Sexual Conflict in Water Striders, Dragonflies and Diving Beetles

AbstractSexual conflict may result in the escalating coevolution of sexually antagonistic traits. However, our understanding of the evolutionary dynamics of antagonistic traits and their role in association with sex-specific escalation remains limited. Here we study sexually antagonistic coevolution in a genus of water striders called Rhagovelia. We identified a set of male grasping traits and female anti-grasping traits used during pre-mating struggles and show that natural variation of these traits is associated with variation in mating performance in the direction expected for antagonistic co-evolution. Phylogenetic mapping detected signals of escalation of these sexually antagonistic traits suggesting an ongoing arms race. Moreover, their escalation appears to be constrained by a trade-off with dispersal through flight in both sexes. Altogether our results highlight how sexual interactions may have shaped sex-specific antagonistic traits and how constraints imposed by natural selection may have influenced their evolution.

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Sexual conflict in its ecological setting

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2017.0418 ◽

2018 ◽

Vol 373 (1757) ◽

pp. 20170418 ◽

Cited By ~ 19

Author(s):

Jennifer C. Perry ◽

Locke Rowe

Keyword(s):

Sex Differences ◽

Local Adaptation ◽

Sexual Conflict ◽

Ecological Factors ◽

Ecological Context ◽

Theme Issue ◽

Antagonistic Coevolution ◽

Water Striders ◽

Sexually Antagonistic Coevolution ◽

Gaining Insight

Sexual conflict can lead to rapid and continuous coevolution between females and males, without any inputs from varying ecology. Yet both the degree of conflict and selection on antagonistic traits are known to be sensitive to local ecological conditions. This leads to the longstanding question: to what extent does variation in ecological context drive sexually antagonistic coevolution? In water striders, there is much information about the impacts of ecological factors on conflict, and about patterns of antagonistic coevolution. However, the connection between the two is poorly understood. Here, we first review the multiple ways in which ecological context might affect the coevolutionary trajectory of the sexes. We then review ecological and coevolutionary patterns in water striders, and connections between them, in light of theory and new data. Our analysis suggests that ecological variation does impact observed patterns of antagonistic coevolution, but highlights significant uncertainty due to the multiple pathways by which ecological factors can influence conflict and its evolutionary outcome. To the extent that water striders are a reasonable reflection of other systems, this observation serves as both an opportunity and a warning: there is much to learn, but gaining insight may be a daunting process in many systems. This article is part of the theme issue ‘Linking local adaptation with the evolution of sex differences'.

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Population structure influences sexual conflict in wild populations of water striders

Behaviour ◽

10.1163/000579510x510520 ◽

2010 ◽

Vol 147 (12) ◽

pp. 1615-1631 ◽

Cited By ~ 9

Author(s):

David Sloan Wilson ◽

John Pepper ◽

Michael Dlugos ◽

Omar Tonsi Eldakar ◽

Galen Holt

Keyword(s):

Population Structure ◽

Sexual Conflict ◽

Wild Populations ◽

Water Striders

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Hox genes mediate the escalation of sexually antagonistic traits in water striders

Biology Letters ◽

10.1098/rsbl.2018.0720 ◽

2019 ◽

Vol 15 (2) ◽

pp. 20180720 ◽

Cited By ~ 2

Author(s):

Antonin Jean Johan Crumière ◽

Abderrahman Khila

Keyword(s):

Sexual Conflict ◽

Hox Genes ◽

Complete Loss ◽

Water Strider ◽

Fitness Costs ◽

Sex Combs Reduced ◽

Hox Gene ◽

Water Striders ◽

Sex Combs ◽

Sex Comb

Sexual conflict occurs when traits favoured in one sex impose fitness costs on the other sex. In the case of sexual conflict over mating rate, the sexes often undergo antagonistic coevolution and escalation of traits that enhance females' resistance to superfluous mating and traits that increase males' persistence. How this escalation in sexually antagonistic traits is established during ontogeny remains unclear. In the water strider Rhagovelia antilleana, male persistence traits consist of sex combs on the forelegs and multiple rows of spines and a thick femur in the rear legs. Female resistance traits consist of a prominent spike-like projection of the pronotum. RNAi knockdown against the Hox gene Sex Combs Reduced resulted in the reduction in both the sex comb in males and the pronotum projection in females. RNAi against the Hox gene Ultrabithorax resulted in the complete loss or reduction of all persistence traits in male rear legs. These results demonstrate that Hox genes can be involved in intra- and inter-locus sexual conflict and mediate escalation of sexually antagonistic traits.

