Evolution of the male genitalia: morphological variation of the aedeagi in a natural population of Drosophila mediopunctata

Abstract

To investigate the size and shape of the aedeagus of Drosophila mediopunctata, we used basic statistics and geometric morphometrics. We estimated the level of phenotypic variation, natural and laboratory heritability as well as the phenotypic correlations between aedeagus and wing measures. The wing was used as an indicator for both body size and shape. Positive significant correlation was obtained for centroid size of aedeagus and wing for field parents and their offspring reared in the laboratory. Many positive significant phenotypic correlations were found among linear measures of both organs. The phenotypic correlations were few for aedeagus and wing shape. Coefficients of variation of the measures were on average larger in the aedeagus than in the wing for offspring reared in laboratory, but not for flies coming from the field. Significant "natural" heritabilities were found for five linear measures of the aedeagus and only one for the wing. Few significant heritabilities were found for aedeagus and wing shape, mostly ones concerning the uniform components. In an exploratory analysis, we found that inversion DS-PC0 is associated with both uniform and nonuniform components of shape, respectively, in the wing and aedeagus. Our results do not support the lock-and-key hypothesis for the male genitalia evolution, but cannot refute the sexual selection and pleiotropy hypotheses.

Genotype × environment interaction is weaker in genitalia than in mating signals and body traits in Enchenopa treehoppers (Hemiptera: Membracidae)

“…It is also consistent with the expected erosion of genetic variation by selection, since E. binotata signals have diverged rapidly under strong sexual selection (Rodríguez et al , 2006Cocroft et al 2010;Sullivan-Beckers and Cocroft 2010). Medium-tohigh H 2 in genitalia is in line with other studies (Arnqvist and Thornhill 1998;Zeng et al 2000;Andrade et al 2009;Higgins et al 2009;Kamimura and Iwase 2010). We detected G 9 E in all signal and body traits and all but one genitalia trait.…”

Sexual selection and the rodent baculum: an intraspecific study in the house mouse (Mus musculus domesticus)

“…Whereas coefficients of variation in genital traits of arthropods are usually substantially lower than those of non-genital traits (e.g. Eberhard et al 1998;Hosken et al 2005;Bertin and Fairbairn 2007; but see also Andrade et al 2009), recent mammalian studies indicate that male genital traits often exhibit higher coefficients of variation compared to non-sexual traits measured in the same species (Miller and Burton 2001;Kinahan et al 2007;Tasikas et al 2009;Miller and Nagorsen 2008), though this is not always the case (e.g. see Long and Frank 1968).…”

Unexpected long-term changes in chromosome inversion frequencies in a Neotropical Drosophila species

“…Thus, the genetic content of the inversions may have accumulated different alleles adapted to different temperatures. Similarly, Andrade et al (2009) showed that different chromosome karyotypes affected not only wing shape, but also male genital (aedeagus) morphology.…”