ECR feature: João Pedro (JP) Fontanelle on stingrays biogeography

João Pedro (JP) Fontanelle is a postdoc at the Institute of Forestry and Conservation at the University of Toronto in Canada. He is an evolutionary biologist interested in how spatial and temporal eco-evolutionary dynamics affect micro- and macroevolution. Here, JP shares his recent work on how stingrays invaded the freshwaters and diversified in South American basins.

João Pedro (JP) Fontenelle getting ready to fish in the Amazon.

Personal links. Twitter | Personal website

Institute. University of Toronto, Institute of Forestry and Conservation

Academic life stage. Postdoc

Major research themes. How changes in environmental properties and connectivity affect the evolution of organisms at micro and macroevolutionary scales, their biogeography, and diversification patterns.

The unique sunset of the Amazon river basin.

Current study system. The Neotropical freshwater stingrays (subfamily Potamotrygoninae) is the only extant lineage of elasmobranchs that is exclusive to freshwater environments. They are morphologically diverse, presenting beautiful dorsal color patterns, making them very famous in the aquarium trade. It is really interesting that this subfamily achieved a high diversity and a broad distribution across almost all South American basins in a relatively short period of evolutionary time (25-20 my). That is especially cool when we think they are a marine-derived lineage, meaning their closest related lineage is found in marine environments.

Recent JBI paper. Fontenelle, J. P. Marques, F. P. L., Kolmann, M. A, Lovejoy, N. R. (2021). Biogeography of the Neotropical freshwater stingrays (Myliobatiformes: Potamotrygoninae) reveals effects of continent scale paleogeographic change and drainage evolution. Journal of Biogeography, 48(6), 1406-1419 https://doi.org/10.1111/jbi.14086

JP (left) and Jonas Batista (Instituto Mamirauá) getting ready to fish in the Amazon.

Motivation behind this paper. It started during my MSc back at the University of São Paulo in Brazil. I was working on the taxonomy of a species-complex of these stingrays (Fontenelle et al. 2017), and I started to notice the correlation between stingray species and their distribution patterns. To try to understand the processes that led to the diversification of these stingrays, I started reading more about the evolution of the group, and consequently the biogeography of Neotropical freshwater fishes, especially Lovejoy et al. (1998), Albert et al. (2006) and Albert and Reis (2011). It was fascinating to see the intimate relationship between fish groups’ diversity, South American geography, and the abiotic properties of the environment, such as water chemistry. Trying to understand a bit more about how environmental and landscape characteristics affect the evolution of freshwater lineages was the biggest inspiration for my PhD. For the stingrays, it was widely accepted that their lineage had invaded freshwater habitats through the Caribbean. However, there were still questions about the age of this event and how the group had colonized the rest of the continent. Fortunately, we were able to compile more than two decades of samples collected all over South America, which allowed us to investigate biogeographical patterns for the whole group at a continental scale.

Key methodologies. We first needed a phylogeny (relationship hypothesis tree) with a good taxonomic representation of the freshwater stingrays. We compiled the most taxonomic rich phylogeny to date, with molecular data from more than 350 specimens, accounting for over 90% of the species and sampling most of the group’s distribution. We then combined geological data and fossil evidence to calibrate key nodes in this phylogeny to produce an age hypothesis for the diversification of the group. Then, based on the literature on biogeographical areas for Neotropical freshwater fishes, we cross-referenced the distribution of our specimens to selected biogeographical areas of relevance. Finally, we reconstructed ancestral ranges over the phylogeny using six different biogeographical models and then tested their fit to our data. These models apply different parameters, such as dispersal, range expansion, vicariance, and extinction, to interpret the differences observed in reconstructed distribution patterns. Our dataset allowed us to identify changes in river connectivity over evolutionary time and how paleogeographical events were fundamental in the dispersal and diversification of the group.

Gentle trawling the bottom of the Rio Tapajós.

Unexpected challenges. One big challenge was how to interpret the ages and the reconstructed ancestral ranges for many nodes of the tree over such a large timescale and geographic area. We had to rely on geography and geology dense papers to identify and properly interpret the biogeographical patterns. These papers helped us narrow down and interpret major events for the biogeography of the stingrays and other fishes and aquatic groups with similar distributions. This led to another series of challenges regarding contrasting biogeographical patterns among different fish groups. By exploring the literature on different fish lineages, we were able to identify evidence for the same paleogeographical event affecting the fish community, but with different outcomes depending on the group. That is, the same paleogeographical event can influence the evolution of distinct groups in different ways, and this can be attributed to differences in their biology and evolutionary history.

Major results. We provided biogeographic evidence for major changes in the paleogeography of South America across 30 million years, especially for the Amazon and associated river basins, which can be used by many other biogeography studies. We presented evidence of how changes in the connectivity between and within river basins are very important to the diversification patterns of aquatic groups and how these changes may affect different freshwater groups differently. From a more fish-focused perspective, we have highlighted the importance of marine incursions on strict freshwater dominated regions for the adaptation and diversification of marine-derived lineages (MDLs) and the importance of the Pebas Mega Wetlands acting as a facilitating route for the dispersal of the stingray lineage and possibly other MDLs, from fishes like drums and pufferfishes, for example, to mammals, molluscs and even plants. It was really nice to interpret the biogeographic patterns and explain the colonization of the South American continent by this interesting group of fishes.

Retrieving longlines at dawn, after the stingrays feed time.

Next steps for this research. By extrapolating the results from this research, we are investigating macroevolutionary patterns involving biogeography, ecology, diversification, and phenotypic changes related to changes in environment and distribution. We are also working on how paleogeographic changes in the South American landscape have influenced the evolution of other fish groups and the signals in their phylogeny. Finally, we are exploring the relationships of these stingrays at a population level to study population dynamics and their relationship to taxonomic and phylogenetic diversity.

If you could study any organism on Earth, what would it be? The easy answer for that is fishes! They are fascinating solely by the fact that what we call ‘fishes’ covers more than half of the vertebrate diversity, and are found in a crazy variety of sizes, shapes and biologies. As one of my undergraduate professors used to say: “there is probably a fish example for that”. It is really hard to choose one group of fish, though. I’m particularly interested in rapidly evolving and diverse groups, and their relationship to changes in habitat; however that still accounts for a bunch of them!

A juvenile stingray in a basin for transportation (right); an adult stingray and its beautiful color pattern, fresh on the boat (left).

Anything else to add? This manuscript is the first published chapter of my PhD thesis. That adds an extra layer of satisfaction as this research is also one of the main reasons I pursued my PhD. I’ve been questioned before about how long it took us to get this manuscript in good shape and out. Still, all the years of intense work have been a real reminder of how difficult it is to work with a diverse group in a diverse area, especially when the evolution of the group is still not very well understood and the taxonomy is very complicated (which is the case of the Neotropical freshwater stingrays). It is great to provide a very important contribution to the study of these fish and the Neotropical region and its biogeography. It has been challenging from start to finish, but so worth it! We have learned a lot.

ECR Feature: Chaim Lasmar on resource use by ants

Chaim Lasmar is a postdoc at Universidade Federal de Lavras. He is an ecologist with a particular interest in ants and their contribution to ecosystem function. Chaim shares his recent work on the variable foraging behaviour of ants across large spatial scales and across different ecoregions in the neotropics.

Chaim Lasmar in his typical habitat.

Personal links. Twitter

Institute. Universidade Federal de Lavras, Brazil

Academic life stage. Postdoc

Research themes. Community Ecology, Macroecology, Biogeography, Landscape Ecology, Ants.

