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My dissertation research focused on variation in sexual signals and reproductive behavior within and between populations, with the goal of understanding how (and whether) such variation contributes to the formation of new species.  Specifically, I studied the mesquite lizard (Sceloporus grammicus) species complex, a taxon of Mexican lizards that live in a variety of habitats and show unusually high levels of chromosomal variation.  I found that they also show quite a bit of variation in their throat colors, both within and among populations. As a whole, my dissertation sought to figure out why this is and what the consequences of this variation might be for divergence among populations and possibly speciation.  Mostly, this involved driving around Mexico and visiting lots of beautiful mountains (see photos below), as well as some exciting laboratory behavioral experiments (see video below). 

Male throat color morphs from Cerro Peña Nevada, Nuevo León, México.
A. Pure orange. B. Pure blue. C. Pure yellow. D. Yellow-orange. E. Blue-
orange. F. Blue-yellow.

Male throat color morphs from San Antonio de las Alazanas, Coahuila,
México. A. Pure orange. B. Pure white. C. Pure yellow. D. Yellow-orange. E. White-
orange. F. White-yellow.

   One of my field sites, in Nopalillo, Hidalgo, México.     Another field site, near Cerro Peña Nevada, Nuevo
                                                                                              León, México (see lizard photos above).

A field site near San Juan Ixtenco, Tlaxcala, México   A field site near General Cepeda, Coahuila, México.
(any day in the field that involves climbing around

 on old Spanish ruins is a pretty successful one).

Here's a video of one of the male aggression trials I did to determine whether male throat color polymorphisms are associated with variation in male agonistic behavior in the mesquite lizard.  There are several other lizard species where that's the case, but the mesquite lizard is unusual in that males in some populations have an orange/yellow/blue trimorphism (like Cerro Peña Nevada, above), whereas others have an orange/yellow/white trimorphism in males (like San Antonio de las Alazanas, above).  I performed dyadic male aggression trials in both these populations.  I found that throat color variation is associated with behavioral variation in males from both places, but the signal content of particular colors differs between populations.  For more details, please see the paper my collaborators and I published in the journal Behavioral Ecology (on my Recent Publications page). 

Lizard Aggression Trial Example

Thanks to Brendan Bane for helping me put the video together and add the text!

This material is based upon work supported by the National Science Foundation under Grant Number (1110497).  Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation