The Effect of Urbanization on the Life History and Color of Black Widow Spiders

Some species thrive in the wake of human disturbance and can out-compete others, often resulting in decreased biodiversity. Latrodectus hesperus (Western Black Widow Spider) is a superabundant urban pest-species known for its brightly colored red hourglass on the opisthosoma. Here we present a field survey of Western Black Widow population ecology, body condition, and hourglass coloration. We found significant spatial and tempo- ral variation across our 8 urban populations in various ecological variables, body condition, and hourglass coloration. Body condition was neither a reliable predictor of hourglass size nor coloration. Rather, the size and spectral qualities of the hourglass were correlated with ecological variables. Thus, our findings offer support for the contention that urbanization creates spatial heterogeneity.