About This Project

Ask the Scientists

What is the context of this research?

What influences gene flow in Latrodectus hesperus across the landscape?

The black widow spider is a common pest in urban areas which often results in large infestations of spiders, given their abundance, we expect to find that city spiders will have a higher likelihood of being more genetically similar between other city spiders, whereas, given their more solitary locations in the desert, desert spiders will be less genetically similar to city spiders, resulting in population differences between city and non-city (desert) spiders.

Historically, Phoenix has undergone a rapid expansion and urbanization compared to other metropolitan areas within the range of L. hesperus, therefore, since black widows are a pest species relying on urban areas to aid in their own expansion/proliferation, this species may have also undergone a population expansion coinciding with this urbanization. If this is true, we would expect to find more genetic similarities within urban/city areas with faster/recent patterns of urbanization than areas that have had slower/older colonizations. We can compare patterns of genetic differences to see if city development/urbanization plays an important role in L. hesperus population differentiation.

What is the significance of this project?

The western black widow spider is a common pest species found in urban areas around houses and sheds. Due to their close proximity to humans, they are considered a pest of medical importance as their venom causes severe muscle pain, cramps, nausea and is potentially lethal to the young and elderly.

Previous studies have found that there are behavioral and ecological differences between urban and non-urban spiders. However, the underlying mechanism driving these differences is not well understood. A population genetic study provides a unique opportunity to asses the effect of urbanization on population differentiation of the western black widow spider.

What are the goals of the project?

These funds will allow me to collect samples in two city locales as well as their surrounding desert areas to compare the effects of urbanization on population differentiation between urban and non-urban spiders.

I will be spending one month in the field for the first locale and one month in the field for the second locale. I will be looking for approximately 40 areas within each city that have black widow infestations that I will collect. I will also be looking for black widows in at least 2 desert areas surrounding the city. Once I have collected the spider samples, I will bring them back to the lab to extract their DNA and sequence a region of their mitochondria that I have previously sequenced for Phoenix city and desert spiders. Once the samples are sequenced, I will compare the sequences between all city and desert locales to examine the possible effects of urbanization on population differentiation.