Seasonal Shifts in Reproduction Depend on Prey Availability for an Income Breeder
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The evolution of reproductive strategies depends on local environmental conditions. When environments are seasonal, selection favors individuals that align changes in key reproductive traits with seasonal shifts in habitat quality. Offspring habitat quality can decline through the season, and increased maternal provisioning to late-produced offspring may compensate. This shift, however, may depend on environmental factors that influence reproduction and are, themselves, subject to temporal changes (e.g., food abundance). We studied the brown anole lizard (Anolis sagrei) to demonstrate how prey abundance modifies seasonal changes in key reproductive traits. We bred lizards in controlled laboratory conditions across the reproductive season and manipulated the availability of food by providing some breeding pairs high prey availability and some low. Halfway through the season, we switched half of the breeding pairs to the opposite treatment. We measured growth of male and female lizards as well as latency to oviposit, fecundity, egg size, egg content (yolk, water, shell mass), and egg quality (steroid hormones, yolk caloric content) over this period. Higher prey availability enhanced lizard growth and some key reproductive traits (egg size, fecundity) but not others (egg content and quality). Moreover, we found that seasonal patterns of reproduction were modified by prey treatment in ways that have consequences for offspring survival. Our results demonstrate that seasonal changes in reproduction are dependent on fluctuations in local environmental conditions. Moreover, researchers must account for seasonal shifts in environmental factors and reproductive traits (and their interactions) when designing experiments and drawing conclusions about how the environment influences reproduction.