Current study system. Ants play important roles in the ecosystem by interacting with several abiotic and biotic factors to obtain resources. Through their foraging activities, ants are important components of terrestrial ecosystems as seed dispersers, granivores, scavengers, predators and for the cycling of nutrients. Additionally, they are mega abundant and diverse, easy to sample and present different feeding habits and diets by consuming several nutrients such as sugar, amino acids, lipids and sodium. Therefore, they are an excellent model organism to understand diversity patterns such as foraging behaviours that may give us insights into the ecosystem functioning.

Recent paper in JBI. Lasmar, C.J., Bishop, T.R., Parr, C.L., Queiroz, A.C.M., Schmidt, F.A. and Ribas, C.R. (2021), Geographical variation in ant foraging activity and resource use is driven by climate and net primary productivity. J Biogeogr. https://doi.org/10.1111/jbi.14089

Motivation behind this paper. Studies in the lab and a few in the field have demonstrated how ants can change their resource use according to the climate and the availability of plant resources. However, most field studies have been performed at small spatial scales. The remaining large spatial scales studies mainly focused on effects of temperature and productivity in similar habitats or evaluated only a few resource types (e.g., sugar and amino acids or sugar and sodium). Thus, there are still knowledge gaps in terms of whether previous findings hold when assessing foraging behaviour at large spatial scales in different ecoregions. Thus, we decided to assess ant foraging behaviour at large spatial scales and in different ecoregions in the neotropics, which are generally poorly studied in terms of ant foraging behaviour.

Chaim placing baited tubes in the Cerrado savannah forest.

Key methodologies. We used a classic baiting approach to assess the influence of climate and productivity on ant foraging activity and resource use. We provided ants four types of resources, sugar, lipids, amino acids and sodium in 60 transects distributed in six Brazilian biomes that were distinct in terms of climate and productivity. By placing 1500 baited tubes for ants, we obtained estimates of overall ant foraging activity and we could also assess the relative use of each resource type in comparison to the other three. We also assessed the current weather and annual and monthly climate and productivity for each of our transects. 

Major results. We made a step forward in our understanding of foraging behaviour by demonstrating how ant foraging activity and resource use was driven by climate and primary productivity at large spatial scales. We suggest that precipitation, temperature seasonality and productivity influence the availability of resources. This resulted in patterns of relative resource use that we considered largely as a trade-off between sugar (where energy availability was low), and amino acids and sodium (where energy availability was high). Temperature likely influenced relative amino acid and lipid use by acting on the physiology of ants. Given that ant foraging activity and resource use involves numerous biotic and abiotic interactions, we suggest that it is conceivable that global climate change and changes in productivity may shift these patterns in foraging behaviour. In turn, changes to foraging could result in changes in ant-mediated ecosystem functions.

Pheidole fracticeps workers (left) and Ectatomma brunneum (right) visiting baited tubes with a cotton ball soaked with lipids in Pantanal

Challenges overcome. Although I had a lot of fun traveling to, and experiencing, the Brazilian biomes, it was challenging to perform the fieldwork at some places. Our research required a huge sampling effort. Sometimes it was not easy to walk along a 750 m transect in the forest while carrying heavy bags full of baited tubes. Some study areas were in very remote places. In the Amazon, for example, there was no road to access the areas and we had to set all transects by foot. This research would not have been possible without the help of many other researchers in the field, and I would like to thank them for their efforts.

Next steps. There are some remaining knowledge gaps concerning the foraging behaviour of ants at large spatial scales. Ant foraging activity is intimately liked to species richness and we were not able to disentangle the direct influence of ecological drivers on foraging activity from the influence of ant species richness. Additionally, it is known that ant resource use also changes across different habitat strata at local scales. Thus, disentangling the relationship between ant species richness, foraging activity and their relation to ecological drivers across habitat strata will certainly contribute to understanding ant foraging behaviour.

Pampa forest habitat.

Pantanal wetland.

If you could study any organism on Earth, what would it be? Well, I think I am very satisfied studying ants and intend to keep studying them for a long time. Recently I started to study (besides ants) other invertebrates (e.g., other insects and spiders) and large mammals, which I also enjoyed. But it would really be great if one day I could also study trees to comprehend more broadly the ecosystems through different taxa.

Anything else to add? As ecologists, we are used to travelling to incredible wild places all over the world, as we try to understand the systems and processes of our natural environments. Yet once our fieldwork is done and our samples are collected, we leave little for the people who live in and around the natural areas we have visited. It was with this in mind that, in addition to our ecological data collection on ant communities in protected areas, we also included scientific dissemination of our work to local people living around these areas. We targeted rural and municipal schools, speaking to students about the importance of biodiversity conservation in Brazil and highlighting the significant role ants play in the ecosystem. We feel this is critical work, particularly as we face a strong wave of science denialism and because Brazil hosts between 15-20% of the world’s biodiversity which has been under severe attacks.

(left) Amazon forest. (right) Atlantic forest.

ECR Feature: Arthur Boom unravels the history of miombo woodlands through study of Brachystegia plastid genomes

Arthur Boom is a PhD student at the Université Libre de Bruxelles. He is interested in the biogeography of African plants and the application of genomic approaches to study their evolutionary. Arthur shares his recent work on trees from the Brachystegia genus to understand the history of miombo woodlands in Africa through sequencing of their plastid genomes.

Arthur Boom

Personal links. ResearchGate | GoogleScholar

Institute. Evolutionary Biology & Ecology unit, Université Libre de Bruxelles (Belgium)

Academic life stage. PhD student.

Research themes. Phylogenomics, Phylogeography, and Biogeography of African plant taxa.

Current study system. My co-authors and I are currently studying the evolutionary history of Brachystegia tree species. This genus is particularly emblematic of southern African savannas and woodlands. With roughly twenty species, it is one of the most dominant tree genera in the vegetation belt stretching from Angola to Tanzania: the miombo woodlands (c. 2.7 million km²). Additionally, eight Brachystegia species are also distributed in the African Guineo-Congolian rain forests. This spatial distribution and diversity of species allow the investigation of global biogeographical questions. Namely, how, and when, tree species diversified in African biomes and how plant lineages may have shifted between biomes. Consequently, Brachystegiaas as a broadly distributed genus is a useful system to explore the onset of current African biodiversity. However, Brachystegia is also a taxonomically challenging taxon to work with, as several species are morphologically variable in addition to having blurred species boundaries. Little is known about what influences patterns of morphological variation for these species and may be due either to hybridization, ecotypic differentiation, or phenotypic plasticity.

Recent paper in JBI. Boom, AF, Migliore, J, Kaymak, E, Meerts, P, Hardy, OJ. Plastid introgression and evolution of African miombo woodlands: New insights from the plastome‐based phylogeny of Brachystegia trees. J Biogeogr. 2021; 48: 933– 946. https://doi.org/10.1111/jbi.14051

Motivation behind this paper. Molecular-dated phylogenies using either large taxonomic coverage, or focusing on some key plant taxa, are essential to understand the tempo and modalities of species diversification. In plants, such phylogenetic investigations have been extensively conducted in Europe and northern America, such that generation of major phylogeographic hypotheses on factors affecting lineage diversification in plants are geographically biased. In the Afrotropics, we are increasingly testing these hypotheses developed on other continents to determine their global generality. In comparison to Europe/northern America, African woodlands and savannas are still poorly investigated despite their wide spatial distribution, their functional properties and unique biodiversity, and their key role in Hominid evolution. Brachystegia genus is typical, dominant, and diverse in the miombo woodlands of Africa and is a potentially useful system to gain new insights on the history African savannas and woodlands. We aimed to explore the phylogenetic relationships and corresponding divergence timing at the genus scale among Brachystegia species.

