Data from: Spatially varying selection shapes life history clines among populations of Drosophila melanogaster from sub-Saharan Africa

Clines in life history traits, presumably driven by spatially varying selection, are widespread. Major latitudinal clines have been observed, for example, in Drosophila melanogaster, an ancestrally tropical insect from Africa that has colonized temperate habitats on multiple continents. Yet, how geographic factors other than latitude, such as altitude or longitude, affect life history in this species remains poorly understood. Moreover, most previous work has been performed on derived European, American and Australian populations, but whether life history also varies predictably with geography in the ancestral Afro-tropical range has not been investigated systematically. Here, we have examined life history variation among populations of D. melanogaster from sub-Saharan Africa. Viability and reproductive diapause did not vary with geography, but body size increased with altitude, latitude and longitude. Early fecundity covaried positively with altitude and latitude, whereas lifespan showed the opposite trend. Examination of genetic variance–covariance matrices revealed geographic differentiation also in trade-off structure, and QST-FST analysis showed that life history differentiation among populations is likely shaped by selection. Together, our results suggest that geographic and/or climatic factors drive adaptive phenotypic differentiation among ancestral African populations and confirm the widely held notion that latitude and altitude represent parallel gradients.

生活史性状的渐变群普遍存在，其形成推测受空间异质性选择驱动。例如，在黑腹果蝇（Drosophila melanogaster）中已观察到显著的纬度渐变群：该物种起源于非洲热带区域，现已在多个大陆的温带生境中定殖。然而，除纬度外的其他地理因素（如海拔或经度）如何影响该物种的生活史，目前仍知之甚少。此外，此前绝大多数相关研究均以欧洲、美洲及澳大利亚的衍生种群为对象，而该物种祖先分布的非洲热带区域内，生活史是否同样随地理因素呈现可预测的变化，尚未得到系统性研究。本研究对撒哈拉以南非洲地区黑腹果蝇种群间的生活史变异展开了调查。研究发现，存活率与生殖滞育并不随地理因素发生变化，但体型随海拔、纬度及经度的升高而增大；早期繁殖力与海拔、纬度呈正相关，而寿命则呈现相反的变化趋势。对遗传方差-协方差矩阵的分析显示，种群间的权衡结构同样存在地理分化；而QST-FST分析表明，种群间生活史的分化大概率由选择作用塑造。综合来看，本研究结果表明，地理及/或气候因素驱动了非洲祖先种群间的适应性表型分化，并证实了学界普遍认可的观点：纬度与海拔代表平行的渐变梯度。