Demography of avian scavengers after Pleistocene megafaunal extinction

Abstract

The late Quaternary megafauna extinctions reshaped species assemblages, yet we know little about how extant obligate scavengers responded to this abrupt ecological change. To explore whether obligate scavengers persisted by depending on contemporary community linkages or via foraging flexibility, we tested the importance of the trophic interaction between pumas (Puma concolor) and native camelids (Vicugna vicugna and Lama guanicoe) for the persistence of Andean condors (Vultur gryphus) in southern South America, and compared the demographic history of three vultures in different continents. We sequenced and compiled mtDNA to reconstruct past population dynamics. Our results suggest that Andean condors increased in population size >10 KYA, whereas vicuñas and pumas showed stable populations and guanacos a recent (<10 KYA) demographic expansion, suggesting independent trajectories between species. Further, vultures showed positive demographic trends: white-backed vultures (Gyps africanus) increased in population size, matching attenuated community changes in Africa, and California condors (Gymnogyps californianus) exhibited a steep demographic expansion ~20 KYA largely concurrent with North American megafaunal extinctions. Our results suggest that dietary plasticity of extant vulture lineages allowed them to thrive despite historical environmental changes. This dietary flexibility, however, is now detrimental as it enhances risk to toxicological compounds harbored by modern carrion resources.

Figure 1

Extended Bayesian Skyline Plots illustrating female effective population size by generation time on a scale of millions of years (MYA) using combined nuclear and mitochondrial DNA sequences of Andean condors, and mitochondrial DNA sequences of pumas and guanacos in southern South America. Dotted line depicts median values; shaded region represents 95% highest posterior density.

Figure 2

Extended Bayesian Skyline Plots illustrating female effective population size by generation time on a scale of millions of years (MYA) for Andean condors, California condors and white-backed vultures. Dotted lines depict median values; shaded region represents 95% highest posterior density.