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The male sexual apparatus in the order Scorpiones (Arachnida): a comparative study of functional morphology as a tool to define hypotheses of homology
BACKGROUND: Insemination in scorpions is carried out by means of a partly sclerotized structure, the spermatophore, which is composed of two separate halves, the hemispermatophores. In most genera these reproductive structures can be used to differentiate species. However, many taxa such as the genu...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5699194/ https://www.ncbi.nlm.nih.gov/pubmed/29201131 http://dx.doi.org/10.1186/s12983-017-0231-z |
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author | Monod, Lionel Cauwet, Lucie González-Santillán, Edmundo Huber, Siegfried |
author_facet | Monod, Lionel Cauwet, Lucie González-Santillán, Edmundo Huber, Siegfried |
author_sort | Monod, Lionel |
collection | PubMed |
description | BACKGROUND: Insemination in scorpions is carried out by means of a partly sclerotized structure, the spermatophore, which is composed of two separate halves, the hemispermatophores. In most genera these reproductive structures can be used to differentiate species. However, many taxa such as the genus Euscorpius and the family Diplocentridae lack the morphological diversity observed in the copulatory organs of many other arthropods, rendering them useless for species level taxonomy. Such structural stasis, however, suggests that hemispermatophores have evolved relatively slowly and may thus provide a stronger phylogenetic signal for recognizing supra-generic ranks than previously thought. Based on the postulate that the phenotypic stability observed in some groups is the consequence of functional constraint, the most comprehensive comparative study of the male sexual apparatus to date was conducted for a complete reassessment of the morphology, phylogenetic value and hypotheses of homology of these structures. RESULTS: Hemispermatophores, pre- and post-insemination spermatophores, as well as the inherent mechanisms of insemination, were studied across the whole order, allowing the recognition and description of a series of five basic bauplans for the capsular region. For the most part, these patterns appear to be consistent within each major taxonomic group, but several cases of incongruence between spermatophore morphology and taxonomy raises questions about the monophyly of some clades. The Bothriuridae are traditionally regarded as a basal scorpionoid family. However, except for the genus Lisposoma, bothriurid hemispermatophores and spermatophores are morphologically more similar to those of the Chactoidea than to those of scorpionoids. On the other hand, the male copulatory structures of the hormurid clade (Hormiops (Hormurus + Liocheles)) are more akin to those of Diplocentridae and Heteroscorpionidae than to those of other hormurids. CONCLUSIONS: Spermatophore capsular patterns appears to be congruent with a recent phylogeny of the order Scorpiones based on phylogenomic data that placed Bothriuridae outside of Scorpionoidea and Liocheles outside of Hormuridae, in contradicton with earlier phylogenetic reconstructions based on morphology. This raises questions about the potential use of functionally constrained traits to assess the reliability of contradicting phylogenetic hypotheses and emphasizes the need for a thorough reassessment of the scorpion phylogenetic relationships. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12983-017-0231-z) contains supplementary material, which is available to authorized users. |
format | Online Article Text |
id | pubmed-5699194 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2017 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-56991942017-12-01 The male sexual apparatus in the order Scorpiones (Arachnida): a comparative study of functional morphology as a tool to define hypotheses of homology Monod, Lionel Cauwet, Lucie González-Santillán, Edmundo Huber, Siegfried Front Zool Research BACKGROUND: Insemination in scorpions is carried out by means of a partly sclerotized structure, the spermatophore, which is composed of two separate halves, the hemispermatophores. In most genera these reproductive structures can be used to differentiate species. However, many taxa such as the genus Euscorpius and the family Diplocentridae lack the morphological diversity observed in the copulatory organs of many other arthropods, rendering them useless for species level taxonomy. Such structural stasis, however, suggests that hemispermatophores have evolved relatively slowly and may thus provide a stronger phylogenetic signal for recognizing supra-generic ranks than previously thought. Based on the postulate that the phenotypic stability observed in some groups is the consequence of functional constraint, the most comprehensive comparative study of the male sexual apparatus to date was conducted for a complete reassessment of the morphology, phylogenetic value and hypotheses of homology of these structures. RESULTS: Hemispermatophores, pre- and post-insemination spermatophores, as well as the inherent mechanisms of insemination, were studied across the whole order, allowing the recognition and description of a series of five basic bauplans for the capsular region. For the most part, these patterns appear to be consistent within each major taxonomic group, but several cases of incongruence between spermatophore morphology and taxonomy raises questions about the monophyly of some clades. The Bothriuridae are traditionally regarded as a basal scorpionoid family. However, except for the genus Lisposoma, bothriurid hemispermatophores and spermatophores are morphologically more similar to those of the Chactoidea than to those of scorpionoids. On the other hand, the male copulatory structures of the hormurid clade (Hormiops (Hormurus + Liocheles)) are more akin to those of Diplocentridae and Heteroscorpionidae than to those of other hormurids. CONCLUSIONS: Spermatophore capsular patterns appears to be congruent with a recent phylogeny of the order Scorpiones based on phylogenomic data that placed Bothriuridae outside of Scorpionoidea and Liocheles outside of Hormuridae, in contradicton with earlier phylogenetic reconstructions based on morphology. This raises questions about the potential use of functionally constrained traits to assess the reliability of contradicting phylogenetic hypotheses and emphasizes the need for a thorough reassessment of the scorpion phylogenetic relationships. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12983-017-0231-z) contains supplementary material, which is available to authorized users. BioMed Central 2017-11-22 /pmc/articles/PMC5699194/ /pubmed/29201131 http://dx.doi.org/10.1186/s12983-017-0231-z 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 Monod, Lionel Cauwet, Lucie González-Santillán, Edmundo Huber, Siegfried The male sexual apparatus in the order Scorpiones (Arachnida): a comparative study of functional morphology as a tool to define hypotheses of homology |
title | The male sexual apparatus in the order Scorpiones (Arachnida): a comparative study of functional morphology as a tool to define hypotheses of homology |
title_full | The male sexual apparatus in the order Scorpiones (Arachnida): a comparative study of functional morphology as a tool to define hypotheses of homology |
title_fullStr | The male sexual apparatus in the order Scorpiones (Arachnida): a comparative study of functional morphology as a tool to define hypotheses of homology |
title_full_unstemmed | The male sexual apparatus in the order Scorpiones (Arachnida): a comparative study of functional morphology as a tool to define hypotheses of homology |
title_short | The male sexual apparatus in the order Scorpiones (Arachnida): a comparative study of functional morphology as a tool to define hypotheses of homology |
title_sort | male sexual apparatus in the order scorpiones (arachnida): a comparative study of functional morphology as a tool to define hypotheses of homology |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5699194/ https://www.ncbi.nlm.nih.gov/pubmed/29201131 http://dx.doi.org/10.1186/s12983-017-0231-z |
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