alpine landscape remind us that this habitat was formerly ice-covered but has since been (re-)colonized by forest trees and their associated plants, fungi and animals. You might wonder how slow-growing, long-lived trees could swiftly cope with the long-term dynamics of past glacial–interglacial cycles by shifting their range to benign habitats outside their alpine terrain—and back again following the retreating ice cover.
Swiss stone pine (Pinus cembra), the emblematic tree species of the timberline ecotone, on the verge of the Aletsch glacier (Switzerland)—yet the largest, but also quickly melting body of ice in the European Alps (photo: César Morales-Molino).
Swiss stone pine (Pinus cembra) is an emblematic tree species with diverse and fascinating growth forms that reflect long-lasting endurance of extreme alpine weather conditions. This species occurs in a beautiful, almost mystical alpine landscape in the European Alps and in scattered places in the Carpathian Mountains, and it displays an intriguing interaction with nutcrackers that hoard its seed for winter food. How could such a species cope with moving to and fro its current habitat in response to shifting climates and glaciers? And how could we best decipher this demographic history using the material at hand? The extant trees reveal their population history through their genealogy: It is common routine to unveil demographic processes using genetic markers (phylogeography, demographic modelling). Similarly hidden information can be retrieved from remains of former occurrences, e.g., in lake sediments or even buried underneath now retreating glaciers: Here, we find fossil pollen deposits, or occasional macrofossils that provide evidence of immediate presence of a given species near the place of discovery. However, both approaches have their limitations: Genetic inference lacks precise dating or localization of the migration routes and of refugial areas, and palaeoecology does not disclose intraspecific differentiation to inform about which genetic lineage occurred at a given site in the past.
Cover article: (Open Access) Gugerli, F., Brodbeck, S., Lendvay, B., Dauphin, B., Bagnoli, F., Tinner, W., Van Der Knaap, W.O., Höhn, M., Vendramin, G.G., Morales-Molino, C. & Schwörer, C. (2023) A range-wide postglacial history of Swiss stone pine based on molecular markers and palaeoecologicalevidence. Journal of Biogeography, 50, 1049–1062. https://doi.org/10.1111/jbi.14586
There are clear benefits if geneticists and palaeoecologists are teaming up. Both disciplines contribute their relevant share when it comes to deciphering the history of a species in a spatio-temporal context and provide complementary insights into the past. Doing this in a wonderful study system such as Swiss stone pine forest makes the (field)work even more appealing. However, sampling often comes with strenuous ascents to high-elevation forests, possibly hauling coring equipment to picturesque mountain lakes. But efforts are well compensated once floating on a coring platform or strolling among bizarre trees to collect needle samples for DNA extractions, with nervous nutcrackers croaking above your head fearing food theft. Not to mention the beautiful view to high-elevation, still glacier-covered mountains nearby. Such work resembles forensics: digging in the “dirt” to uncover the past through palaeoecological evidence in the ground, while conducting molecular-genetic lab work to derive testimonies left behind on the “crime scene”.
The European nutcracker (Nucifraga caryocatactes) is the predominant seed disperser of P. cembra. Cached seed that are not recovered and remain in the ground may subsequently germinate and establish to form the new Swiss stone pine generation (photo: Eike Lena Neuschulz).
Admittedly, the fun part stops once back in the labs—seemingly endless hours of identifying and counting pollen or macrofossils, thousands of pipette tips wasted. But the reward comes back once analyses shape the data piles into meaningful heaps and structures. In the case of Swiss stone pine: We found a remarkably distinct spatial structure of two lineages comprising five genetic clusters, but rather evenly distributed genetic diversity, implying that demographic changes over long periods did not have a marked (negative) effect on genetic diversity. To our surprise, the separation of the two main lineages did not coincide with the pronounced geographical disjunction between the Alps and the Carpathian Mountains, but it appeared in the Central Alps, in an area previously recognized as a bio- and phylogeographic contact zone. This finding suggests a more ancient split of these lineages, and indeed, demographic inference estimated the divergence back to more than 200,000 years ago. This period coincides with a particularly long warm stage (MIS7 interglacial). Such warm periods, but also the very cold phases in-between (glacial stadials), led to geographical isolation, whereas the largest range expansions occurred in the course of cool transitional periods (interstadials) like the Bølling/Allerød during the last deglaciation. While fossil evidence does not reach as far back in time to document the ancient split of lineages, the palaeoecological records compiled allowed us to narrow down refugial areas occupied by Swiss stone pine during the Last Glacial Maximum (LGM) to the Po plain of northern Italy and expanding into Friuli and Slovenia, another area in the Carpathian forelands, in the Hungarian plain, and possibly in the Bohemian massif. The footprints of respective re-colonization routes, inferred from dated palaeoecological findings, match well with the genetic structure identified in extant Swiss stone pine populations—evidence of the added value when combining datasets and looking across disciplinary boundaries.
While these outcomes are interesting per se, they are not the end of the story yet. Is it possible to obtain a refined picture of palaeoecological records? What was the genetic make-up of the refugial populations? Can we track the evolution of genetic clusters along their migration routes? Are there changes in allele frequencies at adaptive loci? Further research avenues consist of coring sediments in places where it has not been done, but where LGM or even older occurrences may be possible, and if not done so, distinguishing Pinus pollen in existing and new samples to the species level to separate P. cembra from P. sylvestris/uncinata. Analyses of DNA retrieved from macrofossils may shed light onto the genetic composition of ancient populations, including environmentally driven changes in adaptive genetic variation.
