My research is focused on sexual selection and on the evolution of sexually selected traits. In particular, I’m interested in understanding how selection acts on pre- and postcopulatory traits, how genetic and phenotypic variability of populations is maintained despite strong selection pressures, and what is the interplay between individuals and environment (biotic and abiotic) in determining the final selection pattern.
Current projects in which I’m involved (in collaboration with John Fitzpatrick, Niclas Kolm and Alberto Corral López):
Genotype by Environment Interaction (GEI) and sperm competition
Ejaculates of different males often compete with those of other rivals, within or outside the female, to fertilize the same eggs. Not all ejaculates, however, are the same and the environmental condition that can favour one, could be not the best for another. Using different fish species my intent is to evaluate the role of biotic and abiotic environment on the outcome of sperm competition, possibly answering to the question of why, despite the final goal is fertilization, so much variability is observed in ejaculate traits.
Non Linear selection analysis and social environment
Selection, in nature, rarely operates on a single individual trait. More often selection takes in to account all the traits that form the individual. Those traits range from microscopically cell attributes to elaborate sexual behaviours. Selection, moreover, is not always directional and sometimes different trait combinations can lead to the same fitness success. Taking in to account what happens before and after the mate, the aim of this project is to describe in detail selection shape on a wide set of traits that describe individuals, placing them in different social environments. For this project I will use different fish species.
Cryptic female choice for genetic compatible partners
Once mated, females are able to strongly influence the outcome of sperm competition favouring some ejaculates over others. This ability can enable females to “chose again” the males and, importantly can help to avoid both inbreeding and outbreeding. The aim of this project is to understand the mechanism through which females are able to distinguish different male sperm and evaluate how much, and in which way, genetic similarity is involved. Do the choice after copulation reflect that done before mating? I use fish and mammal species to answer this question.
I urval från Stockholms universitets publikationsdatabas
Directional postcopulatory sexual selection is associated with female sperm storage in Trinidadian guppies.
2016. Alessandro Devigili (et al.). Evolution 70 (8)Artikel
Female sperm storage (FSS) is taxonomically widespread and often associated with intense sperm competition, yet its consequences on postcopulatory sexual selection (PCSS) are poorly known. Theory predicts that FSS will reduce the strength of PCSS, because sperm characteristics favored before and after FSS may be traded-off, and opportunities for nondirectional PCSS should increase. We explored these questions in the guppy (Poecilia reticulata), by allowing females to mate multiply and by comparing the paternity pattern in two successive broods. Contrary to predictions, the variance in male fertilization success increased after FSS, driven by a change in male paternity share across broods. This change was positively associated with sperm velocity (measured before FSS) but not with the duration of FSS, indirectly suggesting that faster sperm were better in entering female storage organs, rather than in persisting within them. Other male traits, such as male size and orange color, heterozygosity, and relatedness to the female, did not influence paternity after FSS. These results indicate that processes associated with FSS tend to reinforce the strength of PCSS in guppies, rather than weaken it. Further work is necessary to test whether this pattern changes in case of more prolonged FSS.
Multivariate selection drives concordant patterns of pre- and postcopulatory sexual selection in a livebearing fish.
2015. Alessandro Devigili (et al.). Nature Communications 6Artikel
In many species, females mate with multiple partners, meaning that sexual selection on male traits operates across a spectrum that encompasses the competition for mates (that is, before mating) and fertilizations (after mating). Despite being inextricably linked, pre- and postcopulatory sexual selection are typically studied independently, and we know almost nothing about how sexual selection operates across this divide. Here we bridge this knowledge gap using the livebearing fish Poecilia reticulata. We show that both selective episodes, as well as their covariance, explain a significant component of variance in male reproductive fitness. Moreover, linear and nonlinear selection simultaneously act on pre- and postcopulatory traits, and interact to generate multiple phenotypes with similar fitness.