%0 Journal Article
%T Population growth of Mexican free-tailed bats (Tadarida brasiliensis mexicana) predates human agricultural activity
%A Amy L Russell
%A Murray P Cox
%A Veronica A Brown
%A Gary F McCracken
%J BMC Evolutionary Biology
%D 2011
%I BioMed Central
%R 10.1186/1471-2148-11-88
%X We sequenced one haploid and one autosomal locus to determine the rate and time of onset of population growth in T. b. mexicana. Using an approximate Maximum Likelihood method, we have determined that T. b. mexicana populations began to grow ~220 kya from a relatively small ancestral effective population size before reaching the large effective population size observed today.Our analyses reject the hypothesis that T. b. mexicana populations grew in connection with the expansion of human agriculture in North America, and instead suggest that this growth commenced long before the arrival of humans. As T. brasiliensis is a subtropical species, we hypothesize that the observed signals of population growth may instead reflect range expansions of ancestral bat populations from southern glacial refugia during the tail end of the Pleistocene.Modern human populations and their activities have had a significant, and frequently negative, impact on other organisms [1-3]. Human populations exert a tremendous ecological and evolutionary pressure on native species, comparable in total effect to that of glaciations on temperate species but operating over much shorter timescales (101-103 versus 104-105 years; [4,5]). The effect of human activities on native species is not easily predictable, and in some instances human activities have benefited native wildlife, often through increasing habitat or food availability [6,7]. Genetic methods are starting to prove useful for linking demographic processes in animal species to human activity, with recent studies attributing decreasing effective population size and increasing population fragmentation to anthropogenic deforestation, the expansion of agriculture, road construction and the presence of human settlements [8-10]. Here, we use genetic analyses to investigate whether anthropogenic forces, specifically the spread of agriculture, or non-anthropogenic forces such as the retreat of the Laurentide and Cordilleran glaciers, have driven th
%U http://www.biomedcentral.com/1471-2148/11/88