Selection on age at reproduction in Drosophila melanogaster: female mating frequency as a correlated response.

:We examined the effect of selection for age at reproduction on female mating frequency and fertility in female Drosophila melanogaster. Selection for increased age at reproduction (and hence increased lifespan) resulted in higher late life female mating frequencies, while females selected for younger ages at reproduction showed increased early life mating frequencies. These results indicate that the response to selection on age at reproduction has involved changes in the scheduling of female reproductive behavior.

Sgrò CM ，Geddes G ，Fowler K ，Partridge L ... -  《EVOLUTION》

Age-specific effects of novel mutations in Drosophila melanogaster II. Fecundity and male mating ability.

Evolutionary theories of senescence assume that mutations with age-specific effects exist, yet until now, there has been little experimental evidence to support this assumption. In this study, we allowed mutations to accumulate in an outbred, wild population of Drosophila melanogaster to test for age-specific differences in both male mating ability and fecundity. We assayed for age-specific effects of mutations after 10, 20, and 30 generations of mutation accumulation. For mating ability, we found the strongest effects of mutations in the first half of the life span after 20 generations, and at nearly all ages by generation 30. These results are qualitatively consistent with results from a companion study in which age-specific mortality was assayed on the same lines of D. melanogaster. By contrast, effects of fecundity were confined to late ages after 20 generations of mutation accumulation, but by generation 30, as with male mating ability, effects of novel mutations were distributed across all age classes. We discuss several possible explanations for the differences that we observe between generations within traits, and among traits, and the relevance for these patterns to models of aging as well as models of mate choice and sexual selection.

Mack PD ，Lester VK ，Promislow DE 《GENETICA》

Mating frequency and inclusive fitness in Drosophila melanogaster.

In many species, increased mating frequency reduces maternal survival and reproduction. In order to understand the evolution of mating frequency, we need to determine the consequences of increased mating frequency for offspring. We conducted an experiment in Drosophila melanogaster in which we manipulated the mating frequency of mothers and examined the survival and fecundity of the mothers and their daughters. We found that mothers with the highest mating frequency had accelerated mortality and more rapid reproductive senescence. On average, they had 50% shorter lives and 30% lower lifetime reproductive success (LRS) than did mothers with the lowest mating frequency. However, mothers with the highest mating frequency produced daughters with 28% greater LRS. This finding implies that frequent mating stimulates cross-generational fitness trade-offs such that maternal fitness is reduced while offspring fitness is enhanced. We evaluate these results using a demographic metric of inclusive fitness. We show that the costs and benefits of mating frequency depend on the growth rate of the population. In an inclusive fitness context, there was no evidence that increased mating frequency results in fitness costs for mothers. These results indicate that cross-generational fitness trade-offs have an important role in sexual selection and life-history evolution.

Priest NK ，Galloway LF ，Roach DA 《-》

Bidirectional selection for female receptivity in Drosophila melanogaster.

A wild population of Drosophila melanogaster was subjected to selection for high and low female receptivity. Selection was only applied in females on the basis of the mating times observed in a 30-min period. We applied a selection paradigm that allowed us to conclude that females unmated after 30 min correspond to the truncated upper tail of the distribution underlying mating times. Selection was successful, with mean mating times of about 5 min for the high lines, 35 min for the low lines, and 12 min for the control. Receptivity of the selection lines remained steady after 42 generations of relaxed selection, suggesting a lack of natural selection on receptivity in laboratory conditions. We also found a clear relationship between high or low receptivity and high or low frequency of hybridization with D. simulans males, emphasizing the role of female receptivity in maintaining isolation with its sibling species D. simulans.

Piñeiro R ，Carracedo MC ，Izquierdo JI ，Casares P ... -  《BEHAVIOR GENETICS》

Live fast die young life history in females: evolutionary trade-off between early life mating and lifespan in female Drosophila melanogaster.

The trade-off between survival and reproduction is fundamental to life history theory. Sexual selection is expected to favour a 'live fast die young' life history pattern in males due to increased risk of extrinsic mortality associated with obtaining mates. Sexual conflict may also drive a genetic trade-off between reproduction and lifespan in females. We found significant additive genetic variance in longevity independent of lifetime mating frequency, and in early life mating frequency. There was significant negative genetic covariance between these traits indicating that females from families characterized by high levels of multiple mating early in life die sooner than females that engage in less intense early life mating. Thus, despite heritable variation in both traits, their independent evolution is constrained by an evolutionary trade-off. Our findings indicate that, in addition to the well-known male-driven direct costs of mating on female lifespan (mediated by male harassment and harmful effects of seminal fluids), females with a genetic propensity to mate multiply live shorter lives. We discuss the potential role of sexual conflict in driving the evolutionary trade-off between reproduction and lifespan in Drosophila. More generally, our data show that, like males, females can exhibit a live fast die young life history strategy.

Travers LM ，Garcia-Gonzalez F ，Simmons LW 《Scientific Reports》