Integrating development and environment to model reproductive performance in natural populations of an intertidal...

Functional challenges can differ among life-history stages, yet performance at one stage may be linked to the outcome of performance at others. For example, adult performance, in terms of the location or timing of reproduction in response to environmental signals, can set conditions that affect the performance of developmental stages. In marine invertebrates, however, early performance has been studied primarily in the laboratory. I outline an integrative approach to the study of field reproductive performance in a marine gastropod that undergoes development in intertidal habitats. Embryos within gelatinous masses experience high variability in development temperature and frequent exposure to thermal stress. In laboratory experiments, developmental performance was measured as a function of maximum temperature (T(max)) experienced during fluctuations that mimicked field tidal profiles. Performance curves showed declines that coincided with temperature thresholds for heat shock protein (Hsp) expression, a signal of cellular stress. Application of laboratory results to field records of T(max) predicted large variation in the survival of embryos deposited on different days. Timing of field reproduction was non-random with respect to T(max), suggesting that adults could help to buffer embryos from environmental stress. Embryo survival, however, was not predicted to benefit from the non-random pattern of adult reproduction. Adults may be constrained to respond to information that only weakly predicts conditions that embryos will experience. Studies that incorporate linkages between life cycle stages in the field may better reveal how performance capacities and constraints at one stage can influence performance and selection at others.