Parkash R, Karan D, Munjal A K
Department of Biosciences, Maharshi Dayanand University, Rohtak, India.
Hereditas. 1998;128(3):201-5. doi: 10.1111/j.1601-5223.1998.00201.x.
There are significant geographical variations for four quantitative traits among eight natural populations of Drosophila kikkawai along the Indian latitudinal transect (8.29 to 33 degrees N). Body weight, wing length, thorax length, and ovariole number exhibit significant clinal variation with increase in latitutde. Genetic correlations between all the four traits are significantly higher. Slope values for body weight and wing length are higher (2.32 per degree latitude) while lower for thorax length (0.70) and ovariole number (0.56). South Indian populations are characterised by lower mean values but higher variances as well as CV values as compared with northern populations. Multiple regression analyses (on the basis of temperature related climatic variables) evidence significantly higher association between all the four traits and coefficient of variation of mean annual temperature (seasonal thermal amplitude; TCV). Thus, genetic differentiations for quantitative traits in D. kikkawai are due to selective pressure from variable seasonal environmental conditions occurring on the southern tropical versus northern subtropical regions of the Indian subcontinent.
在沿着印度纬度断面（北纬8.29度至33度）的八群喜喀果蝇自然种群中，四种数量性状存在显著的地理变异。体重、翅长、胸长和卵巢管数量随纬度增加呈现显著的渐变变异。所有这四种性状之间的遗传相关性显著更高。体重和翅长的斜率值更高（每度纬度2.32），而胸长（0.70）和卵巢管数量（0.56）的斜率值较低。与北方种群相比，南印度种群的特征是平均值较低，但方差以及变异系数（CV）值较高。多元回归分析（基于与温度相关的气候变量）表明，所有这四种性状与年平均温度的变异系数（季节性热振幅；TCV）之间存在显著更高的关联。因此，喜喀果蝇数量性状的遗传分化是由于印度次大陆南部热带与北部亚热带地区出现的可变季节性环境条件的选择压力所致。
