- 题目：Environment-dependent pleiotropic effects of mutations on the maximum growth rate r and carrying capacity K of population growth
- 时间：2019 年 02 月 20 号（星期三），美西时间（Pacific Time）6:00 PM
- 地点：YouTube live stream
- 主讲人：魏馨竹 Postdoc in Rasmus Nielsen’s Lab at UC Berkeley
中文摘要
r/K 选择理论是上世纪生态学和演化学上关于不同物种平衡后代数量和质量上的生存策略理论。其中，r代表最大生长速率，K代表环境对种群数量的承载能力。普遍的观点认为，r-K之间应该呈现负相关关系。然而，几十年的研究发现r-K在自然群体之间既可以正相关也可以负相关，而这一现象缺乏生物学解释。由于自然选择可以使遗传层面上负相关或者没有相关性的两个性状在个体层面表现为正相关，只有搞清楚其遗传学上的相关性才能理解r-k在个体和物种之间的现象。我们计算了7000多个酵母重组基因型的在9个不同的环境下的生长速率和环境承载力，研究r-K之间的关系，以及环境对其关系的影响。我们也使用了统计遗传学的方法分析影响r的数量性状位点（QTL）和影响K的QTL，以及之间的基因多效性。我们发现基因多效性广泛的影响r-K之间关系，并且基因多效性与环境有相互作用。我们建立了一个新的模型解释我们观察到的现象和r-K关系，这一模型包括ATP合成速率和效率之间的博弈以及个体用于维持生命所必需的能量与用于产生后代所需的能量之间的博弈。我们的研究用统计遗传的方法解释了r-K之间的复杂关系以及其生物学成因，其结果对于解释很多生态学，演化学，和生物医学中的现象都有所帮助。
English abstract:
Maximum growth rate per individual ® and carrying capacity (K) are key life-history traits that together characterize the density-dependent population growth and therefore are crucial parameters of many ecological and evolutionary theories such as r/K selection. Although r and K are generally thought to correlate inversely, both r/K tradeoffs and trade-ups have been observed. Nonetheless, neither the conditions under which each of these relationships occur nor the causes of these relationships are fully understood. Here, we address these questions using yeast as a model system. We estimated r and K using the growth curves of over 7,000 yeast recombinants in nine environments and found that the r–K correlation among genotypes changes from 0.53 to −0.52 with the rise of environment quality, measured by the mean r of all genotypes in the environment. We respectively mapped quantitative trait loci (QTLs) for r and Kin each environment. Many QTLs simultaneously influence r and K, but the directions of their effects are environment dependent such that QTLs tend to show concordant effects on the two traits in poor environments but antagonistic effects in rich environments. We propose that these contrasting trends are generated by the relative impacts of two factors—the tradeoff between the speed and efficiency of ATP production and the energetic cost of cell maintenance relative to reproduction—and demonstrate an agreement between model predictions and empirical observations. These results reveal and explain the complex environment dependency of the r–K relationship, which bears on many ecological and evolutionary phenomena and has biomedical implications.