Collaborative Research: Origins and drivers of extinction of Caribbean Avifauna

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Current vertebrate diversity has been dramatically shaped by an ongoing mass extinction event that began after the last ice age ended, approximately 18,000 years ago. The timing of at least some of these extinctions often coincides with human arrival into newly colonized areas. While extinctions since the last ice age have occurred worldwide, the islands that make up the Caribbean have been perhaps the single hardest hit region. This island system, rich in well-preserved paleontological and archaeological sites, has preserved a spectacular record of both past bird diversity and human occupation. Still, our knowledge of the patterns, causes, and consequences of long-term changes to Caribbean bird communities remains surprisingly limited. This knowledge gap hampers our understanding of past diversity changes and its causes, and thus our ability to manage and conserve remaining diversity into the future. This research focuses on closing these knowledge gaps using DNA from fossils (ancient DNA) to understand taxonomic affinities of extinct species, and radiocarbon dating to determine the last occurrence of a species. This approach provides critical information to determine who these species were, and to time their losses in relation to climate change and waves of human arrivals to the islands. This project also focuses on the characteristics of species that have made them more vulnerable to extinction (for example, flightlessness) as a means to more completely understand the causes of extinction in the past and forecast the extinction risk for existing species. This project has broad societal impact through its educational and outreach components. The project will provide training for underrepresented students in science, focusing on extinction and ancient DNA, and develop classroom content for K-12 classes in Florida in partnership with the University of Florida Thomson Earth Science Institute’s (TESI) Scientist in Every Florida School (SEFS) program. And to further public understanding of science, and to bolster conservation efforts for threatened Caribbean birds, the researchers will develop a documentary video in both English and Spanish and work with museum-based outreach efforts to inform wide audiences across the Caribbean islands.It is estimated that 12% of the bird species in the Caribbean either went extinct or were extirpated since the late Pleistocene, with many more now considered to be endangered or threatened. Less well understood is the role humans have played in these extinctions and population losses. Because human arrival to these islands occurred much later than on the mainland, archeological and paleontological evidence can be used to determine how humans interacted with the local fauna upon their arrival to domesticate, translocate, and cause the extinction of some species. Evidence of this lost avian diversity is fragmentary, often represented by only a few specimens with limited morphological characters. This causes challenges for proper phylogenetic placement, especially given potential for convergence due to shared life histories such as flightlessness. In this project researchers will build phylogenetic trees of clades of birds including modern, extinct and extirpated taxa to determine the phylogenetic and trait affinities of these species. This work will also elucidate biogeographic patterns of the full endemic fauna of the Caribbean, that has been obscured due to extinctions of enigmatic taxa, and build a picture of the level of biodiversity loss in terms of phylogenetic and trait diversity. A key next step is to then integrate new phylogenetic knowledge into a larger context of overall avian diversity patterns to explicitly quantify past loss of phylogenetic diversity across the Caribbean. We will generate a new metric, diversity loss risk, that integrates insight from phylogenetics, traits, and past extinction events to reveal which extant species are of greatest concern for preventing permanent phylogenetic diversity loss.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.