Sexual isolation between North American and Bogota strains of Drosophila pseudoobscura

Abstract

Sexual isolation, the reduced ability of organisms of different species to successfully mate, is one of the reproductive barriers that prevent gene flow between different taxa. Various species-specific signals during courtship are attributed to the sexual isolation between them. Drosophila pseudoobscura has been widely used to study the behavioral and genetic mechanisms underlying selection for sexual isolation, as a model system for speciation. D. pseudoobscura and its sibling species, D. persmilis, live together in many locations but are reproductively isolated from one another. North American geographic strains of D. pseudoobscura from the American West mate at random. Several decades ago, D. pseudoobscura was collected in the vicinity of Bogota, Colombia, and later named the subspecies D. pseudoobscura bogotana. Nearly 5,000 matings were observed in this study. We analyzed mating behavior and cuticular hydrocarbon profiles as well as courtship within and between North American and Bogota strains of D. pseudoobscura. Here we report for the first time that Bogota strains of D. pseudoobscura do show statistically significant sexual isolation from North American strains. In addition, there are quantitative variations in cuticular hydrocarbons as well as in courtship behavior between Bogota and North American strains, and females of both North American and Bogota strains show strong preference for North American strain males having high mating propensities, suggesting that the Bogota strains are at an early stage that could lead to a separate species.

Evidence for no sexual isolation between Drosophila albomicans and D. nasuta

“…However, the biases are drastically reduced in studies with big sample sizes, for example, in Kim et al. () and this study as well, where χ 2 and I PSI are similar. Last but not least, different strains, temperatures, illumination, and humidity in different laboratories certainly contribute to the discrepancies in these studies.…”

“…They particularly criticized the v 2 and joint isolation statistics for having the largest variances of asymptotic biases due to uncorrected marginal effect, and for being more affected by sample sizes than any other statistics. However, the biases are drastically reduced in studies with big sample sizes, for example, in Kim et al (2012) and this study as well, where v 2 and I PSI are similar. Last but not least, different strains, temperatures, illumination, and humidity in different laboratories certainly contribute to the discrepancies in these studies.…”

“…One commonly used cue is the cuticular hydrocarbons (CHCs) that have been known to play pheromonal roles in Drosophila mate recognition and courtship (reviewed in Ferveur 2005). There is significant intra-and interspecific variation in CHCs among many species, and CHCs are part of the architecture of reproductive isolation between geographic strains and between species (Etges and Jackson 2001;Liimatainen and Jallon 2007;Alves et al 2010;Kim et al 2012;Sharma et al 2012). In recent years, advances in molecular and statistical tools have facilitated the elucidation of the genetic bases for traits influencing sexual isolation between species (Doi et al 2001;Takahashi et al 2001;Ting et al 2001;Shaw and Parsons 2002;Gleason and Ritchie 2004;Moehring and Mackay 2004;Gleason et al 2009).…”

The Genetic Basis of Female Mate Preference and Species Isolation inDrosophila

“…Assuming that low intraspecific choosiness results in high hybridization rates, we would then expect isolated island species to have high levels of hybridization. Although we do find this relationship in the North American and Bogota strains of D. pseudoobscura [38], we see the opposite trend in many other species pairs [19]. For example, D. mauritiana and D. sechellia females, both from island populations, are more choosy against males from the closely related mainland species, D. simulans , than mainland females are against island males.…”

Announcement of the Fulker Award for a Paper Published in Behavior Genetics, Volume 42, 2012

“…Among the nominees were papers by: Bergin et al (2012) on the genetic and environmental transmission of fluctuations in Body Mass Index, a health related phenotype; on methods for testing the hypothesis of an X-linked genetic influence resulting in the increased representation of males in the high end of the IQ distribution, by Giummo and Johnson (2012), by Kim et al (2012) on sexual isolation in natural strains of Drosophila pseudoobscura that are possibly in the early stages of speciation; by Martin et al (2012) on conspecific ant aggression and kin recognition; a study by Barclay et al (2012) on the non-shared environmental influences on sleep quality; and a study of Orangutan personality, by Mark Adams and colleagues that was based on subjects from 42 zoos, connected through known pedigrees, across the USA, Canada, Australia and Singapore. One of the pleasures of being the Editor of Behavior Genetics is reading the wide range of innovative studies published in the journal, and making the almost impossible choice of the 'best' paper from among the Associate Editors' nominations.…”