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Bottlenecks and Microhabitat Preference in Invasive Wall Lizard, Podarcis muralis

Homan, Cassandra M.

Abstract Details

2013, MS, University of Cincinnati, Arts and Sciences: Biological Sciences.
We investigated two critical aspects of an animal invasion: the possibility of a genetic bottleneck upon introduction, and microhabitat choice during the spread into a novel environment. Many invasive species seem likely to undergo a genetic bottleneck upon introduction since only a few individuals are needed to found a population. However, bottlenecks are uncommon in invasive species, suggesting that there may be an important cost to bottlenecks. We studied an invasive population of common wall lizard (Podarcis muralis) in Cincinnati, Ohio that is thought have been the product of a single introduction of a few individuals in the early 1950's. Our microsatellite analysis of genetic samples collected directly from the source population and compared them to samples collected from the Cincinnati population confirmed a substantial loss of genetic diversity, indicating a genetic bottleneck. Simulations suggest that the bottleneck was likely on the scale of three individuals. The loss of allelic diversity was so large that we were unable to confirm the Italian source of the Cincinnati population. Despite this clear loss of genetic diversity, Podarcis muralis is still thriving in the introduced range. Previous studies have found that environmental niche modeling does not fully predict the invasion success of introduced P. muralis. We attempted to characterize microhabitat use as a more effective or complementary means to predict the extent of invasion of this species. Cincinnati P. muralis have been noted to prefer south facing artificial rock walls. We quantified 17 variables in sites with confirmed high densities of lizards and compared those with low or zero density sites nearby to determine the components of microhabitat most contribute to the proliferation of the species. Our results indicate that the most important factor for high density is not rock substrate, but substrate crack density, which is likely a source of refuge for the species. Other factors such as total amount of suitable substrate and overall distribution of cover types were less important. Our results suggest that this lizard is not necessarily limited to urban areas. This ability to use a broad range of microhabitats, combined with their ability to thrive at even very low levels of genetic diversity suggests Podarcis muralis is a very robust invader, whose full impact on native species may not yet be apparent.
Kenneth Petren, Ph.D. (Committee Chair)
Bruce Jayne, Ph.D. (Committee Member)
Stephen Matter, Ph.D. (Committee Member)
61 p.

Recommended Citations

Citations

  • Homan, C. M. (2013). Bottlenecks and Microhabitat Preference in Invasive Wall Lizard, Podarcis muralis [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377868885

    APA Style (7th edition)

  • Homan, Cassandra. Bottlenecks and Microhabitat Preference in Invasive Wall Lizard, Podarcis muralis. 2013. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377868885.

    MLA Style (8th edition)

  • Homan, Cassandra. "Bottlenecks and Microhabitat Preference in Invasive Wall Lizard, Podarcis muralis." Master's thesis, University of Cincinnati, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377868885

    Chicago Manual of Style (17th edition)