Some of the specimens that were collected in the frame of this study (A, B, and C: Brachystegia spiciformisB. longifolia and B. boehmii). In addition to herbarium vouchers, we also collected leaflets and dried them using silica gel (in D, left to right: B. spiciformisB. longifolia and B. taxifolia). DNA is generally better conserved using the latter approach.

Key methodologies. Our approach used African field collections and herbarium vouchers in combination with high-throughput sequencing technologies. We took advantage of recent advances in molecular biology to extract DNA from ancient plant material and to assemble plastid genomes of 25 different Brachystegia tree taxa. Bioinformatic tools were thus essential to reconstruct the Brachystegia plastid phylogeny, using Bayesian and Maximum-Likelihood methods. To infer the temporal dynamics of Brachystegia diversification, we conducted a two-step dating approach. Firstly, a dated phylogeny covering the Fabaceae family allowed the use of multiple fossils for time calibrations and to estimate the divergence time between Brachystegia and a near-relative genus, Julbernardia. We then applied this divergence time estimate to calibrate the Brachystegia plastid phylogeny.

Major results. Our main contribution is a proposed scenario for the past history of Brachystegia settlements, allowing us to better understand the history of miombo woodlands. In our JBI paper, plastid genomes proved to be very informative for tracking the past dynamics of the genus Brachystegia. In southern Africa, Brachystegia plastid clades appear older in eastern regions than in western ones, suggesting a possible historical westwards expansion of miombo vegetation, during the Plio-Pleistocene. Our results bring explicit insights of the past distribution of one of the largest African woodland types.

Unexpected outcomes. We were particularly surprised that the Brachystegia clades revealed by the plastid phylogeny exhibited a strong geographical structuring independently of their species delineation. Specimens from the same species were rarely monophyletic, except when they were geographically close. This unexpected tree topology could be explained by hybridisation with subsequent backcrosses. This highlights possible cytoplasmic introgression between species that co-occur in the same area and share closely related plastid genomes. To our knowledge, our study is one of the first to report such a phenomenon of spatially dependent introgression in a tree genus from the Afrotropics, but such introgression has been observed in Quercus and Eucalyptus trees in Neartic, Paleartic and Australasian realms.

(left) Miombo woodlands have a closed but not overly dense canopy, allowing the growth of an herbaceous layer. They are dominated by trees such as Brachystegia, Isoberlina, and Julbernardia (Lubumbashi surroundings, Democratic Republic of Congo). (right) Collection of branches and leaves from a Brachystegia tree using a long-reach pruner.

Next steps? Using plastid genomes, we now have a better view about the miombo spatial and temporal dynamics. However, further investigations are needed to provide a dated species phylogenetic tree of the Brachystegia species. We are thus currently sequencing several hundred low-copy nuclear genes, using a targeted enrichment genomic approach. Additionally, by increasing our geographical cover, we would like to deeply investigate the Brachystegia genus developing continuous phylogeographic and phylodynamic inferences using additional plastid sequences. Such investigations would be conducted in a comparative framework using other emblematic trees from miombo woodlands such as Julbernardia and Isoberlina.

If you could study any organism on Earth, what would it be?Without surprise, if I could study any organism on Earth, it would be trees! Through my ongoing PhD thesis, I was particularly surprised by the large knowledge gaps in the phylogeographic history of trees! I am especially interested in tropical trees, which are poorly studied despite their ecosystem engineer role in most of the hotspots of biodiversity. Among the questions coming to my mind: how do tropical and dominant trees diversify? How is such diversity maintained through time? These questions reflect a more global interest on hybridisation and the concepts of plant species. Oaks are particularly interesting in this context as recent genomic and ecological investigations have broader implications on how dominant trees diversify, coexist, cooperate and compete. I am also convinced that tropical taxa can be very promising in evolutionary ecology. Apart from plants, I am also fond of jellyfish, bumblebees, and dinosaurs!

Anything else to add? Collecting plant materials from tropical African species, like Brachystegia, distributed on such a wide spatial scale (18 countries), including narrowly and disjunctly distributed taxa was definitively a challenging aspect of this study. It was also a unique opportunity to discover unforgettable landscapes in Democratic Republic of Congo, to explore precious herbarium collections (BR, BRLU, FHO & LISC), and to develop innovative genome skimming sequencing. Even fairly old vouchers can be of use with such an approach. Indeed, one of the samples used in this study was collected in 1933! Finally, we were helped in many ways during this study, and I’d like to take the opportunity to thank all the people that made this study feasible, researchers, those involved in the field collections, curators and lab colleagues.

ECR Feature: Felipe Camurugi on gladiator treefrog biogeograhy

Felip Camurugi is a postdoc at Universidade Federal do Mato Grosso do Sul. He is a biogeographer with an interest in anurans and their diversity. Felipe shares his recent work on gladiator treefrogs from South American and his tests for the presence (or absence) of cryptic lineages in this species.

Felipe Camurugi in the field, collecting herps. Photo credit: Sandro Paulino.

Personal links. ResearchGate

Institute. Universidade Federal do Mato Grosso do Sul

Academic life stage. Postdoc

Current study system. My main research focus is to explore the roles of landscape heterogeneity on the genetic divergence of anurans from open and dry environments of South America. The gladiator treefrog, Boana raniceps, is distributed at a continental scale, occurring in lowlands of the South American open and dry formations. Therefore, it is an interesting organism to study how past and current landscape changes can affect species’ distributions and gene flow across these environments. In addition, Boana raniceps is a generalist species associated with lentic water bodies of almost all major river basins, which enables the testing of several hypotheses on diversification in the Neotropics.

Recent paper in JBI. Camurugi, F., Gehara, M., Fonseca, E.M., Zamudio, K.R., Haddad, C.F., Colli, G.R., Thomé, M.T.C., Prado, C.P., Napoli, M.F. and Garda, A.A., 2021. Isolation by environment and recurrent gene flow shaped the evolutionary history of a continentally distributed Neotropical treefrog. Journal of Biogeography. 48: 760-772 https://doi.org/10.1111/jbi.14035

Motivation behind this paper. The seasonally dry tropical forest Caatinga, the Cerrado savanna, and the Chaco have a complex geomorphological and climatic history. Only in the past few years have we begun testing the main promoters of genetic divergence and testing new hypotheses about diversification processes for the region. Given the wide distribution of Boana raniceps, which occurs across a broad environmental gradient, we were curious as to whether this “species” actually exhibited cryptic diversification (undescribed species forming a species complex), or, conversely, was an uncommon case of an anuran species with a broad, continental-level distribution. Additionally, this species provided a good system to test classical biogeographic hypotheses of how landscape features have shaped historical and contemporary patterns of genetic variation. 

Gladiator treefrog (Boana raniceps) in northeast Brazil.

Key methodologies. The combination of phylogeographic and landscape genetics tools has increased in the past few years, providing new opportunities to disentangle the relative roles of historical and contemporary processes of landscape changes on connectivity and genetic diversity among populations, and divergence among species. Using several complementary approaches, such as population assignment tests, species distribution models, approximate Bayesian computation, and niche comparisons, we could identify the geographical break of lineages and infer the main mechanisms involved in the processes of population/species diversification.

