科研之友
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摘要
Phenotypic variability of several morphological traits was investigated in the two sibling cosmopolitan species (Drosophila melanogaster and D. simulans) collected simultaneously at the same place (Marrakech, Morocco). The phenotypic plasticity of wild living flies due to heterogeneous (but unknown) environmental conditions (HEC) was compared to the plasticity due to growth temperature in the protected environment of laboratory. Three metric, size-related traits were measured and 3 shape indices calculated. A meristic trait, thoracic bristles was also analyzed as well as another quantitative trait, abdomen pigmentation. Measurements were done on both sexes, allowing the analyses of sexual dimorphism. Developmental temperature in laboratory experiments (17 and 25 C) confirmed a known plasticity, i.e. larger and darker flies at a lower temperature, while the bristle number was almost not affected. In nature, the main result was an average smaller size and a huge increase in the phenotypic variance of size. This suggests that, in nature, larval feeding conditions are less favorable and highly variable. Bristle number remained, as well as pigmentation, practically not affected by HEC. A negative correlation, between pigmentation and wing loading, suggested that, although wild flies were collected at the same time and place, the breeding sites were not exactly at the same temperature. D. simulans developed, on average, at a lower temperature than D. melanogaster, in agreement with a known behavioral difference, with respect to domestic habitats. Sexual dimorphism (SD) revealed a consistent shape difference between sexes, i.e. a more elongated thorax in females. In D. simulans size SD was significantly less in nature, suggesting that males were less affected by HEC. SD of pigmentation was always close to one in D. melanogaster, while it could be much more in D. simulans.
- 出版日期2011-12
