Genetic detection of sperm from forced copulations between sympatric populations of Poecilia reticulata and Poecilia picta

Abstract

The reproductive success of the sneaky mating tactic is difficult to determine in fish with internal fertilization. We approached this problem by developing an assay that allows the recovery of sperm DNA from the reproductive tract of females. This assay was used to test whether sperm transfer occurs between sympatric populations of the guppy, Poecilia reticulata , and its putative sister species, Poecilia picta . Six hundred females of both species from two sympatric sites in Trinidad were collected, and then the contents of the females' reproductive tracts were analysed using reciprocally diagnostic microsatellite markers. Conspecific sperm occurred in approximately 86% of females, whereas heterospecific sperm were found in only 4% of females. Because females of either species do not mate willingly with heterospecific males, the results indicate that sneaky mating results in the transfer of sperm. The data are consistent with the idea that sexual conflict can result in differences in the strength of behavioural isolation between the sexes, and they suggest that behavioural isolation is unlikely to have driven speciation between the guppy and P. picta .

Extreme heterogeneity in sex chromosome differentiation and dosage compensation in livebearers

“…Moreover, although P. picta inhabit a range of areas, from freshwater to brackish waters, there are regions where their distribution overlaps with that of P. reticulata (60). Both species exhibit similar life-history traits (60), however there is evidence of reproductive barriers between them (61). On the other hand, hybridization between P. reticulata and P. wingei , for example, occurs frequently in areas of sympatry (62).…”

Major histocompatibility complex similarity and sexual selection: different does not always mean attractive

“…In guppies, heterospecific matings can occur because, although females avoid heterospecific males, they can nevertheless receive heterospecific sperm through forced copulation (Russell et al . ), with obvious costs for the offspring (Rosenthal & García de León ). Also ‘hybridization’ among different natural populations can impair offspring fitness (Russell & Magurran ), and the results we found in the present study (although our study involved only one population) are in agreement with the findings that fertilization success is biased towards males from the female's own population (Ludlow & Magurran ), likely more genetically similar to the female.…”

Integrating mechanisms and function: prospects for future research

“…In species with male ARTs, reproductive parasites or "sneakers" may participate in fertilization attempts of other species (Crapon de Caprona 1986, Taborsky 1994, Jansson and Ost 1997, Wirtz 1999 or forcefully copulate with heterospecific females (Seymour 1990, Russell et al 2006. This causes hybridization, a speciation mechanism that is often underrated (Mallet 2007).…”