PARENT SESSION
Poster Session # 21: Biogeography, Biodiversity, Populations, and Genetics.

Thursday, August 7 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Genetic variation vs. phenotypic plasticity in growth rates of side-blotch lizards.

Hanks, Joseph^*,1, Hatch, Kent¹, ¹ Brigham Young University, Provo, UT

ABSTRACT- Variation in growth rates has been hypothesized to be an important adaptive response of many species of lizards. Common garden experiments have been used to distinguish genetic and environmental components of variation in growth among populations of several of these species. However, the interaction between genetically based physiological differences and behavioral thermoregulation has never been separated. This study demonstrates that observed differences in the growth rates of five populations of side-blotch lizards (Uta stansburiana) are primarily genetically based and have a strong physiological component. We compared the growth rates of 100 adult individuals, collected from 5 different altitudes and latitudes (20 from each population), and held under different environmental temperature regimes. Individuals from each population were randomly assigned to one of two treatments – 1) exposure to constant temperature (26°C, 32°C, 35°C, or 38°C), and 2) thermoregulation in a temperature gradient of 26°C-38°C. Snout-vent-length and weight were measured weekly. We found that populations at lower latitudes and altitudes grew faster at all fixed temperatures. However, when allowed to behaviorally thermoregulate, growth rates of all populations became more similar.

Key words: side-blotch lizard, behavioral thermoregulation, Uta stansburiana, growth rates