The garter snake as a model system in evolutionary biology, ecology and physiology Garter snakes are the most studied snake model system in the areas of ecology, evolution, behavior, and physiology. Not only is the breadth of work considerable, but the seminal selleck chem inhibitor nature of work in behavior genetics, development of personality, toxin resistance, pheromonal communication, and reproductive physiology places the genus Thamnophis among the major vertebrate models for organismal biology. Garter snakes have provided their most significant contributions as a model to investigate biological questions in the context of natural populations in the wild. Evolutionary diversification Garter snakes have historically been the most important snake group for examining speciation and differentiation of ecologically important phenotypes.
Some of the original work describing the concept of ring species and the ��artenkreis�� problem of population differentiation emerged from work on western Thamnophis species including T. sirtalis [2-4]. Since that time, robust phylogenies have been developed at the species and population level [5-7]. These studies indicate at least occasional hybridization between species [8], suggesting incomplete reproductive isolation and the potential for introgression leading to local adaptation. Population and genetic differentiation in a range of behavioral and morphological traits have been modeled as evolving through quantitative genetic processes.
Research on prey preferences, color pattern polymorphism, skeletal morphology, life history profiles, and antipredator behaviors of Thamnophis all stand as primary empirical examples of selective and genetic processes that lead to population level differences in traits [9-14]. Ecological studies of diet differences, thermal biology, homing, and hibernation physiology and behavior show similar patterns of trait differentiation influenced by environmental contexts [13,15-18]. Thamnophis populations have been important subjects for field studies of natural selection that reveal not only the targets of selection, but complex surfaces that are predicted to lead to genetic integration and changes in genetic variance. Field studies of color pattern and escape behavior demonstrated epistatic selection on phenotypic traits due to predation [19,20].
Other studies have quantified selection on skeletal morphology, locomotor performance, and exercise physiology [21,22]. Evolutionary developmental biology and axial patterning Snakes feature several radical departures from the ancestral amniote body plan, perhaps most notably the absence of limbs and a pre-sacral vertebral column composed of highly similar vertebrae. Remarkably, the absence of forelimbs and the homomorphy of vertebrae might be developmentally GSK-3 and genetically linked.