Background
After two years of postdoc at the Max Planck Institute for Ornithology
under the supervision of professeur
Bart Kempenaers, I start a new postdoc at the laboratory
‘‘
Biométrie et Biologie
évolutive’’, in
collobaration with Prof. Dominique
Allainé. the objective of this postdoc is to understand the
determinism and mecanisms involded in mate choice, and in particular,
to better understand the role of the major histocompatibility complex
in this choice.
My thesis project, carried out
at the laboratory ‘‘
Biométrie et Biologie
évolutive’’, under the supervision of
Prof. Dominique
Allainé, addressed the evolutionary causes of extra-pair
paternities in the
Alpine marmot, Marmota marmota, one of the rare socially monogamous
mammals.
My first postdoctoral project, at The
Max Planck, brought one step further on my
thesis work and focused on the adaptive value of the extra-pair
paternities in
another socially monogamous species, the blue tit, Parus caeruleus.
Thematic
Monogamous species has been
defined assuming that their social structure
(life in pair) mirrors their genetic mating system (exclusive
mating with
a single partner). However, extra-pair copulations have now been widely
reported and it is well known that they lead to extra-pair paternities.
Then,
social monogamy and genetic monogamy
must be distinguished and the extra-pair paternities could
modify the
classical view of both male and female reproductive success and
consequently
the classical view of sexual selection in monogamous species.
In higher vertebrates, males
reproductive success depends on the number
of sexual partners while females one depends
on the quality of sexual partners. In monogamous species,
males
reproductive success is constrained by access to a single female, their
social
partner. The benefits for males to engage in extra-pair paternities are
straightforward since by fertilizing extra-pair females, they increase
their
reproductive success by fathering additional offspring without
providing
paternal care. The occurrence of this tactic in females is more
puzzling since
their reproductive success is not constrained by the number of sexual
partners.
Nevertheless, extra-pair copulations are often actively elicited by
females,
suggesting that they also obtain fitness benefits. Extra-pair
paternities have
thus been proposed as a way for females to adjust their mate choice and
to gain
phenotypic or genetic advantages.
.
My work follow three main directions:
Do females choose to engage in extra-pair copulations? If yes, according to what criteria? What mechanisms are involved in this choice? What can constrain females choice?
II - Adaptive value of extra-pair copulations
Do individuals engaging in extra-pair copulations benefit from a fitness point of view?
III - Extra-pair copulations and sexual selection
Impact of extra-pair copulations on the strength and direction of sexual selection.
Lastest news
A. COHAS, D. Allainé (2009) Social structure influences extra-pair paternity in socially monogamous mammals. Biology Letters, 5:313-316. Download pdfA. COHAS, C. Bonenfant, B. Kempenaers, D. Allainé (2009) Age-specific effect of heterozygosity on survival in alpine marmots, Marmota marmota. Molecular Ecology 18:1491-1503. Download pdf
A. COHAS, N.G Yoccoz, C. Bonenfant, B. Goossens, C.Genton, M. Galan, B. Kempenaers, D. Allaine (2008) The genetic similarity between pair members influences the frequency of extrapair paternity in alpine marmots. Animal Behaviour, 76:87-95. Download pdf