Data from: Rural selection drives the evolution of an urban-rural cline in coat color in gray squirrels

Phenotypic differences between urban and rural populations are
well-documented, but the evolutionary processes driving trait variation
along urbanization gradients are often unclear. We combined spatial data
on abundance, trait variation, and measurements of fitness to understand
cline structure and test for natural selection on heritable coat color
morphs (melanic, gray) of eastern gray squirrels (Sciurus carolinensis)
along an urbanization gradient. Population surveys using remote cameras
and visual counts at 76 sites along the urbanization gradient revealed a
significant cline in melanism, decreasing from 48% in the city center to
<5% in rural woodlands. Among 76 squirrels translocated to test for
phenotypic selection, survival was lower for the melanic than gray morph
in rural woodlands, whereas there was no difference in survival between
color morphs in the city. These results suggest the urban-rural cline in
melanism is explained by natural selection favoring the gray morph in
rural woodlands combined with relaxed selection in the city. Our study
illustrates how trait variation between urban and rural populations can
emerge from selection primarily in rural populations rather than
adaptation to novel features of the urban environment. This reposotory
contains a) occupancy data, point count data, and R code used to estimate
the urban-rural cline in melanism, and b) radiotelemetry data and R code
used to estimate differential survival between color morphs in urban and
rural environments.