Sexual selection gradients change over time in a simultaneous hermaphrodite

Autor: Joris M. Koene, Janine Mariën, Jacintha Ellers, Jeroen N.A. Hoffer
Přispěvatelé: Animal Ecology
Rok vydání: 2017
Předmět:
Zdroj: eLife, Vol 6 (2017)
Hoffer, J N, Mariën, J, Ellers, J & Koene, J M 2017, ' Sexual selection gradients change over time in a simultaneous hermaphrodite ', eLife, vol. 6, e25139 . https://doi.org/10.7554/eLife.25139
eLife
eLife, 6:e25139. eLife Sciences Publications
ISSN: 2050-084X
DOI: 10.7554/elife.25139
Popis: Sexual selection is generally predicted to act more strongly on males than on females. The Darwin-Bateman paradigm predicts that this should also hold for hermaphrodites. However, measuring this strength of selection is less straightforward when both sexual functions are performed throughout the organism’s lifetime. Besides, quantifications of sexual selection are usually done during a short time window, while many animals store sperm and are long-lived. To explore whether the chosen time frame affects estimated measures of sexual selection, we recorded mating success and reproductive success over time, using a simultaneous hermaphrodite. Our results show that male sexual selection gradients are consistently positive. However, an individual’s female mating success seems to negatively affect its own male reproductive success, an effect that only becomes visible several weeks into the experiment, highlighting that the time frame is crucial for the quantification and interpretation of sexual selection measures, an insight that applies to any iteroparous mating system. DOI: http://dx.doi.org/10.7554/eLife.25139.001
eLife digest Many factors affect an organism’s ability to survive and reproduce. These factors are often called “selection pressures” and include the availability of food and shelter, conditions in the environment such as temperature, and the presence of diseases and predators. Males and females experience different selection pressures so they often evolve to look different – consider, for example, the male deer’s antlers and the peacock’s colourful tail feathers. Such traits arise from a phenomenon called sexual selection, the selection pressures that act on an organism’s ability to obtain a mate. Measuring sexual selection is not only of interest to scientists looking to understand how evolutionary processes work; it also has wider applications, including in wildlife conservation. For instance, knowing which cues are important for successful reproduction could help efforts to breed endangered animals in captivity and stop them from going extinct. Scientists study sexual selection in a species by measuring how successful males and females are at mating and reproducing. Past studies have found that a female’s reproductive success mainly depends on there being enough resources available for her to produce eggs, while a male’s success depends on him getting access to these eggs. However, most research into sexual selection has been on species with separate sexes. It is more difficult to measure sexual selection in species – like snails and slugs – where each individual is male and female at the same time. As such, it is not clear if reproductive success in these species, which are known as simultaneous hermaphrodites, depends on the same factors as those species with separate sexes. To address this, Hoffer et al. measured sexual selection in the great pond snail Lymnaea stagnalis, a simultaneous hermaphrodite. Most studies estimate sexual selection based on measurements taken over several days. Instead, Hoffer et al. observed the great pond snail over a period of eight weeks, which is about a quarter of its reproductive life. The experiments showed that mating multiple times, especially with multiple partners, overall improves the development of the snail’s offspring. The male part of the great pond snail gains the most reproductive success from repeated mating, whereas the female part may in fact be negatively affected. These negative effects were only seen several weeks into the experiment, and so they show that sexual selection pressures change over time. Future research is needed to determine what causes the negative effects on the female part of the great pond snail. Overall, these findings stress the need for careful consideration of the time frame over which future measurements of sexual selection take place, not just in hermaphrodites, but in all species. DOI: http://dx.doi.org/10.7554/eLife.25139.002
Databáze: OpenAIRE
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