Meeting Abstract
P1.11 Saturday, Jan. 4 15:30 Evolution of communication modalities and brain morphology in lizards ROBINSON, C.D.*; PATTON, M.S.; JOHNSON, M.A.; Trinity University crobins3@trinity.edu
Animals communicate using a variety of sensory mechanisms, including visual, chemical, auditory, and tactile modalities, but little is known regarding how brain morphology is associated with these modalities in reptiles. In this study, we quantified the communication behaviors of six lizard species from six different families: Anolis carolinensis (green anole), Aspidoscelis gularis (spotted whiptail), Hemidactylus turcicus (Mediterranean house gecko), Leoicephalus carinatus (curly-tail), Sceloporus olivaceus (Texas spiny lizard), and Scincella lateralis (little brown skink). Using data from 110 hours of behavioral observation, our results indicate that anoles and curly tails use primarily visual modalities to communicate, whiptails and skinks use primarily chemical signals, and geckos and spiny lizards used both visual and chemical modalities (other modalities, including auditory, were not assessed in this study). We collected brains of 12 adult male lizards from each species, sectioned them via cryostat at 20 µm, and stained them with thionin for morphological measurements. Measures of the cross-sectional area of the broadest section of the brain, standardized by snout-vent length, indicate that relative brain size is not associated with mode of communication. Measures of neuron size and density in brain regions associated with visual and chemical signaling will also be assessed: the optic tectum and the lateral geniculate nucleus, both thought to be associated with vision, and the nucleus sphericus of the amygdala and the hypoglossal nucleus, both involved in chemical signaling. This study takes an early step toward identifying associations between brain morphology and communication behaviors, contributing to our understanding of the mechanisms underlying the repeated evolution of signaling modalities in reptiles.
