Rival seminal fluid induces enhanced sperm motility in a polyandrous ant

Abstract Background Promiscuous mating and sperm competition often induce arms races between the sexes with detrimental outcomes for females. However, ants with multiply-inseminated queens have only a single time-window for sperm competition and queens are predicted to gain control over the outcome...

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Main Authors: Joanito Liberti, Boris Baer, Jacobus J. Boomsma
Format: Article
Language:English
Published: BMC 2018-03-01
Series:BMC Evolutionary Biology
Subjects:
Online Access:http://link.springer.com/article/10.1186/s12862-018-1144-y
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author Joanito Liberti
Boris Baer
Jacobus J. Boomsma
author_facet Joanito Liberti
Boris Baer
Jacobus J. Boomsma
author_sort Joanito Liberti
collection DOAJ
description Abstract Background Promiscuous mating and sperm competition often induce arms races between the sexes with detrimental outcomes for females. However, ants with multiply-inseminated queens have only a single time-window for sperm competition and queens are predicted to gain control over the outcome of sperm storage quickly. The seminal fluid of Acromyrmex leaf-cutting ants reduces the viability of rival sperm, but how confrontations between unrelated ejaculates affect sperm storage remains unknown. Results We investigated the effects of ejaculate admixture on sperm motility in A. echinatior and found that the proportion of motile spermatozoa, sperm swimming speed, and linearity of sperm movement increased when rival ejaculates were mixed in vitro. Major effects induced by the seminal fluid of rival males were of similar magnitude to those generated by queen reproductive tract secretions, whereas own seminal fluid induced lower sperm activation levels. Conclusions Our results suggest that ant sperm respond via a self–non-self recognition mechanism to similar or shared molecules expressed in the reproductive secretions of both sexes. Lower sperm motility in the presence of own seminal fluid indicates that enhanced motility is costly and may trade-off with sperm viability during sperm storage, consistent with studies in vertebrates. Our results imply that ant spermatozoa have evolved to adjust their energetic expenditure during insemination depending on the perceived level of sperm competition.
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spelling doaj.art-68aebc51693a4322b751aa6128a151182022-12-21T18:25:56ZengBMCBMC Evolutionary Biology1471-21482018-03-0118111210.1186/s12862-018-1144-yRival seminal fluid induces enhanced sperm motility in a polyandrous antJoanito Liberti0Boris Baer1Jacobus J. Boomsma2Centre for Social Evolution, Department of Biology, University of CopenhagenCentre for Integrative Bee Research (CIBER), Department of Entomology, University of California RiversideCentre for Social Evolution, Department of Biology, University of CopenhagenAbstract Background Promiscuous mating and sperm competition often induce arms races between the sexes with detrimental outcomes for females. However, ants with multiply-inseminated queens have only a single time-window for sperm competition and queens are predicted to gain control over the outcome of sperm storage quickly. The seminal fluid of Acromyrmex leaf-cutting ants reduces the viability of rival sperm, but how confrontations between unrelated ejaculates affect sperm storage remains unknown. Results We investigated the effects of ejaculate admixture on sperm motility in A. echinatior and found that the proportion of motile spermatozoa, sperm swimming speed, and linearity of sperm movement increased when rival ejaculates were mixed in vitro. Major effects induced by the seminal fluid of rival males were of similar magnitude to those generated by queen reproductive tract secretions, whereas own seminal fluid induced lower sperm activation levels. Conclusions Our results suggest that ant sperm respond via a self–non-self recognition mechanism to similar or shared molecules expressed in the reproductive secretions of both sexes. Lower sperm motility in the presence of own seminal fluid indicates that enhanced motility is costly and may trade-off with sperm viability during sperm storage, consistent with studies in vertebrates. Our results imply that ant spermatozoa have evolved to adjust their energetic expenditure during insemination depending on the perceived level of sperm competition.http://link.springer.com/article/10.1186/s12862-018-1144-ySocial insectsSexual selectionSperm competitionSperm motilitySexual conflicts
spellingShingle Joanito Liberti
Boris Baer
Jacobus J. Boomsma
Rival seminal fluid induces enhanced sperm motility in a polyandrous ant
BMC Evolutionary Biology
Social insects
Sexual selection
Sperm competition
Sperm motility
Sexual conflicts
title Rival seminal fluid induces enhanced sperm motility in a polyandrous ant
title_full Rival seminal fluid induces enhanced sperm motility in a polyandrous ant
title_fullStr Rival seminal fluid induces enhanced sperm motility in a polyandrous ant
title_full_unstemmed Rival seminal fluid induces enhanced sperm motility in a polyandrous ant
title_short Rival seminal fluid induces enhanced sperm motility in a polyandrous ant
title_sort rival seminal fluid induces enhanced sperm motility in a polyandrous ant
topic Social insects
Sexual selection
Sperm competition
Sperm motility
Sexual conflicts
url http://link.springer.com/article/10.1186/s12862-018-1144-y
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AT borisbaer rivalseminalfluidinducesenhancedspermmotilityinapolyandrousant
AT jacobusjboomsma rivalseminalfluidinducesenhancedspermmotilityinapolyandrousant