Antioxidant supplementation during early development reduces parasite load but does not affect sexual ornament expression in adult ring-necked pheasants Phasianus colchicus

ArticleCopyright © 2012 The Authors. Functional Ecology © 2012 British Ecological Society1. The ‘parasite-mediated sexual selection’ (PMSS) hypothesis predicts that exaggerated male ornamentation could provide a signal to females of a males ability to resist parasites. Empirical tests of the PMSS have been largely equivocal, however, which may be because most have not considered the role of early life-history effects. 2. Many sexually-selected traits are carotenoid-based. Allocation of dietary-derived carotenoids to sexual ornaments may trade-off with allocation to pro-inflammatory immune response and/or antioxidant functions, mediated by the oxidative status of individuals. Exposure to parasites can increase oxidative stress, so under this scenario sexually-selected traits indicate ability to resist oxidative stress rather than ability to resist parasites per se. Such life-history trade-offs, mediated by oxidative status of individuals, are particularly acute during growth and development. 3. Here we use ring-necked pheasants, Phasianus colchicus, a strongly sexually-selected species, to test whether supplementation with dietary antioxidants (vitamin E) can mitigate the effects of early exposure to parasites (the nematode, Heterakis gallinarum), via alteration of the oxidative status of individuals, and positively affect the expression of sexual ornaments at adulthood. 4. We found that vitamin E mediated the effect of early exposure to parasites on levels of oxidative damage at 8 weeks of age and reduced the parasite load of individuals at adulthood as predicted. However, the expression of sexual ornaments, immune function, and growth were unaffected by either early vitamin E supplementation or manipulation of parasite load. In contrast to the predictions of the PMSS hypothesis the intensity of sexual ornament expression was not related to either parasite load or oxidative status of individuals (current or long-term). Consequently there was no evidence that the expression of sexual ornaments provided information on the ability of males to resist infection from parasites.NERCRoyal Societ

Genetic structure of the Black Bog Ant (Formica picea Nylander) in the United Kingdom

Social Hymenoptera have been relatively little studied in terms of conservation genetics even though their sociality and omplementary sex determination potentially influence the interaction of genetics with extinction risk. Using microsatellite markers, we investigated the social and genetic structure of nests and populations of the Black Bog Ant Formica picea at four sites in the UK, where this habitat specialist has a localized and fragmented range. Nests were weakly polygynous (effective queen number, 4–27 per nest) with low orker relatedness. Isolation by distance tended to be present within sites, indicating limited dispersal, but inbreeding was rare. The four study sites fell into three main populations (two in South Wales, one in southern England). We conclude that, although UK F. picea populations are not at immediate risk from genetic factors, their limited dispersal abilities at both within- and between-site scales should inform conservation management decisions