Phenotypic plasticity in reproductive traits: geographical variation in plasticity in a viviparous snake

1, Previous experiments showed that Checkered Garter Snakes (Thamnophis mar cianus) from south Texas, USA tan environment subject to high seasonal and annual variation in environmental conditions), demonstrated marked phenotyp ic plasticity in clutch size and clutch mass in response to experimental ch anges in prey availability. 2, In this study, the extent of phenotypic plasticity in life-history trait s in Checkered Garter Snakes from south Texas was experimentally compared w ith a population of the same species from south-eastern Arizona, where the environment may be more constant. 3, Unlike results from south Texas, Checkered Garter Snakes from Arizona sh owed no significant phenotypic plasticity in clutch size, clutch mass or an y other life-history trait in response to changes in food availability, at least within the boundaries of our experimental conditions. 4, The data indicate that the degree of phenotypic plasticity in life-histo ry traits differs among populations within the same species. However, these differences are subject to both adaptive and non-adaptive explanations.