Optimal offspring provisioning when egg size is constrained : a case study with the painted turtle Chrysemys picta

摘要: Classic egg size theory predicts that, in a given environment, there is level of maternal investment per offspring that will maximize fitness. However, positive correlations among and female body are observed within populations diverse animal taxa. A popular explanation for this phenomenon some populations, morphological constraints on size, such as ovipositor (insects) or pelvic aperture width (lizards turtles), limit size. Egg may therefore increase with due to size-specific offspring, coupled selection towards an optimal We use 17 years data from population painted turtles Chrysemys picta evaluate hypothesis. In accordance our predictions, we find (1) apparent only relatively small females, similarly (2) mass exhibits strong asymptotic relationship suggesting optimized at large sizes, (3) clutch not mass, varies condition, (4) more than across years. Contrary observe (5) the mass-clutch tradeoff less pronounced sizes. Our do fully support traditional hypothesis, recent models suggest hypothesis indeed overly simplistic. When selective environment female's influenced by her phenotype, vary phenotypes. This concept can explain many taxa, well patterns present study. paradigm, tight coupling (or other ‘constraints’) occur even when features causally related variation spirit, question validity invoking covariation