Abdominal pigmentation and growth temperature in Drosophila melanogaster: Similarities and differences in the norms of reaction of successive segments

Abstract

In Drosophila melanogaster females, pigmentation of the abdominal tergites exhibits a large phenotypic variability which depends on growth temperature. The phenotypic plasticity of this trait was investigated in a European population, using isofemale lines, by rearing the larvae and pupae at 6 different temperatures ranging from 14 to 31" C. For the last three abdominal segments (5, 6 and 7), the dark pigmented area decreases when growth temperature increases. However, the shapes of the response curves are significantly different, as shown by analysing slope variations, suggesting that genes interact differently in regulating the phenotypic expression of successive segments.Also, the correlation between the values of the same line at two temperatures exhibited a decrease proportional to the temperature interval considered. Genetic variability between lines was analyzed by calculating the coefficient of intraclass correlation, t. This parameter was not influenced by growth temperature and, according to the segment, ranged from 0.40 to 0.54. Such high values suggest a large proportion of non-additive effects. A multivariate analysis helped to visualize the diversity of the reaction norms among lines. Overall pigmentation variations are presumed to have an adaptive significance, related to the thermal balance of adult flies; on the other hand, the differences between segments could reflect developmental constraints without a direct adaptive value.

Microspatial structure of Drosophila melanogaster populations in Brazzaville: evidence of natural selection acting on morphometrical traits

“…For the pigmentation of the abdomen, we estimated the relative extent of the black pigment on each of the last three tergites (segments 5, 6 and 7) of the females. A total of 10 phenotypic classes were used, scoring from 0 (completely yellow tergite) to 10 (completely black) (see David et al, 1990). For each trait and population, data are available for 600 females.…”

Reaction norms of size characters in relation to growth temperature in Drosophila melanogaster: an isofemale lines analysis

“…In the present work, we analysed the shapes of the response curves by calculating empirical derivatives, as has been done previously for pigmentation (David et al, 1989 .…”

GROWTH TEMPERATURE AND ADULT PIGMENTATION IN TWODROSOPHILASIBLING SPECIES: AN ADAPTIVE CONVERGENCE OF REACTION NORMS IN SYMPATRIC POPULATIONS?

“…In Drosophila, phenotypic plasticity of numerous traits has been investigated: bristle number (Gupta and Lewontin 1982), wing and thorax length (Scheiner and Lyman 1989;David et al 1994), body pigmentation David et al 1990), viability (Gebhart and Stearns 1993), and ovariole number (Delpuech et al 1995). Two major types of environmental variables have been used, namely, developmental temperature and larval feeding conditions.…”

“…In the case of body pigmentation, phenotypic plasticity leads to lighter flies at high temperatures and darker flies at low temperatures David et al 1990). Such a phenomenon, which is observed in numerous insects and also in other animals (Watt 1968;Jones et al 1977;Merrel 1981;Goulson 1994), is generally interpreted by the thermal budget hypothesis: at low ambient temperatures, it is better to be dark for better absorption of solar radiation, thus increasing internal temperature.…”