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Male clasping ability, female polymorphism and sexual conflict: fine-scale elytral morphology as a sexually antagonistic adaptation in female diving beetles

Journal of The Royal Society Interface ◽

10.1098/rsif.2013.0409 ◽

2013 ◽

Vol 10 (86) ◽

pp. 20130409 ◽

Cited By ~ 33

Author(s):

Kristina Karlsson Green ◽

Alexander Kovalev ◽

Erik I. Svensson ◽

Stanislav N. Gorb

Keyword(s):

Sexual Conflict ◽

Adhesive Force ◽

Beetle Species ◽

Female Polymorphism ◽

Diving Beetles ◽

Males And Females ◽

Suction Cups ◽

Female Morph ◽

Diving Beetle ◽

Sexually Antagonistic Coevolution

During sexual conflict, males and females are expected to evolve traits and behaviours with a sexually antagonistic function. Recently, sexually antagonistic coevolution was proposed to occur between male and female diving beetles (Dytiscidae). Male diving beetles possess numerous suction cups on their forelegs whereas females commonly have rough structures on their elytra. These rough structures have been suggested to obstruct adhesion from male suction cups during mating attempts. However, some diving beetle species are dimorphic, where one female morph has a rough elytra and the other has a smooth elytra. Here, we used biomechanics to study the adhesive performance of male suction cups on the female morphs in two diving beetle species: Dytiscus lapponicus and Graphoderus zonatus . We compared adhesion on the rough and the smooth female morphs to infer the function of the rough elytral modifications. We found that the adhesive force on the rough structures was much lower than on other surfaces. These findings support the suggestion of sexual conflict in diving beetles and a sexually antagonistic function of the rough female structures. In addition, males differed in their adhesive capacity on different female surfaces, indicating a male trade-off between adhering to smooth and rough female morphs.

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Observed shifts in the contact zone between two forms of the diving beetleHydroporus memnoniusare consistent with predictions from sexual conflict

PeerJ ◽

10.7717/peerj.2089 ◽

2016 ◽

Vol 4 ◽

pp. e2089 ◽

Cited By ~ 3

Author(s):

David T. Bilton ◽

Garth N. Foster

Keyword(s):

Contact Zone ◽

Sexual Conflict ◽

Climatic Warming ◽

Population Replacement ◽

Trade Offs ◽

Diving Beetles ◽

Using Data ◽

Cuticular Surface ◽

Diving Beetle ◽

Sexually Antagonistic Coevolution

Sexual conflict drives both inter- and intrasexual dimorphisms in many diving beetles, where male persistence and female resistance traits co-evolve in an antagonistic manner. To date most studies have focussed on species where rough and smooth females and their associated males typically co-occur within populations, where phenotype matching between morphs may maintain forms as stable polymorphisms. The Palaearctic diving beetleHydroporus memnoniusis characterised by having dimorphic (rough var.castaneusand smooth, shining) females and associated males which differ in persistence traits; the two forms being largely distributed parapatrically. In this species, instead of mating trade-offs between morphs, males associated withcastaneusfemales should have a mating advantage with both this form and shining females, due to their increased persistence abilities on either cuticular surface. This may be expected to lead to the replacement of the shining form withcastaneusin areas where the two come into contact. Using data collected over a thirty year period, we show that this process of population replacement is indeed occurring,castaneushaving expanded significantly at the expense of the shining female form. Whilst populations of both forms close to the contact zone appear to differ in their thermal physiology, these differences are minor and suggest that the expansion ofcastaneusis not linked to climatic warming in recent decades. Instead we argue that the observed spread ofcastaneusand its associated male may result from the dynamics of sexually antagonistic coevolution in this beetle.

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