SICB 2015: If You Want to Invade, You Better Be Bold

Lauren Davis presenting her work on invasion success in lizards.

As our planet becomes increasingly connected and humans facilitate novel species interactions, we must ask why some introduced species are destructive and others relatively harmless. Lauren Davis, a senior in Dr. Michele Johnson’s lab at Trinity University, conducted a study on behaviors, and their neural correlates, that may influence the invasiveness of non-native lizards. She compared the invasive Anolis sagrei to the native Anolis carolinensis, the invasive House Gecko (Hemidactylus turcicus), and the native Texas Banded Gecko (Coleonux brevis). They hypothesized that highly invasive species display more ‘bold’ behaviors (in this case, the number of enclosure boundaries crossed during an experimental period) and have larger and/or denser neurons in associated brain regions than less invasive species. While there are many documented behavioral trials with boldness in Anolis, geckos have received little attention in this regard. Lauren and her fellow researchers found that A. sagrei is indeed bolder than A. carolinensis, but that the two gecko species do not differ in traits associated with the boldness syndrome (Fig. 1).

Figure 1: Invasive Brown Anoles are bolder than native Green Anoles

The researchers also found that neuron size in brain regions known to influence boldness and aggression were opposite than expected values, so the team plans to analyze neuron density in these regions to help explain the observed behaviors. This is one of the first studies comparing behavior and brain morphology to invasion success, and it paves an exciting path towards our understanding of species interactions in our changing world.

Lauren is graduating in May, and hopes to work in conservation or public health before continuing her education in graduate school.