The Zoological Society of Japan, Hokkaido Branch, 614th Branch Lecture
Date: Thursday, August 6, 2026, 17:00 – 18:00
Location: Hokkaido University, Faculty of Science, Building No. 5, 8th Floor, Room 813
Speaker: Dr. Jun Ishigooka (Friedrich Miescher Laboratory of the Max Planck Society, Germany)
Title: Beyond errors: Phenotypic stochasticity as a fuel for adaptive evolution
Abstract: 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.
Caretaker:
Kazuhiro Watada (Faculty of Science, Hokkaido University)
wada[a]sci.hokudai.ac.jp
Please change [a] to @.
Ezo squirrel (Provided by Minorukaz Nagahara, Asahikawa Medical University RI Research Facility)
