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Role of Natural and Sexual Selection in the Evolution of a Sexual Trait in an Old Insect Order

Tschol, Maximilian (2018) BIOP01 20162
Degree Projects in Biology
Abstract
Wing pigmentation in dragonflies and damselflies (odonates) functions as a secondary sexual trait with a role in courtship and antagonistic male-male interactions. Recently, a thermoregulatory function of wing pigmentation has also been suggested. This study aimed to elucidate how both sexual and natural selection have influenced the evolution and global distribution of wing pigmentation in odonates. I examined the role of wing patch colour in intra- and inter-sexual selection in the banded demoiselle (Calopteryx splendens) utilizing manipulation experiments. While no clear effect of wing patch colour on female preference was found, male C. splendens showed reduced aggression towards males with red manipulated wing patches, suggesting that... (More)
Wing pigmentation in dragonflies and damselflies (odonates) functions as a secondary sexual trait with a role in courtship and antagonistic male-male interactions. Recently, a thermoregulatory function of wing pigmentation has also been suggested. This study aimed to elucidate how both sexual and natural selection have influenced the evolution and global distribution of wing pigmentation in odonates. I examined the role of wing patch colour in intra- and inter-sexual selection in the banded demoiselle (Calopteryx splendens) utilizing manipulation experiments. While no clear effect of wing patch colour on female preference was found, male C. splendens showed reduced aggression towards males with red manipulated wing patches, suggesting that colour mediates information that is used in territorial male conflicts. Additionally, I reconstructed the evolutionary history of this sexual trait and tested for a macroevolutionary association between latitude zone and wing pigmentation, with the expectation that thermoregulatory benefits promote wing pigmentation in temperate regions. I found wing pigmentation evolved several times in multiple lineages of dragonflies and damselflies and a high number of secondary trait loss is in agreement with the view that this sexual trait is costly. Pigmented species were found to be more prevalent in the tropics and evolutionary rates of wing pigment loss were higher in the temperate region. Together, my results do not support the view that a thermoregulatory benefit at temperate regions has promoted the emergence and maintenance of this trait. Instead, other unknown selective pressures in the tropical regions may have shaped the evolutionary trajectory of wing pigmentation. There may be a more important role of this visually appealing sexual signal in intra-and inter-specific interactions in the tropics compared to the temperate regions. (Less)
Popular Abstract
Evolution of a Sexual Signal in Dragonflies and Damselflies

Animals often use visual signals to choose mates or communicate fighting ability between rivals. Some dragonfly and damselfly species exhibit colourful pigmentation patterns on their wings which females use as a cue while selecting a mate and males to determine if they want to get into a fight with another competing male. I conducted field experiments to learn more about the role of wing pigmentation in one species of damselfly (Calopteryx splendens) and additionally used phylogenetic comparative methods to look at the evolution of this sexual signal across many dragonfly and damselfly species.

To better understand how abiotic and biotic factors contribute to the diversity... (More)
Evolution of a Sexual Signal in Dragonflies and Damselflies

Animals often use visual signals to choose mates or communicate fighting ability between rivals. Some dragonfly and damselfly species exhibit colourful pigmentation patterns on their wings which females use as a cue while selecting a mate and males to determine if they want to get into a fight with another competing male. I conducted field experiments to learn more about the role of wing pigmentation in one species of damselfly (Calopteryx splendens) and additionally used phylogenetic comparative methods to look at the evolution of this sexual signal across many dragonfly and damselfly species.

To better understand how abiotic and biotic factors contribute to the diversity of life, we often select specific traits that we study more closely. One prominent biotic factor is the interaction between the sexes. Some traits that are important in this interaction function as sexual signals, like in the case of wing pigmentation in dragonflies and damselflies. I conducted two field experiments where I manipulated the wing patch colour of male C. splendens and recorded the reactions of either free ranging females or resident territorial males. It turns out, while females did not prefer or discriminate more between different colours, resident males showed less aggression towards individuals with red coloured wings. This suggests a possible role of the wing patch in signalling information towards other competing males.

In an evolutionary perspective, this signalling role might get lost over time because of other forces acting against it. So could potentially increased predation on individuals with wing pigmentation lead to the loss of the trait in the whole species and its ancestors. In my between species phylogenetic comparative study I found a pattern that fits this prediction. Wing pigmentation evolved several times in different lineages of dragonflies and damselflies, and was subsequently lost three times more often. Interestingly, my analyses also indicate a difference in the evolutionary history of wing pigmentation between tropical and temperate species, possibly indicating different selective pressures acting on this trait in both regions. This will have to be investigated more closely in the future!

Master’s Degree Project in Biology 60 credits 2018
Department of Biology, Lund
Advisor: Erik Svensson
Evolutionary ecology/ Department of Biology (Less)
Please use this url to cite or link to this publication:
author
Tschol, Maximilian
supervisor
organization
course
BIOP01 20162
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
8937971
date added to LUP
2018-03-23 14:30:43
date last changed
2018-03-23 14:30:43
@misc{8937971,
  abstract     = {Wing pigmentation in dragonflies and damselflies (odonates) functions as a secondary sexual trait with a role in courtship and antagonistic male-male interactions. Recently, a thermoregulatory function of wing pigmentation has also been suggested. This study aimed to elucidate how both sexual and natural selection have influenced the evolution and global distribution of wing pigmentation in odonates. I examined the role of wing patch colour in intra- and inter-sexual selection in the banded demoiselle (Calopteryx splendens) utilizing manipulation experiments. While no clear effect of wing patch colour on female preference was found, male C. splendens showed reduced aggression towards males with red manipulated wing patches, suggesting that colour mediates information that is used in territorial male conflicts. Additionally, I reconstructed the evolutionary history of this sexual trait and tested for a macroevolutionary association between latitude zone and wing pigmentation, with the expectation that thermoregulatory benefits promote wing pigmentation in temperate regions. I found wing pigmentation evolved several times in multiple lineages of dragonflies and damselflies and a high number of secondary trait loss is in agreement with the view that this sexual trait is costly. Pigmented species were found to be more prevalent in the tropics and evolutionary rates of wing pigment loss were higher in the temperate region. Together, my results do not support the view that a thermoregulatory benefit at temperate regions has promoted the emergence and maintenance of this trait. Instead, other unknown selective pressures in the tropical regions may have shaped the evolutionary trajectory of wing pigmentation. There may be a more important role of this visually appealing sexual signal in intra-and inter-specific interactions in the tropics compared to the temperate regions.},
  author       = {Tschol, Maximilian},
  language     = {eng},
  note         = {Student Paper},
  title        = {Role of Natural and Sexual Selection in the Evolution of a Sexual Trait in an Old Insect Order},
  year         = {2018},
}