MS prize winners

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Keith Bowers John Maynard Smith Prize winner 2016

Silver spoons, sexy sons, and constraints on sex allocation
One component of sex-allocation theory posits that sons and daughters are differentially affected by early rearing conditions, whereby the amount of parental care received has differing effects on the fitness of males and females. When this occurs, selection is expected to favor offspring sex-ratio adjustment according to anticipated fitness returns. Here, I describe a series of questions related to sex-by-environment effects on the development, survival, and future reproduction of offspring and associated variation in primary offspring sex ratios. What emerges is a pattern of consistent, and persistent, sex-specific effects of natal environmental conditions on offspring, thus favoring the adjustment of offspring sex ratios by mothers. However, increased sensitivity of males to environmental conditions should also contribute to shaping an optimal offspring sex ratio, with implications for the evolution of sex-ratio adjustment.

 
Amanda Kyle Gibson John Maynard Smith Prize winner 2017
 
What use is sex?
Over forty years ago, John Maynard Smith inspired one of the outstanding problems in evolutionary biology: the maintenance of sexual reproduction. First, Iíll show that Maynard Smithís simple model, the two-fold cost of males, holds in a natural system. I combined theory and experimental data to directly quantify the cost of sex in the freshwater snail Potamopyrgus antipodarum. Consistent with Maynard Smithís prediction, the per-capita birth rate of asexual lineages is at least twice that of sexual lineages.  So, in Maynard Smith's terms: what use is sex? Second, Iíll present tests of the Red Queen hypothesis, which proposes that host-parasite coevolution maintains sex. Observations of a natural population, paired with experimental manipulations, show that coevolution can explain fine-scale spatial and temporal variation in the frequency of sexual snails. Field data spanning a fifteen-year period reveal a dynamic coevolutionary process, with parasites switching to select against sexual reproduction as asexual lineages become rare. Taken together, these results support coevolving parasites in maintaining coexistence of reproductive modes.

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