環境科学院 植物生態学セミナー   2012-05-15 (Tue) 10:30
(Room: A809 )

Mathematical model for evolutionary condition of sex-determining system
-- genetic sex determination vs. temperature-dependent sex determination --

Shoichi Yamada
Abstract:TSD (temperature-dependent sex determination) is a mechanism that sex of individuals is determined by interaction with exposed temperatures during differentiation into an embryo, a larva or an adult. The mechanism is thought to have some sort of adaptive significance. One of hypothesizes is ``If fitness functions of males and females are dependent on temperature, TSD is more adaptive than sex determination by a chromosome (GSD: genetic sex determination)''. Additionally, it is shown from phylogenetic study that species with TSD and with GSD have evolved to species with one another (Ewert and Nelson, 1991), that is to say, sex-determining system can evolve from TSD to GSD and from GSD to TSD. The purpose of my study is to investigate a condition that sex- determining system can evolve from GSD to TSD and from TSD to GSD. To investigate the condition, we construct a model of organisms with TSD (T-model) and a model of organisms with GSD (G-model), and compare a reproductive success of T-model with that of G-model under varying conditions of parameters (temperature variance in a habitat, heritability and temperature-dependent fitness). Additionally, we obtain mathematically analytical solutions of the reproductive successes. I present the future plan of the study.
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