title: Drastic population fluctuations explain the rapid extinction of the passenger pigeon.
abstract: To assess the role of human disturbances in species' extinction requires an understanding of the species population history before human impact. The passenger pigeon was once the most abundant bird in the world, with a population size estimated at 3-5 billion in the 1800s; its abrupt extinction in 1914 raises the question of how such an abundant bird could have been driven to extinction in mere decades. Although human exploitation is often blamed, the role of natural population dynamics in the passenger pigeon's extinction remains unexplored. Applying high-throughput sequencing technologies to obtain sequences from most of the genome, we calculated that the passenger pigeon's effective population size throughout the last million years was persistently about 1/10,000 of the 1800's estimated number of individuals, a ratio 1,000-times lower than typically found. This result suggests that the passenger pigeon was not always super abundant but experienced dramatic population fluctuations, resembling those of an "outbreak" species. Ecological niche models supported inference of drastic changes in the extent of its breeding range over the last glacial-interglacial cycle. An estimate of acorn-based carrying capacity during the past 21,000 y showed great year-to-year variations. Based on our results, we hypothesize that ecological conditions that dramatically reduced population size under natural conditions could have interacted with human exploitation in causing the passenger pigeon's rapid demise. Our study illustrates that even species as abundant as the passenger pigeon can be vulnerable to human threats if they are subject to dramatic population fluctuations, and provides a new perspective on the greatest human-caused extinction in recorded history.
authors: Department of Life Science and.
authors: Chih-Ming
authors: CM
authors: Hung
authors: Department of Life Science and.
authors: Pei-Jen L
authors: PJ
authors: Shaner
authors: Department of Ecology, Evolution, and Behavior, and Bell Museum, University of Minnesota, St. Paul, MN 55108;
authors: Robert M
authors: RM
authors: Zink
authors: Institute of Statistical Science, Academia Sinica, Taipei 11529, Taiwan;
authors: Wei-Chung
authors: WC
authors: Liu
authors: Department of Computer Science and Information Engineering, National Taiwan Normal University, Taipei 116, Taiwan;
authors: Te-Chin
authors: TC
authors: Chu
authors: Department of Biology, National Museum of Natural Science, Taichung 404, Taiwan; andDepartment of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan wshuang@mail.nmns.edu.tw t43028@ntnu.edu.tw.
authors: Wen-San
authors: WS
authors: Huang
authors: Department of Life Science and wshuang@mail.nmns.edu.tw t43028@ntnu.edu.tw.
authors: Shou-Hsien
authors: SH
authors: Li
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D010856:Columbidae / Q000502:physiology*; D053476:Extinction, Biological; D005523:Food Supply; D016678:Genome / Q000235:genetics; D005843:Geography; D008390:Markov Chains; D011156:Population Density; D011157:Population Dynamics; D029963:Quercus / Q000502:physiology; D014481:United States
keywords: ancient DNA; genome sequences; toe pad