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Maternal effects and life history trade-offs in a cooperative breeder, the sociable weaver (Philetairus socius)

Abstract : Maximizing of the number copies of genes that are transmitted to the next generations involves a series of tradeoffs. In cooperatively breeding species some sexually mature individuals do not breed but instead help other individuals to raise their offspring. These helpers are particularly interesting in a life history context as they create a predictably favorable breeding environment and their presence can thus influence evolutionary trade-offs. A major evolutionary trade-off that is often neglected in studies on cooperative breeding is maternal allocation, notably through maternal effects that are epigenetic modifications of offspring phenotype. Here we investigate whether there are maternal effects induced by the presence of helpers and their possible consequences on females and their offspring in a colonial cooperative breeder of southern Africa, the sociable weaver Philetairus socius. Our results show that females lay smaller eggs in the presence of helpers and in addition these eggs have lower corticosterone and testosterone concentrations. Our results also show a higher survival probability of females breeding in groups, which may be partially due to their lower investment in eggs. In addition, a study of roosting chamber temperatures in relation to group size suggests further benefits for parents and helpers, particularly through lower costs of thermoregulation that could also allow energy savings for survival. To start understanding the consequences of helpers presence and differential maternal allocation for offspring we conducted a cross fostering experiment. Our results show that eggs produced by females breeding in larger groups produce chicks that beg at a lower rate, showing that maternal effects may influence chicks’ behavior. Finally, we investigated post-fledging survival through capture-recapture analyses and, surprisingly, found that fledglings have a lower survival probability when raised with helpers. Taken together, these results demonstrate the importance of studying maternal effects on cooperative breeders and open several research prospects on family conflicts and life history trade-offs according to the presence of helpers.
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https://tel.archives-ouvertes.fr/tel-01139370
Contributor : Matthieu Paquet <>
Submitted on : Saturday, April 4, 2015 - 3:49:07 PM
Last modification on : Tuesday, September 22, 2020 - 3:50:02 AM
Long-term archiving on: : Sunday, July 5, 2015 - 10:10:46 AM

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  • HAL Id : tel-01139370, version 1

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Matthieu Paquet. Maternal effects and life history trade-offs in a cooperative breeder, the sociable weaver (Philetairus socius). Biodiversity and Ecology. Université Montpellier 2, 2013. English. ⟨tel-01139370⟩

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