Phenotypic plasticity of body pigmentation in Drosophila melanogaster: Genetic repeatability of quantitative parameters in two successive generations

Abstract

In Drosophila melanogaster, body pigmentation is a quantitative trait that depends on developmental temperature. When investigated over the whole thermal range of the species, pigmentation exhibits nonlinear reaction norms that differ among segments. The isofemale line method was used to analyse the genetic variability in two natural populations that affected the shape of reaction norms. Each line was considered as an experimental repeat, and polynomial reaction norms fitted to calculate the characteristic values (eg the coordinates of a maximum). In total, 20 lines from two geographically distant populations (France and India) were investigated at seven developmental temperatures (12-311C) in two successive generations (G2 and G3). We analysed the genetic repeatability (ie the correlation between generations) of three kinds of parameters: intraclass correlation coefficients (isofemale heritability), family means at different temperatures and the characteristic values of the reaction norms. For intraclass correlation, a low genetic repeatability was found. For family mean values grown at various temperatures, an overall positive and highly significant repeatability was found (r ¼ 0.5570.024). Finally, a positive significant G2-G3 correlation was also the rule for the characteristic values of the reaction norms. Significant differences could be found between values describing either the trait or its plasticity, but with no general trend. A slightly higher repeatability was observed in the Indian population. These results show that, with a family selection design, the shape of the reaction norms might be modified in various ways.

Phenotypic plasticity of abdomen pigmentation in two geographic populations of Drosophila melanogaster: male–female comparison and sexual dimorphism

“…While Bordeaux is typical of a cool temperate locality with mild summer and cold winter, Rohtak is typical of a subtropical arid climate with mild winter but very hot summer. A set of 20 lines was randomly taken from each locality and the phenotypic plasticity of female abdomen pigmentation was investigated by two different observers (Gibert et al 1998a(Gibert et al , 2004b. Each observer analyzed 10 lines from France and 10 lines from India.…”

“…We also compare two distant geographic populations, a French one (Bordeaux) living under a mild humid temperate climate and an Indian one (Rohtak) adapted to a tropical climate with a very hot and arid summer. Previous investigations already evidenced an overall lighter pigmentation in Rohtak females (Gibert et al 1998a(Gibert et al , 2004b as well as a better tolerance of spermatogenesis to heat stress (Rohmer et al 2004). As a control, we also measured the thoracic (trident) pigmentation, which is known to be very similar in both sexes but different among populations (David et al 1985;Capy et al 1988;Munjal et al 1997).…”

“…Each tergite reacts to developmental temperature with a specific response curve (the reaction norm) (Gibert et al 1998b(Gibert et al , 2000(Gibert et al , 2004b. All studies on abdomen pigmentation have been done, up to now, on females only.…”

What is hot in tree rings? The wood density of surviving Douglas-firs to the 2003 drought and heat wave

“…dendrochronology). Few attempts have been made to use wood density as an indicator of the reaction of trees to immediate climate, and as a measure of plasticity; that is malleable by directional selection (Scheider and Lyman, 1989;Gibert et al, 2004). Recently, some authors pointed at this possibility, by showing that some microdensity variables are good indicators of extreme climate events (Rozenberg et al, 2002;Bower et al, 2005;Martinez-Meier et al, 2008), and that they seem to have significant genetic control Martinez-Meier et al, 2008).…”

Ring density record of phenotypic plasticity and adaptation to drought in Douglas-fir

“…The evaluation of phenotypic plasticity requires the construction of a norm of reaction (NoR), a phenotypic response by a given genotype to an environmental gradient (Sarkar, 1999;Fuller, 2003;Gibert et al, 2004). The NoR obtained from a microdensity profile is denoted here with the neologism dendroplasticity.…”