Loading...
Assembling the Philippine snake fauna: Diversification and biotic exchange in a tropical archipelago
Weinell, Jeffrey L
Weinell, Jeffrey L
Citations
Altmetric:
Abstract
Chapter 1 investigates the mechanisms that shaped modern species distributions in island archipelagos, which have been fundamental model systems in studies of ecological and historical biogeography, and of adaptive versus non-adaptive diversification. To investigate predictions of lineage assembly hypotheses, we generated the most comprehensively sampled genetic dataset of the Philippine Archipelago’s terrestrial snake fauna, inferred phylogenetic relationships, colonization and divergence times, and assessed support for hypothesized colonization routes, paleotransport mechanisms, and diversification models. Our results supported numerous biotic exchanges, primarily from Sundaland, during the Miocene, whereas tectonic rift-associated vicariance and paleotransport on the Palawan Microcontinent was not supported. Our results suggested historical biotic transfers via island-hopping and paleotransport from Sundaland to Luzon or its paleoisland precursors, and from Australasia to Philippine Mobile Belt islands via hypothesized Melanesian “lost arcs”. In contrast to expectations of a hypothesized depauperate fauna assembled by numerous Pleistocene colonizations, our results supported both early and recent in situ diversification. Some recent divergences were consistent with expectations of the Pleistocene Aggregate Island Complex model of diversification. Additional studies are needed to test for adaptive radiation, although our results implied only limited adaptive divergence compared to previously studied adaptive radiations. Our results agreed with earlier statements that Philippine snake species diversity is vastly underestimated. This study highlights the advantage of comprehensive phylogenetic sampling and robust divergence time estimation, and sets the stage for future studies that apply modern genomic methods to answer diverse questions related to diversification and adaptation.Chapter 2 investigates the sources of phylogenetic uncertainty in estimates of the evolutionary history of the superfamily Elapoidea, which includes a group of snakes distributed worldwide in tropical and subtropical areas that has undergone multiple rapid radiations. We sampled all higher-level elapoid lineages and multiple outgroup lineages, using a targeted sequence-capture approach resulting in a novel genetic dataset that included 3000 loci. Compared to earlier studies, our dataset included a greater number of informative loci, which allowed us to harness species tree and network methods that consider variation in genealogical histories during phylogenomic inference. Our results suggested that low per-locus phylogenetic signal in datasets from earlier studies may explain low phylogenetic support recovered in those studies. As expected, gene concordance factors were low at descendant nodes of short internal branches, possibly the result of discordance due to ILS or DTR, or due to low phylogenetic signal at short branches, or a combination of two or all three of these factors. Chapter 3 investigates phylogenetic relationships and genetic geographic population structure within the cyclocorid genus Oxyrhabdium, which is thought to include a greater number of species than currently recognized. To test the validity of currently described species, and to investigate whether additional, undescribed species lineages likely exist, we generated multilocus Sanger DNA and ddRADseq datasets from tissues sampled from throughout the geographic ranges of currently described taxa. With our novel datasets, we inferred phylogenetic relationships, characterized geographical genetic structure, and estimated locations of migration barriers. Our results did not support traditionally recognized taxonomy, and supported the existence of undescribed species of Oxyrhabdium.
Description
Date
2022-08-31
Journal Title
Journal ISSN
Volume Title
Publisher
University of Kansas
Collections
Research Projects
Organizational Units
Journal Issue
Keywords
Evolution & development, Biology, biogeography, evolution, islands, phylogenomics, reptiles, speciation