Similarity selection and the evolution of sex: revisiting the red queen.

For over 25 years, many evolutionary ecologists have believed that sexual reproduction occurs because it allows hosts to change genotypes each generation and thereby evade their coevolving parasites. However, recent influential theoretical analyses suggest that, though parasites can select for sex u...

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Main Author: Aneil F Agrawal
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2006-08-01
Series:PLoS Biology
Online Access:http://europepmc.org/articles/PMC1523229?pdf=render
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author Aneil F Agrawal
author_facet Aneil F Agrawal
author_sort Aneil F Agrawal
collection DOAJ
description For over 25 years, many evolutionary ecologists have believed that sexual reproduction occurs because it allows hosts to change genotypes each generation and thereby evade their coevolving parasites. However, recent influential theoretical analyses suggest that, though parasites can select for sex under some conditions, they often select against it. These models assume that encounters between hosts and parasites are completely random. Because of this assumption, the fitness of a host depends only on its own genotype ("genotypic selection"). If a host is even slightly more likely to encounter a parasite transmitted by its mother than expected by random chance, then the fitness of a host also depends on its genetic similarity to its mother ("similarity selection"). A population genetic model is presented here that includes both genotypic and similarity selection, allowing them to be directly compared in the same framework. It is shown that similarity selection is a much more potent force with respect to the evolution of sex than is genotypic selection. Consequently, similarity selection can drive the evolution of sex even if it is much weaker than genotypic selection with respect to fitness. Examination of explicit coevolutionary models reveals that even a small degree of mother-offspring parasite transmission can cause parasites to favor sex rather than oppose it. In contrast to previous predictions, the model shows that weakly virulent parasites are more likely to favor sex than are highly virulent ones. Parasites have figured prominently in discussions of the evolution of sex, but recent models suggest that parasites often select against sex rather than for it. With the inclusion of small and realistic exposure biases, parasites are much more likely to favor sex. Though parasites alone may not provide a complete explanation for sex, the results presented here expand the potential for parasites to contribute to the maintenance of sex rather than act against it.
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spelling doaj.art-36450e03a8e445f4bcd52d561652656f2022-12-21T22:22:57ZengPublic Library of Science (PLoS)PLoS Biology1544-91731545-78852006-08-0148e26510.1371/journal.pbio.0040265Similarity selection and the evolution of sex: revisiting the red queen.Aneil F AgrawalFor over 25 years, many evolutionary ecologists have believed that sexual reproduction occurs because it allows hosts to change genotypes each generation and thereby evade their coevolving parasites. However, recent influential theoretical analyses suggest that, though parasites can select for sex under some conditions, they often select against it. These models assume that encounters between hosts and parasites are completely random. Because of this assumption, the fitness of a host depends only on its own genotype ("genotypic selection"). If a host is even slightly more likely to encounter a parasite transmitted by its mother than expected by random chance, then the fitness of a host also depends on its genetic similarity to its mother ("similarity selection"). A population genetic model is presented here that includes both genotypic and similarity selection, allowing them to be directly compared in the same framework. It is shown that similarity selection is a much more potent force with respect to the evolution of sex than is genotypic selection. Consequently, similarity selection can drive the evolution of sex even if it is much weaker than genotypic selection with respect to fitness. Examination of explicit coevolutionary models reveals that even a small degree of mother-offspring parasite transmission can cause parasites to favor sex rather than oppose it. In contrast to previous predictions, the model shows that weakly virulent parasites are more likely to favor sex than are highly virulent ones. Parasites have figured prominently in discussions of the evolution of sex, but recent models suggest that parasites often select against sex rather than for it. With the inclusion of small and realistic exposure biases, parasites are much more likely to favor sex. Though parasites alone may not provide a complete explanation for sex, the results presented here expand the potential for parasites to contribute to the maintenance of sex rather than act against it.http://europepmc.org/articles/PMC1523229?pdf=render
spellingShingle Aneil F Agrawal
Similarity selection and the evolution of sex: revisiting the red queen.
PLoS Biology
title Similarity selection and the evolution of sex: revisiting the red queen.
title_full Similarity selection and the evolution of sex: revisiting the red queen.
title_fullStr Similarity selection and the evolution of sex: revisiting the red queen.
title_full_unstemmed Similarity selection and the evolution of sex: revisiting the red queen.
title_short Similarity selection and the evolution of sex: revisiting the red queen.
title_sort similarity selection and the evolution of sex revisiting the red queen
url http://europepmc.org/articles/PMC1523229?pdf=render
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