Pischedda, A., Stewart, A.D., Little, M.K. & Rice, W. 2011. Male genotype influences female reproductive investment in Drosophila melanogaster. Proc Biol Sci 278:2165-72.
This study is the first form of direct evidence that males vary genetically in their influences on female fecundity, egg sizes and overall female investment in reproduction. Female Drosophila melanogasters were mated with males from 10 different ‘worldwide lines’ (to account for genetic variation) for 2 hours. After this time, females were placed into individual oviposition vials for 22 hours, followed by transfer into a new oviposition vial for another 22 hours. After that, all of the females who mated with males from the same worldwide line were put into the same egg laying chamber and allowed 4 hours to oviposition. Eggs from the chamber were then photographed and measured. Results found that a male’s population of origin did not affect egg size, but did affect females' fecundity in the first 22 hours after mating. The genotype of the males within a population did however account for some of the variation seen in egg size. This study is very useful to me, as it relates directly to the question at the forefront of my research. It does not however address the mechanisms causing the variations seen, such as female cryptic choice or manipulations by males, so leaves room for further investigation and analysis.