Abstract
The western terrestrial garter snake (Thamnophis elegans) varies significantly in individual growth rates and life-history traits (maturation, reproduction, and survival) among adjacent populations in nature. This study focuses on assessing the genetic and environmental components of the substantial among-population variation in growth rates. Litters of neonates from nine populations inhabiting either mountain meadow or lakeshore habitat were reared for one year in a common-garden experiment with two temperature treatments. Diet, frequency of feeding, light exposure, and daytime temperatures were identical for all individuals. The two different nighttime temperatures (20°C and 25°C) were chosen to mirror field differences in nighttime thermoregulatory constraints for mountain-meadow and lakeshore snakes, respectively. Temperature and source habitat interacted to affect first-year growth rate. Neonates from meadow dams grew fastest in the cooler treatment, whereas those from lakeshore dams grew fastest in the warmer treatment. The observation that naive neonates, which were gestated and raised under identical conditions, grew fastest in environments characteristic of their natal population is evidence both that there are genetic differences among populations for growth and that these differences reflect adaptation to local habitats at a very small geographic scale. In addition, significant directional selection for large birthweight was measured for neonates from all populations. These results are considered in the context of population colonization history, migration and selection, and competing models for growth rate variation.Corresponding Editor: E. Brodie III
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
