title: Do candidate genes mediating conspecific sperm precedence affect sperm competitive ability within species? A test case in Drosophila.
abstract: When females mate to multiple males, the last male to mate fathers the majority of progeny. When males of different species inseminate a female, the sperm of the male conspecific to the female is favored in fertilization in a process known as conspecific sperm precedence (CSP). A large number of studies in Drosophila have assayed the genetic basis of sperm competition, with a main focus on D. melanogaster and accessory gland protein genes. Only a few studies have attempted to disentangle the genetic basis of CSP between related species of Drosophila. Although there is no a priori reason to believe that genes influencing intraspecific sperm competitive ability might also mediate conspecific sperm precedence, no study has addressed the question. Here, we test a group of candidate CSP genes between D. simulans and D. mauritiana for their effect on sperm competition in D. melanogaster. The use of P-element insertion lines identified CG14891 gene disruption as the only one causing a significant decrease in second male paternity success relative to wild-type and ebony tester males. The gene disruption affected both sperm displacement and the sperm fertilizing ability. Out of five genes tested using RNA interference, only gene knockdown of CG6864(Mst89B) [corrected] significantly reduced the male's ability to father progeny when second to mate. Our results suggest that CG14891 and CG6468 might have been co-opted from an intraspecies gene function (i.e., sperm competition) into an interspecies avoidance phenotype (i.e., CSP). Alternatively, the dual role of these genes could be a consequence of their pleiotropic roles.
authors.affiliation: Department of Biology, University of Winnipeg, Winnipeg, MB, R3B 2E9 Canada a.civetta@uwinnipeg.ca.
authors.forename: Alberto
authors.initials: A
authors.lastname: Civetta
authors.affiliation: Department of Biology, University of Winnipeg, Winnipeg, MB, R3B 2E9 Canada.
authors.forename: Scott
authors.initials: S
authors.lastname: Finn
mesh_terms: D000818:Animals; D004251:DNA Transposable Elements; D004331:Drosophila melanogaster / Q000235:genetics* / Q000502:physiology; D005260:Female; D015870:Gene Expression; D017344:Genes, Insect; D008297:Male; D034622:RNA Interference; D012098:Reproduction / Q000235:genetics*; D013094:Spermatozoa / Q000502:physiology*
chemical_list: D004251:DNA Transposable Elements
keywords: conspecific sperm precedence; gene co-option; pleiotropy; sperm competition