Major results. Our study suggests that the evolutionary history of the gladiator treefrog, Boana raniceps, was mediated by climatic shifts during the Pleistocene and topographic complexity in central Brazil. We identified two lineages that occupied different environmental niches. These lineages diverged during the mid-Pleistocene (~340,000 years ago) and kept gene flow until Last Glacial Maximum (LGM: ~21,000 years ago). During the dry and cold periods, such as the LGM, areas facilitating connectivity between populations probably shrank, reducing historical gene flow. In addition, Boana raniceps lives in lowland areas, which means that areas with a very complex topography may have hindered the migration of individuals over thousands of years, and together with the contraction of open and dry biomes during LGM, have reinforced the genetic differences within this species. Areas with this profile are located, for example, in the Brazilian Central Plateau region, which coincides with the geographical division between the two lineages. However, the environmental factors that restricted gene flow over years were clearly semipermeable, as the overall genetic divergence among populations was shallow.

Landscapes of open and dry environments of South America: Caatinga.

Challenges and unexpected outcomes. To evaluate divergence among populations of Boana raniceps, we of course needed to obtain specimens from across most of the South American continent! This involved collaborations across many institutes to obtain samples covering most of the species’ distribution. In the end, we obtained a collection of approximately 300 individuals at 115 localities encompassing four countries. Anurans typically have high phylogeographic structure due to their life history strategies, such as a tendency towards philopatry and expected low dispersal ability. Consequently, species of frogs widely distributed are frequently expected to potentially show high levels of cryptic diversity. We were surprised to find that in South American, B. raniceps is a single species that is widely distributed across the continent. Despite evidence of unique, spatially structured lineages, the amount of divergence was weak and shallow. Therefore, this pattern of intense and recurrent gene flow in a highly complex landscape was unexpected.  

Landscapes of open and dry environments of South America: Chaco.

Next steps of this research. The acoustic communication in anurans is an important component in the evolution of these organisms. Thus, the next step in this research is to investigate whether does trait divergence correlates with genetic divergence and whether sexual selection can have reinforced the geographic structure in Boana raniceps. Testing whether B. raniceps females prefer calls from males of their own lineage, or if they can mate indiscriminately, can give us a clue if behavioral isolation is a possible driver of genetic differentiation, in addition to landscape features.

If you could study any organism on Earth, what would it be? I would continue to study amphibians! I am very curious about salamanders. In South America, they are relatively less diverse but still little studied. Since I saw my first Bolitoglossa salamander in the Brazilian Amazon, I’ve wondered about the ecological and historical factors that have shaped the evolutionary history of the genus in the continent. However, my curiosity about salamanders is not regionalized and it would be really cool to study them in any part of the globe.

Water bodies where Boana raniceps can typically be found.

Anything else to add? This research is part of my thesis on the biogeography and evolution of acoustic signals of Neotropical anurans, particularly the gladiator frogs of the Boana albopunctata group. Besides biogeography of amphibians at different scales (from taxa, lineages, and genealogies, for example), the frog calling behavior and its consequences on the evolutionary histories of species is a thrilling theme for me, and having water up to my waist whilst recording and collecting frogs always makes for a great time in the field. Currently, I am combining my interests in the natural history of amphibians with genetic data to explore the roles of landscape features and biotic interactions as drivers of genetic divergence at a community level.

ECR Feature: William Nanavati on monkey-puzzle trees and global change

William “Buzz” Nanavati is a postdoc at Portland State University. He is a palaeoecologist and biogeographer, interested in how environmental changes through time affect ecosystems. William shares his recent work on previous climates and land-use change on the dynamics of monkey-puzzle forests in Patagonian.

William “Buzz” Nanavati, a monkey-puzzle tree, and a canine companion (Eddy Nanavati).

Personal links. Web page | Twitter

Institute. Global Environmental Change Lab, Department of Geography, Portland State University

Academic life stage. National Science Foundation Postdoctoral Fellow

Research themes. I focus on palaeoecology, biogeography, and the nonlinear, interacting relationships between fire, climate, humans and the environment through time.

Current study system. My current research focuses on the environmental histories of two regions: the forest-steppe ecotone of Patagonia, Argentina and Chile, and forests of the western Cascade Mountain Range in Pacific Northwest of the United States of America. Forest-grassland transitions (or ecotones) in temperate latitudes are regions that are sensitive to natural (i.e., climate-driven) and anthropogenic pressures and are thus valuable for understanding ecosystem dynamics under changing climate and disturbance regimes. In these biomes, forest is typically promoted by high levels of moisture and/or low fire activity, whereas in drier settings, grassland is maintained by seasonal or annual moisture deficits and/or high levels of burning.

Recent paper in JBI. Nanavati, William, Cathy Whitlock, Valeria Outes, and Gustavo Villarosa. “A Holocene history of monkey puzzle tree (pehuén) in northernmost Patagonia.” Journal of Biogeography (2020). https://doi.org/10.1111/jbi.14041

A pollen grain of Araucaria araucana.

Motivation behind this paper. In our recent paper, we try to provide a better understanding how changes in climate and land use have altered monkey-puzzle tree (pehuén; Araucaria araucana) forest ecosystem dynamics through time. We believe that by better understanding such complexities in socioecological history, we can better interpret management goals in the face of future disturbance and climate change. Recognizing the Patagonian forest-steppe ecotone as a mosaic of nearly-pristine and humanized landscapes can provide a pragmatic guide for land management strategies and intensities, where natural processes can be left to play out in nearly-pristine landscapes, while active management of humanized landscapes can either restore ecosystems to nearly-pristine states or preserve cultural landscapes, dependent on the decisions of stakeholders and community members. As land use increases throughout Patagonia and anthropogenic global warming changes climate conditions at an alarming rate, we believe that combined paleoecological-archaeological efforts can help inform projections of future ecosystem dynamics and guide management decisions to protect native ecosystems.

This picture was taken near the Laguna Portezuelo paleoecological site in northwestern Neuquén, Argentina. It features an open monkey-puzzle (pehuénAraucaria araucana) forest at its northeasternmost border with grass (Poaceae) steppe. Antarctic beech (ñireNothofagus antarctica) is in the foreground and the Copahue stratovolcano is in the background.

Key methodologies. Sedimentary pollen and charcoal from Laguna Portezuelo (37.9°S, 71.0°W; 1730 m elevation; 11,100 cal yr BP bottom date) were compared with other paleoecological, independent paleoclimate, and historical records to assess how changes in climate and land use influenced local-to-regional environmental history. An important aspect about this study is its reliance on high-resolution pollen and charcoal counting that facilitates nearly decadal interpretation of change in local vegetation and fire history for the last 1000 years. By focusing our analyses at such a high resolution, it made it much easier for us to compare our results with historical and dendroecological research from the region.  

Major results. Araucaria was present in the central valley of Chile during the last glaciation until rapid postglacial warming and drying limited its distribution in the valley. In the middle and late Holocene, decreased temperatures and greater seasonality and El Niño-Southern Oscillation activity increased precipitation variability allowing Araucaria expansion at its north-eastern limit, near Laguna Portezuelo. Greater abundance of Araucaria and heightened fire activity at Laguna Portezuelo after about 440 years ago coincided with increased Mapuche-Pehuenche American Indian land use, suggesting that Araucaria may have been managed in a human-altered landscape. Our results suggest that past American Indian land use likely altered natural ecosystem dynamics at local-to-landscape spatial scales in northernmost Patagonia. Variations in human land-use intensity and location in the late Holocene likely created a mosaic of landscapes that ranged from the nearly pristine to highly altered prior to European arrival.

