CARACTERÍSTICAS DO SISTEMA DE ACASALAMENTO DE Drosophila maculifrons (DIPTERA; DROSOPHILIDAE)

Abstract

Drosophila maculifrons (Diptera, Drosophilidae) is a generalist and endemic species that occurs in forest fragments of South America. Researches on reproductive characters of neotropical generalist and forest dwelling species are scarce. This makes the populations of this species an important material for studying reproductive characters that are under sexual selection, such as copulation duration and polyandry, because these parameters are very diverse among species of the genus. Thus, the objective of this work was to analyze pre and postzygotic parameters of the mating system in D. maculifrons, such as mating speed (MS), copulation duration (CD), risk of sperm competition/polyandry (SC) and productivity (P), in order to better understand which forces could be important in the evolution of reproductive characteristics of a generalist Neotropical species. For MS, CD and P analyses, 16 crosses were performed between two isofemale lines from Parque Natural Municipal das Araucárias (PMA) and two from Parque Municipal São Francisco da Esperança (SSF), both conservation units located in Guarapuava/PR municipality. For SC, F1 paternity of inseminated females collected in PMA and SSF was established using five microsatellite loci. The MS parameter evidenced a long time to initiate copulation (98.37±40.12 min), with no significant difference among crosses. The CD was longer than most Drosophila species analyzed so far, and it was significantly different between populations (24.45±8.7 min for PMA, and 40.69±16.18 min for SSF). CD for ♀PMAx♂SSF was not statistically different than ♀SSFx♂SSF, neither ♀SSFx♂PMA was different of ♀PMAx♂PMA, suggesting that CD could be driven by D. maculifrons males. The differential sexual conflict between the analyzed D. maculifrons populations regarding CD did not result in reproductive isolation as no significant difference was detected in P for the crosses performed. The estimated number of sires per brood (PMA = 3.14 and SSF = 2.88) and the proportion of females inseminated by multiple males (PMA = 0.84 and SSF = 0.80) were significantly lower in SSF (H = 407.1; p<0.001 to α), while the proportion of the progeny sired by the last male was significantly higher (PMA = 0.57 and SSF = 0.63, H = 2088; p<0.001). These parameters, associated with the higher CD for SSF, could be indicatives that longer CD reduces the risk of SC by limiting female remating frequency. The reproductive characters analyzed in this work evidenced that D. maculifrons exhibits pattern A of Drosophila mating system, characterized by high male investment in reproduction, probably as a consequence of the occurrence of polyandry in this species.