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1. Complex patterns of Gondwanan biogeography revealed in a dispersal‐limited arachnid

   https://doi.org/10.1111/jbi.14080  

   Derkarabetian, Shahan ; Baker, Caitlin_M ; Giribet, Gonzalo ( March 2021 , Journal of Biogeography)

   We explore the biogeographic history of the Gondwanan lineage Triaenonychidae, a dispersal‐limited arachnid taxon that underwent a recent taxonomic revision based on phylogenomic data. We explicitly test hypotheses related to a biogeographical pattern of ‘common vicariance, rare dispersal’, predicted for dispersal‐limited taxa.

   Continental landmasses of former temperate Gondwanan terranes (southern South America, southern Africa, Madagascar, Australia, New Zealand, and New Caledonia).

   Triaenonychidae, Opiliones, Arachnida.

   Utilizing a recently published phylogenomic data set based on ultra‐conserved elements, we conduct Bayesian divergence dating analyses, ancestral area estimation in a likelihood model testing framework, and analyses of macroevolutionary dynamics. Results are correlated with geological history and palaeoclimate reconstructions to infer biogeographic history and distribution.

   We find that divergence dates of ancestral Triaenonychidae pre‐date continental breakup of Gondwana and could be attributed to palaeoclimatic differentiation across Gondwana. There is evidence for two separate expansion routes that span eastern and western Gondwana corresponding to northern warmer climate and southern cooler climate lineages. Many divergences across intercontinental lineages coincide with the timing of continental fragmentation, supporting vicariance as a dominant force. However, some lineages are supported as obvious examples of rare long‐distance dispersal. Biogeographic results support the predicted pattern of common vicariance and rare dispersal for these dispersal‐limited organisms.

   Vicariance due to continental fragmentation was important in the early diversification of Triaenonychidae. Their unique combination and degrees of dispersal ability and microhabitat preference resulted in complex phylogenetic patterns of geographic distribution not typically seen in other animal taxa. Examining biogeographic patterns across recent studies of arachnid taxa with varying dispersal ability, it is clear that biological characteristics play an important role in the relative importance of dispersal and vicariance (dispersal–vicariance continuum) for any given taxon and can be useful in forming testable a priori hypotheses.

    

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2. Shifting ecosystem connectivity during the Pleistocene drove diversification and gene‐flow in a species complex of Neotropical birds (Tityridae: Pachyramphus)

   https://doi.org/10.1111/jbi.13862  

   Musher, Lukas J. ; Galante, Peter J. ; Thom, Gregory ; Huntley, Jerry W. ; Blair, Mary E. ( April 2020 , Journal of Biogeography)

   We aim to test the biogeographic drivers of diversification and gene‐flow at the Isthmus of Panama using a species complex of suboscine birds as a case study. We specifically evaluate whether diversification in these birds is better explained by continuous parapatry or a Refuge Model of periodic isolation and gene‐flow due glacial cycling.

   The Isthmus of Panama (Neotropics).

   Pachyramphus aglaiaeandPachyramphus homochrous(Aves: Tityridae).

   We develop an approach to distinguish among the two biogeographic hypotheses—parapatric ecological speciation versus climatically mediated speciation—by making explicit predictions for demographic history, niche evolution and change in geographic connectivity over time. We sequenced genome‐wide markers (ultraconserved elements) to estimate the evolutionary and demographic history of this group. We applied both phylogenomic network analyses and demographic modelling using a supervised machine learning approach. These genetic analyses were combined with a novel distribution modelling method that estimates the probability of interspecies contact as a function of climatic conditions through time.

   We found that both spatial and genetic analyses revealed concordant results. All speciation events occurred during the Pleistocene and were characterized by non‐continuous gene‐flow, supporting a scenario of climate‐mediated diversification. Spatial connectivity was highest at present, consistent with our best demographic model of secondary contact.

   This study exemplifies a mechanism by which speciation, dispersal and introgression unfold in an important region for Neotropical diversification—the Isthmus of Panama—where periods ofbothisolation and introgression probably drive diversification. Overall, our results are consistent with the Refuge Model of biotic diversification, but suggest that introgression may be a crucial yet underappreciated component of this classic paradigm.

    

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3. Biogeography of the neotropical freshwater stingrays (Myliobatiformes: Potamotrygoninae) reveals effects of continent‐scale paleogeographic change and drainage evolution

   https://doi.org/10.1111/jbi.14086  

   Fontenelle, João Pedro ; Portella Luna Marques, Fernando ; Kolmann, Matthew A. ; Lovejoy, Nathan R. ; Floeter, ed., Sergio ( March 2021 , Journal of Biogeography)

   Paleogeographic changes have had profound effects on the evolution and diversity of the Neotropical biota. However, the influence of marine incursions on the origin, diversification, and distribution of fishes is still incompletely understood. We investigate the biogeographical and chronological patterns of diversification for the marine‐derived Neotropical freshwater stingrays (subfamily Potamotrygoninae) at a continental scale.

