User:Ishabansal20/Blue-tailed damselfly

Female Polymorphisms

Male mate harassment

This article specifically expands on the idea of male harassment that was mentioned in the first article and will give a good background on why this occurs and the mechanisms that have been used to counter it.

Evolution of polymorphism

This article will help provide evidence of the evolution of female polymorphism in this species to reduce male mating harassment.

Further discusses impact of female behavior on female mating success and its relation to their polymorphism. Provides more information on the topic of polymorphism that is discussed in other articles.

Male-mate preference

Explores the different cues that males can use to detect females of the same morph as them specifically via odour and how it helps them differentiate between the morphs.

This is another article exploring male preferences in female polymorphism and different possibly hypotheses that can be used to contrast or compare the preferences stated in the other articles.

This article discusses the ways in which the androchrome morph of this species encounters less mating opportunities and the possible reasons for this occurring.

Sex reversibility

Sex reversibility and how it is dependent on social context and a possible consequence of the males ability to choose between female morphs.

Impact of environment on polymorphisms

This article expands on polymorphism but specifically looks at the affects of thermal plasticity in shaping the three main polymorphisms.

Discusses the adaptations developed in response to climatic environmental changes and their effects on phenotypes. Goes along with discussions from the paper on thermal plasticity.

Dispersal rates of different female morphs and males depending on the demands of their environment and associated phenotypic changes.

Female Polymorphism

In damselfly populations, there is often a surplus of males displaying male mate harassment. In order to avoid unwanted mating attempts, females have developed polymorphisms that allow some of them to avoid recognition by males by mimicking male phenotypes. There are three specific morphs found in the Ischnura elegans species: androchromes, aurantiaca and infuscans. The androchromes resemble the male coloration, and the gynochromes, which can be either aurantiaca or infuscan, do not resemble males. The aurantiaca female morph is a pink-orange color with a blue abdominal patch that eventually disappears after maturation. The third morph, infuscan, displays an olive-green coloration with no color on its abdominal patch. Females are able to fully mature into their differing morph colorations just a few days after they finish their transition from aquatic larvae to their mature forms.

Although having an increased number of morphs makes it more difficult for males to distinguish between males from females, the levels of male mate harassment is different between the different morphs. Males primarily rely on visual cues to distinguish between the morphs and can also use odour cues, secondarily. Androchromes are often seen to face less male mate harassment because they resemble males and are less desired. This gives androchromes an advantage in that they are able to spend more time allowing their eggs to mature instead of exerting energy avoiding unwanted mating attempts. Along with that, the morphs also display different mate avoidance tactics. Androchromes are more likely to face off with males by spreading their wings and curling their abdomens while gynochromes tend to fly away to avoid mating. Despite potentially having more time for egg maturation, the androchromes are still disadvantaged because their abdomens, like males, are more narrow which prevents them from being able to carry as many eggs as gynochromes.

There are also five main hypotheses that attempt to understand how the different female polymorphisms are continually maintained in this species. The reproductive isolation hypothesis states that there is a greater predation pressure on androchromes, which is seen as a trade-off to maintain the more inconspicuous morph. The male-mimicry hypothesis, mentioned previously, proposes that the androchromes ability to mimic male coloration allows them to avoid unwanted mating attempts and allocate more time to egg maturation. The density-dependent hypothesis states that the maintenance of the polymorphisms is attributed to the changing population densities. The habituation hypothesis states that males are actually most attracted to the morph that is most abundant. Lastly, the neutral hypothesis proposes that the female morphs are maintained by genetic drift, mutations, and founders effect all working together as well as that they might be more neutral to selection.

Mating and Behavior

The I. elegans species of damselflies participate in a male scramble mate choice mating system in which a males mating success is determined by how fast they are able to find a mate. This includes many hours of copulations in which males are unable to monopolize a single female and some males are often left with no mates at all. Due to this, the I. elegans species displays intense male-male competition which leads to males forcing copulations with females. Along with the lengthy copulations, the reproductive lifespan of this species is only a few weeks. Cooperation from both males and females is required for copulation and females have the ability to reject sperm transfer from unwanted mating attempts. A tandem formation is created by males through the clasping of the female pronotum.

I. elegans have the ability to rapidly adapt to their environments which puts them under heavy selective pressures. As this species has originated from tropical environments, their hatching times are often shorter in warmer temperatures than cooler temperatures. Females are also more likely to spend time near bodies of water as that is where they lay their eggs. In response to changing social contexts and population densities, males may change their sexual preferences and choose to mate with other males.