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Data from: The strength of sex-specific selection in the wild
Singh, Amardeep; Punzalan, David — 2018-10-04 Anisogamy predisposes the sexes to very different patterns of selection on shared traits. Selective differences between the sexes may manifest as changes in the direction or strength of selection acting on shared phenotypes. Although previous studies have found evidence for widespread differences in the direction of selection between the sexes, surprisingly little is known regarding potential differences in the magnitude of selection and whether such differences might be confined to specific components of fitness. We conducted a meta-analysis using 865 estimates of phenotypic selection from wild populations to characterize sex differences in the strength of selection and to ask whether different components of fitness exhibit differences in sex bias in the strength of selection. Overall, consistent with past results, we find evidence of male bias in the strength of selection, driven primarily by components of fitness related to mating success and we discuss several evolutionary implications.
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Data from: Ecological specialization in populations adapted to constant versus heterogeneous environments
Wang, Ao; Singh, Amardeep; Huang, Yuheng; Agrawal, Aneil F. — 2019-02-28 Populations vary in their degree of ecological specialization. An intuitive, but often untested, hypothesis is that populations evolving under greater environmental heterogeneity will evolve to be less specialized. How important is environmental heterogeneity in explaining among-population variation in specialization? We assessed juvenile viability of 20 Drosophila melanogaster populations evolving under one of four regimes: (i) a salt-enriched environment, (ii) a cadmium-enriched environment, (iii) a temporally varying environment, and (iv) a spatially varying environment. Juvenile viability was tested in both the original selective environments and a set of novel environments. In both the original and novel environments, populations from the constant cadmium regime had the lowest average viability and the highest variance in viability across environments but populations from the other three regimes were similar. Our results suggest that variation in specialization among these populations is most simply explained as a pleiotropic by-product of adaptation to specific environments rather than resulting from a history of exposure to environmental heterogeneity.
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Data from: Environmental complexity and the purging of deleterious alleles
Singh, Amardeep; Agrawal, Aneil F.; Rundle, Howard D. — 2017-07-31 Sexual interactions among adults can generate selection on both males and females with genome-wide consequences. Sexual selection through males is one component of this selection that has been argued to play an important role in purging deleterious alleles. A common technique to assess the influence of sexual selection is by a comparison of experimental evolution under enforced monogamy vs. polygamy. Mixed results from past studies may be due to the use of highly simplified lab conditions that alter the nature of sexual interactions. Here we examine the rate of purging of 22 gene disruption mutations in experimental polygamous populations of Drosophila melanogaster in each of two mating environments: a simple, high density environment (i.e., typical fly vials) and a lower density, more spatially complex environment. Based on past work, we expect sexual interactions in the latter environment to result in stronger selection in both sexes. Consistent with this, we find that mutations tend to be purged more quickly in populations evolving in complex environments. We discuss possible mechanisms by which environmental complexity might modulate the rate at which deleterious alleles are purged and putatively ascribe a role for sexual interactions in explaining the treatment differences in our experiment.
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Data from: The physical environment mediates male harm and its effect on selection in females
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Yun, Li; Chen, Patrick J.; Singh, Amardeep; Agrawal, Aneil F.; Rundle, Howard D. — 2017-06-01 Recent experiments indicate that male preferential harassment of high-quality females reduces the variance in female fitness, thereby weakening natural selection through females and hampering adaptation and purging. We propose that this phenomenon, which results from a combination of male choice and male-induced harm, should be mediated by the physical environment in which intersexual interactions occur. Using Drosophila melanogaster, we examined intersexual interactions in small and simple (standard fly vials) versus slightly more realistic (small cages with spatial structure) environments. We show that in these more realistic environments, sexual interactions are less frequent, are no longer biased towards high-quality females, and that overall male harm is reduced. Next, we examine the selective advantage of high- over low-quality females while manipulating the opportunity for male choice. Male choice weakens the viability advantage of high-quality females in the simple environment, consistent with previous work, but strengthens selection on females in the more realistic environment. Laboratory studies in simple environments have strongly shaped our understanding of sexual conflict but may provide biased insight. Our results suggest that the physical environment plays a key role in the evolutionary consequences of sexual interactions and ultimately the alignment of natural and sexual selection.

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(Author: Singh, Amardeep)

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