Fabrice Helfenstein

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Evidence of multiple genetic criteria of mate choice is accumulating in numerous taxa. In many species, females have been shown to pair with genetically dissimilar mates or with extra-pair partners that are more genetically compatible than their social mates, thereby increasing their offsprings' heterozygosity which often correlates with offspring fitness.(More)
Sperm cells are highly vulnerable to free radicals, and sperm quality and male fertility are critically affected by oxidative stress. Recently, sexual ornaments, particularly carotenoid-based colourful traits, have been proposed to depend on a male's capacity to resist oxidative stress, and thus to signal sperm quality. We conducted an experimental test of(More)
Sperm competition exerts strong selection on males to produce spermatozoa with an optimal morphology that maximizes their fertilization success. Long sperm were first suggested to be favored because they should swim faster. However, studies that investigated the relationship between sperm length and sperm competitive ability or sperm swimming velocity(More)
Stressful conditions experienced by individuals during their early development have long-term consequences on various life-history traits such as survival until first reproduction. Oxidative stress has been shown to affect various fitness-related traits and to influence key evolutionary trade-offs but whether an individual's ability to resist oxidative(More)
Oxidative stress was recently demonstrated to affect several fitness-related traits and is now well recognized to shape animal life-history evolution. However, very little is known about how much resistance to oxidative stress is determined by genetic and environmental effects and hence about its potential for evolution, especially in wild populations. In(More)
F. Helfenstein (correspondence), Evolutionary Ecology Group, Zoological Institute, University of Bern, Baltzerstrasse 6, CH-3012 Bern, Switzerland. E-mail: fabrice.helfenstein@free.fr. R. H. Wagner, Konrad Lorenz Institute, Austrian Academy of Sciences, Savoyenstrasse 1a, A-1160 Vienna, Austria. T. Szép, Institute of Environmental Sciences, College of(More)
Sarah Leclaire, Vincent Bourret, Richard H. Wagner, Scott A. Hatch, Fabrice Helfenstein, Olivier Chastel, and Étienne Danchin CNRS, UPS, ENFA, EDB (Laboratoire Évolution & Diversité Biologique), UMR5174, 118 Route de Narbonne, 118 Route de Narbonne, 31062 Toulouse Cedex 9, France, Université de Toulouse, UMR5174, 31062 Toulouse Cedex 9, France, Konrad(More)
Oxidative stress has been suggested as a proximate cost of reproduction and hence as a major constraint in the evolution of life histories, and it is therefore thought that antioxidants alleviate the effects of reproductive effort on oxidative stress. Furthermore, carotenoid-based ornaments have been proposed to mirror male ability to resist oxidative(More)
Sperm aging is known to be detrimental to reproductive performance. However, this apparently general phenomenon has seldom been studied in an evolutionary context. The negative impact of sperm aging on parental fitness should constitute a strong selective pressure for adaptations to avoid its effects. We studied the impact of sperm aging on black-legged(More)
When females copulate with multiple males the potential exists for female sperm choice. Females may increase the probability of being fertilized by preferred males by selectively retaining their sperm while ejecting the sperm of unfavoured males. An alternative criterion to male quality for female sperm choice may be sperm age because old sperm degrade and(More)