Dr Jane Younger1, Robert Lauer1, Dr Arpad Nyari2, Dr Steven Goodman3, Dr Sushma Reddy4
1Loyola University Chicago, Chicago, United States, 2University of Tennessee, Knoxville, United States, 3Field Museum of Natural History, Chicago, United States, 4University of Minnesota, St Paul, United States
Madagascar is a biodiversity hotspot that is under threat from both deforestation and climate change. Madagascar’s birds are likely to respond to these threats via population declines and/or range shifts, but their likely responses are as yet unstudied. In this study we used a comparative phylogeographic framework to gain insight into the past responses of Malagasy birds (Bernieridae and Vangidae, 23 genera) to climate fluctutations throughout the Quaternary, and the role of species’ traits in mediating those responses. We also aimed to identify key barriers to dispersal that may limit future range shifts. Our integrative approach combined genomic data (>4,000 UCEs) for >400 individuals, ecological niche modeling, and estimates of dispersability (hand-wing index, genetic connectivity). We found that closely related species appear to have responded very differently to past climate fluctuations and to have different barriers to their dispersal. Species traits, including elevational tolerance and forest-dependence, are more indicative of likely climate change responses than shared ancestry. A key finding was that elevational tolerance is a key determinant in speciation dynamics for Madagascar’s birds; taxa with limited elevational tolerance tend to have greater rates of microendemism, and elevation appears to act as a dispersal barrier. This suggest that future range shifts may include upward elevational shifts to track preferred montane habitat. This new understanding of dispersal barriers, habitat tolerances, and past responses to climate change lays the foundation for the development of hypotheses regarding the future distributional shifts of Malagasy bird species.
Jane is a postdoc at Loyola University in Chicago, where she works on the evolution of Madagascar’s endemic birds.