GENETICS OF INCIPIENT SPECIATION INDROSOPHILA MOJAVENSIS. I. MALE COURTSHIP SONG, MATING SUCCESS, AND GENOTYPE X ENVIRONMENT INTERACTIONS

Abstract

Few studies have examined genotype by environment (GxE) effects on premating reproductive isolation and associated behaviors, even though such effects may be common when speciation is driven by adaptation to different environments. In this study, mating success and courtship song differences among diverging populations of Drosophila mojavensis were investigated in a two-environment quantitative trait locus (QTL) analysis. Baja California and mainland Mexico populations of D. mojavensis feed and breed on different host cacti, so these host plants were used to culture F 2 males to examine host-specific QTL effects and GxE interactions influencing mating success and courtship songs. Linear selection gradient analysis showed that mainland females mated with males that produced songs with significantly shorter L(long)-IPIs, burst durations, and interburst intervals. Twenty-one microsatellite loci distributed across all five major chromosomes were used to localize effects of mating success, time to copulation, and courtship song components. Male courtship success was influenced by a single detected QTL, the main effect of cactus, and four GxE interactions, whereas time to copulation was influenced by three different QTLs on the fourth chromosome. Multiplelocus restricted maximum likelihood (REML) analysis of courtship song revealed consistent effects linked with the same fourth chromosome markers that influenced time to copulation, a number of GxE interactions, and few possible cases of epistasis. GxE interactions for mate choice and song can maintain genetic variation in populations, but alter outcomes of sexual selection and isolation, so signal evolution and reproductive isolation may be slowed in diverging populations. Understanding the genetics of incipient speciation in D. mojavensis clearly depends on cactus-specific expression of traits associated with courtship behavior and sexual isolation.

Endogenous synchronization of the chemical signature of Reticulitermes (Isoptera: Rhinotermitidae) worker termites

“…Moreover, the new environment, in particular the food factor, is certainly not determinant, given that the points of the individuals in the environmental controls from the Plexiglas boxes (F), fed with a piece of wood, are included in the circle enclosing the points for the individuals from the Petri dishes, fed with fi lter paper, taken at the same fi nal time (blank controls and termites fed on JH-III at 35 days from the Petri dishes). At the end of the experiment, there were, therefore, no signifi cant diff erences in CHCs owing to diet, as shown by Liang and Silverman (2000) for the Argentine ant, or by Etges et al for the lack of infl uence of host plants and sexual maturity in drosophila CHCs (Etges et al 2007(Etges et al , 2009. Furthermore, the workers in the Plexiglas boxes also evolved in a social environment diff erent from the environments in the Petri dishes (more than a hundred in a Plexiglas box as against 50 in Petri dishes).…”

Variation in the Male Pheromones and Mating Success of Wild Caught Drosophila melanogaster

“…Elements of courtship song, for example interpulse interval, can evolve quickly and play a role in female choice in a variety of Drosophila species [36], [37], [38], [39]. If present, courtship song variation could have contributed to variation in mating success, especially the strong tendency for SC line females to mate faster with males from their own line than with laboratory males.…”

Sexual isolation between North American and Bogota strains of Drosophila pseudoobscura

“…Understanding the genetic architecture of a given behavior requires identifying and mapping genes which contribute to the trait and affect natural variation in the trait. Advances in molecular and statistical tools have identified QTLs for traits influencing sexual isolation between species (see Williams et al 2001;Gleason et al 2002;Huttunen et al 2004 for courtship song; Doi et al 2001;Shaw and Parsons 2002;Civetta and Cantor 2003;Moehring et al 2004 for mating behavior; Gleason et al 2005Gleason et al , 2009Etges et al 2007Etges et al , 2009 for cuticular hydrocarbons). Currently, we are analyzing QTLs affecting variation in courtship behavior and cuticular hydrocarbons conferring sexual isolation between the two D. pseudoobscura subspecies.…”

“…Courtship song and cuticular hydrocarbons have been identified as important elements in mating behavior (see Ferveur 2005;Gleason 2005;Hoikkala 2005 for review). Several studies estimated the number of loci that contribute to factors preventing gene exchange between species (Macdonald and Goldstein 1999;Williams et al 2001;Civetta et al 2002;Gleason et al 2002Gleason et al , 2005Gleason et al , 2009Civetta and Cantor 2003;Huttunen et al 2004;Moehring et al 2004;Etges et al 2007Etges et al , 2009. For example, in a study of differences between the sibling species Drosophila pseudoobscura and D. persimilis in courtship song, three quantitative trait loci (QTLs) for courtship song interpulse interval (IPI) were identified, all associated with inversions that differentiate these two species (Williams et al 2001).…”