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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2010.03.022 Byline: Fiona C. Ingleby, Zenobia Lewis, Nina Wedell Abstract: The risk and intensity of sperm competition can influence male adaptations that ultimately affect male fertilization success, for example investment in sperm production and strategic sperm allocation patterns. Previous studies have examined male behavioural responses to variation in immediate levels of sperm competition. Here we quantified the evolutionary responses of male adaptations resulting from long-term manipulation of the level of sperm competition. By varying the adult sex ratio of populations of the Indian meal moth, Plodia interpunctella, we successfully altered the frequency of male and female copulations, and thus the level of sperm competition experienced by males. As predicted by theory, males evolving under higher levels of sperm competition increased investment in sperm production and differed in their sperm allocation patterns across matings, compared to males evolving under intermediate and low levels of sperm competition. However, we found no evidence for trade-offs between ejaculate components, or between total sperm production and male body size in this species. Author Affiliation: Centre for Ecology and Conservation, University of Exeter, Cornwall Campus, U.K. Article History: Received 23 January 2010; Revised 4 March 2010; Accepted 23 March 2010 Article Note: (miscellaneous) MS. number: 10-00051

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2009.03.013 Byline: Zenobia Lewis, Nina Wedell Abstract: Sperm production carries costs and males frequently tailor their ejaculates to maximize their reproductive success. Previous work shows that males are sensitive to variation in female quality, and to the risk and intensity of sperm competition, and adjust their ejaculates accordingly. Males and females of many species are sensitive to the relatedness of their mating partners and may forego mating with related individuals altogether to avoid the costs of inbreeding. In addition, in polyandrous species, females can potentially invoke postcopulatory mechanisms to avoid using related males' sperm, but to date no study has demonstrated that males also discriminate against related females at the level of the gamete. In this study on the Indian meal moth, Plodia interpunctella, males provided unrelated females with more fertile and nonfertile sperm than their sisters. These results indicate that male moths can minimize the potential costs of inbreeding by carefully managing their limited sperm supplies in relation to partner relatedness. Author Affiliation: School of Biosciences, University of Exeter, Cornwall Campus, U.K. Article History: Received 13 January 2009; Revised 20 February 2009; Accepted 30 March 2009 Article Note: (miscellaneous) MS. number: 09-00027

Abstract: In recent years, there has been a surge in interest in the effects of the microbiota on the host. Increasingly, we are coming to understand the importance of the gut microbiota in modulating host physiology, ecology, behavior, and evolution. One method utilized to evaluate the effect of the microbiota is to suppress or eliminate it, and compare the effect on the host with that of untreated individuals. In this study, we evaluate some of these commonly used methods in the model organism, Drosophila melanogaster. We test the efficacy of a low‐dose streptomycin diet, egg dechorionation, and an axenic or sterile diet, in the removal of gut bacteria within this species in a fully factorial design. We further determine potential side effects of these methods on host physiology by performing a series of standard physiological assays. Our results showed that individuals from all treatments took significantly longer to develop, and weighed less, compared to normal flies. Males and females that had undergone egg dechorionation weighed significantly less than streptomycin reared individuals. Similarly, axenic female flies, but not males, were much less active when analyzed in a locomotion assay. All methods decreased the egg to adult survival, with egg dechorionation inducing significantly higher mortality. We conclude that low‐dose streptomycin added to the dietary media is more effective at removing the gut bacteria than egg dechorionation and has somewhat less detrimental effects to host physiology. More importantly, this method is the most practical and reliable for use in behavioral research. Our study raises the important issue that the efficacy of and impacts on the host of these methods require investigation in a case‐by‐case manner, rather than assuming homogeneity across species and laboratories. [ABSTRACT FROM AUTHOR]

The animal gut commonly contains a large reservoir of symbiotic microbes. Although these microbes have obvious functions in digestion and immune defence, gut microbes can also affect behaviour. Here, we explore whether gut microbiota has a role in kin recognition. We assessed whether relatedness, familiarity and food eaten during development altered copulation investment in three species of Drosophila with diverse ecologies. We found that a monandrous species exhibited true kin recognition, whereas familiarity determined kin recognition in a species living in dense aggregations. Finally, in a food generalist species, food eaten during development masked kin recognition. The effect of food type on copulation duration, in addition to the removal of this effect via antibiotic treatment, suggests the influence of bacteria associated with the gut. Our results provide the first evidence that varied ecologically determined mechanisms of kin recognition occur in Drosophila, and that gut bacteria are likely to have a key role in these mechanisms. [ABSTRACT FROM AUTHOR]