Unexpected outcomes. There were two unexpected results that came out of this study: (1) Araucaria migrated into the Laguna Portezuelo watershed relativity recently, with sporadic presence between from 6500 to 440 years ago, when its presence increased coincident with increased fire activity and an influx of Mapuche peoples east of the Andes. We attribute the arrival and expansion of Araucaria in the Laguna Portezuelo watershed to wetter-than-before middle- and late-Holocene conditions and, possibly, American Indian management. (2) Non-native, Eurasian taxa likely arrived in the Laguna Portezuelo watershed prior to Euro-American settlement, this supports the hypothesis that the spread of non-native plants outpaced Euro-American settlement in the Patagonian forest-steppe ecotone.

This photo depicts the dry, shrub-steppe that dominates east of the forest-steppe ecotone in Patagonia, near Tecka, Chubut, Argentina.

Next steps. We intend to compare changes in postglacial vegetative composition and fire activity with simulations of ecosystem dynamics. These comparisons could determine where and when the vegetation and fire history of individual sites does not match simulated climate-fuel-fire relationships. Anomalous events recorded in the paleoecological data could be compared with the archaeological record to determine if land use explains the deviation from the model and if so, to what extent land use altered ecosystem dynamics. Furthermore, following model validation through data-model comparison, we hope to co-develop model simulation scenarios with local land managers and community members to inform land management decisions in Araucaria forest ecosystems.

If you could study any organism on Earth, what would it be? I would probably pick the most confusing one of them all: humans! I am specifically interested in how we interact and coevolve with our environments. Humans had and will continue to have an incredible imprint on the environment. Hopefully by better understanding linkages between climate, humans, vegetation, and fire, we can help inform management and policy decisions that lead to a more sustainable future.

ECR feature: Taís F. R. Guimarães on the sea-level impact on coastal lagoon fish communities

Taís F. R. Guimarães is a postdoc at the Universidade Federal de Viçosa (UFV) in Brazil. She is an ecologist interested in elucidating spatio-temporal processes affecting the community of freshwater fishes. Here, Taís shares her recent work on the effect of sea level on the beta diversity of coastal lagoon fish communities in South America.

Taís presenting the preliminary results of this study at the 2nd Meeting of the Brazilian Association of Ecological Science and Conservation (RABECO) and the 6th edition of the Theoretical Ecology Symposia (SET) organized by the University of Campinas in September of 2018 in Brazil.

Personal links. Research Gate

Institute. Universidade Federal de Viçosa (UFV) – Brazil

Academic life stage. Postdoc

Major research themes. Landscape ecology, community ecology

Current study system. I am currently a postdoc at the Rio Doce Aquatic Biodiversity Monitoring Program. In this project, we evaluate the effect and implications of an iron ore tailings dam breach on the fish community from the Doce River basin, southeastern Brazil. What makes this study interesting is that entire fish populations died immediately after the disaster, and we are responsible for monitoring and evaluating how the restocking process is happening along this river basin.

Recent JBI paper. Guimarães, T. de F. R., Petry, A. C., Hartz, S. M., & Becker, F. G. (2021). Influence of past and current factors on the beta diversity of coastal lagoon fish communities in South America. Journal of Biogeography, 48(3), 639–649 https://doi.org/10.1111/jbi.14029

Sampling the ichthyofauna in the Itapeva lagoon, Rio Grande do Sul, southern Brazil.

Motivation behind this paper. Although the study was part of my doctoral thesis, I’ve been studying coastal lagoon fish communities since my undergrad. My motivation for the development of this study came from a need to understand how the colonization process by the fish community happened during the formation of the lagoons along the Atlantic coast of South America. Several studies point to the importance of the sea-level fluctuations since the Last Glacial Maximum (LGM) impacting populations and communities of freshwater fishes in coastal streams. From reading these works, I asked myself if these historical sea-level changes could affect the ichthyofauna of geologically more recent environments, such as lagoons that are considered geologically younger than the streams. These coastal lagoons are situated in a portion of the continental shelf that was covered by the sea during the last marine transgression. After a reduction in the sea level to its current level, this area was exposed, allowing the establishment of freshwater environments around 5k years ago. Thus, in this study, I aimed to identify if there is a historical sign from the LGM on the fish diversity in coastal lagoons.

Key methodologies. In this study, we combined methodologies that have been applied in other studies to infer the impact of historical and contemporary factors on the beta diversity of coastal lagoon fish communities. For example, we used a bathymetric shapefile to project the coastline during the LGM event. Based on sea-level fluctuation estimates over time, we measured the amount of time these current drainages are isolated. We also used a night light image as a proxy of physical and biotic anthropogenic influence on coastal lagoons. Combining these data with species occurrence in 129 lagoons along the Atlantic coast, we were able to disentangle the effect of current and past factors in shaping the ichthyofauna diversity.

The Preta lagoon (left of the photo) and its proximity to the sea (right of the photo) at Parque Nacional da Restinga de Jurubatiba, Rio de Janeiro, southeastern Brazil.

Unexpected challenges. The first challenge was to compile and organize the ichthyofauna data. It was challenging to bring together data from different papers and contact researchers. The Geographic Information System (GIS) portion of choosing and manipulating the images to extract the required variables also needed dedication and study. Another major challenge was the data analysis, and I’m grateful to the manuscript reviewers who provided essential contributions to increase the power of the statistical analysis. Anyway, the whole development of this research was a learning process and a lot of dialogue between the co-authors. The final result was gratifying.

Major results. In this study, we provided evidence that the signal of past biogeographical events, such as connectivity between currently isolated drainages due to sea-level retreat, might be present in freshwater environments, even in communities that were supposedly formed at more recent geological times. A broader implication of these results is that high regional beta-diversity can be rapidly generated, even in regions and ecosystems of relatively recent origin, such as coastal plains and freshwater coastal lagoons. These lagoons were formed about five thousand years ago, being recolonized by freshwater fishes’ species that persisted in landscape refuges during past sea level increases.

Emboabinha lagoon, Rio Grande do Sul, southern Brazil.

Next steps for this research. The biogeographic and paleobiogeographic history of coastal lagoons is complex, and past conditions are challenging to measure. Thus, the next step in this research is to test different quantitative metrics of past habitats, such as obtaining paleosalinity from water bodies, estimate the area and spatial configuration of the lagoons during the LGM. These metrics can capture distinct characteristics of the past landscape, adding new insights for understanding current diversity patterns. However, perhaps it is more urgent to pay attention to the processes that are currently taking place. In recent years, the presence and expansion of exotic fish species have increased in lagoons and rivers. For this reason, another next step should be to identify the routes of dispersion for these invasive alien species to mitigate or prevent changes in the community.

If you could study any organism on Earth, what would it be? I would continue to study fishes. I like fishes because they are “mysterious” in the sense of being unseen organisms because they are underwater and out of sight. Also, they are often neglected in conservation strategies, especially in Brazil.

Negra lagoon, Rio Grande do Sul, southern Brazil

Anything else to add? The manuscript had contributions from many friends who heard my ideas and helped me to develop them. I believe that these non-formal conversations contributed a lot and provided new insights during the elaboration process. The reviewers’ comments and criticisms were also very important for the final result of the study.

ECR Feature: Magdalena Nagler on methanogenic archaeal assemblages

Magdalena is a postdoc at the Institute of Microbiology, University Innsbruck, Austria. She is a microbial ecologist interested in the ecosystem services and industrial applications of micro-organisms. Magdalena shares her recent work on characterising different methanogenic archaeal assemblages from stream habitats across Europe.

Personal links. Twitter | Webpage

Institute. Institute of Microbiology, University Innsbruck, Austria

Major research themes. Microbial ecology all-rounder, highly interested in anaerobic habitats and organisms, especially methanogenic archaea and anaerobic fungi, both potential key players when it comes to full exploitation of resources in renewable energy production.

