Turnover in functional and phylogenetic diversity of avian assemblages across continental scales

Marta A. Jarzyna (1) , Walter Jetz (1)

1 Department of Ecology and Evolutionary Biology, Yale University, 165 Prospect Street, New Haven, CT, 06520

Research on the implications of climate change to biodiversity has mostly focused on shifting species distributions and resulting changes in species richness. Species richness alone, however, often fails to fully describe community structure and can compromise our ability to understand the implications of climate change to biodiversity. Metrics of functional and phylogenetic diversity contain invaluable information regarding ecosystem functioning and community evolutionary history and are thus better suited to identifying the underlying processes that determine biodiversity dynamics and thus the consequences of climate change. Here, we quantified temporal changes in avian functional and phylogenetic diversity over the span of five decades by using bird species occurrence data from the North American Breeding Bird Survey. Using Gower’s distances and UPGMA clustering, we built functional and phylogenetic dendrograms and estimated diversity by summing up dendrogram branch lengths. To estimate assemblage dissimilarity across time, we considered the commonly used Sørensen dissimilarity index. We found that species richness, functional diversity, and phylogenetic diversity increased through time, but assemblage dissimilarity was the highest for functional diversity. We suggest that climate change has impacted certain functional traits in a selective fashion, thus contributing to the higher dissimilarity in functional characteristics than in species richness or phylogenetic characteristics.