From Father to Son: Passing Down the Secrets of Paternal Success.

Abstract

Males and females typically share the same genome. Intra-locus sexual conflict is when the needs of each sex exert unique selection pressures on the shared genome. We are interested in investigating the effects of intra-locus sexual conflict by removing one of the two sexes from the conflict. Male limited (ML) selection allows males to directly pass genes to their sons without female selection playing a role. This is facilitated through clone generator females with translocated and marked autosomes and conjoint X chromosomes that induce reversed inheritance of sex chromosomes. ML males should be able to accumulate changes beneficial to male reproductive fitness much more quickly than matched control (MC) males bound by bilateral gene expression. We have conducted 75 generations of this male-limited protocol on Drosophila melanogaster flies and have demonstrated that ML flies show higher fitness within ML conditions.
 In nature, male flies compete with each other to sire offspring, as a result of genetic differences, some males become more successful. We assayed the post copulatory success of our target males by introducing target males to control females after the females were mated with recessively marked Control males. This design allows for adaptations resulting from selection to be investigated, adaptations can either result from the choosiness of females or the physical traits of males like the shape, number, and chemicals contained in sperm.
 My assays found that experimental males tended to be more successful in sperm offence when compared to control males within the ML protocol. Males with double dose ML chromosomes performed significantly worse than Controls, suggesting that adaptation to overcome genetic artifacts from the ML protocol (mutant backgrounds and haploid selection) was predominant to resolving intra-locus sexual conflict. There is also the possibly that a lack of genetic variation prevented adaptations from arising.