Current study system. I work on the growth requirements and exploitation potential of Neocallimastigomycota, a group of archaic, anaerobic fungi. This group of fungi was originally found in the bovine rumen and is known to produce a large set of enzymes with the potential to break down otherwise hard-to-degrade plant fibres. Knowing the needs of these microorganisms will allow better utilisation of natural resources in anthropogenic context, such as how to more efficiently use maize or corn straw in renewable energy production (e.g., biogas or bioethanol).

Ora, northern Italy

Recent paper in JBI. Nagler, M, Praeg, N, Niedrist, GH, et al. Abundance and biogeography of methanogenic and methanotrophic microorganisms across European streams. J Biogeogr. 2021; 48: 947– 960. https://doi.org/10.1111/jbi.14052

Motivation behind this paper. During my PhD, I became part of a collaborative European freshwater science project for early career researchers that aimed to study CO2 fluxes from European running waters (EuroRun). This led to a follow-up project focussing on sediment methane production in streams (EuroMethane). Utilizing the network of early career scientists from all over Europe, many streams could be sampled within a short time span, providing an exciting sample set that allowed us to investigate the role of these ecosystems in carbon cycling and retaining heavy metals. Having a solid background in microbial biogeography, microbial community analyses and methanogenic archaeal assemblages, I elaborated a concept together with project leader, Pascal Bodmer, to directly investigate how methanogenic and methanotrophic microorganisms contribute to methane production and oxidation rates of stream sediments across Europe.

Sampling of stream sediments using cut-off syringes.

Key methodologies. The first key methodology was the simultaneous sampling of 16 rivers in 10 European countries that required a lot of coordination to have everyone on the same track and ensure comparable results. During sampling, we aimed to gather as much information as possible on fine and large scale environmental constraints of each sampling point, so that we could link those factors to certain microbial community compositions. Fine scale variables included, for example, sediment grain size, nutrient availability and physico-chemical conditions; large-scale variables involved the characterisation of land-use types within the river’s catchment and of the river’s general ecological and hydrodynamic features.

The big aim of our study was a holistic examination of the sediment-associated methane-cycle that involved not only a direct measurement of potential methane production and oxidation, but also a qPCR-based direct quantification of genes associated to methane -producing and -oxidizing microorganisms coupled with an in-depth 16S rDNA-based taxonomic characterisation.

Major results. Methanogenic and methanotrophic communities mainly grouped into three habitat types, namely (I) warm streams with large stream areas, draining catchments with high proportions of agricultural and urban land cover, (II) cold, medium‐ to small‐sized streams with less agricultural and urban land use within their catchment and (III) high‐order and high discharge streams draining large catchments. Such distinguishable microbial communities suggest that future climate‐ and land use changes may influence the prevailing microbes involved in the stream‐related methane cycle. Increasing water temperatures from climate change, in combination with agricultural intensification and urban land use, might thereby lead to higher abundances of highly efficient hydrogenotrophic methane producers (i.e., Methanospirillaceae,Methanobacteriaceae and Methanosarcinaceae). It is still unclear how increasing anthropogenic disturbances might affect methane consumers, but we believe that there will be a net increase of methane released from streams in the future.

Unexpected outcomes. When we compared the qPCR data to the measured methane production and oxidation rates, we found a significant relationship between methanogenic archaeal abundance and potential methane production, but failed to find a relationship between methanotrophic bacterial abundance and methane oxidation potentials. We argued that this discrepancy might arise from the heterogeneity of microorganisms with the capacity to oxidize methane. This group not only includes bacteria, but also some recently described anaerobic methane oxidizing archaea (ANME). Most of these microorganisms are not exclusively oxidizing methane as source of energy, but can perform other ways of energy production, which would obscure the signal between the abundance of methanotrophic microogranisms and the measured methane oxidation potential. This hypothesis has yet to be tested!

Tratzberg, Austria

Next steps. We are currently working on an article processing the findings from CO2 flux measurements from running waters (EuroRun). The measurements were performed during day and night and clearly showed that streams emit more CO2 at night, a fact that so far has not been considered in global CO2-budget calculations. We are also working on a second article of the EuroMethane project, which focuses on the magnitudes and drivers of methane production and oxidation in streams across Europe.

If you could study any organism on Earth, what would it be? The holy grail of any mycologist is to reveal the secret about fruiting body development in edible, but not yet cultivable mushrooms such as Boletus edulis. Unfortunately, this is currently not my expertise, but if I could, I would jump right into disclosing this secret that might finally satisfy my craving for fresh porcini!

ECR feature: Elizabeth Joyce on floristic exchange tracks

Elizabeth Joyce is a PhD candidate at the Australian Tropical Herbarium & James Cook University. She is an evolutionary biologist interested in the origins of the northern Australian flora. Here, Lizzy shares her recent work on the routes used by plants to disperse between Australia and Southeast Asia.

Elizabeth Joyce during fieldwork to collect Aglaia elaeagnoidea in the Kimberley, north-western Australia.

Personal links. Twitter | Research Gate

Institute. Australian Tropical Herbarium & James Cook University

Academic life stage. PhD Candidate

Major research themes. Broadly, I am interested in how Earth’s biodiversity has come to be the way it is today. My PhD research has focused on understanding the exchange of flora between the Sunda continental shelf (mainland Asia and parts of Indonesia and the Philippines) and Sahul continental shelf (Australia and New Guinea) across Wallacea throughout the Cenozoic. I have been exploring the drivers of the Sunda-Sahul Floristic Exchange and the effect that it has had on the assembly of the flora throughout Southeast Asia and northern Australia.

Close-up of the fruit of Aglaia elaeagnoidea from the Cape York Peninsula, Australia (Photo by John Elliott, reproduced with permission).

Current study system. I love working across scales and lineages to understand evolution, but the bulk of my research focuses on lineages within the order of flowering plants Sapindales. This is an order of nine families and around 6,550 species, including citrus, mahogany, cashew, mango, pistachio, frankincense, myrrh, lychee and maple, as well as many groups important for medicinal compounds. It’s a fascinating group for studying the dynamics of the Sunda-Sahul Floristic Exchange because of its species richness in the tropics, as well as its morphological and ecological diversity.

Recent paper in JBI. Joyce, E.M., Pannell, C.M., Rossetto, M., Yap, J.‐Y.S., Thiele, K.R., Wilson, P.D. and Crayn, D.M. (2021) Molecular phylogeography reveals two geographically and temporally separated floristic exchange tracks between Southeast Asia and northern Australia. Journal Biogeography, 48(5), 1213-1227. https://doi.org/10.1111/jbi.14072

Distribution map of Aglaia elaeagnoidea; the shaded area represents the known distribution of A. elaeagnoidea, and the dots represent the 129 A. elaeagnoidea specimens sampled for this study. The Kimberley and Cape York Peninsula of northern Australia are outlined (Image taken from the article published in Journal of Biogeography).

Motivation behind this paper. When considering the migration of Southeast Asian plant lineages into northern Australia, it was previously assumed that exchange has only occurred between New Guinea and the Cape York Peninsula of north-eastern Australia. However, there is evidence that fauna and humans have also entered Australia from Southeast Asia via north-western Australia (a region called the Kimberley). Additionally, the Kimberley is known to have many plant species in common with Southeast Asia. So we wanted to test: did these plants reach the Kimberley via one exchange track between New Guinea and the Cape York Peninsula prior to spreading across northern Australia, or is there a second floristic exchange track between Southeast Asia and the Kimberley?

