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Sexual and natural selection in the evolution of extended phenotypes: the use of green nesting material in starlings
Author(s) -
Rubalcaba J. G.,
Polo V.,
Maia R.,
Rubenstein D. R.,
Veiga J. P.
Publication year - 2016
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1111/jeb.12893
Subject(s) - biology , sexual selection , natural selection , courtship , sexual dimorphism , selection (genetic algorithm) , ecology , evolutionary biology , mate choice , stabilizing selection , attractiveness , disruptive selection , nesting (process) , zoology , mating , psychology , materials science , artificial intelligence , computer science , psychoanalysis , metallurgy
Although sexual selection is typically considered the predominant force driving the evolution of ritualized sexual behaviours, natural selection may also play an important and often underappreciated role. The use of green aromatic plants among nesting birds has been interpreted as a component of extended phenotype that evolved either via natural selection due to potential sanitary functions or via sexual selection as a signal of male attractiveness. Here, we compared both hypotheses using comparative methods in starlings, a group where this behaviour is widespread. We found that the use of green plants was positively related to male‐biased size dimorphism and that it was most likely to occur among cavity‐nesting species. These results suggest that this behaviour is likely favoured by sexual selection, but also related to its sanitary use in response to higher parasite loads in cavities. We speculate that the use of green plants in starlings may be facilitated by cavity nesting and was subsequently co‐opted as a sexual signal by males. Our results represent an example of how an extended phenotypic component of males becomes sexually selected by females. Thus, both natural selection and sexual selection are necessary to fully understand the evolution of ritualized behaviours involved in courtship.