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Fitness differences suppress the number of mating types in evolving isogamous species.

ABSTRACT: Sexual reproduction is not always synonymous with the existence of two morphologically different sexes; isogamous species produce sex cells of equal size, typically falling into multiple distinct self-incompatible classes, termed mating types. A long-standing open question in evolutionary biology is: what governs the number of these mating types across species? Simple theoretical arguments imply an advantage to rare types, suggesting the number of types should grow consistently; however, empirical observations are very different. While some isogamous species exhibit thousands of mating types, such species are exceedingly rare, and most have fewer than 10. In this paper, we present a mathematical analysis to quantify the role of fitness variation-characterized by different mortality rates-in determining the number of mating types emerging in simple evolutionary models. We predict that the number of mating types decreases as the variance of mortality increases.

SUBMITTER: Krumbeck Y

PROVIDER: S-EPMC7062084 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Fitness differences suppress the number of mating types in evolving isogamous species.

Krumbeck Yvonne Y Constable George W A GWA Rogers Tim T

Royal Society open science 20200226 2

Sexual reproduction is not always synonymous with the existence of two morphologically different sexes; isogamous species produce sex cells of equal size, typically falling into multiple distinct self-incompatible classes, termed mating types. A long-standing open question in evolutionary biology is: what governs the number of these mating types across species? Simple theoretical arguments imply an advantage to rare types, suggesting the number of types should grow consistently; however, empiric ...[more]

PMID: 32257356

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