The descent of damselflies and variation in relation to sex

Research output: ThesisDoctoral Thesis (compilation)

Abstract

Sexual conflict over mating shapes the interactions between males and females in many animals and is also responsible for dramatic adaptations in both sexes. In some species of pond damselflies (Odonata:Coeangrionidae), sexual conflict maintains discrete female-limited colour morphs over multiple generations and within populations. One of the female morphs is typically male-coloured and considered a male mimic. This is because their male-like appearance provides a frequency-dependent advantage against excessive male mating attempts. In this thesis, I investigate three major questions regarding the evolutionary consequences of this pervasive sexual conflict. First, how is phenotypic variation in ecological traits distributed among heritable female colour morphs? Second, how does sexual conflict shape phenotypic variation within the lifespan of females? Finally, how, where and why do female-limited morphs arise in the first place?
In the Common Bluetail damselfly (Ischnura elegans), female morphs differ in multiple phenotypic traits. My results uncover further phenotypic associations between the two most common morphs of the Common Bluetail in Sweden. One morph is more resistant to infections by parasitic mites, whereas the other is instead more tolerant. These morphs also differ in their developmental sensitivity to temperature, which in turn influences how morph frequencies are distributed across European populations. Moreover, my findings provide some insights as to how these profound phenotypic differences are produced over the course of adult development, and suggest that male mimics and non-mimics differ in the regulation of important developmental processes.
Females of the Common Bluetail undergo dramatic colour changes as they become sexually mature. My thesis shows that immature colour patterns in non-mimic female morphs reduce male pre-mating harassment, and may have evolved by co-opting male colour signals to be expressed as immature signals of reproductive unsuitability. These results suggest that female colour patterns might be highly evolutionarily labile. Yet, a large-scale phylogenetic framework is required to gain a full understanding of the macroevolutionary consequences of sexual conflict on the evolution of female-limited colour variation.
I inferred a multi-locus phylogeny for the damselfly superfamily Coeangrionoidea. I then used this phylogeny to show that female-limited colour polymorphisms have arisen repeatedly in this clade, and in association with ecological conditions that foster sexual conflict over mating. Finally, my results uncover a stark contrast between the consequences of sexual conflict at micro and macroevolutionary scales. While sexual conflict promotes diversity within populations by maintaining alternative female morphs, the presence of these morphs is also associated with increased extinction risk and a fast lineage turnover. Together, my results reveal how sexual conflict can influence the origin, distribution and loss of diversity.

Details

Authors
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Evolutionary Biology
  • Ecology

Keywords

  • sexual conflict, development, diversification, pleiotropy, correlational selection, damselfly
Original languageEnglish
QualificationDoctor
Awarding Institution
Supervisors/Assistant supervisor
Award date2018 Oct 12
Place of PublicationLund
Publisher
  • Lund University, Faculty of Science, Department of Biology
Print ISBNs978-91-7753-818-9
Electronic ISBNs978-91-7753-819-6
Publication statusPublished - 2018 Sep
Publication categoryResearch

Bibliographic note

Defence details Date: 2018-10-12 Time: 09:30 Place: The Blue Hall, the Ecology Building, Sölvegatan 37, Lund External reviewer(s) Name: Monteiro, Antónia Title: Professor Affiliation: National University of Singapore and Yale-NUS College, Singapore ---

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