Key methodologies. To investigate exchange tracks between Southeast Asia and northern Australia, we conducted a molecular phylogeographic case study on a species of a tropical tree called Aglaia elaeagnoidea (in Meliaceae, the mahogany family), which is distributed from India, throughout Southeast Asia, in the Kimberley and Cape York Peninsula of Australia and out into the Pacific islands. We used Single Nucleotide Polymorphisms (SNPs) obtained using DArT-seq from samples across the range of A. elaeagnoidea and conducted a variety of population genetic analyses. In conjunction with this, we did some Environmental Niche Modelling of the Last Glacial Maximum when sea levels were lowest between Southeast Asia and Australia to understand where suitable tracks of environment for A. elaeagnoidea might have been at that time. A particularly nifty thing about this study is that we obtained most of our samples from herbarium specimens, including a specimen collected by Robert Wight almost 200 years ago!

Dr. Caroline Pannell (the monographer of Aglaia; left) and Elizabeth Joyce (right) looking through the Aglaia collection at Kew Herbarium in 2019 for sampling (Photo by Marija Joyce, reproduced with permission).

Unexpected challenges. An interesting result (although not entirely unexpected) was that Aglaia elaeagnoidea, as currently circumscribed, actually comprises more than one species. We did anticipate this might be an outcome due to the notoriously difficult-to-wrangle morphological variation of Aglaia. We were able to account for the separate species in our sampling thanks to the previous taxonomic work by Dr. Caroline Pannell and previous phylogenetic work on the genus led by Prof. Alexandra Muellner-Riehl. Therefore we were still able to identify the samples relevant to our question of exchange tracks between Southeast Asia and Australia and continue our work. We are currently in the process of writing up the taxonomic implications of this study in a separate paper. We also learned plenty about using herbarium specimens for a phylogeographic study, particularly about which specimens we could and could not retrieve DNA from – lots of lab-work trial and error was involved! We found that the storage conditions of the specimens, as well as the plant collection method, had a huge impact on the quality and quantity of DNA we were able to extract. It was usually impossible to extract useful DNA from specimens that had been stored in tropical conditions for many years or those that had been collected into alcohol. Interestingly, treatment with mercury or gamma irradiation didn’t seem to have as much of an impact and we could often extract DNA from these sheets suitable for DArT-seq. After sampling hundreds of herbarium specimens we were able to pick which herbarium specimens were going to work by eye. The simple, but effective rule of thumb is: the greener the specimen, the better the DNA.

Image of the Aglaia elaeagnoidea specimen collected by Robert Wight in India in 1835 from which we were able to extract DNA and include in this phylogeographic study (Image courtesy of the C. V. Starr Virtual Herbarium of the New York Botanical Garden, http://sweetgum.nybg.org/science/vh/).

Major results. We found that Aglaia elaeagnoidea has two exchange tracks between northern Australia and Southeast Asia: a contemporary track (with ongoing gene flow) between New Guinea and the Cape York Peninsula of north-eastern Australia, and a historical exchange track (with no ongoing gene flow and relatively high genetic differentiation) between Timor-Leste and the Kimberley of north-western Australia. We also found that the climate fluctuations throughout the Quaternary likely induced repeated expansion-contraction cycles in A. elaeagnoidea throughout its range, which is likely to have caused the high degree of genetic structuring that we observed throughout Southeast Asia. These findings support the idea that the Kimberley, Top End and Cape York Peninsula have had independent evolutionary histories, but not just because the biogeographic barriers across northern Australia prevent gene flow between them, but because they have also had separate incursions of Southeast Asian lineages through these exchange tracks. It also emphasizes the complexity of the phylogeography of Southeast Asia, and suggests that movement across the region has been reticulate and iterative with climate fluctuations (especially in the Quaternary). The genetic structuring this leads to might promote speciation and could have contributed to the diversity of the region.

Next steps for this research. This study has raised so many questions! Firstly, the pattern we observed of multiple exchange tracks needs to be tested on other plant lineages, including lineages that are also present in the Top End (Northern Territory) of Australia to see whether it applies at a floristic scale. Secondly, more work needs to be done to understand fully how these exchange tracks have affected northern Australian phytogeography, and whether there is any signature of this also affecting the phytogeography of southern Australia. Our results support the idea that the Kimberley, Top End and Cape York Peninsula have had independent evolutionary histories, but has there been any relationship between these three northern Australian regions with southern Australia? How often do Southeast Asian lineages get into southern Australia and how do they get there? Investigating the relationship between northern Australian phytogeography and southern Australian phytogeography could give us vital clues for better understanding the timing and nature of the aridification of Australia. Finally, the role of animal dispersers in maintaining the exchange tracks between northern Australia and Southeast Asia – particularly fruit pigeons like the Pied Imperial Pigeon (Ducula bicolor) – also needs to be tested. Fruit pigeons such as these are likely to have played a major role in these exchange tracks – and rainforest phylogeography in the region more generally – yet we know hardly anything about their dispersal ecology!

A pair of Pied Imperial Pigeons, the only known dispersers of Aglaia elaeagnoidea on the Cape York Peninsula (Photo by Elizabeth Joyce).

If you could study any organism on Earth, what would it be? How does anyone answer this question!? I really love comparative studies and think they’re hugely insightful, so studying large groups of organisms like the angiosperm order Sapindales gets me excited and is the focus of my current phylogenomic research. Still, if I had to pick only one organism to study right now, I would switch to ‘the dark side’ of animals and study the Pied Imperial Pigeon. But only for plants’ sake! The influence of these guys as dispersers on the phytogeography and phylogeography of Australian and Southeast Asian rainforests, as well as the Sunda-Sahul Floristic Exchange, is likely to be immense, and we really don’t know enough about them. I would love to study the dispersal ecology of these pigeons and their correlations with plant evolution and biogeography.

Caves, biogeography and tiny arachnids

Palpigrades are as precious as pebbles from the Moon … hidden in the deepest fractures of rocks of caves and other kinds of subterranean habitats.

Above: A cave-dwelling palpigrade found in an Alpine caves. Photo: Alberto Chiarle

The Austrian professor Dr. Erhard Christian, one of the few experts worldwide on the taxonomy of the enigmatic arachnid order of Palpigradi (microwhip scorpions), used to say that “palpigrades are as precious as pebbles from the Moon”. Now that Americans and Chinese are chauffeuring different rovers around Mars, we should probably revise this quote and match the new incredible advances of space technology because palpigrades remain very precious organisms, especially in zoological collections around the world.

Cover article: (Free to read online for a year.)
Mammola, S., Souza, M.F.V.R., Isaia, M. and Ferreira, R.L. (2021), Global distribution of microwhip scorpions (Arachnida: Palpigradi). J Biogeogr. 48:1518–1529. https://doi.org/10.1111/jbi.14094 

The rarity of palpigrades is a fact: apart from a few relatively common species traveling around the world with the soil used in greenhouses (e.g., Eukoenenia mirabilis, the first palpigrades ever described in 1885), most palpigrades live hidden in the deepest fractures of rocks of caves and other kinds of subterranean habitats. Very few researchers have seen them alive. Some lucky subterranean biologists accidentally find them trapped in secluded water ponds or in the footprints that speleologists left in the mud covering the ground of the deepest parts of caves. And there is where the magic happens: some tiny flashing on the water ponds and a closer look reveal the presence of a clumsy and fragile long-tailed organism of less than 1 millimeter, struggling to remain atop the water surface—but perhaps also taking advantage of the possible prey sharing their secluded retreat (https://doi.org/10.1038/s41598-021-84521-1).


