Bleiweiss R
Department of Zoology, University of Wisconsin, Madison 53706, USA.
Proc Natl Acad Sci U S A. 1998 Jan 20;95(2):612-6. doi: 10.1073/pnas.95.2.612.
Estimates of relative rates of molecular evolution from a DNA-hybridization phylogeny for 26 hummingbird species provide evidence for a negative association between elevation and rate of single-copy genome evolution. This effect of elevation on rate remains significant even after taking into account a significant negative association between body mass and molecular rate. Population-level processes do not appear to account for these patterns because (i) all hummingbirds breed within their first year and (ii) the more extensive subdivision and speciation of bird populations living at high elevations predicts a positive association between elevation and rate. The negative association between body mass and molecular rate in other organisms has been attributed to higher mutation rates in forms with higher oxidative metabolism. As ambient oxygen tensions and temperature decrease with elevation, the slow rate of molecular evolution in high-elevation hummingbirds also may have a metabolic basis. A slower rate of single-copy DNA change at higher elevations suggests that the dynamics of molecular evolution cannot be separated from the environmental context.
对26种蜂鸟的DNA杂交系统发育分子进化相对速率的估计，为海拔高度与单拷贝基因组进化速率之间的负相关提供了证据。即使考虑到体重与分子速率之间存在显著的负相关，海拔对速率的这种影响仍然显著。种群水平的过程似乎无法解释这些模式，因为：（i）所有蜂鸟都在第一年繁殖；（ii）生活在高海拔地区的鸟类种群有更广泛的细分和物种形成，这预测海拔与速率之间呈正相关。其他生物中体重与分子速率之间的负相关，被归因于氧化代谢较高的形态具有更高的突变率。随着海拔升高，环境氧气张力和温度降低，高海拔蜂鸟分子进化速率较慢也可能有代谢基础。在较高海拔处单拷贝DNA变化速率较慢，这表明分子进化的动态过程无法与环境背景相分离。
