日本動物学会北海道支部 第614回支部講演会
日時：2026年8月6日（木） 17:00～18:00
場所：北海道大学 理学部5号館8階 813号室
演者：石郷岡 潤 博士（Friedrich Miescher Laboratory of the Max Planck Society, Germany）
演題：Beyond errors: Phenotypic stochasticity as a fuel for adaptive evolution
要旨：For decades, it has been known that organisms of the same genotype in the same environment still look different from each other. Such variability has been attributed to technical errors in measurement or dismissed as uninformative noise. More recently, experiments have shown that the amount of within-genotype variability—phenotypic stochasticity—is genetically regulated. Despite this knowledge, most theoretical models of adaptation have not incorporated genetic variation in phenotypic stochasticity, and they still predict evolutionary outcomes solely based on the assumption of the deterministic genotype-phenotype map. As a consequence, a fundamental question remains: Does genetically regulated phenotypic stochasticity matter for adaptive evolution?
To answer this, we develop mathematical and computational models of population and quantitative genetics treating phenotypic stochasticity itself as a trait. We find that high phenotypic stochasticity is favored when a population sits far from the fitness optimum, and that genetic variation in stochasticity changes the trajectory of the adaptive walk across rugged fitness landscapes. To test these theoretical predictions empirically, we establish the first selection experiment of its kind with Drosophila melanogaster to compete low- and high-stochasticity alleles. We use tim0, a mutation in the circadian clock gene timeless causing arrhythmic eclosion, and the rhythmic wild-type as the high- and low-stochasticity alleles. By selecting flies eclosing in a pre-defined time window over generations, we compare the experimentally obtained frequency trajectory of tim0 with the theoretical predictions. Our study, combining novel theoretical and experimental approaches, sheds light on the underappreciated role of biological randomness in adaptive evolution.
世話人：
和多 和宏（北海道大学 理学研究院）
wada[a]sci.hokudai.ac.jp
[a]を@に変えてください
エゾリス（旭川医科大学RI実験施設 長原稔和氏提供）
