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Sexual selection on phenotypic traits in a hybrid zone of Littorina saxatilis (Olivi)
Author(s) -
Cruz R.,
RolánÁlvarez E.,
García C.
Publication year - 2001
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 - 10.1046/j.1420-9101.2001.00324.x
Subject(s) - biology , selection (genetic algorithm) , hybrid , hybrid zone , sexual selection , evolutionary biology , population , stabilizing selection , littorina , ecology , zoology , gastropoda , genetic variation , genetics , gene , botany , demography , gene flow , artificial intelligence , sociology , computer science
Step clinal transitions in inherited character(s) between genetically distinct populations are usually referred to as hybrid zones. An example is found in the population of the intertidal snail Littorina saxatilis in Galicia (NW Spain). We studied the shape of the overall fitness surface for sexual selection in this hybrid zone, and the position of hybrids and pure morphs on this surface. We found that sexual divergent selection acted on a combination of phenotypic traits separating the pure morphs, and therefore that sexual selection contributed to morph differentiation. The average fitness of hybrids as a group was not significantly different from that of the pure morphs, but they did show divergent sexual selection in some traits. These results are in agreement with a model of divergent selection favouring both the pure morph as well as those hybrids most resembling each morph. The finding of divergent selection is remarkable because quadratic selection gradients are usually weak in nature.