Morphological variation in a natural population of Drosophila mediopunctata: altitudinal cline, temporal changes and influence of chromosome inversions

Abstract

To characterize the morphological variation in a natural population of Drosophila mediopunctata, males were collected on three occasions at a single locality. From each wild-caught male 14 body measures were taken and the karyotype for inversions on chromosomes X and II was determined. Through a principal components analysis, two sources of variation, identified as size and shape, accounted for approximately 80 and 6 per cent of the total morphological variability, respectively. The shape component was determined primarily by variations in the position of the wing second longitudinal vein. Differences between collections were detected both for size and shape. An altitudinal dine was observed in respect of wing shape, although altitude explained only a small part of the shape variation. Size and shape were affected by chromosome II inversions. However, in respect of size, no direct differences were detected between karyotypes but a significant interaction between collecting date and karyotype was found. This suggests that karyotypes might differ in their norms of reaction in the field.

Colour polymorphism in Drosophila mediopunctata: genetic (chromosomal) analysis and nonrandom association with chromosome inversions

“…Several studies have demonstrated the influence of Drosophila chromosome inversions on morphological characters such as wing size and shape in D. mediopunctata (Bitner-Mathé et al, 1995), extra bristles in D. melanogaster (Izquierdo et al, 1991), size-related traits in D. buzzati (Bertrán et al, 1998) and more recently in traits showing clinal variation (Weeks et al, 2002;Calboli et al, 2003). Our results show that the colour polymorphism in D. mediopunctata is associated with chromosome inversions.…”

“…Ford also proposed that polymorphic adaptations occurred mainly through a genetic architecture in which genes are tightly linked so that they act as a single unit. Inversion polymorphisms in Drosophila have been associated with several fitness-related characters (Rodríguez et al, 1999), behaviour (Dahlgaard et al, 2001) and morphological traits (Izquierdo et al, 1991;Bitner-Mathé et al, 1995;Bertrán et al, 1998). Recently there has been a resurgence of interest in the significance of chromosomal inversions in evolution and speciation.…”

Genetic architecture of wing morphology in Drosophila simulans and an analysis of temperature effects on genetic parameter estimates

“…Here we found strong indications of genotype-temperature interaction affecting wing size. In addition, other laboratory studies have shown evidence of genotype-environment interaction for size-related characters (Gupta and Lewontin, 1982;David et al, 1994;Bitner-Mathé et al, 1995;Noach et al, 1996). Conversely, the cross-environment heritability estimates of SH did not change with the increasing difference between the temperature in which mothers and their offspring were reared.…”

Correlations among size-related traits are affected by chromosome inversions in an adaptive polymorphism in Drosophila buzzatii

“…Although morphometric effects of chromosome inversions have been observed in some insects, including Drosophila species (Krimbas, 1967;Prevosti, 1967;Stalker, 1980;Ruiz et al, 1991;Bitner-Mathe et a!., 1995), to our knowledge, no study has examined the possible effects on the correlation among traits. Because phenotypic correlations are the weighted sums of genetic and environmental correlations (Falconer, 1989), the finding that CP-R may differ greatly between inversion genotypes (karyotypes) within and between populations ( Table 2) strongly suggests that inversions are factors affecting the genetic correlation among traits.…”