Genetic analysis of female mating recognition between Drosophila ananassae and Drosophila pallidosa: application of interspecific mosaic genome lines

Abstract

Drosophila ananassae and Drosophila pallidosa are closely related species that can produce viable and fertile hybrids of both sexes, although strong sexual isolation exists between the two species. Females are thought to discriminate conspecific from heterospecific males based on their courtship songs. The genetic basis of female discrimination behavior was analyzed using isogenic females from interspecific mosaic genome lines that carry homozygous recombinant chromosomes. Multiple regression analysis indicated a highly significant effect of the left arm of chromosome 2 (2L) on the willingness of females to mate with D. ananassae males. Not only 2L but also the left arm of chromosome X (XL) and the right arm of chromosome 3 (3R) had significant effects on the females' willingness to mate with D. pallidosa males. All regions with strong effects on mate choice have chromosome arrangements characterized by species-specific inversions. Heterospecific combinations of 2L and 3R have previously been suggested to cause postzygotic reproductive isolation. Thus, genes involved in premating as well as postmating isolation are located in or near chromosomal inversions. This conclusion is consistent with the recently proposed hypothesis that "speciation genes" accumulate at a higher rate in non-recombining genome regions when species divergence occurs in the presence of gene flow.

The Genetic Basis of Female Mate Preference and Species Isolation inDrosophila

“…Behavioral isolation loci between D. santomea and D. yakuba were found near the centromere on 3R [7], and near the telomere for both the D. simulans and D. mauritiana species pair [6] and the M and Z forms of D. melanogaster [92]. Loci responsible for the behavioral isolation between D. ananassae and D. pallidosa [121], and the isolation between D. pseudoobscura and D. persimilis [84] all fell within interspecific inversion polymorphisms. Although this was not true for the regions responsible for increased behavioral isolation caused by reinforcement in the latter species pair [109], these loci for reinforcement were not confirmed by further studies [124].…”

“…for D. ananassae female's willingness to mate with D. pallidosa males. All of the identified regions had species specific inversions [121], suggesting that regions of the genome with reduced recombination between the species may be more likely to harbor behavioral isolation loci.…”

Effect of chromosome arrangements on mate recognition system leading to behavioral isolation in Drosophila ananassae

“…Thus, inversion polymorphism may have a partial behavioral basis and males may be more subject to intrasexual selection than females (Singh and Chatterjee 1986). Multiple regression analysis by using interspecific mosaic genome lines of D. ananassae and D. pallidosa indicated highly significant effects on 2L for female mating willingness with D. ananassae males and on XL, 2L and 3R for that with D. pallidosa males (Sawamura et al 2008).…”

Origin of sexual isolation in Drosophila ananassae due to founder effects

“…ananassae. Arrow indicates the discrimination between groups of females (Square) to particular males (Oval) Multiple regression analysis by using interspecific mosaic genome lines of D.ananassae and D. pallidosa indicated highly significant effects on 2L for female mating willingness with D.ananassae males and on XL, 2L and 3R for that with D. pallidosa males (Sawamura et al 2008). Behavioural isolation has been found between two karyotypically different homozygous strains of D. ananassae derived from same geographic population which shows that chromosome arrangements may affect mate recognition system in D. ananassae (Nanda and Singh 2011b).…”