title: No association between sperm competition and sperm length variation across dung flies (Scathophagidae).
abstract: Sperm length is extremely variable across species, but a general explanation for this variation is lacking. However, when the risk of sperm competition is high, sperm length is predicted to be less variable within species, and there is some evidence for this in birds and social insects. Here, we examined intraspecific variation in sperm length, both within and between males, and its potential associations with sperm competition risk and variation in female reproductive tract morphology across dung flies. We used two measures of variation in sperm size, and testis size was employed as our index of sperm competition risk. We found no evidence of associations between sperm length variation and sperm competition or female reproductive tract variation. These results suggest that variation in sperm competition risk may not always be associated with variation in sperm morphology, and the cause(s) of sperm length variation in dung flies remains unclear.
authors.affiliation: Centre for Conservation & Ecology, College of Life and Environmental Sciences, University of Exeter, Tremough, Penryn, UK.
authors.forename: M D
authors.initials: MD
authors.lastname: Sharma
authors.forename: A M
authors.initials: AM
authors.lastname: Minder
authors.forename: D J
authors.initials: DJ
authors.lastname: Hosken
mesh_terms: D000818:Animals; D048429:Cell Size; D004175:Diptera / Q000166:cytology / Q000502:physiology*; D005260:Female; D008297:Male; D012044:Regression Analysis; D012726:Sexual Behavior, Animal; D013094:Spermatozoa / Q000166:cytology*
keywords: Diptera; Scathophaga; Scatophaga; comparative study; sperm; sperm competition