Data from: Variation in the post-mating fitness landscape in fruitflies

Sperm competition is pervasive and fundamental to determining a male’s
overall fitness. Sperm traits and seminal fluid proteins (Sfps) are key
factors. However, studies of sperm competition may often exclude females
that fail to remate during a defined period. Hence, the resulting datasets
contain fewer data from the potentially fittest males that have most
success in preventing female remating. It is also important to consider a
male’s reproductive success before entering sperm competition, which is a
major contributor to fitness. The exclusion of these data can both hinder
our understanding of the complete fitness landscapes of competing males
and lessen our ability to assess the contribution of different
determinants of reproductive success to male fitness. We addressed this
here, using the Drosophila melanogaster model system, by (i) capturing a
comprehensive range of intermating intervals that define the fitness of
interacting wild type males, and (ii) analysing outcomes of sperm
competition using selection analyses. We conducted additional tests using
males lacking the sex peptide (SP) ejaculate component versus genetically
matched (SP+) controls. This allowed us to assess the comprehensive
fitness effects of this important Sfp on sperm competition. The results
showed a signature of positive, linear selection in wild type and SP+
control males on the length of the intermating interval and on male sperm
competition defense. However, the fitness surface for males lacking SP was
distinct, with local fitness peaks depending on contrasting combinations
of remating intervals and offspring numbers. The results suggest that
there are alternative routes to success in sperm competition and provide
an explanation for the maintenance of variation in sperm competition
traits.