Coring platform on an alpine lake (Lai da Vons, Switzerland), with Swiss stone pine overseeing that sediment coring is done accurately (photo: Christoph Schwörer).
But the most pressing question remains yet unanswered: What is the fate of Swiss stone pine in view of a seemingly super interglacial as a consequence of anthropogenic climate warming? These trees are among the oldest in European mountain forests, as such reflecting demographic stasis, but they are deemed to respond quickly to rapidly changing climate by moving uphill. Unless demographic (dispersal) or adaptive processes keep up the pace of climate warming, we anticipate a gradual decline through competitive exclusion and possibly local extinction of Swiss stone pine—a worrying perspective for this magnificent timberline forest ecosystem and the species it is composed of.
Felix Gugerli, Senior Scientist, Biodiversity & Conservation Biology, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland
César Morales-Molino, Postdoctoral researcher, Grupo de Ecología y Restauración Forestal, Departamento de Ciencias de la Vida, Facultad de Ciencias, Universidad de Alcalá, Alcalá de Henares, Spain
Christoph Schwörer, Group leader, Institute of Plant Sciences and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
Sandra H. Arenas is a PhD student at Rey Juan Carlos University, Spain. She is a marine biologist with a special focus on seaweeds ecophysiology and distribution. Here, Sandra shares her recent work on adaptation of seaweeds to climate change.
Recent JBIpaper. Hernández, S., García, A. G., Arenas, F., Escribano, M. P., Jueterbock, A., De Clerck, O., Maggs, C. A., Franco, J. N., & Martínez, B. D. C. (2023). Range-edge populations of seaweeds show niche unfilling and poor adaptation to increased temperatures. Journal of Biogeography, 50, 780-791. https://doi.org/10.1111/jbi.14572
Video abstract. Since global warming is affecting the distribution of species worldwide and the degree of adaptation to high temperatures is still unknown in most cases, this study aims to study whether the European populations of two macroalgae species differ in their thermal tolerance ranges. To do this, we selected European populations from 8 different localities of the brown alga Ascophyllum nodosum (Linnaeus) Le Jolis and 6 of the red alga Chondrus crispus Stackhouse. These populations underwent a thermal gradient experiment ranging from 12º – 30ºC to determine their upper survival temperatures (USTs). Those USTs, approximately 24°C, were used as thresholds to assess the existence of safety margins and thermal niche unfilling states by comparing then with the maximum seawater surface temperature. Both species had thermal safety margins over the last few decades. However, these safety margins are projected to disappear in the Bay of Biscay (Spain) under RCP4.5 and RCP6.0 2090–2100 IPCC scenarios for C. crispus and under RCP8.5 for both species, since those southern marginal populations are not better adapted to global warming, as revealed by the USTs.
Biography. I’m Sandra Hernández Arenas, a pre-doctoral researcher in the Biodiversity Area at Rey Juan Carlos University in Madrid, Spain. I obtained my Biology Degree from the same university in 2011-2015. Subsequently, I pursued a Marine Biology Master’s at Vigo University in Galicia, Spain from 2015-2017. Additionally, I completed an Education Master’s at Rey Juan Carlos University from 2018-2019 to become a secondary teacher.
My passion for the underwater world has led me to acquire various dive qualifications in recreational diving. I am also deeply interested in the field of education, and I fill my time by teaching laboratory classes at the university. However, I do not rule out dedicating myself fully to teaching in the future if my time through the world of research cannot continue.
My recently published paper in the Journal of Biogeography is a part of my Ph.D. thesis focused on marine macroalgae. My research primarily revolves around ecophysiology, species distribution models, niche changes, and alien species. The overarching goal of my work is conservation, specifically investigating how climate change might impact macroalgae populations along our coastlines.
Victoria Glynn is a PhD candidate at McGill University, Canada. She is an ecologist & science educator with a special focus on coral adaptation to environmental stressors. Here, Victoria shares her recent work on the factors structuring coral-algal symbioses.
Recent JBIpaper. Glynn, V. M., Vollmer, S. V., Kline, D. I., & Barrett, R. D. H. (2023) . Environmental and geographical factors structure cauliflower coral’s algal symbioses across the Indo-Pacific. Journal of Biogeography, 50(4), 669–684. https://doi.org/10.1111/jbi.14560
Caption. There is a complex interplay between thermal history and geographic isolation in structuring the symbioses of cauliflower corals (Pocillopora spp.) and their dinoflagellates (family Symbiodiniaceae). When analyzing publicly available dinoflagellate marker-gene data from the nuclear ribosomal DNA internal transcribed spacer 2 (ITS2), cauliflower corals across the Indo-Pacific were found to associate with three different dinoflagellate genera: Cladocopium spp., Durusdinium spp., and Symbiodinium spp.
(1) We found some evidence that geographic isolation could explain dinoflagellate community differences, but the effect was relatively weak.
