Williams Lab

Publications and their PDFs can be found on Google Scholar and Research Gate

These are a few of the significant projects in the lab:

Ecology and Conservation of Texas Horned Lizards 

Our lab developed the molecular markers for this species, and after many years of sampling, we determined how this species was genetically structured across its range in the U.S. Texas Parks and Wildlife and Texas zoos (Fort Worth Zoo, Dallas Zoo, and San Antonio Zoo) then set up captive breeding and reintroduction programs to reflect the different genetic regions we found across Texas. The Fort Worth Zoo and Dallas Zoos breed lizards from the northern plains, and the San Antonio Zoo breeds individuals from the southern plains. Experimental reintroductions are taking place at two sites, Mason Mountain WMA in the northern plains and at a site in Williamson County in the southern plains, to determine the best reintroduction methods for this species. Since 2020, our lab has been studying the ecology (survival, diet, habitat use, movement patterns, and nest site selection) of reintroduced individuals at Mason Mountain WMA and comparing their behavior to a nearby natural population on a private ranch. These studies are being conducted to evaluate the quality of the reintroduction site and whether reintroduced individuals are behaving in a way that is expected for this species.

We also conducted a long-term population study of Texas horned lizards living in two small South Texas towns (Kenedy and Karnes City) from 2013-2021. The central question was how horned lizards can persist in these human-altered habitats. On the negative side, we found that small towns isolate lizards from surrounding populations and that urbanization curtailed dispersal, leading to a significant decrease in genetic diversity relative to more natural areas. On the positive side, the towns had a fortuitous mix of factors such as relatively low predation, alternative food sources, and ideal habitat for foraging and thermoregulation.

Invasion Genetics of  Weeds

Our work with invasive plants (Brazilian peppertree, hydrilla, alligator weed, Cuban bulrush) has been part of a long-term collaboration with researchers from the US Army Corp, USDA, University of Florida, and CSIRO. Our primary focus has been determining their introduction history, geographic origins, hybridization, and population structure in the invaded and native ranges. The distribution of genetic diversity in invasive plants can have important management implications. Different genotypes of the same species and inter- or intraspecific hybrids can require different control methods due to differing growth potential or resistance to particular biological control agents or herbicides. Investigations into the distribution of genetic diversity across the invasive range can shed light on whether management efforts need to be tailored to specific regions or whether an overall broad strategy can be employed. Understanding and comparing the distribution of genetic diversity in native and invasive ranges can also shed light on the number of introductions and evolutionary processes acting during invasion (founder effects, bottlenecks, etc.) and identify source regions in the native range to facilitate the exploration for biological control agents and the design of appropriate host-specificity plant tests.

Wind Energy Impacts on Bats

Wind energy facilities are a significant source of mortality for bat species. The reasons for such high mortality are poorly understood. Our lab has collaborated with Amanda Hale (WEST Inc.) and Victoria Bennett (TCU, Environmental Science) to study bat fatalities at wind energy facilities. We conducted extensive DNA barcoding to identify species and developed the first molecular sex markers for bats to determine the sex of bat fatalities. These studies determined that it was critical to use these genetic methods to accurately identify the species and sex of bat carcasses, which can often be degraded and difficult to identify by eye in the field. We also leveraged the large number of samples we collected to learn about the genetic population structure of some of these poorly known species, such as red bats, hoary bats, and yellow bats, and to evaluate some hypotheses for why bats might be attracted to wind energy facilities.