MEPS 493:207-217 (2013)  -  DOI: https://doi.org/10.3354/meps10496

ABSTRACT: At the inter-specific level, per offspring investment (POI) is associated with larval development mode and follows a macro-ecological trend within the marine environment; higher POI and its associated greater degree of endotrophy and abbreviated development is found in cooler, high latitude regions. Here, the implications of between-brood-variation in hatchling energy content (measured as carbon mass) on larval starvation resistance and developmental plasticity within the caridean shrimp Palaemonetes varians were assessed. Results demonstrate that greater POI provides increased endotrophy and the potential for abbreviated development. In the absence of food, P. varians larvae from broods of higher hatchling energy content developed to more advanced larval stages and survived for longer before succumbing to starvation. In the presence of food, P. varians larvae from broods of higher hatchling energy content developed through fewer larval instars, showed higher growth rates, and had shorter development times. Also, for larvae developing through the same number of larval instars, larvae from broods of higher hatchling energy content developed to greater juvenile dry weight. These data support the hypothesis that macro-ecological trends in development mode are driven by inter-specific variations in POI. At the intra-specific level, phenotypic plasticity allows for environmentally mediated variations in POI. Under differential selection pressures, this flexibility may, thus, eventually permit the evolution of the diverse and complex life cycles observed in the marine environment.

KEY WORDS: Carry-over effects · Evolution of lecithotrophy · Larval ecology · Palaemonidae · Palaemonetes varians · POI