(2) Sea surface temperature was the factor that most strongly affected community composition, such that corals from locations most similar in temperature had more similar dinoflagellate communities.
(3) Additionally, when considering time since the last mass bleaching event, corals that had more recently bleached (within the last 5 years) had similar proportions of Cladocopium spp. and Durusdinium spp. Meanwhile, corals that had not recently bleached were additionally associated with Symbiodinium spp. Together, our findings highlight how local environmental conditions and bleaching history can impact coral-dinoflagellate symbioses, even in a coral genus with a widespread distribution.
Biography. Victoria Marie Glynn is a PhD candidate at McGill University (Montréal, Québec) and a Fellow at the Smithsonian Tropical Research Institute (STRI) in Panama. She is broadly interested in how corals and their microorganisms (microbiome) implement a diversity of strategies to cope with environmental stress. Victoria implements cutting-edge molecular techniques to answer the overarching question: who is there, and what are they doing? As a STRI Fellow, she leverages the unique conditions of Panama’s Tropical Eastern Pacific, where upwelling occurs on a seasonal basis and El Niño events are common, to study the mechanisms underlying coral bleaching. Outside research, Victoria is involved in various science outreach and equity, diversity, and inclusion projects as a Science Education Fellow in the Office of Science Education at McGill and the Redpath Museum’s graduate public programming representative. She also creates scientific illustrations to add a storytelling element to her practice, so that fellow researchers and the general public alike can better understand the various scales and dynamics she is investigating.
Ella is a PhD student at the University of Toronto, Canada. She is broadly interested in species interactions and plant ecology and evolution, and is currently studying urban eco-evolutionary dynamics. Here, Ella shares her perspective about the study of global patterns while living a global pandemic.
Ella, at her desk at home in April 2020.
Institute. University of Toronto.
Academic life stage. PhD.
Recent JBIpaper. Martin, E., & Hargreaves, A. L. (2023). Gradients in the time seeds take to germinate could alter global patterns in predation strength. Journal of Biogeography, 50(5), 884–896. https://doi.org/10.1111/jbi.14582
Big questions, small world: studying global patterns while living a global pandemic. I began this project in March 2020. I was three months into my Master’s degree at McGill University and was stuck at home learning to accept the growing likelihood that my plans for fieldwork in the Galapagos islands were not going to happen any time soon. While awaiting news of university verdicts on international fieldwork, one of my co-supervisors, Dr. Anna Hargreaves pitched me the idea: a synthesis study exploring latitudinal gradients in the time seeds take to germinate. The idea came out of her work on latitudinal gradients in the strength of species interactions, especially her recent-at-the-time “B.I.G. Experiment”, a large-scale standardized seed predation experiment. This project, and several others like it were testing the hypothesis that species interactions should be stronger (and therefore more ecologically and evolutionarily important) at lower latitudes and elevations, originally proposed by Charles Darwin nearly two hundred years before.
An illustration of the biotic interactions hypothesis. Tropical latitudes are usually warmer, more biodiverse, and have higher productivity. In these more climatically favourable environments, species interactions are expected to be stronger, in this case: higher rates of daily seed predation.
To test this hypothesis, researchers used standardized prey: artificial or commercial versions of early life stages that don’t belong to any particular environment, and so avoid any cases of local adaptation. This method allows researchers to set out prey, and return at a later time to count how many had been eaten, obtaining comparable measures of daily predation rates at locations around the world. What it ignores, however, is exposure time: the duration of time a prey is exposed to predators which determines its risk of being predated over its lifetime, and thus the actual ecological or evolutionary importance of predation. This is where I came in. Using seeds as our study system and published literature as our data source, we set out to try to answer whether seeds’ exposure time (the length of time between dispersal and germination) varied geographically, potentially altering the predicted global patterns of seed predation strength. To do so, I set out to collect as much data on germination times from as many species and locations as I could, in hopes of revealing large-scale patterns.
I adapted to the work of conducting a synthesis project at the same time as I adapted to the work-from-home lifestyle. Rather than spending my summer working outdoors in an exotic location, I spent it at home, travelling the world from the couch, the back porch, the kitchen table, or my bed, through the papers I was reading and extracting data from. I filled spreadsheets with germination times as I spent time watching the plants grow back in my garden and on my walks around the neighbourhood. By the end of the summer, I had filtered through thousands and read over a hundred papers on germination times (often in the middle of the night as I had also lost all concept of time and become semi-nocturnal).
We had realized that compiling data on germination times was not so straightforward due to the large variability in methods. Some studies tested germination timing in the natural field conditions, some in outdoor pots, some in greenhouses, and some in growth chambers under a variety of conditions. Some studies pretreated seeds to induce germination, whereas others did not. Some studies reported time to germination as a mean, or a time to 50% germination, or a maximum or a minimum. I spent the next year doing analyses: excluding some data, adding new data, adding and removing model terms, trying different modelling approaches, looking at relationships between time to germination and latitude, elevation, temperature, precipitation, seed size, and phylogeny. I began to realize and use the wealth of data that exists online free for public use. I could instantly download climate data from all over the world, I could find databases of seed sizes, and plant phylogenies that could help me answer global-scale questions spanning over a thousand species.
An example of a seed depot used in standardized seed predation experiments, this one in my backyard with sunflower seeds, for a different project.
