Sexual dimorphism as a facilitator of worker caste evolution in ants

Abstract Ant societies are primarily composed of females, whereby labor is divided into reproductive, or queen, and non‐reproductive, or worker, castes. Workers and reproductive queens can differ greatly in behavior, longevity, physiology, and morphology, but queen–worker differences are usually mod...

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Main Author: Chris R. Smith
Format: Article
Language:English
Published: Wiley 2023-02-01
Series:Ecology and Evolution
Subjects:
Online Access:https://doi.org/10.1002/ece3.9825
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author Chris R. Smith
author_facet Chris R. Smith
author_sort Chris R. Smith
collection DOAJ
description Abstract Ant societies are primarily composed of females, whereby labor is divided into reproductive, or queen, and non‐reproductive, or worker, castes. Workers and reproductive queens can differ greatly in behavior, longevity, physiology, and morphology, but queen–worker differences are usually modest relative to the differences in males. Males are short‐lived, typically do not provide the colony with labor, often look like a different species, and only occur seasonally. It is these differences that have historically led to their neglect in social insect research, but also why they may facilitate novel phenotypic variation – by increasing the phenotypic variability that is available for selection. In this study, worker variation in multivariate size–shape space paralleled male–queen variation. As worker variation increased within species, so did sexual variation. Across species in two independent genera, using head width as a proxy for body size, sexual size dimorphism correlated with worker polymorphism regardless of whether the ancestral condition was large or small worker/sexual dimorphism. Mounting molecular data support the hypothesis that queen–worker caste determination has co‐opted many genes/pathways from sex determination. The molecular evidence, coupled with the observations from this study, leads to the hypothesis that sexual selection and selection on colony‐level traits are non‐independent, and that sexual dimorphism may even have facilitated the evolution of the distinct worker caste.
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spelling doaj.art-1ae99b228afb4c99a0eda88e474cb6d32023-02-27T08:56:39ZengWileyEcology and Evolution2045-77582023-02-01132n/an/a10.1002/ece3.9825Sexual dimorphism as a facilitator of worker caste evolution in antsChris R. Smith0Department of Biology Earlham College Richmond Indiana USAAbstract Ant societies are primarily composed of females, whereby labor is divided into reproductive, or queen, and non‐reproductive, or worker, castes. Workers and reproductive queens can differ greatly in behavior, longevity, physiology, and morphology, but queen–worker differences are usually modest relative to the differences in males. Males are short‐lived, typically do not provide the colony with labor, often look like a different species, and only occur seasonally. It is these differences that have historically led to their neglect in social insect research, but also why they may facilitate novel phenotypic variation – by increasing the phenotypic variability that is available for selection. In this study, worker variation in multivariate size–shape space paralleled male–queen variation. As worker variation increased within species, so did sexual variation. Across species in two independent genera, using head width as a proxy for body size, sexual size dimorphism correlated with worker polymorphism regardless of whether the ancestral condition was large or small worker/sexual dimorphism. Mounting molecular data support the hypothesis that queen–worker caste determination has co‐opted many genes/pathways from sex determination. The molecular evidence, coupled with the observations from this study, leads to the hypothesis that sexual selection and selection on colony‐level traits are non‐independent, and that sexual dimorphism may even have facilitated the evolution of the distinct worker caste.https://doi.org/10.1002/ece3.9825division of labordronesexual selectionsocial insect
spellingShingle Chris R. Smith
Sexual dimorphism as a facilitator of worker caste evolution in ants
Ecology and Evolution
division of labor
drone
sexual selection
social insect
title Sexual dimorphism as a facilitator of worker caste evolution in ants
title_full Sexual dimorphism as a facilitator of worker caste evolution in ants
title_fullStr Sexual dimorphism as a facilitator of worker caste evolution in ants
title_full_unstemmed Sexual dimorphism as a facilitator of worker caste evolution in ants
title_short Sexual dimorphism as a facilitator of worker caste evolution in ants
title_sort sexual dimorphism as a facilitator of worker caste evolution in ants
topic division of labor
drone
sexual selection
social insect
url https://doi.org/10.1002/ece3.9825
work_keys_str_mv AT chrisrsmith sexualdimorphismasafacilitatorofworkercasteevolutioninants