RAPID: Recovering at-risk Holocene fossils to test phylogenetic & ecological hypotheses for extinction in crocodiles (Crocodylus) & giant tortoises (Aldabrachelys) of Mada

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AbstractIn 2014 cave divers from the Madagascar Karst Diving Project unexpectedly identified a treasure trove of Holocene and recent fossil material in two caves in Southwestern Madagascar. An NSF funded expedition led by researchers from the University of Massachusetts in Amherst and the University of Antananarivo in Madagascar further explored the submerged caves to document fine-scale environmental changes and their relationship to major extinction events on the island. This project provides an opportunity to recover and document a large number of specimens of extinct crocodiles and giant tortoises and to document how alteration of ecological processes may have led to recent patterns of extinction and decline among the megafaunal communities of Madagascar. The sampling and documentation of the fauna will be used in ongoing ancient DNA work to resolve the evolutionary relationships of extinct species and to identify drivers of extinction over a period of 5000 years. The research will specifically address hypotheses regarding the taxonomic and phylogenetic relationships between modern and recently extinct Madagascan crocodiles and giant tortoises. Additionally, these collections and associated stratigraphic data will allow us to identify the relationship between fine scale temporal dynamics of genomic diversity, diet and faunal change in these taxa and the arrival of humans in southwestern Madagascar during the pre-extinction period. Comparison of this intact depositional series with previous collections of these and other Holocene taxa across Madagascar will help explain changes in species composition, abundance, and genetic diversity within communities following the arrival of humans and during known climate shifts on the island. Societal impacts of the proposed work will include co-generation of knowledge by US and Malagasy researchers. Additional engagement is ensured through abundant opportunities for outreach and education via planned museum activities and public lectures. More broadly, this research promotes continued interdisciplinary research and interaction among academic researchers and local stakeholders from the U.S. and Madagascar.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.