Undergraduate Honors Theses


Phenotypic change in anthropogenic Carnivora: testing morphological variation between populations of coyotes and raccoons

Thesis Defended

Fall 2018

Document Type


Type of Thesis

Departmental Honors


Ecology and Evolutionary Biology

First Advisor

Joanna E. Lambert


Anthropogenic (human-modified) landscapes introduce new selective pressures that affect the ecology of native species. While some species can shift behavior in novel environments and morphologically adjust to anthropogenic foods in captivity, the effects of anthropogenic landscapes on wild, non-captive populations of carnivorans have yet to be assessed in detail. Recent work on mammalian cranial (skull) morphology has demonstrated trends related to land use changes and food sources, supporting the hypothesis that anthropogenic activity can introduce mechanisms that select for phenotypic change. However, results of previous studies vary across species and habitats, necessitating further work on spatial and temporal trends in the skull morphology of various populations. Living in close proximity with humans may also produce early signs of domestication, although this remains to be tested. Museum specimens provide a physical record of natural history through time and serve as a valuable resource for investigating the evolution of morphological trends over time and space. In this work, I use linear measurement data to describe variation in the cranial morphology for two species of Carnivora that have successfully invaded urban environments: Canis latrans (coyote) and Procyon lotor (raccoon). I found that individuals of C. latrans collected after 1990 show a significant difference between rural and urban populations in means of two ratios that describe skull shape: skull index (SI) and width index (WI). These two ratios exhibit trends over time when compared with all specimens measured. While individuals of P. lotor display no significant difference in SI or WI, a linear regression indicates for some decrease in absolute skull length. These results provide preliminary support for the hypothesis that the selective pressures present in human-modified environments may influence the phenotype of wild animals.

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