Morphological Polymorphism and Phenotypic Plasticity in Bactrocera dorsalis (Diptera: Tephritidae) of Taiwan
Date Issued
2012
Date
2012
Author(s)
Wei, Shih-Tsai
Abstract
Morphological polymorphism could be induced by either genetic or environmental variations. However, they usually worked together at the same time. The phenomenon of environmental effects on morphological change is called phenotypic plasticity, which plays an important role in evolution. In some cases, this phenomenon could help researchers exploring taxonomic problem in more detail. In current study, we investigated the morphological polymorphism on Bactrocera dorsalis in Taiwan including the color pattern on occiput, thoracic brown patterns, the position of intra-alar bristles, and the black patterns on the abdominal tergites. These color patterns showed seasonal variations in the wild-type flies. Therefore, one of the environmental factors, temperature, was selected for further analysis. In the laboratory populations, we found that the temperature-dependent variations of melanism on scutum, subscutellum, mediotergite, and abdomen do exist in oriental fruit flies (B. dorsalis). The reaction norm that higher melanism happened under lower temperature was similar to those in other insects. Besides, temperature also affected wing shape in rearing populations according to our geometric morphometric results, while no obvious pattern was found in the field samples. Contrast to those characters mentioned above, the sensilla numbers on tibiae have no difference under different seasons or rearing temperature. According to the results, we suggest that both the color patterns and wing shape of the fly could be affected by temperature. However, most of them were considered diagnostic taxonomic morphological characters used to divide different species in B. dorsalis complex. Therefore, further studies on environmentally-induced morphological changes in other species in dorsalis complex need to be conducted, which might provide another explanation on these phytophagous sibling species with high morphological similarity.
Subjects
Bactrocera dorsalis
phenotypic plasticity
temperature
melanism
wing shape
geometric morphometrics
Type
thesis
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