Across all of our analyses, the results remained consistent, if somewhat difficult to explain. We observed that, in natural environments, seeds germinated faster at high latitudes, but low elevations, despite our expectations that these two gradients would be analogous. In terms of climate, seeds in nature germinated faster in warmer, drier environments with high temperature seasonality. What this tells us is that it is unlikely that seeds in high predation (low latitude, low elevation, warm, wet, consistent) environments are unlikely to have universally evolved faster germination to escape predation. In fact, tropical seeds tended to have longer germination times, meaning that they not only have a higher daily risk of predation, but they are exposed to predators over a longer period, resulting in a much greater lifetime risk of predation than seeds at high latitudes, which appear to experience low predation rates over short time periods. For elevational gradients, however, faster exposure times in low predation environments (low elevations), means that seeds would experience similar predation risks across elevations.
Clearly, there is still much to learn about how seeds respond to predation. Syntheses projects have their limits, but being able to take on this type of large-scale biogeographic question, to try to inform our understanding of global patterns in species traits, without leaving the house in the midst of a pandemic, was still a fascinating experience. My perception of the world simultaneously condensed to my home and immediate surroundings, and expanded as I learned about species from around the world and thought about these global patterns, with only a laptop and an internet connection.
An emerging white clover (Trifolium repens) in a growth chamber.
A species that is locally common can be globally rare and vice versa. But why? Turns out that tolerance of climatic conditions drives plant species commonness towards global spatial scales, while at finer local scales, competitive ability is relatively more decisive. Accounting for this scale dependence in species occupancy is important when anticipating the effects of climate change or invasive species at local vs. broader scales.
Above: Arctic vegetation, like on the slopes of this mount Saana in North-Finland, is threatened by climate change. Species that are specialized to cold environments are directly affected by warming climate, while those not being strong in competition with other species are threatened also locally by the spread of boreal species northwards. Photo by Miska Luoto.
Why are some species common while others are rare? Trying to answer this question has a long history in biogeography, but despite the decades of studies and suggested and supported reasons, there is no ultimate answer. The quest for the answer is even more topical now, when climate change and invasive species together with other human related actions alter the environment. Indeed, maybe one should rather ask why and which species will become more common or rarer in the future?
While reading through examples of studies investigating the reasons behind species commonness vs. rarity – a feature called ‘occupancy’ in ecology – I stumbled on a study by Heino and Tolonen (2018). They made a short note that the used spatial scale might have affected the outcome of their study, where they found that habitat availability was the most important driver of occupancy while species’ traits or taxonomy played only minor role.
Editors’ choice / Cover article: (Free to read online for two years.) Mod, H. K., Rissanen, T., Niittynen, P., Soininen, J., & Luoto, M. (2023). The relationships of plant species occupancy to niches and traits vary with spatial scale. Journal of Biogeography, 00, 1– 13. https://doi.org/10.1111/jbi.14608
Having studied spatial scale and its effect on decisiveness of different drivers behind ecological phenomena, our immediate thought then was that habitat availability, as representing species preferences of environmental conditions, could be more decisive at broader spatial scales where environmental conditions are thought to determine species growth and survival. Instead, at more local scales, where organisms are close enough to each other to compete, biotic interactions would dictate which species get along in a specific location. As species’ ability to compete can be deduced from some of its traits (such as size, effectiveness of resource usage, reproductive capacity), what the species is like, in comparison to other species, would appear important for occupancy only at very fine spatial scales. Species preference and tolerance of environmental conditions are called abiotic ‘niche marginality’ and ‘niche breadth’, respectively, describing how specialist or generalist a species is in terms of environmental conditions, while from species traits one can derive a measure of how varying the species itself can be, i.e., ‘intraspecific trait variability’ (ITV), and a measure of how much its traits deviates from the traits of other species (‘trait distinctiveness’). High niche breadth and low niche marginality should thus lead to high occupancy through availability of potential habitats, while high ITV and trait distinctiveness would lead to high occupancy due to being assets in competition with other species.
In our study we thus wanted to investigate whether spatial scale affects the role of these niche and trait measures in driving species occupancy. For this we needed information on how often a species is encountered at study areas of different scales and information of niches and traits of these species. For this we chose four arctic study areas that varied in size from a few square kilometers to all of terrestrial non-glaciated area north of Arctic Circle and in studied plot sizes from 0.04 m2 to 4 km2. The analyses were done for 106 plant species occurring in the study areas with varying occupancies and niche and trait metrics.
The four study areas of different scales are located north of the Arctic Circle. From each study area we mapped in the field or derived from open databases species occurrences to calculate occupancy, i.e., how often species are encountered, per spatial scale. The location of the study area at the finest scale and the extent of the study area at the next finest scale are marked with yellow and orange squares, respectively. The study area at the second coarsest scale covers mainland Finland, Sweden, and Norway north of Arctic Circle (in purple) and the study area at the coarsest scale covers all terrestrial non-glaciated area north of Arctic Circle (in blue).
The results supported our hypothesis. At the two largest study areas species occupancy was most related to their niche breadth: the species that tolerate range of climatic conditions are more common than those that can only stand certain type of conditions. In contrast, at the more local and finer scales, species that are strong competitors, such as those that can adjust their resource use effectiveness, were found to be more common than those that have traits indicating lower competitive ability.
