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1. Biogeography of the Caribbean Cyrtognatha spiders

   https://doi.org/10.1038/s41598-018-36590-y  

   Čandek, Klemen ; Agnarsson, Ingi ; Binford, Greta J. ; Kuntner, Matjaž ( January 2019 , Scientific Reports)

   Island systems provide excellent arenas to test evolutionary hypotheses pertaining to gene flow and diversification of dispersal-limited organisms. Here we focus on an orbweaver spider genusCyrtognatha(Tetragnathidae) from the Caribbean, with the aims to reconstruct its evolutionary history, examine its biogeographic history in the archipelago, and to estimate the timing and route of Caribbean colonization. Specifically, we test ifCyrtognathabiogeographic history is consistent with an ancient vicariant scenario (the GAARlandia landbridge hypothesis) or overwater dispersal. We reconstructed a species level phylogeny based on one mitochondrial (COI) and one nuclear (28S) marker. We then used this topology to constrain a time-calibrated mtDNA phylogeny, for subsequent biogeographical analyses in BioGeoBEARS of over 100 originally sampledCyrtognathaindividuals, using models with and without a founder event parameter. Our results suggest a radiation of CaribbeanCyrtognatha, containing 11 to 14 species that are exclusively single island endemics. Although biogeographic reconstructions cannot refute a vicariant origin of the Caribbean clade, possibly an artifact of sparse outgroup availability, they indicate timing of colonization that is much too recent for GAARlandia to have played a role. Instead, an overwater colonization to the Caribbean in mid-Miocene better explains the data. From Hispaniola,Cyrtognathasubsequently dispersed to, and diversified on, the other islands of themore »Greater, and Lesser Antilles. Within the constraints of our island system and data, a model that omits the founder event parameter from biogeographic analysis is less suitable than the equivalent model with a founder event.

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2. Island Ancestors and New World Biogeography: A Case Study from the Scorpions (Buthidae: Centruroidinae)

   https://doi.org/10.1038/s41598-018-33754-8  

   Esposito, Lauren A. ; Prendini, Lorenzo ( March 2019 , Scientific Reports)

   Scorpions are an excellent system for understanding biogeographical patterns. Most major scorpion lineages predate modern landforms, making them suitable for testing hypotheses of vicariance and dispersal. The Caribbean islands are endowed with a rich and largely endemic scorpion fauna, the origins of which have not been previously investigated with modern biogeographical methods. Three sets of hypotheses have been proposed to explain present patterns of diversity in the Caribbean: (1) connections via land bridges, (2) vicariance events, and (3) overwater dispersal from continents and among islands. The present study investigates the biogeographical diversification of the New World buthid scorpion subfamily Centruroidinae Kraus, 1955, a clade of seven genera and more than 110 species; infers the ancestral distributions of these scorpions; and tests the relative roles of vicariance and dispersal in the formation of their present distributions. A fossil-calibrated molecular phylogeny was estimated with a Bayesian criterion to infer the dates of diversification events from which ancestral distributions were reconstructed, and the relative likelihood of models of vicariance vs. dispersal, calculated. Although both the timing of diversification and the ancestral distributions were congruent with the GAARlandia land-bridge hypothesis, there was no significant difference between distance-dependent models with or without the land-bridge.HeteroctenusPocock,more »1893, the Caribbean-endemic sister taxon ofCentruroidesMarx, 1890 provides evidence for a Caribbean ancestor, which subsequently colonized Central America and North America, and eventually re-colonized the Greater Antilles. This ‘reverse colonization’ event of a continent from an island demonstrates the importance of islands as a potential source of biodiversity.

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3. World Travelers: Parthenogenesis and Ecological Tolerance Enable Multiple Colonization Events by the Widespread Short-Tailed Whipscorpion, Stenochrus portoricensis (Schizomida: Hubbardiidae)

   https://doi.org/10.1093/isd/ixab032  

   Monjaraz-Ruedas, Rodrigo ; Francke, Oscar F. ; Prendini, Lorenzo ; Esposito, ed., Lauren ( January 2022 , Insect Systematics and Diversity)

