Demography of avian scavengers after Pleistocene megafaunal extinction

Paula L Perrig,Sergio A Lambertucci,Emily D Fountain,Jonathan N Pauli

doi:10.1038/s41598-019-45769-w

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.

Highlights

Historical species assemblages can provide insight into the contemporary structure and functioning of communities[1]
We found independent historical demographic trajectories among pumas, condors and wild camelids in southern South America, and no support for the condor-puma-camelid being a historical relationship that allowed the persistence of Andean condors despite the loss of megafauna
While the 95% highest posterior density of population changes for our Extended Bayesian Skyline Plot coalescent models (EBSP) analysis overlapped zero[42], we attribute this to a lack of power to detect slight demographic changes from a small sample size (n = 23)[43]

Summary

Introduction

Historical species assemblages can provide insight into the contemporary structure and functioning of communities[1]. Www.nature.com/scientificreports tightly-linked community module of pumas (Puma concolor) preying largely on wild camelids, guanacos (Lama guanicoe) and vicuñas (Vicugna vicugna), emerged in Patagonia and the southern Andes[29] These species exhibited a demographic expansion (increased effective population size) in the mid-Holocene[30,31,32], leading to a rapid reorganization of the ecological community to one that became dominated by mid-sized vertebrates[29,33]. If carrion availability is from other resources (e.g., marine24) or other sources of ungulate mortality (e.g., malnutrition, disease, extreme weather events18), there should be independent population size changes between predators, scavengers and ungulates To test these competing hypotheses, we first explored past trophic linkages in South American communities. We sequenced mitochondrial (mtDNA) and nuclear loci (nDNA) of Andean condors and compiled available mtDNA sequences from GenBank to study changes in population size of pumas, Andean condors, vicuñas, guanacos, California condors and white-backed vultures via neutrality tests, mismatch distributions, and Extended Bayesian Skyline Plot coalescent models (EBSP)

Methods

Results

Conclusion