   Neotropics, South America.

   Neotropical freshwater stingrays. Subfamily Potamotrygoninae (Myliobatiformes: Chondrichthyes).

   We generated a time‐calibrated phylogeny for 35 of the 38 valid species of Neotropical freshwater stingrays, from most of the major river basins of South America, using four genes. We used BEAST2 to determine the chronology of population and species divergence events, and “BioGeoBEARS” to infer historical biogeographic patterns.

   The Potamotrygoninae originated during the early/middle Miocene in the upper Amazon region. We recover clades associated with particular geographic areas and detect a recurrent pattern of upper Amazon clades sister to clades in adjacent basins. The timing of dispersals from the upper Amazon to adjacent areas corresponds with the end of the Pebas wetlands. Lower Amazon and Shield associated taxa are relatively young.

   We propose that the origin of the Neotropical freshwater stingrays is related to marine incursions that occurred during the Oligocene/Miocene. Subsequent diversification of Potamotrygoninae occurred in the Pebas wetland system in the upper Amazon with colonization of adjacent basins. These movements were generally unidirectional, with few lineages returning to the upper Amazon, and we speculate that ecological factors drove this pattern. We observed a burst of potamotrygonine diversification 5 Ma that appears to be related to the modern channelization of the Amazon Basin.

    

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4. Biogeographic history of a large clade of ectomycorrhizal fungi, the Russulaceae, in the Neotropics and adjacent regions

   https://doi.org/10.1111/nph.18365  

   Hackel, Jan ; Henkel, Terry W. ; Moreau, Pierre‐Arthur ; De Crop, Eske ; Verbeken, Annemieke ; Sà, Mariana ; Buyck, Bart ; Neves, Maria‐Alice ; Vasco‐Palacios, Aída ; Wartchow, Felipe ; et al ( July 2022 , New Phytologist)

   The biogeography of neotropical fungi remains poorly understood. Here, we reconstruct the origins and diversification of neotropical lineages in one of the largest clades of ectomycorrhizal fungi in the globally widespread family Russulaceae.

   We inferred a supertree of 3285 operational taxonomic units, representing worldwide internal transcribed spacer sequences. We reconstructed biogeographic history and diversification and identified lineages in the Neotropics and adjacent Patagonia.

   The ectomycorrhizal Russulaceae have a tropical African origin. The oldest lineages in tropical South America, most with African sister groups, date to the mid‐Eocene, possibly coinciding with a boreotropical migration corridor. There were several transatlantic dispersal events from Africa more recently. Andean and Central American lineages mostly have north‐temperate origins and are associated with North Andean uplift and the general north–south biotic interchange across the Panama isthmus, respectively. Patagonian lineages have Australasian affinities. Diversification rates in tropical South America and other tropical areas are lower than in temperate areas.

   Neotropical Russulaceae have multiple biogeographic origins since the mid‐Eocene involving dispersal and co‐migration. Discontinuous distributions of host plants may explain low diversification rates of tropical lowland ectomycorrhizal fungi. Deeply diverging neotropical fungal lineages need to be better documented.

    

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5. Sensitivity of mangrove range limits to climate variability

   https://doi.org/10.1111/geb.12751  

   Cavanaugh, Kyle C. ; Osland, Michael J. ; Bardou, Rémi ; Hinojosa‐Arango, Gustavo ; López‐Vivas, Juan M. ; Parker, John D. ; Rovai, André S. ( August 2018 , Global Ecology and Biogeography)

   Correlative distribution models have been used to identify potential climatic controls of mangrove range limits, but there is still uncertainty about the relative importance of these factors across different regions. To provide insights into the strength of climatic control of different mangrove range limits, we tested whether temporal variability in mangrove abundance increases near range limits and whether this variability is correlated with climatic factors thought to control large‐scale mangrove distributions.

   North and South America.

   1984–2011.

   Avicennia germinans,Avicennia schuaeriana,Rhizophora mangle,Laguncularia racemosa.

   We characterized temporal variability in the enhanced vegetation index (EVI) at mangrove range limits using Landsat satellite imagery collected between 1984–2011. We characterized greening trends at each range limit, examined variability in EVI along latitudinal gradients near each range limit, and assessed correlations between changes in EVI and temperature and precipitation.

   Spatial variability in mean EVI was generally correlated with temperature and precipitation, but the relationships were region specific. Greening trends were most pronounced at range limits in eastern North America. In these regions variability in EVI increased toward the range limit and was sensitive to climatic factors. In contrast, EVI at range limits on the Pacific coast of North America and both coasts of South America was relatively stable and less sensitive to climatic variability.

   Our results suggest that range limits in eastern North America are strongly controlled by climate factors. Mangrove expansion in response to future warming is expected to be rapid in regions that are highly sensitive to climate variability (e.g. eastern North America), but the response in other range limits (e.g. South America) is likely to be more complex and modulated by additional factors such as dispersal limitation, habitat constraints, and/or changing climatic means rather than just extremes.

    

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