Color Variation in Black Widows

THERESA GBUREK

There is an opportunity to gain insight into an animal’s behavioral adaptations by understanding the relationship between physiological mechanisms and fitness consequences.  In general, interactions between genes and the environment shape the physiological mechanisms by which phenotypes are produced. I am particularly interested in coloration characteristics that are adaptively coupled to a specific behavior.  In collaboration with Kevin McGraw, we are exploring the underlying mechanisms of widow coloration so we can begin to understand the sources responsible for the development and variation in black widow color.  More specifically, we are interested in the functional significance of the notorious red hourglass on the abdomen of the black widow.  While it has been widely speculated that the red hourglass is aposematic (i.e. anti-predator warning signal) in function, little research has been done to support this claim.  We suggest that the red hourglass plays an integral role in black widow anti-predation behavior when faced with visual nocturnal predators such as lizards and geckos.  By manipulation of the size and hue of the red hourglass belonging to widows presented with the threat of predation, we hope to determine if the red hourglass functions as a warning signal.

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Gburek T, Johnson JC (2018)  The effects of urbanization on the life history and                color of black widow spiders.  Urban Naturalist, 18: 1-16. PDF Link Here

Johnson, JC,  Highfill T, *Stevens, D.  (2017)  Black widows in an urbanized                        desert: spatial variation and condition dependence of the red hourglass.                Journal of Urban Ecology, 3(1): doi.org/10.1093/jue/jux013.

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