So, coming back to the burning question: ‘why and which species will become more common or rarer in the future?’, the answer according to our results is that it depends on the spatial scale. Towards the global scale, the species that tolerate varying environmental conditions are likely to remain as common as they are now under a changing climate, while those specializing to certain environmental conditions are at risk of becoming even rarer. On a local scale, in turn, tolerating varying climatic conditions is not much of an asset in being or becoming common, whereas a good ability to compete with other species drives commonness and those that don’t have the properties to compete with other species are at risk to become even locally extent. This can mean that the Arctic is in double jeopardy: cold-adapted arctic vegetation as a whole is under the threat of warming climate while the spread of competitive boreal species northwards threatens the arctic plants also locally.
However, our study do not provide the ultimate answers to the question of underlying mechanisms of species occupancy nor to the question of the future of the Arctic. It still remains to be tested if our findings hold for other species groups than plants and for other niche and trait metrics than those we used. Also, there are additional factors influencing the future of Arctic environment and vegetation than those included in our study. Thus, the quest continues!
Written by: Heidi Mod, university lecturer, Department of Geosciences and Geography, University of Helsinki, Finland
Tuuli Rissanen, PhD candidate, Department of Geosciences and Geography, University of Helsinki, Finland
Pekka Niittynen, Post doc, Department of Geosciences and Geography, University of Helsinki, Finland & Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
Janne Soininen, professor, Department of Geosciences and Geography, University of Helsinki, Finland Miska Luoto, professor, Department of Geosciences and Geography, University of Helsinki, Finland
Daubian Santos is a postdoc at the Universidade Federal do ABC, Brazil. He is a evolutionary biologist with special focus on biogeography of craneflies. Here, Daubian presents SAMBA, a method for revealing shared patterns of biotic distribution.
Dr. Daubian Santos, postdoc at Universidade Federal do ABC, Brazil
Institute. Universidade Federal do ABC, Brazil, Institute of Systematics and Evolution of Animals
Academic life stage. Postdoc
Major research themes. Biogeography and Palaeontology
Current study system. I study craneflies. Craneflies are mosquitoes with long legs that may reach impressive sizes. This infraorder is ancient, highly endemic, and widely distributed throughout the world. They inhabit a range of environments, from glaciers to deserts, from urban areas to the canopy of tropical forests. Interestingly, the number of species within this group exceeds the combined number of mammals and birds. Despite the large number of known species, there are still many yet to be discovered, including some of the larger size ones. Therefore, studying craneflies presents an excellent opportunity to explore biodiversity.
Recent JBIpaper. Santos, D., Sampronha, S., Hammoud, M., Gois, J. P., & Santos, C. M. D. (2023). SAMBA: Super area‐cladogram after resolving multiple biogeographical ambiguities. Journal of Biogeography, 50(4), 816–825. https://doi.org/10.1111/jbi.14569
A piece of Baltic amber containing a specimen of Eloeophila eocenica, the newest described species
Motivation behind this paper. Historical biogeography has been a relevant field for a considerable period, providing insights into species evolution and dispersal over time. However, with the discovery of more complex species distributions, more efficient methods are required to tackle these challenges. Unfortunately, there are not many new and effective methods available, and most of them do not have online software, which makes it difficult for researchers to access them. In response, we became very motivated to develop a new methodology based on simple theoretical principles, providing reliable results to overcome the lack of consensus in area cladograms. Improving methods in historical biogeography will provide a better understanding of life’s evolution and distribution on Earth.
Key methodologies. The main key methodology of SAMBA is to avoid using assumptions. By avoiding the use of assumptions, SAMBA aims to reduce the amount of noise in the analysis, resulting in more accurate and reliable findings. It is crucial in the field of historical biogeography to see the individual complexity of the distributions and identify the recurrent pattern accurately. As a novel approach, we adapted the method of super-trees that allows an efficient summarization of information from area cladograms. The innovative approach of SAMBA, and its online implementation, is a new way to analyse the data and may provide new insights into the distribution of life on Earth. More and more studies with new methods may bring a lot of new information.
Fossil of the family Limoniidae from the Brazilian Cretaceous period
Unexpected challenges. Proposing and developing something new is never an easy task. After establishing the theoretical framework of the methodology, the further step was to test it. However, since the computational implementation was developed later, we had to conduct many (and many) tests before arriving at the final SAMBA protocol. This testing period provided us valuable time to rethink certain aspects of the methodology. The adaptation of the super-tree concept came later, but it was essential in refining the SAMBA method. The implementation of the super-tree concept allowed us to summarise information from area cladograms and achieve a more consensus-based approach. Although the development process was challenging, the final product is a robust and reliable methodology. The thinking-and-rethinking process is necessary to make any method useful.
Major results. My work formalized the new method of historical biogeography called SAMBA. This methodology avoids using assumptions and aims to summarise information with minimal noise. In addition to the methodology, we tried to provide a computational implementation to increase the method’s applicability and efficiency. This method was tested under real examples and theoretical models and compared with other previous methodologies. This new method is efficient to summarise the area cladogram information. We believe that the SAMBA methodology and its computational implementation can provide a valuable tool for researchers in the field of historical biogeography with a simplified theoretical basis.
