Abstract
Humans have altered the biotic and abiotic environmental conditions of most organisms. In some cases, such as intensive agriculture, an organism’s entire ecosystem is converted to novel conditions. Thus, it is striking that some species continue to thrive under such conditions. The prairie deer mouse (Peromyscus maniculatus bairdii) is an example of such an organism, and so we sought to understand what role evolutionary adaptation played in the success of this species, with particular interest in adaptations to novel foods. In order to understand the evolutionary history of this species’ masticatory structures, we examined the maxilla, zygomatic plate, and mandible of historic specimens collected prior to 1910 to specimens collected in 2012 and 2013. We found that mandibles, zygomatic plates, and maxilla have all changed significantly since 1910, and that morphological development has shifted significantly. We present compelling evidence that these differences are due to natural selection as a response to a novel and ubiquitous food source, waste grain (corn, Zea mays and soybean, Glycine max).
Highlights
Rapid changes to environmental conditions such as climate and landscape have become the normal conditions under which contemporary species must survive and reproduce
Period is a significant predictor of the allometric regression intercepts after accounting for location. Further investigation of these patterns revealed that allometric slopes of contemporary specimens were shallower than historic specimens (0.08 vs. 0.19 and 0.09 vs. 0.13; Fig 4), with a significant effect of period on slope for upper jaws (MSE = 0.003, F1,305 = 10.48, p = 0.001)
Period, size, and interactions were modeled as predictors of mandible and upper jaw morphology, using a Procrustes distance metric and resampling techniques
Summary
Rapid changes to environmental conditions such as climate and landscape have become the normal conditions under which contemporary species must survive and reproduce. Rapid microevolutionary changes may be critical to the survival of species in an anthropogenic world. Few studies have examined morphological changes due to landscape change [7, 8]. Intensive agriculture provides a natural experiment of rapid and extensive modifications to food and habitats in ways that are almost certain to represent strong natural selection. This rapid change provides an opportunity to study the rate at which a species can change to cope with a dramatically new environment
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