Road Mortality Contributes to the Evolution of an Urban–Rural Cline in Squirrel Coat Color
ABSTRACT Cities impose unique selection pressures on wildlife and generate clines in phenotypic traits along urban–rural gradients. Roads are a widespread feature of human‐dominated landscapes and are known to cause direct wildlife mortality; however, whether they act as a selective force influencin...
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| Format: | Article |
| Language: | English |
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Wiley
2025-05-01
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| Series: | Evolutionary Applications |
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| Online Access: | https://doi.org/10.1111/eva.70109 |
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| author | Adam F. Parlin Bradley J. Cosentino Richard M. Lehtinen John E. McDonald Emma C. C. Sinclair James P. Gibbs |
| author_facet | Adam F. Parlin Bradley J. Cosentino Richard M. Lehtinen John E. McDonald Emma C. C. Sinclair James P. Gibbs |
| author_sort | Adam F. Parlin |
| collection | DOAJ |
| description | ABSTRACT Cities impose unique selection pressures on wildlife and generate clines in phenotypic traits along urban–rural gradients. Roads are a widespread feature of human‐dominated landscapes and are known to cause direct wildlife mortality; however, whether they act as a selective force influencing phenotypic trait variation along urban–rural gradients remains unclear. This study tested the hypothesis that roads influence natural selection of coat color in the eastern gray squirrel (Sciurus carolinensis), a species with two distinct coat colors: a gray morph that is common in all areas and a melanic morph more prevalent in urban areas than in rural ones. Vehicular collisions are a significant cause of mortality in eastern gray squirrels, with the melanic morph more visually conspicuous on roads and more easily detected and avoided by drivers than the gray morph. Standardized road cruise surveys along an urbanization gradient in Syracuse, New York, USA, revealed that the prevalence of melanism among living squirrels in Syracuse was negatively related to distance from the city center, whereas there was no urban–rural cline in melanism among road‐killed individuals, with the melanic morph underrepresented among road‐killed squirrels by up to 30% along the urbanization gradient. An examination of the prevalence of each color morph on and off road surfaces in a range‐wide compilation of > 100,000 photographs of S. carolinensis also indicated that the melanic morph was underrepresented among road‐killed squirrels imaged. Our study highlights vehicular collisions as an important source of natural selection on phenotypic traits, suggesting a potential role in shaping patterns of urban evolution and contributing to the maintenance of urban–rural clines. |
| format | Article |
| id | doaj-art-56840d472e2c4b298552bf5b2c7c59cc |
| institution | DOAJ |
| issn | 1752-4571 |
| language | English |
| publishDate | 2025-05-01 |
| publisher | Wiley |
| record_format | Article |
| series | Evolutionary Applications |
| spelling | doaj-art-56840d472e2c4b298552bf5b2c7c59cc2025-08-20T03:12:26ZengWileyEvolutionary Applications1752-45712025-05-01185n/an/a10.1111/eva.70109Road Mortality Contributes to the Evolution of an Urban–Rural Cline in Squirrel Coat ColorAdam F. Parlin0Bradley J. Cosentino1Richard M. Lehtinen2John E. McDonald3Emma C. C. Sinclair4James P. Gibbs5Department of Environmental Biology State University of New York College of Environmental Science and Forestry Syracuse New York USADepartment of Biology Hobart & William Smith Colleges Geneva New York USADepartment of Biology The College of Wooster Wooster Ohio USADepartment of Environmental Science Westfield State University Westfield Massachusetts USADepartment of Biology Queen's University Kingston Ontario CanadaDepartment of Environmental Biology State University of New York College of Environmental Science and Forestry Syracuse New York USAABSTRACT Cities impose unique selection pressures on wildlife and generate clines in phenotypic traits along urban–rural gradients. Roads are a widespread feature of human‐dominated landscapes and are known to cause direct wildlife mortality; however, whether they act as a selective force influencing phenotypic trait variation along urban–rural gradients remains unclear. This study tested the hypothesis that roads influence natural selection of coat color in the eastern gray squirrel (Sciurus carolinensis), a species with two distinct coat colors: a gray morph that is common in all areas and a melanic morph more prevalent in urban areas than in rural ones. Vehicular collisions are a significant cause of mortality in eastern gray squirrels, with the melanic morph more visually conspicuous on roads and more easily detected and avoided by drivers than the gray morph. Standardized road cruise surveys along an urbanization gradient in Syracuse, New York, USA, revealed that the prevalence of melanism among living squirrels in Syracuse was negatively related to distance from the city center, whereas there was no urban–rural cline in melanism among road‐killed individuals, with the melanic morph underrepresented among road‐killed squirrels by up to 30% along the urbanization gradient. An examination of the prevalence of each color morph on and off road surfaces in a range‐wide compilation of > 100,000 photographs of S. carolinensis also indicated that the melanic morph was underrepresented among road‐killed squirrels imaged. Our study highlights vehicular collisions as an important source of natural selection on phenotypic traits, suggesting a potential role in shaping patterns of urban evolution and contributing to the maintenance of urban–rural clines.https://doi.org/10.1111/eva.70109adaptive evolutionanimal colorcitizen sciencenatural selectionphenotypic variationroad ecology |
| spellingShingle | Adam F. Parlin Bradley J. Cosentino Richard M. Lehtinen John E. McDonald Emma C. C. Sinclair James P. Gibbs Road Mortality Contributes to the Evolution of an Urban–Rural Cline in Squirrel Coat Color Evolutionary Applications adaptive evolution animal color citizen science natural selection phenotypic variation road ecology |
| title | Road Mortality Contributes to the Evolution of an Urban–Rural Cline in Squirrel Coat Color |
| title_full | Road Mortality Contributes to the Evolution of an Urban–Rural Cline in Squirrel Coat Color |
| title_fullStr | Road Mortality Contributes to the Evolution of an Urban–Rural Cline in Squirrel Coat Color |
| title_full_unstemmed | Road Mortality Contributes to the Evolution of an Urban–Rural Cline in Squirrel Coat Color |
| title_short | Road Mortality Contributes to the Evolution of an Urban–Rural Cline in Squirrel Coat Color |
| title_sort | road mortality contributes to the evolution of an urban rural cline in squirrel coat color |
| topic | adaptive evolution animal color citizen science natural selection phenotypic variation road ecology |
| url | https://doi.org/10.1111/eva.70109 |
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