Karan D, Munjal A K, Gibert P, Moreteau B, Parkash R, David J R
Department of Biosciences, Maharshi Dayanand University, Rohtak, India.
Genet Res. 1998 Feb;71(1):31-8. doi: 10.1017/s0016672397003054.
Natural populations of Drosophila kikkawai were collected in India and Sri Lanka, along a latitudinal transect ranging from 6.8 degrees to 31.8 degrees N latitude. Six morphometrical traits were analysed: wing and thorax length, body weight, ovariole number, and abdominal and sternopleural bristle numbers. Significant clines were observed for the three-size related traits and for ovariole number, corresponding to a regular increase in the mean value with latitude, but not for bristle numbers. Due to the utilization of two types of laboratory food, data were distributed into two separate data sets. A low-nutrient food produced smaller flies on average because of more intense crowding. The two rearing conditions produced significant clines but with significantly different slopes. The wing/thorax ratio, which is inversely related to wing loading, also increased with latitude. The analysis of Indian climatic conditions suggested that winter temperature, decreasing from south to north, could be more efficient than summer temperature, which varies in an opposite way, as a selective factor for inducing the clinal variations. The sibling species D. leontia, which is known only from the humid tropics, was found to be much smaller than D. kikkawai and did not fit the clinal regressions. Such morphological differences should help to identify the two species when found in sympatry.
在印度和斯里兰卡沿着北纬6.8度至31.8度的纬度横断面收集了黑腹果蝇的自然种群。分析了六个形态测量特征：翅长、胸长、体重、卵巢管数量以及腹部和腹板刚毛数量。观察到与大小相关的三个特征以及卵巢管数量存在显著的渐变群，其对应于平均值随纬度的规律性增加，但刚毛数量不存在这种情况。由于使用了两种类型的实验室食物，数据被分为两个单独的数据集。低营养食物由于拥挤程度更高，平均产生的果蝇体型更小。两种饲养条件产生了显著的渐变群，但斜率显著不同。与翼载荷呈反比的翅/胸比率也随纬度增加。对印度气候条件的分析表明，从南向北递减的冬季温度，作为诱导渐变变异的选择因素，可能比以相反方式变化的夏季温度更有效。仅在潮湿热带地区已知的同属物种莱昂蒂果蝇，被发现比黑腹果蝇小得多，并且不符合渐变回归。这种形态差异在同域分布时应有助于识别这两个物种。
