Time filter

Source Type

Christiansfeld, Denmark

Moller A.P.,University Paris - Sud | Moller A.P.,Center for Advanced Study | Erritzoe J.,Taps Old Rectory | Karadas F.,Yuzuncu Yil University | Mousseau T.A.,University of South Carolina
Journal of Evolutionary Biology

Extreme environmental perturbations are rare, but may have important evolutionary consequences. Responses to current perturbations may provide important information about the ability of living organisms to cope with similar conditions in the evolutionary past. Radioactive contamination from Chernobyl constitutes one such extreme perturbation, with significant but highly variable impact on local population density and mutation rates of different species of animals and plants. We explicitly tested the hypothesis that species with strong impacts of radiation on abundance were those with high rates of historical mutation accumulation as reflected by cytochrome b mitochondrial DNA base-pair substitution rates during past environmental perturbations. Using a dataset of 32 species of birds, we show higher historical mitochondrial substitution rates in species with the strongest negative impact of local levels of radiation on local population density. These effects were robust to different estimates of impact of radiation on abundance, weighting of estimates of abundance by sample size, statistical control for similarity in the response among species because of common phylogenetic descent, and effects of population size and longevity. Therefore, species that respond strongly to the impact of radiation from Chernobyl are also the species that in the past have been most susceptible to factors that have caused high substitution rates in mitochondrial DNA. © 2010 European Society For Evolutionary Biology. Source

Moller A.P.,University Paris - Sud | Moller A.P.,Center for Advanced Study | Erritzoe J.,Taps Old Rectory | Rozsa L.,Hungarian Academy of Sciences

The uropygial gland of birds secretes wax that is applied to the plumage, where the secretions are hypothesized to eliminate fungi and bacteria, thereby potentially providing important benefits in terms of plumage maintenance. We analyzed variation in size of the uropygial gland in 212 species of birds to determine the function and the ecological correlates of variation in gland size. Bird species with larger uropygial glands had more genera of chewing lice of the sub-order Amblycera, but not of the sub-order Ischnocera, and more feather mites. There was a fitness advantage associated with relatively large uropygial glands because such species had higher hatching success. These findings are consistent with the hypothesis that the uropygial gland functions to manage the community of microorganisms, and that certain taxa of chewing lice have diverged as a consequence of these defenses. © 2009 Springer-Verlag. Source

Moller A.P.,University Paris - Sud | Moller A.P.,Center for Advanced Study | Erritzoe J.,Taps Old Rectory | Tottrup Nielsen J.,Espedal 4
Functional Ecology

Summary: 1. The uropygial gland of birds produces chemical substances with antimicrobial properties that have been shown to reduce the abundance of feather degrading bacteria and other microorganisms. These microorganisms would affect the flight capabilities of birds and, consequently, a relationship between size of uropygial glands and probability of capture by aerial predators should exist. 2. We tested this hypothesis by estimating the susceptibility of 56 species of prey of the goshawk Accipiter gentilis Linnaeus to predation as the observed abundance of prey relative to the expected abundance from mean population density. 3. In a comparative analysis of the relationship between relative size of the uropygial gland and susceptibility to predation we found a strong negative relationship accounting for 16% of the variance. This relationship was present in analyses that accounted for similarity due to common phylogenetic descent, the fact that prey of intermediate size were preferred, and that larger prey species have larger uropygial glands. 4. These observations are consistent with uropygial glands being under strong selection from aerial predators that are likely mediated by the effect of uropygial glands on feather degrading bacteria and therefore on flight capabilities of birds. © 2009 The Authors. Journal compilation © 2009 British Ecological Society. Source

Moller A.P.,University Paris - Sud | Moller A.P.,Center for Advanced Study | Erritzoe J.,Taps Old Rectory | Karadas F.,Yuzuncu Yil University

Numerous animals have successfully invaded urban habitats, although the factors associated with invasion success remain poorly understood. Urban areas are characterized by warmer microclimates, higher levels of primary productivity, longer breeding seasons and higher levels of pollutants. All these factors should cause oxidative stress, favoring invasion by species that have access to high levels of antioxidants. We analyzed concentrations of two categories of dietary, fat-soluble antioxidants (total carotenoids, total vitamin E) in the liver, the main storage organ in birds. Individuals killed by cats had lower levels of vitamin E than individuals that died for other reasons, showing natural selection on stored antioxidants. Bird species that had successfully colonized urban areas had significantly higher levels of vitamin E and total carotenoids than species that did not succeed, and rural populations had higher concentrations of vitamin E and total carotenoids than urban populations of the same species. Interspecific differences in concentrations of fat-soluble antioxidants, and differences between rural and urban populations of the same species, were accounted for by diet, but also by time since urbanization and number of generations since urbanization. These findings suggest that antioxidants, and by implication the ability to cope with oxidative stress, have contributed to successful invasion of urban areas by birds, and that the concentration of these antioxidants has changed in response to the urban environment. © Springer-Verlag 2009. Source

Moller A.P.,University Paris - Sud | Moller A.P.,Center for Advanced Study | ErritzoE J.,Taps Old Rectory
Journal of Evolutionary Biology

Colour preferences from sexual or social contexts are assumed to have arisen owing to preferences for specific kinds of food, representing a sensory bias, but once colour preferences have evolved in a sexual context, they may also be expressed during foraging. We tested whether preferences for specific body colours (i.e. plumage and soft parts) were related to colour preferences for grit ingested by birds. Birds eat grit to facilitate break down of food by the gizzard, and this function is independent of the colour of grit, but depends on the physical properties of stones. Bird species were significantly consistent in colour of grit, and grit of different colours varied in prevalence among species, even when analyses were restricted to a sample from a single locality. There were positive correlations between presence of lilac and red grit in the gizzard and presence of sexually dichromatic lilac and red colour on the body. There was a positive correlation between red grit colour and red sexually monochromatic body colour. Bird species with many different sexual colours, but not sexually monochromatic colours on their body had many different colours of grit. Males had more lilac and red grit than females, with this effect differing among species, whereas that was not the case for grit of other colours. These findings are consistent with the sensory bias hypothesis that birds express preferences for grit of specific colours and a high diversity of colours related to sexual colouration of the body, even when the colour of such grit is only visible to the individual at the moment of ingestion. © 2009 The Authors. Journal Compilation © 2009 European Society For Evolutionary Biology. Source

Discover hidden collaborations