Browsing by Subject "PALEOGEOGRAPHY"

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  • Salminen, Johanna; Hanson, Richard; Evans, David A. D.; Gong, Zheng; Larson, Tierney; Walker, Olivia; Gumsley, Ashley; Soderlund, Ulf; Ernst, Richard (2018)
  • Penny, Amelia; Kroger, Bjorn (2019)
    The unprecedented diversifications in the fossil record of the early Palaeozoic (541-419 million years ago) increased both within-sample (alpha) and global (gamma) diversity, generating considerable ecological complexity. Faunal difference (beta diversity), including spatial heterogeneity, is thought to have played a major role in early Palaeozoic marine diversification, although alpha diversity is the major determinant of gamma diversity through the Phanerozoic. Drivers for this Phanerozoic shift from beta to alpha diversity are not yet resolved. Here, we evaluate the impacts of environmental and faunal heterogeneity on diversity patterns using a global spatial grid. We present early Palaeozoic genus-level alpha, beta and gamma diversity curves for molluscs, brachiopods, trilobites and echinoderms and compare them with measures of spatial lithological heterogeneity, which is our proxy for environmental heterogeneity. We find that alpha and beta diversity are associated with increased lithological heterogeneity, and that beta diversity declines over time while alpha increases. We suggest that the enhanced dispersal of marine taxa from the Middle Ordovician onwards facilitated increases in alpha diversity by encouraging the occupation of narrow niches and increasing the prevalence of transient species, simultaneously reducing spatial beta diversity. This may have contributed to a shift from beta to alpha diversity as the major determinant of gamma diversity increase over this critical evolutionary interval.
  • Murillo Ramos, Leidys Del Carmen; Chazot, Nicolas; Sihvonen, Pasi; Õunap, Erki; Jiang, Nan; Han, Hongxiang; Clarke, John T.; Davis, Robert B.; Tammaru, Toomas; Wahlberg, Niklas (2021)
    Understanding how and why some groups have become more species-rich than others, and how past biogeography may have shaped their current distribution, are questions that evolutionary biologists have long attempted to answer. We investigated diversification patterns and historical biogeography of a hyperdiverse lineage of Lepidoptera, the geometrid moths, by studying its most species-rich tribe Boarmiini, which comprises ca. 200 genera and ca. known 3000 species. We inferred the evolutionary relationships of Boarmiini based on a dataset of 346 taxa, with up to eight genetic markers under a maximum likelihood approach. The monophyly of Boarmiiniis strongly supported. However, the phylogenetic position of many taxa does not agree with current taxonomy, although the monophyly of most major genera within the tribe is supported after minor adjustments. Three genera are synonymized, one new combination is proposed, and four species are placed in incertae sedis within Boarmiini. Our results support the idea of a rapid initial diversification of Boarmiini, which also implies that no major taxonomic subdivisions of the group can currently be proposed. A time-calibrated tree and biogeographical analyses suggest that boarmiines appeared in Laurasia ca. 52 Mya, followed by dispersal events throughout the Australasian, African and Neotropical regions. Most of the transcontinental dispersal events occurred in the Eocene, a period of intense geological activity and rapid climate change. Diversification analyses showed a relatively constant diversification rate for all Boarmiini, except in one clade containing the species-rich genus Cleora. The present work represents a substantial contribution towards understanding the evolutionary origin of Boarmiini moths. Our results, inevitably biased by taxon sampling, highlight the difficulties with working on species-rich groups that have not received much attention outside of Europe. Specifically, poor knowledge of the natural history of geometrids (particularly in tropical clades) limits our ability to identify key innovations underlying the diversification of boarmiines.