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Sexual selection and the evolution of male pheromone glands in philanthine wasps (Hymenoptera, Crabronidae)

BACKGROUND: Sexual selection is thought to promote evolutionary changes and diversification. However, the impact of sexual selection in relation to other selective forces is difficult to evaluate. Male digger wasps of the tribe Philanthini (Hymenoptera, Philanthinae) scent mark territories to attrac...

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Autores principales: Weiss, Katharina, Herzner, Gudrun, Strohm, Erhard
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5461632/
https://www.ncbi.nlm.nih.gov/pubmed/28587589
http://dx.doi.org/10.1186/s12862-017-0963-6
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author Weiss, Katharina
Herzner, Gudrun
Strohm, Erhard
author_facet Weiss, Katharina
Herzner, Gudrun
Strohm, Erhard
author_sort Weiss, Katharina
collection PubMed
description BACKGROUND: Sexual selection is thought to promote evolutionary changes and diversification. However, the impact of sexual selection in relation to other selective forces is difficult to evaluate. Male digger wasps of the tribe Philanthini (Hymenoptera, Philanthinae) scent mark territories to attract receptive females. Consequently, the organs for production and storage of the marking secretion, the mandibular gland (MG) and the postpharyngeal gland (PPG), are subject to sexual selection. In female Philanthini, these glands are most likely solely subject to natural selection and show very little morphological diversity. According to the hypothesis that sexual selection drives interspecific diversity, we predicted that the MG and PPG show higher interspecific variation in males than in females. Using histological methods, 3D-reconstructions, and multivariate statistical analysis of morphological characters, we conducted a comparative analysis of the MG and the PPG in males of 30 species of Philanthini and three species of the Cercerini and Aphilanthopsini, two related tribes within the Philanthinae. RESULTS: We found substantial interspecific diversity in gland morphology with regard to gland incidence, size, shape and the type of associated secretory cells. Overall there was a phylogenetic trend: Ensuing from the large MGs and small PPGs of male Cercerini and Aphilanthopsini, the size and complexity of the MG was reduced in male Philanthini, while their PPG became considerably enlarged, substantially more complex, and associated with an apparently novel type of secretory cells. In some clades of the Philanthini the MG was even lost and entirely replaced by the PPG. However, several species showed reversals of and exceptions from this trend. Head gland morphology was significantly more diverse among male than among female Philanthinae. CONCLUSION: Our results show considerable variation in male head glands including the loss of an entire gland system and the evolution of a novel kind of secretory cells, confirming the prediction that interspecific diversity in head gland morphology is higher in male than in female Philanthini. We discuss possible causes for the remarkable evolutionary changes in males and we conclude that this high diversity has been caused by sexual selection. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12862-017-0963-6) contains supplementary material, which is available to authorized users.
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spelling pubmed-54616322017-06-07 Sexual selection and the evolution of male pheromone glands in philanthine wasps (Hymenoptera, Crabronidae) Weiss, Katharina Herzner, Gudrun Strohm, Erhard BMC Evol Biol Research Article BACKGROUND: Sexual selection is thought to promote evolutionary changes and diversification. However, the impact of sexual selection in relation to other selective forces is difficult to evaluate. Male digger wasps of the tribe Philanthini (Hymenoptera, Philanthinae) scent mark territories to attract receptive females. Consequently, the organs for production and storage of the marking secretion, the mandibular gland (MG) and the postpharyngeal gland (PPG), are subject to sexual selection. In female Philanthini, these glands are most likely solely subject to natural selection and show very little morphological diversity. According to the hypothesis that sexual selection drives interspecific diversity, we predicted that the MG and PPG show higher interspecific variation in males than in females. Using histological methods, 3D-reconstructions, and multivariate statistical analysis of morphological characters, we conducted a comparative analysis of the MG and the PPG in males of 30 species of Philanthini and three species of the Cercerini and Aphilanthopsini, two related tribes within the Philanthinae. RESULTS: We found substantial interspecific diversity in gland morphology with regard to gland incidence, size, shape and the type of associated secretory cells. Overall there was a phylogenetic trend: Ensuing from the large MGs and small PPGs of male Cercerini and Aphilanthopsini, the size and complexity of the MG was reduced in male Philanthini, while their PPG became considerably enlarged, substantially more complex, and associated with an apparently novel type of secretory cells. In some clades of the Philanthini the MG was even lost and entirely replaced by the PPG. However, several species showed reversals of and exceptions from this trend. Head gland morphology was significantly more diverse among male than among female Philanthinae. CONCLUSION: Our results show considerable variation in male head glands including the loss of an entire gland system and the evolution of a novel kind of secretory cells, confirming the prediction that interspecific diversity in head gland morphology is higher in male than in female Philanthini. We discuss possible causes for the remarkable evolutionary changes in males and we conclude that this high diversity has been caused by sexual selection. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12862-017-0963-6) contains supplementary material, which is available to authorized users. BioMed Central 2017-06-06 /pmc/articles/PMC5461632/ /pubmed/28587589 http://dx.doi.org/10.1186/s12862-017-0963-6 Text en © The Author(s). 2017 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research Article
Weiss, Katharina
Herzner, Gudrun
Strohm, Erhard
Sexual selection and the evolution of male pheromone glands in philanthine wasps (Hymenoptera, Crabronidae)
title Sexual selection and the evolution of male pheromone glands in philanthine wasps (Hymenoptera, Crabronidae)
title_full Sexual selection and the evolution of male pheromone glands in philanthine wasps (Hymenoptera, Crabronidae)
title_fullStr Sexual selection and the evolution of male pheromone glands in philanthine wasps (Hymenoptera, Crabronidae)
title_full_unstemmed Sexual selection and the evolution of male pheromone glands in philanthine wasps (Hymenoptera, Crabronidae)
title_short Sexual selection and the evolution of male pheromone glands in philanthine wasps (Hymenoptera, Crabronidae)
title_sort sexual selection and the evolution of male pheromone glands in philanthine wasps (hymenoptera, crabronidae)
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5461632/
https://www.ncbi.nlm.nih.gov/pubmed/28587589
http://dx.doi.org/10.1186/s12862-017-0963-6
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