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Multilevel and sex‐specific selection on competitive traits in North American red squirrels
Author(s) -
Fisher David N.,
Boutin Stan,
Dantzer Ben,
Humphries Murray M.,
Lane Jeffrey E.,
McAdam Andrew G.
Publication year - 2017
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/evo.13270
Subject(s) - biology , selection (genetic algorithm) , natural selection , population , sexual selection , disruptive selection , ecology , group selection , demography , multilevel model , zoology , statistics , artificial intelligence , sociology , computer science , mathematics
Individuals often interact more closely with some members of the population (e.g., offspring, siblings, or group members) than they do with other individuals. This structuring of interactions can lead to multilevel natural selection, where traits expressed at the group‐level influence fitness alongside individual‐level traits. Such multilevel selection can alter evolutionary trajectories, yet is rarely quantified in the wild, especially for species that do not interact in clearly demarcated groups. We quantified multilevel natural selection on two traits, postnatal growth rate and birth date, in a population of North American red squirrels ( Tamiasciurus hudsonicus ). The strongest level of selection was typically within‐acoustic social neighborhoods (within 130 m of the nest), where growing faster and being born earlier than nearby litters was key, while selection on growth rate was also apparent both within‐litters and within‐study areas. Higher population densities increased the strength of selection for earlier breeding, but did not influence selection on growth rates. Females experienced especially strong selection on growth rate at the within‐litter level, possibly linked to the biased bequeathal of the maternal territory to daughters. Our results demonstrate the importance of considering multilevel and sex‐specific selection in wild species, including those that are territorial and sexually monomorphic.