Christiansfeld, Denmark
Christiansfeld, Denmark

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Galvan I.,University Paris - Sud | Erritzoe J.,Taps Old Rectory | Karadas F.,Yuzuncu Yil University | Moller A.P.,University Paris - Sud
Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology | Year: 2012

Antioxidants have a large potential to coevolve with life-histories because of their capacity to counteract the negative effects of free radicals on fitness. However, only a few studies have explored the association between antioxidant levels and life-history strategies comparing a large number of species. Here we used an extensive dataset of 125 species of birds to investigate the association between concentrations of antioxidants (carotenoids and vitamin E) in the liver, which is the main storage organ for fat-soluble antioxidants, and life-history and morphology. We found that high liver antioxidant concentrations were associated with life-history strategies characterized by "live slow, die old", in clear contrast to previous studies reporting a relationship between high plasma antioxidants and life-histories characterized by "live fast, die young". Thus, high carotenoid concentrations were present in species with large body, brain and egg sizes, high absolute metabolic rate and a resident lifestyle, while high vitamin E concentrations were present in species with large brain size and long life span and incubation period. Our results indicate that antioxidants and life-histories coevolve, and that this may be mediated by positive fitness consequences of the accumulation of liver antioxidants, as species with higher antioxidant levels live longer. © 2012 Springer-Verlag.


Moller A.P.,University Paris - Sud | Moller A.P.,Center for Advanced Study | Erritzoe J.,Taps Old Rectory | Rozsa L.,Hungarian Academy of Sciences
Oecologia | Year: 2010

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.


Moller A.P.,University Paris - Sud | Moller A.P.,Center for Advanced Study | Erritzoe J.,Taps Old Rectory
Ethology | Year: 2010

Larger eyes capture more information from the environment than small eyes, but also require more brain space for information processing. Therefore, individuals have to optimize the size of their eyes, leading to the prediction that larger eyes should have evolved in species with greater benefits from large eyes, such as species subject to intense predation risk. In a comparative analysis of 97 bird species, we found that species that fled at longer distances from an approaching potential predator indeed had relatively large eyes for their body size. In contrast, there was no indication that large eyes had evolved in species living in secluded habitats, or in species eating mobile prey. These findings are consistent with the assumption that eye size is labile and can evolve in response to changing predator environments. They also suggest that eye size may act as a constraint on optimal anti-predator behavior, if the predator community changes as a consequence of introductions or invasions. © 2010 Blackwell Verlag GmbH.


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 | Year: 2010

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.


Moller A.P.,University Paris - Sud | Erritzoe J.,Taps Old Rectory
Journal of Evolutionary Biology | Year: 2014

Prey avoid being eaten by assessing the risk posed by approaching predators and responding accordingly. Such an assessment may result in prey-predator communication and signalling, which entail further monitoring of the predator by prey. An early antipredator response may provide potential prey with a selective advantage, although this benefit comes at the cost of disturbance in terms of lost foraging opportunities and increased energy expenditure. Therefore, it may pay prey to assess approaching predators and determine the likelihood of attack before fleeing. Given that many approaching potential predators are detected visually, we hypothesized that species with relatively large eyes would be able to detect an approaching predator from afar. Furthermore, we hypothesized that monitoring of predators by potential prey relies on evaluation through information processing by the brain. Therefore, species with relatively larger brains for their body size should be better able to monitor the intentions of a predator, delay flight for longer and hence have shorter flight initiation distances than species with smaller brains. Indeed, flight initiation distances increased with relative eye size and decreased with relative brain size in a comparative study of 107 species of birds. In addition, flight initiation distance increased independently with size of the cerebellum, which plays a key role in motor control. These results are consistent with cognitive monitoring as an antipredator behaviour that does not result in the fastest possible, but rather the least expensive escape flights. Therefore, antipredator behaviour may have coevolved with the size of sense organs, brains and compartments of the brain involved in responses to risk of predation. © 2013 European Society For Evolutionary Biology.


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 | Year: 2010

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.


Galvan I.,University Paris - Sud | Erritzoe J.,Taps Old Rectory | Wakamatsu K.,Health Science University | Moller A.P.,University Paris - Sud
Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology | Year: 2012

The crystalline lens of the eyes of vertebrates focuses light on the retina. Therefore, maintaining the lens clear is necessary for proper visual function. However, oxidative damage to proteins of the lens leads to opacification and lens dysfunction, termed cataract. Antioxidants thus have a role in avoiding the development of cataracts through their reduction of oxidative stress, and glutathione (GSH), a key intracellular antioxidant, belongs to the primary antioxidant defence mechanism of the lens. Other physiological mechanisms that require GSH may compete with the antioxidant mechanism of the eye. Pheomelanin is a main type of melanin, the most common pigment in vertebrates, and its synthesis consumes GSH. Here, we use data on 81 bird species to test the hypothesis that species producing large amounts of pheomelanin should have diminished capacity to use GSH to protect their eyes and, as a consequence, higher prevalence of cataracts. As predicted, the proportion of pheomelanic plumage was positively associated with the proportion of individuals with cataracts across species, suggesting that production of pheomelanin may have profound fitness consequences, as birds with cataracts have limited ability to perform vital activities. This constitutes the first comparative study of cataracts in wild animals. © 2012 Elsevier Inc.


Galvan I.,University Paris - Sud | Moller A.P.,University Paris - Sud | Erritzoe J.,Taps Old Rectory
Journal of Evolutionary Biology | Year: 2011

Melanin is mainly found in the integument of animals, but it also appears in several extracutaneous tissues. The presence of melanin in testes has been anecdotally reported in all vertebrate groups, but the causes and functions of this melanin remain unknown. Similar to other extracutaneous melanins, testicular melanin may protect male germ cells from oxidative stress. Given the high respiratory activity of spermatozoa, oxidative stress generated by mitochondrial dysfunction as a consequence of mtDNA mutations directly affects sperm viability. Thus, natural selection may favour testicular melanization in males of species with high historical mutation rates in the mitochondrial genome. Here, we tested this hypothesis using information on occurrence of testicular melanization and mutation accumulation as reflected by cytochrome b mtDNA base pair substitution rates in a large set of 134 species of birds, controlling for the confounding effects of body mass, reproductive activity and phylogeny. We found that testicular melanization has evolved in species with high rates of accumulated mitochondrial mutations and propose that this is an adaptive response related to the protective capacity of melanin against oxidative stress. In support of this hypothesis, testicular melanization was more frequently observed during the breeding season of birds (i.e. when spermatogenesis is likely to occur) than during reproductive inactivity. In contrast to other extracutaneous melanins whose abundance seems to reflect skin and coat colour, we did not find a correlation between the proportion of plumage coloured by melanins and occurrence of testicular melanization. Whereas future experimental studies should test these hypotheses, our study highlights for the first time that melanization patterns in animals may evolve as a response to historical mutation rates. © 2011 The Authors. Journal of Evolutionary Biology © 2011 European Society For Evolutionary Biology.


Moller A.P.,University Paris - Sud | Moller A.P.,Center for Advanced Study | Erritzoe J.,Taps Old Rectory | Karadas F.,Yuzuncu Yil University
Oecologia | Year: 2010

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.


Moller A.P.,University Paris - Sud | Moller A.P.,Center for Advanced Study | ErritzoE J.,Taps Old Rectory
Journal of Evolutionary Biology | Year: 2010

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.

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