Described paratypes of Aphrophila edwardsi
Next steps for this research. I will start a post-doctoral research project focusing on mosquitoes preserved in Baltic amber. This project is particularly interesting because it will provide insights into the composition of Eocene ecosystems, in which craneflies played an essential role. During this period, Europe was characterized by subtropical forests, and the insect fauna that followed was more similar to the modern pattern. However, the shift of biotas during this time is not yet fully understood. Craneflies are the most commonly found Diptera in the paleontological record, and studying these species is crucial to unravelling this fascinating period of evolution.
If you could study any organism on Earth, what would it be? I would like to study the first winged insect. The evolution of wings is still one the greatest mysteries in Entomology.
Anything else to add? When I started college, I had a strong desire to study any animal, except mosquitoes. However, it was precisely them that I ended up studying! I was both surprised and fascinated by its enormous diversity. It is incredible how much we can learn from these small, but enchanting beings.
The geographic ranges of mammals in Africa are limited in size by the variation in habitats across space (habitat heterogeneity), but surprisingly not by the variation in elevations (topographic heterogeneity). Mammalian ranges will be sensitive to future habitat destruction and alteration, as climate change and human impacts continue to intensify.
Above: The cheetah (Acinonyx jubatus) is one of many African mammals whose range size may be constrained by the variation in habitats across landscapes, i.e., habitat heterogeneity (picture taken by Michael S. Lauer).
In the summer of 2019, I attended the Ecological Society of America’s annual conference in Louisville, Kentucky. I remember walking around a massive room with hundreds of posters, and as I made my rounds, I couldn’t help but notice that many of the posters had the word “heterogeneity” in their title. Fast forward a few months to the fall of 2019, when my co-author and aca-brother (Dr. Benjamin Shipley) introduced me to some of the aspects of mammalian biogeography that were still unknown. Fast forward again to the spring of 2020, when I took a course titled “Biodiversity on a Changing Planet” taught by my co-author and graduate advisor Dr. Jenny McGuire. Why am I listing three seemingly unrelated experiences? As it turns out, all three together served as the foundation of our recent paper. Had I not gone to the conference, I would not have internalized how important landscape heterogeneity (i.e., the variation in environmental conditions across space) is to ecology and biogeography. Had I not conversed with Ben, I would not have been initially enticed to study mammalian geographic ranges and the associated knowledge gaps. And had I not taken the course, I would have not been assigned the project that morphed into the initial draft of this paper. All of this is to say that sometimes the most exciting ideas come from a “heterogeneity” of experiences and perspectives.
Cover article: (Free to read online for two years.) Lauer, D. A., Shipley, B. R., & McGuire, J. L. (2023). Habitat and not topographic heterogeneity constrains the range sizes of African mammals. Journal of Biogeography, 50, 846 – 857. https://doi.org/10.1111/jbi.14576
Ultimately, it was the combined perspectives of myself, Ben, and Jenny that led us to ask the following question: are mammalian geographic range sizes in Africa more constrained by the variation in habitats (habitat heterogeneity) or the variation in physical elevations (topographic heterogeneity) across space? We knew from prior research that species ranges are constrained in heterogeneous landscapes because to co-exist, each species adapts to the specific environmental conditions of specific areas. But we wanted to take this idea a step further. We were motivated to compare the effects of habitat and topographic heterogeneity specifically because they represent two fundamentally different things about landscapes. Habitat heterogeneity is fluid, as habitats come and go rapidly depending on how climates change and how humans behave. Consider, for example, a landscape that is heterogeneous because it possesses small patches of intertwined forest and grassland habitats. Such a landscape could become rapidly homogeneous if its trees are cut down and it transforms into an extensive grassland. Contrast that to topographic heterogeneity, which is much more set in stone. A landscape that is heterogeneous because it is hilly is likely to remain hilly for a long time. Hills and mountains don’t disappear overnight.
The landscape on the left has low habitat but high topographic heterogeneity, as it exhibits only forest habitat but is hilly. The landscape on the left is the opposite, as it exhibits forest, grassland, and aquatic habitats but is flat (pictures taken by Daniel A. Lauer).
At first, we were thinking that both habitat and topographic heterogeneity would at least have some constraining effect on species range sizes. But in a fashion that often makes science so exciting, we were surprised to arrive at an unexpected result. While we found evidence that habitat heterogeneity had a strong limiting effect on range size, our analyses suggested that topographic heterogeneity had no effect at all! This contrast became particularly interesting and important to us as we thought about its implications. Essentially the contrast suggests that when landscape heterogeneity limits mammalian ranges, it does so via its fluid, subject-to-change habitats, and not via its rigid physical structure. Consequently, the persistence and geographic occurrences of mammals may be highly susceptible to habitat change, destruction, and alteration by climate change and human land use. We channeled these ideas to think about how our results could be meaningful for both ecological theory and environmental conservation. Regarding the former – we were able to add a new layer of nuance to the theory of how landscape heterogeneity constrains ranges. And regarding the latter – we would suggest that conservation efforts should focus on the small-ranged mammals that occur in regions of high habitat heterogeneity, particularly considering that a small range can often mean a higher extinction risk.
