Diet and social conditions during sexual maturation have unpredictable influences on female life history trade‐offs

Abstract

The trade‐off between gametes and soma is central to life history evolution. Oosorption has been proposed as a mechanism by which females can redirect nutrients invested in oocytes into survival when conditions for reproduction are poor. Although positive correlations between oocyte degradation and lifespan have been documented in oviparous insects, the adaptive significance of this process in species with more complex reproductive biology has not been explored. Further, environmental condition is a multivariate state, and combinations of environmental stresses may interact in unpredictable ways. Previous work on the ovoviviparous cockroach, Nauphoeta cinerea, revealed that females manipulated to mate late relative to sexual maturation experience age‐related loss in fecundity because of loss of viable oocytes via apoptosis. This loss in fecundity is correlated with a reduction in female mate choice. Food deprivation while mating is delayed further increases levels of oocyte apoptosis, but the relationship between starvation‐induced apoptosis and life history are unknown. To investigate this, virgin females were either fed or starved from eclosion until provided with a mate at a time known to be suboptimal for fertility. Following mating, females were fed for the duration of their lifespan. We measured lifetime reproductive performance. Contrary to predictions, under conditions of delayed mating opportunity, starved females had greater fecundity, gave birth to more high‐quality offspring and had increased longevity compared with that of fed females. We suggest that understanding proximal mechanisms underlying life history trade‐offs, including the function of oocyte apoptosis, and how these mechanisms respond to varied environmental conditions is critical.

Separate and combined effects of nutrition during juvenile and sexual development on female life-history trajectories: the thrifty phenotype in a cockroach

“…The advantage, if any, of this reallocation is unclear. Developmental constraints may mean that body size is canalized, and females must reach a threshold size to mature; N. cinerea females are larger than males and take longer to develop (Barrett et al 2009). …”

“…At 18 days, all females are sexually receptive, even under poor nutritional conditions (Barrett et al 2009). We placed each experimental female into a 17 Â 12 Â 6.5 cm clear plastic mating arena with a randomly assigned virgin 10-day-old male.…”

“…We manipulated diet quality in two life-history stages; juvenile development (from first instar to adult eclosion) and sexual maturation (from eclosion to 18 days, Barrett et al 2009). Juvenile and sexual maturation diet was either a poor-quality unbalanced diet (P), or a good-quality balanced diet (G).…”

“…Previous studies on N. cinerea have shown that females evaluate food availability during sexual maturation and use this information to alter adaptively reproductive strategy (Barrett et al 2009). Individuals were either maintained on the initial juvenile diet or switched to the opposite diet for the period of sexual maturation prior to mating.…”

Quantitative genetic variation in the control of ovarian apoptosis under different environments

“…These genes are under different selection than the selection experienced by the genes controlling apoptosis during normal developmental progression. Interestingly, females that mate late relative to sexual maturation in the absence of food have higher fecundity and increased longevity compared with females that delay mating in the presence of food (Barrett et al, 2009). Thus, the difference in genetic architecture of ovarian apoptosis in starved females that delay mating is reflected in variation in fitness consequences of timing of reproduction in the two nutritional environments.…”