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Référence
Current Biology, vol 14, 10, 25 mai 2004, 906-910
"Reproductive Consequences of Population Divergence through
Sexual Conflict",
Oliver Y. Martin, David J. Hosken
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Résumé :
On présume que la sélection sexuelle a toujours pour
conséquence d'améliorer la fitness. Mais ce n'est
pas évident, car les conflits sexuels, fréquents dans
la nature, peuvent aussi être coûteux pour les individus.
Deux chercheurs de l'Université de Zurich, Oliver Martin
et David Hosken, ont ainsi étudié 44 générations
d'une population de mouches. Celle-ci était placée
en contact avec des mâles d'une autre population dont le comportement
sexuel divergeait, créant ainsi une conflictualité
haute, basse ou moyenne. Une compétition sexuelle forte représente
un coût adaptatif pour les femelles, que ce soit en termes
de longévité après l'accouplement ou de succès
reproductif à l'échelle d'une vie. L'optimum adaptif
semble se situer dans une zone de conflits sexuels modérés.
Abstract :
Sexual-selection research increasingly focuses on reproductive conflicts
between the sexes [1-4]. Sexual conflict, divergent evolutionary
interests of males and females [5], can cause rapid antagonistic
coevolution of reproductive traits [6] and is a potentially powerful
speciation engine [7-11]. This idea has theoretical and comparative
support [10-12] but remains controversial [13-14]. Recent experimental
evidence from Sepsis cynipsea indicates that populations with greater
sexual conflict diverged more quickly; females were less likely
to mate with males from other populations when flies had evolved
under high levels of sexual conflict [15]. The consequences of this
divergence have not been addressed, so here we assess two female
fitness surrogates after 44 generations of evolving (and diverging)
under three different levels of sexual conflict. Longevity after
copulation was negatively associated with the degree of sexual conflict
under which flies evolved, and housing females with males also reduced
female longevity. Female lifetime reproductive success (LRS) also
tended to decrease with increasing conflict. However, there was
evidence of either sexual-selection fitness benefits at intermediate
levels of sexual selection and conflict or inbreeding depression
in the smallest populations (those with the lowest levels of conflict).
Nevertheless, the results indicate that there can be a fitness load
associated with sexual selection [2] and support claims that sexual
conflict can lead to reproductive isolation [7-11, 15].
© Current Biology
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