Optimal Life-History Strategy Differs between Philopatric and Dispersing Individuals in a Metapopulation
Résumé
Abundant empirical evidence for dispersal syndromescontrasts with the rarity of theoretical predictions about the evolutionof life-history divergence between dispersing and philopatric indi-viduals. We use an evolutionary model to predict optimal differencesin age-specific reproductive effort between dispersing and philopatricindividuals inhabiting the same metapopulation. In our model, onlyyoung individuals disperse, and their lifelong reproductive decisionsare potentially affected by this initial event. Juvenile survival declinesas density of adults and other juveniles increases. We assume a trade-off between reproduction and survival, so that different patterns ofage-specific reproductive effort lead to different patterns of aging.We find that young immigrant mothers should allocate more re-sources to reproduction than young philopatric mothers, but theselife-history differences vanish as immigrant and philopatric individ-uals get older. However, whether the higherearly reproductive effortof immigrants results in higher fecundity depends on the postim-migration cost on fecundity. Dispersingindividuals have conse-quently a shorter life span. Ultimately, these life-history differencesare due to the fact that young dispersing individuals most often livein recently founded populations, where competition is relaxed andjuvenile survival higher, favoring larger investment in offspring pro-duction at the expense of survival.
Domaines
Evolution [q-bio.PE]
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