Along our collaborative journey I learned many things, and together we opened some avenues for future researchers to explore. I internalized the power that many experiences, as well as ideas from other scientists, can have in forming a meaningful scientific question. I learned how cool it can be to answer such a question by collecting data from many sources and combining that data into a single analytical pipeline. And I learned that the most exciting science can emerge from the results that were wildly unexpected. Our work calls for an enhanced understanding of the specific species that live in regions of high habitat heterogeneity in Africa. What are these species? What are their functional traits and evolutionary histories? How do they compare to species that occur in more homogeneous environments? What would be the most effective conservation strategies to prevent their extinction? Time will tell, but for now we can say that the sky (or the heterogeneity of the landscape?) is the limit.
Daniel A. Lauer (Ph.D. Candidate)1,2, Benjamin R. Shipley (Ph.D.)2, Jenny L. McGuire (Assistant Professor)1-3
1Interdisciplinary Graduate Program in Quantitative Biosciences, Georgia Institute of Technology, Atlanta, GA, USA
2School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA3School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
Julian G. de Aledo is a PhD candidate at the Universidad Autónoma de Madrid, Spain. She is a ecologist with special focus on biodiversity of tropical plants. Here, Julia shares her recent work on plant diversity and distribution in the western Amazonia.
Institute. Universidad Autónoma de Madrid and Universidad Rey Juan Carlos, Spain
Academic life stage. PhD candidate
Major research themes. My major research interests revolve around plant diversity, distribution, and uses in western Amazonia, particularly focusing on how plants and people interact in tropical ecosystems across gradients.
Current study system. I am currently studying the woody plants of western Amazonia, which include approximately 110 different families with distinct growth forms, from large trees, to palms, ferns, small bushes, lianas and hemiepiphytes. Despite an estimated 50,000 plant species in the Amazon basin, only 14,000 tree species have been described, which highlights the vast amount of work still to be done.
Recent JBIpaper. de Aledo, J. G., Paneghel, M., Cayuela, L., Matas-Granados, L., Ben Saadi, C., Salinas, N., La Torre-Cuadros, M. d. l. Á., García-Villacorta, R., & Macía, M. J. (2023). Floristic diversity, composition and dominance across Amazonian forest types respond differently to latitude. Journal of Biogeography, 50, 673–698. https://doi.org/10.1111/jbi.14561
Motivation behind this paper. During fieldwork, we have observed distinct variations in species diversity and composition across different forest types. We noticed that floodplain forests appeared to have a lower diversity of species compared to the well-drained forests yet filled with species with different physiological adaptations to the seasonal flood pulse. On the other hand, in submontane forests, diversity seemed to peak at higher elevations (500 m). These observations led us to question whether there was a discernible pattern in how plant species respond to latitude in each forest type to ultimately understand the causes of the vast diversity of the Amazonian ecosystem.
Drawing of the diversity of species and life forms in western Amazon.
Key methodologies. In the fieldwork, we gathered information from unexplored areas using 10 temporary plots per region located 300 meters apart. This approach allowed us to obtain maximum floristic variability within an area, which is crucial when studying diverse ecosystems. Moreover, all data were gathered by the authors themselves, and no data from existing databases were used.
In terms of the analysis, we made a plot called non-metric multidimensional scaling (NMDS) and used a smooth line to show how latitude affects the changes in species composition across plots . This helped us see if there was a trend or pattern in how each forest type responds to latitude. Additionally, we explored dominant species through their changes in abundance, which helped us understand how these species adapt and dominate over large areas. We used a novel stream graph approach to better illustrate these changes, providing new insights into their distribution and dispersion peaks.
Forest vertical structure of woody plants in Reserva Yanesha, Peru.
Unexpected challenges. In this type of field campaign, nothing can be predicted in advance. Nonetheless, we encountered some outcomes and challenges even beyond our imagination. For example, we ended up collecting more species than we had expected. This led to difficulties in transporting the collected material, as well as troubles in the final identification of some of the specimens, mostly the ones without fertile material. Another important challenge was reaching high trees (over 20 meters) for collection, which required specialized equipment and climbing expertise. Finally, the flooding of the rivers due to heavy rains made the fieldwork complicated, leaving us confined to the campsite for several days. Despite this, the team was able to ultimately export 5000 vouchers and identifying 1300 species for future research.
Major results. Our recent work confirms the latitudinal diversity gradient towards the equator both for alpha and beta diversity. This provides further evidence for the importance of tropical forests in maintaining global biodiversity. However, the finding that floodplain forests did not increase their diversity towards the equator as much as other forest types did, highlights the need for further research on these forests and their species performance. Despite this, the number of species found was still very high, with 100 species per 0.1 ha.
Concerning species dominance, this study also reveals different responses to latitude. Floodplain forests harbored more homogenous dominant species abundances, while well-drained forests had dominant species that peaked heterogeneously along the gradient, giving insights of differences in dispersion strategies.
An additional important contribution is that the field team have generated a comprehensive database of almost 30,000 individuals that is available for use by other researchers in the field of tropical community ecology of tropical forests (https://datadryad.org/stash/dataset/doi:10.5061/dryad.jm63xsjcc). Botanical vouchers obtained in this research were deposited in different herbariums in Ecuador (QCA, QCNE), Bolivia (LPB), Peru (USM, MOL) and Spain (MA).
