Adaptive Seasonal Variation in Grasshopper Offspring Size

Abstract

Seasonal increases and decreases in offspring size are both common, and some populations show even more complex responses.These studies have shown population level changes in offspring size, as well as phenotypic plasticity by individual females, with varying offspring sizes produced among a female's successive clutches.Although there has been some discussion relating observed seasonal changes in offspring size with seasonal changes in biotic and abiotic conditions (e.g., Kerfoot, 1974;Brody and Lawlor, 1984;Perrin, 1988), more work is needed concerning whether these seasonal responses are adaptive or not and, if adaptive, what selective pressures favor such plasticity.Many theoretical models have been developed, beginning with Smith and Fretwell (1974), which predict optimal offspring size, based on the relationship between offspring size and offspring fitness (e.g.,