Costs of reproduction in a temperate-zone lizard, Elgaria coerulea

As a means of predicting and explaining variation in reproductive investment in lizards and snakes, Shine and Schwarzkopf (1992) attempted to determine the relative importance of the two kinds of costs to individual lifetime fitness (the SS model). They concluded that most lizard species are unlikely to make trade-offs between current and future reproduction (fecundity costs). In this study of a temperate-zone lizard, Elgaria coerulea , I have three main objectives: (1) to provide the first natural history data for a Canadian population of this species, (2) to describe life-history traits for this population, and (3) to formally test the predictions of the SS model and discuss its potential predictive power.; Individual Elgaria coerulea occupy relatively small areas, thus minimising costs associated with a long-distance migration. In addition to having limited movement, Elgaria coerulea rely on hiding as one of their main anti-predator strategies, although there is sex-dependent variation in their retreat-site selection. Emergence patterns of male Elgaria coerulea did not change over their reproductive cycle.; Annual survival rate of adult females was 44% and juvenile survival rate was 22%. The survival rate of adult males likely fell in between these values, but I was not able to estimate it directly because of small sample sizes. I infer from the female's relatively high survival rate that the necessity for gravid females to spend more time in the open during gestation does not translate simply to increased mortality.; Gravid females have reduced sprint speed and sprint speed was inversely related to the burden of the clutch. Therefore, gravid females presumably could reduce their predation risk by remaining closer to cover than males or juveniles. However, this is not the case; all northern alligator lizards remained close to cover. Thus, the lack of shift in anti-predator behaviour of gravid females may be a result of all Elgaria coerulea relying on crypsis rather than sprinting as an anti-predator defence.; Another important anti-predator strategy in Elgaria coerulea is tail autotomy, and once again I measured variation in this trait between males and females. Gravid females never lose small parts of their tails, perhaps giving them extra time to escape from a predator. Furthermore, recent tail loss was not seen in gravid females during late gestation.; Finally, I show that some Elgaria coerulea trade current reproduction for growth. (Abstract shortened by UMI.)...