Left: aerial image of Amazonian forest surrounding the Tambopata River in the Tambopata National Reserve (Madre de Dios, Peru). Right: photo of Coussapoa ovalifolia tree with aerial roots in Amazonian flooded forest.
Next steps for this research. Further investigation can be done to understand the underlying mechanisms driving the observed latitudinal diversity gradient in our study. This can involve exploring in depth floodplain forests to highlight its importance, promote their conservation and to understand its species adaptations. Also, including in situ mechanistic factors as temperature, precipitation, and soil nutrients in the analysis could improve the latitudinal model. Incorporating phylogenetic information can also provide insights into the evolutionary history of tropical plant communities and their responses to environmental change. By studying functional attributes of the species, we can understand the adaptation of species to seasonally harsh conditions. Finally, efforts can be made to expand this investigation to other regions and biomes to compare the latitudinal patterns observed in our study in other environments.
If you could study any organism on Earth, what would it be? Tropical woody plants are fascinating. In particular, I like lianas, which are a unique group of plants with unique growth form which allows them to climb up trees and compete for resources, affecting the structure and dynamics of the forest community. The Lecythidaceae family is also an interesting group to study because of their large flowers and fruits, which are important food sources for many animals and humans.
Drawing of Couratari guianensis (Lecythidaceae) fruit by Julia G. de Aledo
Anything else to add? In addition to my work on tropical woody plants, I also conduct research on ethnobotany, ecosystem services, and the cultural diversity of indigenous communities in tropical forests in western Amazonia. I believe that including people in ecology research is essential for understanding how species respond to changes in their environment, and for developing effective conservation and management strategies. Additionally, I am interested in using visual data analysis techniques, including bioinformatics, modelling, statistics, and data visualization, to better understand complex ecological systems.
Changes in the abundance of each dominant species by forest type in western Amazonia.
Plants can reproduce clonally or by seeds. What are the circumstances that clonal reproduction is favoured, and which type of species are most likely to be clonal?
Above: Plants reproduce asexually via rhizomes.
Sexual reproduction from seeds is common in the plant kingdom. However, many plants reproduce through vegetative propagation or clonal growth such as sprouting from rhizomes, thus they are called clonal plants. Back in 2018, we studied the Australian flora and found that the proportion of clonal species increases with latitudes across the whole continent. Thereafter, we asked why — we would like to know the underlying mechanisms for this geographic pattern. Despite having many studies on the prevalence of sexual versus clonal reproduction and its associations with abiotic conditions at smaller scales, we still have much to learn about the circumstances under which sexual versus clonal reproduction are favoured, and which type of species are most likely to be clonal or sexual at the continental scale.
Editors’ choice / Cover article: (Open access) Zhang, H., Chen, S.-C., Bonser, S. P., Hitchcock, T., & Moles, A. T. (2023). Factors that shape large-scale gradients in clonality. Journal of Biogeography, 50, https://doi.org/10.1111/jbi.14577.
To better understand the ecological and evolutionary significance of reproductive mode, we studied 4116 seed species and their 914456 occurrence records in the Australia flora, together with a series of factors that might influence plant clonality. In this way, we could directly compare the effects of the four plant characteristics and sixteen environmental variables on determining the likelihood of a species to exhibit clonal reproduction or not.
Plants reproduce by seeds (left panel; sexual reproduction organ of the walking stick palm Linospadix monostachya; Photo: Si-Chong Chen) and by rhizomes (right panel; clonal reproduction organ of Hydrocotyle sibthorpioides; Photo: Hongxiang Zhang).
We found that plant characteristics explained more than two times the variation in the probability of species having clonal reproduction than did environmental variables. Our findings suggest that we may need to consider species’ traits as a coordinated suite that respond to environmental conditions, rather than studying them one at a time in the future. For example, one potential direction for future research is whether big plants (e.g. trees and tall plants) tend to sexual reproduction and have greater seed dispersal ability and distances to counterbalance the longer time to first reproduction, while small plants (e.g. herbs and shorter plants) tend to be clonal reproduction and have higher seed dormancy and seed persistence in the soil. A hot topic about relationships between environmental conditions and sexual vs clonal reproduction is whether stress conditions favour sexual or clonal reproduction. Sexual reproduction is found to be predominant in stress conditions such as drought and low fertility, while clonal reproduction is common in harsh conditions, e.g. low temperature and high altitudes. Our results showed that clonality tended to be favoured when environmental resource availability was high, like high water availability and high soil nutrient conditions. Therefore, we suggest clonal reproduction may be a ‘weapon’ of plants for population expansion in resource-abundant sites, rather than as a reproductive assurance under environmental stress. This would be an interesting and important direction for future research at multiple geographical regions and scales
Our study is the first continental-scale cross-species analysis to date of plant characteristics and environmental factors in shaping plant clonality. The findings advance understanding of broad patterns in reproductive strategies and help improve understanding of species’ capacity to adapt and migrate in response to future climate change.
Written by: Hongxiang Zhang, Full Professor, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences. Si-Chong Chen, Full Professor, Wuhan Botanic Garden, Chinese Academy of Sciences.