Center for Studies in Physics and Biology, and Laboratory of Living Matter, The Rockefeller University, 1230 York Avenue, Box 34, New York, NY 10021, USA.
Proc Natl Acad Sci U S A. 2010 Jul 20;107(29):13183-8. doi: 10.1073/pnas.0912538107. Epub 2010 Jul 2.
The strength of selection in populations has traditionally been inferred by measuring changes in bulk population parameters, such as mean reproductive rates. Untangling the effect of selection from other factors, such as specific responses to environmental fluctuations, poses a significant problem both in microbiology and in other fields, including cancer biology and immunology, where selection occurs within phenotypically heterogeneous populations of cells. Using "individual histories"--temporal sequences of all reproduction events and phenotypic changes of individuals and their ancestors--we present an alternative approach to quantifying selection in diverse experimental settings. Selection is viewed as a process that acts on histories, and a measure of selection that employs the distribution of histories is introduced. We apply this measure to phenotypically structured populations in fluctuating environments across different evolutionary regimes. Additionally, we show that reproduction events alone, recorded in the population's tree of cell divisions, may be sufficient to accurately measure selection. The measure is thus applicable in a wide range of biological systems, from microorganisms--including species for which genetic tools do not yet exist--to cellular populations, such as tumors and stem cells, where detailed temporal data are becoming available.
传统上，通过测量群体的总体参数（如平均繁殖率）的变化来推断选择的强度。在微生物学以及包括癌症生物学和免疫学在内的其他领域中，从其他因素（如对环境波动的特定反应）中理清选择的作用是一个重大问题，因为选择发生在细胞表型异质群体中。我们使用“个体历史”——个体及其祖先的所有繁殖事件和表型变化的时间序列——提供了一种在不同实验环境中量化选择的替代方法。选择被视为一种作用于历史的过程，并且引入了一种使用历史分布的选择度量。我们将此度量应用于不同进化状态下环境波动中的表型结构群体。此外，我们表明，仅在种群细胞分裂树中记录的繁殖事件就足以准确测量选择。因此，该度量适用于广泛的生物系统，从微生物（包括尚未存在遗传工具的物种）到细胞群体，如肿瘤和干细胞，在这些群体中，详细的时间数据正在变得可用。
