Evolution of the density response of juvenile hormone concentration in the determination of wing type

Takahiro Kamioka, Yoh Iwasa

Research output: Contribution to journalArticle

Abstract

Question: What is the evolutionarily stable density-dependent juvenile hormone concentration that determines wing type in wing-polymorphic insects? Key assumptions: An asexual species with larval and adult stages living in many patches. Larval growth rate depends on within-patch resources that are depleted by feeding larvae. Dispersal-type adults migrate out of the natal patch just before the reproductive stage, whereas reproductive-type adults do not disperse but are more fertile than dispersal types. The proportions of the two wing types are determined by juvenile hormone concentration, which follows a normal distribution with the mean decreasing linearly with density (larval biomass per unit resource). The carrying capacity of resources fluctuates between high and low values. Method: We studied the evolution of three quantities controlling juvenile hormone concentration: (1) baseline value of the mean, γ0; (2) density dependence of the mean, γ1; and (3) variance, σ2. Results: If γ0 and γ1 evolved with σ2 fixed, juvenile hormone production was high at low density and decreased with increasing density. If σ2 evolved with γ0 and γ1 fixed, the variance evolved to be smaller for larger environmental fluctuations. If all three quantities (γ0, γ1, and σ2) evolved simultaneously, the variance attained a minimum value when environmental fluctuation was large. In all three cases, evolution increased the proportion of dispersal-type individuals, which increased with density in an accelerating manner.

Original languageEnglish
Pages (from-to)621-636
Number of pages16
JournalEvolutionary Ecology Research
Volume18
Issue number6
Publication statusPublished - Nov 1 2017

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics

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