   Whereas morphology remains a powerful tool for the diagnosis and description of short-tailed whip scorpions, or schizomids (Order Schizomida Petrunkevitch, 1945), especially when adults of both sexes are available, the systematics of some schizomid taxa is difficult to resolve due to a lack of characters in these morphologically conserved arachnids. Stenochrus portoricensis Chamberlin, 1922, defined on a single character of the female spermathecae, is the most widespread schizomid in the New World. Numerous records in the Neotropics, from the southern United States to Brazil, throughout the Caribbean, and further afield, including the Galapagos Islands and Europe, raise the question as to whether S. portoricensis is indeed a single widespread species or a complex of multiple species with conserved morphology? The present study uses a multilocus dataset and the broadest geographical sample currently available to address the phylogeography of S. portoricensis with molecular divergence dating and ancestral area reconstruction of all currently known species of Stenochrus Chamberlin, 1922. Analyses recovered S. portoricensis as paraphyletic. Two species previously synonymized are revalidated and transferred to Stenochrus. Population structure analyses recovered the remaining samples of S. portoricensis as a single monophyletic species with low genetic divergence and comprising two subclades. Ancestral area reconstructionmore »suggests a Mesoamerican origin for Stenochrus, which contains a widespread species, recently introduced to multiple localities. Introductions to Europe and the Caribbean occurred from a single clade in the Yucatán Peninsula, Mexico, within which genetic divergence is minimal, confirming the hypothesis of multiple independent introductions with successful colonization facilitated by parthenogenetic reproduction.

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4. When adaptive radiations collide: Different evolutionary trajectories between and within island and mainland lizard clades

   https://doi.org/10.1073/pnas.2024451118  

   Patton, Austin H. ; Harmon, Luke J. ; del Rosario Castañeda, María ; Frank, Hannah K. ; Donihue, Colin M. ; Herrel, Anthony ; Losos, Jonathan B. ( October 2021 , Proceedings of the National Academy of Sciences)

   Oceanic islands are known as test tubes of evolution. Isolated and colonized by relatively few species, islands are home to many of nature’s most renowned radiations from the finches of the Galápagos to the silverswords of the Hawaiian Islands. Despite the evolutionary exuberance of insular life, island occupation has long been thought to be irreversible. In particular, the presumed much tougher competitive and predatory milieu in continental settings prevents colonization, much less evolutionary diversification, from islands back to mainlands. To test these predictions, we examined the ecological and morphological diversity of neotropicalAnolislizards, which originated in South America, colonized and radiated on various islands in the Caribbean, and then returned and diversified on the mainland. We focus in particular on what happens when mainland and island evolutionary radiations collide. We show that extensive continental radiations can result from island ancestors and that the incumbent and invading mainland clades achieve their ecological and morphological disparity in very different ways. Moreover, we show that when a mainland radiation derived from island ancestors comes into contact with an incumbent mainland radiation the ensuing interactions favor the island-derived clade.
5. Species Delimitation, Phylogenomics, and Biogeography of Sulawesi Flying Lizards: A Diversification History Complicated by Ancient Hybridization, Cryptic Species, and Arrested Speciation

   https://doi.org/10.1093/sysbio/syad020  

   Mcguire, Jimmy A. ; Huang, Xiaoting ; Reilly, Sean B. ; Iskandar, Djoko T. ; Wang-Claypool, Cynthia Y. ; Werning, Sarah ; Chong, Rebecca A. ; Lawalata, Shobi Z. S. ; Stubbs, Alexander L. ; Frederick, Jeffrey H. ; et al ( April 2023 , Systematic Biology)

   The biota of Sulawesi is noted for its high degree of endemism and for its substantial levels of in situ biological diversification. While the island’s long period of isolation and dynamic tectonic history have been implicated as drivers of the regional diversification, this has rarely been tested in the context of an explicit geological framework. Here, we provide a tectonically informed biogeographical framework that we use to explore the diversification history of Sulawesi flying lizards (the Draco lineatus Group), a radiation that is endemic to Sulawesi and its surrounding islands. We employ a framework for inferring cryptic speciation that involves phylogeographic and genetic clustering analyses as a means of identifying potential species followed by population demographic assessment of divergence-timing and rates of bi-directional migration as means of confirming lineage independence (and thus species status). Using this approach, phylogenetic and population genetic analyses of mitochondrial sequence data obtained for 613 samples, a 50-SNP data set for 370 samples, and a 1249-locus exon-capture data set for 106 samples indicate that the current taxonomy substantially understates the true number of Sulawesi Draco species, that both cryptic and arrested speciations have taken place, and that ancient hybridization confounds phylogenetic analyses that do notmore »explicitly account for reticulation. The Draco lineatus Group appears to comprise 15 species—9 on Sulawesi proper and 6 on peripheral islands. The common ancestor of this group colonized Sulawesi ~11 Ma when proto-Sulawesi was likely composed of two ancestral islands, and began to radiate ~6 Ma as new islands formed and were colonized via overwater dispersal. The enlargement and amalgamation of many of these proto-islands into modern Sulawesi, especially during the past 3 Ma, set in motion dynamic species interactions as once-isolated lineages came into secondary contact, some of which resulted in lineage merger, and others surviving to the present. [Genomics; Indonesia; introgression; mitochondria; phylogenetics; phylogeography; population genetics; reptiles.]

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