Female common bluetail damselfly4/8/2023 ![]() Therefore, although the main mechanism is male competition, it was impossible to measure the relative importance of each of these behaviors individually. The experimental design did not allow us to completely tease apart the influences of competition between males and female choosiness. Life’s hard for a female bluetail damselfly, especially when they have males like this one constantly harassing them with mating attempts (Image Credit: Joy-of-Nature, CC BY-SA 4.0) Problems Together, our results show evidence that adaptation to parasites has evolved due to sexual selection. And the effect of parasites in fecundity has also changed, showing that individuals with parasites are not as strongly affected as before, which is evidence of parasite tolerance. Therefore, resistance to being parasitized has increased. Therefore, there is sexual selection and it seems to be caused by competition between males.Īcross the 15 years of data, the number of parasites has not changed, but the number of damselflies with parasites has decreased. These results suggest that males with parasites have less energy and cannot compete with healthy males for access to females. ![]() The experiments show that competition between males was the main driver of sexual selection. Interestingly, there was not an effect of parasites on fecundity. What They Foundīeing parasitized reduced mating success of both sexes, but it had a stronger effect on males (being parasitized was more detrimental to mating for males than females). Male damselflies also scrape out the sperm from previous matings, just to make doubly-sure that they are the ones who father the offspring the female lays. Males on the other hand have to ensure that they are the ones to fertilize the eggs that are laid, so they increase their fitness by mating as much as possible. ![]() Any egg that a female lays is hers, so they all increases her fitness. Females increases fitness by laying more eggs/having more offspring. Males and females from species that reproduce sexually both increases their fitness by passing their genes on to the next generation, but they do it in different ways. males with parasites mated more and females with parasites laid more eggs), it would be evidence for local adaptation. If the host is progressively less affected by the parasite over time (e.g. This allowed us to identify if sexual selection was driven mainly by females choosing males or by the males competing for females.įinally, we estimated how the parasite affected male and female fitness over the 15 year study. Then, we conducted competition experiments in which we paired females with either a single male (parasitized or non-parasitized) or two males (one with parasites, one without). if you’re a damselfly that tends to have more parasites, does that affect how often you mate?) Doing this allowed us to relate mating success to parasite load (e.g. This involved using data from 15 years of mating and parasitism data for the common bluetail damselfly ( Ischnura elegans). We used a long-term monitored population to quantify how parasites affected mating success and female fecundity in a damselfly. We were interested in the strength of selection by parasites and if there was subsequent adaptation by the host in a wild population. Our study looked at adaptation to one of nature’s ubiquitous pressures: parasitism. Sexual selection is thought to promote rapid adaptation to such environmental changes, but most of the evidence comes from laboratory studies. Due to this pressure, one of the biggest questions for conservation biology is if species are able to adapt fast enough to keep up with environmental changes. These changes mean that organisms are under a constant pressure to adapt to local conditions. The natural world changes constantly: temperatures fluctuate, predators and parasites enter into the ecosystem, and the landscape itself could change (looking at you, Yellowstone). Male-Male Competition Causes Parasite-Mediated Sexual Selection for Local Adaptation (2020) Gómez-Llano et al., The American Naturalist, h ttps://doi.org/10.5061/dryad.cjsxksn35 The Crux Guest post by Miguel Gómez-Llano (Image Credit: Sharp Photography, CC BY-SA, Image Cropped)
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