Meeting Abstract
Introduced species can diverge from their source population when established in a new ecosystem. The Texas horned lizard (Phrynosoma cornutum) is native to the western United States, but was historically introduced to several locations in the southeastern United States. We studied three introduced populations in South Carolina to determine 1) if the introduced populations exhibit dietary, morphological and genetic divergence from the native western populations and 2) if diet, morphology and genetics significantly vary between the three introduced populations. We expected little divergence from western populations and among introduced populations because P. cornutum is a highly specialized species whose biology is shaped by its diet of Pogonomyrmex harvester ants. Our data show that the introduced populations experienced founder effects and went through a bottleneck that resulted in decreased genetic diversity. However, introduced populations are still genetically distinct from each other and exhibit genetic diversity similar to some western populations found in urban areas. South Texas was likely the source population for the introduction. The majority of the diet in South Carolina is ants (94%), but surprisingly, P. cornutum in South Carolina do not eat Pogonomyrmex harvester ants. Introduced lizards primarily eat Dorymyrmex ants, but each introduced population complement Dorymyrmex with significantly different amounts of other species of ants, insects and plant matter. Introduced populations differ in limb and head shape when compared to western populations and when compared to each other. This study shows a dietary specialist can exhibit phenotypic change that allows it to take advantage of ecological opportunity in the introduced range.
