Selection on sperm morphology under relaxed sperm competition in a wild passerine bird.
Theories regarding the role of sexual selection on the evolution of sperm traits are based on an association between pre-copulatory (e.g. female preference) and post-copulatory (e.g. ejaculate quality) male reproductive traits. In tests of these hypotheses, sperm morphology has rarely been used, despite its high heritability and intra-individual consistency. We found evidence of selection for longer sperm through positive phenotypic associations between sperm size and the two major female preference traits in the pied flycatcher, Ficedula hypoleuca. Our results support the sexually selected sperm hypothesis in a species under low sperm competition and demonstrate that natural and pre-copulatory sexual selection forces should not be overlooked in studies of intraspecific sperm morphology evolution.
Calhim
Sara
S
Department of Animal & Plant Sciences, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK. s.calhim@gmail.com
Lampe
Helene M
HM
Slagsvold
Tore
T
Birkhead
Tim R
TR
D000818:Animals; D008297:Male; D052586:Mating Preference, Animal; D046109:Passeriformes / Q000033:anatomy & histology / Q000235:genetics* / Q000502:physiology; D012641:Selection, Genetic; D013094:Spermatozoa / Q000166:cytology*