Eukoenenia strinatii dwelling on the surface of a pond in a remote section of the Bossea cave, in Piedmont (NW-Italy) Photo: Alberto Chiarle

When you tell such a story to a wildlife photographer keen on arthropods, the endeavor becomes even more challenging: first you have to find the palpigrades and, second, you necessarily have to squeeze the photographer and their one-thousand dollar equipment into the hairline-crack-like entrance of the cave where the palpigrade lives. The wonderful cover photograph of the Journal of Biogeography issue hosting our research is the successful outcome of such a caving trip, embellished by the use of a U.V. lamp to illuminate a specimen of Eukeonenia strinatii, a specialized species inhabiting a very few caves in the South-Western Italian Alps. For this picture we took advantage of the propriety of the cuticle of the palpigrades to reflect UV light (https://doi.org/10.1111/jzo.12493). The specimen was photographed by Emanuele Biggi in the Bossea cave in Piedmont (NW-Italy) which is also the so-called “type locality” of this species, namely the place where it was first collected and described.


A microwhip scorpion under U.V. light. Photo: Emanuele Biggi.

In this paper, we examined the global distribution of these tiny creatures, asking ourselves about their typical range size, the ecological factors driving their distributions, and to what extent sampling bias may influence the observed patterns. Despite their rarity, we manage to assemble a dataset of over 1,000 localities of more than 120 species. This led us to test for differences in range sizes of soil- and cave-adapted species and to explore how different factors such as climate, nutrient availability, and geology drive the observed distribution patterns. In asking whether the pattern we detected should reflect the distribution of experts rather than palpigrades themselves, we verified the so-called people-species correlation, i.e. whether the number of occurrence records and the number of palpigrades’ researchers was related (a ‘palpigradologist effect’). We also found the typical range of any species of palpigrade is very small, only 0.01 km2. Europe and Brazil are the most relevant centers of diversification of cave-dwelling palpigrades, while soil species are mostly distributed over a broader geographical range, mainly in the Southern Hemisphere. The distribution of palpigrades seems to primarily match specific climatic conditions and historical biogeographic factors.

However, all these observations are inevitably generic, not only because of the global scale of our study, but also because we are just scraping the surface about the distribution of these enigmatic organisms. We see this study just as a start, a jumping-off point for future studies on the ecology and conservation of these poorly known organisms. There are certainly so many surprises in store into the fractures of rocks, in the voids among particles of soils, and in the darkest recesses of caves.

Written by:
Prof. Marco Isaia (University of Turin, Italy)
Dr. Stefano Mammola (Finnish Museum of Natural History, Finland ; National Research Council, Italy)

Additional information:
Twitter: @Italian_Spiders ; @stefanomammola1
https://www.cnr.it/en/people/stefano.mammola
https://www.unito.it/persone/marco.isaia

From Europe to India – A little investigated route of migratory birds

Overcoming multiple setbacks, and teaming up with researchers from across Europe, finally brought insight into the previously mysterious travels of the common rosefinch.

Above: A male common rosefinch equipped with a 0.5 gram light-level geolocator
(Photo credit: Benjamin Metzger)..

To me, the common rosefinch is still a rather exotic bird species. In the last decades the bird with its iconic song that is often rendered as “pleased to meet you” (check it out yourself), has expanded its huge breeding range westwards, and we have seen small populations emerging at new sites in Europe. During my undergraduate studies, my friend and co-author Roland Neumann was investigating a population at the Baltic Sea Coast. Since very little was known about their routes and their destinations, he was catching and banding individuals with the hope to get resightings from their wintering sites or from any location during their migratory journey. Unfortunately, the massive efforts didn’t pay off.

Editors’ Choice article: (Free to read online for a year.)
Lisovski, S., Neumann, R., Albrecht, T., Munclinger, P., Ahola, M.P., Bauer, S., Cepak, J., Fransson, T., Jakobsson, S., Jaakkonen, T., Klvana, P., Kullberg, C., Laaksonen, T., Metzger, B., Piha, M., Shurulinkov, P., Stach, R., Ström, K., Velmala, W. and Briedis, M. (2021), The Indo-European flyway: Opportunities and constraints reflected by Common Rosefinches breeding across Europe. J Biogeogr. 48:1255–1266. https://doi.org/10.1111/jbi.14085 

We were thus super excited that, in collaboration with the Swiss Ornithological Institute and co-funded by the German Ornithologists’ Society, we could deploy light-level geolocators on male rosefinches in 2011. These devices were still somewhat new in the sense that they have just gotten small enough to use on a 25g bird such as the common rosefinch. Those so called geolocators record light intensity that can be used after recapture and download of the data in the following year, to approximate their migratory journeys. At the same time, we were in close contact with colleagues from Czechia also working on this species and equally thrilled to deploy these loggers on some of the individuals from their Bohemian Mountain populations.

Fieldwork went exceptionally and we had almost an entire year to make plans for the next field season in which we needed to especially look out for returning birds with geolocators, recapture them and retrieve the data containing so much information and the answer to our main questions of the birds’ whereabouts outside the breeding season. Both in northern Germany and in Czechia, we recaptured around 30% of the individuals (a reasonable return rate and the sample size we hoped for) just to learn that none of the devices recorded any data! Obviously, quite a downer that required some time to digest and to even think about rosefinch migration again. Yet, we decided to give it another go and repeat the study in 2013. This time we succeeded and collected useful data from several individuals.


Roland Neumann and Benjamin Metzger banding and measuring common rosefinches in the dunes of the Baltic Sea in Germany (left). Tomas Albrecht and Jaroslav Cepak preparing their mobile lab after a successful catch of rosefinches in the mountains of Bulgaria (right). (Photo credit: Simeon Lisovski, Pavel Munclinger)

In the meantime, we learned that other research groups from across Europe were also collecting migration data from rosefinches. Colleagues from Finland deployed geolocators on males breeding as far north as Oulu (65°N), a Swedish research team collected tracks from males in southern Sweden, and besides the German and Czech data, Bulgarian colleagues were also successful in tracking rosefinches from their southern European breeding site (41°N). Since all of us were dealing with rather small sample sizes (3-10 tracks), we were all easily convinced and excited to pool the data allowing us to not only investigate population specific migration pattern in isolation but extend our objectives towards a flyway wide approach. Now, we saw the opportunity to identify general migration routes, bottlenecks as well as barriers on the so far understudied Indo-European flyway.

Inspired, by previous large-scale research on the effects of wind on bird migration (Kranstauber et al. 2015 Ecology Letters) we constructed simple theoretical migration models that optimized the routes with respect to wind and resource availability during migration. These theoretical tracks revealed interesting patterns with seasonally specific bottlenecks such as the areas south of the Caspian Sea during spring migration. The comparison between the theoretical tracks and the collected empirical tracks also showed that rosefinches seem to make use of the straighter winds from India to Europe during spring, probably allowing for fast and direct migration to the breeding sites, while engaging in larger detours during autumn following the routes that provide highest security in terms of resources.

To me, this study shows how valuable even small and local studies can be, if seen as puzzle pieces helping to reveal the larger picture. Obviously, this needs an open and collaborative network of researchers which I am very glad to have encountered during this project. I would like to thank all of my co-authors for sharing not only their data but for providing their insights into the study systems, for fruitful discussion, for pushing me hard to explain the modeling approach and forcing me to meet empirical fieldwork and theory halfway!

Written by:
Simeon Lisovski, Postdoctoral researcher, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Potsdam, Germany

Additional information:
@S_Lisovski