How do guppies have sex

Males vary in the degree to which they invest in mating. Particularly, female quality affects male reproductive success. Here, we studied whether male guppies Poecilia reticulata strategically allocated more mating effort, in terms of mating behaviour and male—male competition, when they were matched with a receptive R female than a non-receptive one. In accordance with our prediction, we found that males increased their mating behaviour when they were with a receptive female.

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Male guppies ensure successful mating with genital claws | EurekAlert! Science News

TORONTO, ON - Some males will go to great lengths to pursue a female and take extreme measures to hold on once they find one that interests them, even if that affection is unrequited. New research from evolutionary biologists at the University of Toronto shows that the male guppy grows claws on its genitals to make it more difficult for unreceptive females to get away during mating. Genitalia differ greatly in animal groups, even among similar species - so much so that even closely related species may have very different genitalia. The reasons for these differences are unclear but sexual conflict between males and females may be a source. Sexual conflict occurs when the fitness interests of males and females differ, which is rooted in differences in egg and sperm sizes.
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Mating effort and female receptivity: how do male guppies decide when to invest in sex?

February 14, Male guppies pay a high cost for their sexual harassment of female guppies — including much higher mortality rates — a new study from Macquarie University has found. Sexual harassment in guppies, or unwanted male attention, is a product of males attempting to mate as many times as possible due to the low energy cost of sperm production.
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Sex chromosomes regularly evolve suppressed recombination, distinguishing them from other chromosomes, and the reason for this has been debated for many years. It is now clear that non-recombining sex-linked regions have arisen in different ways in different organisms. A major hypothesis is that a sex-determining gene arises on a chromosome and that sexually antagonistic SA selection sometimes called intra-locus sexual conflict acting at a linked gene has led to the evolution of recombination suppression in the region, to reduce the frequency of low fitness recombinant genotypes produced. The sex chromosome system of the guppy Poecilia reticulata is often cited as supporting this hypothesis because SA selection has been demonstrated to act on male coloration in natural populations of this fish, and probably contributes to maintaining polymorphisms for the genetic factors involved. I review classical genetic and new molecular genetic results from the guppy, and other fish, including approaches for identifying the genome regions carrying sex-determining loci, and suggest that the guppy may exemplify a recently proposed route to sex chromosome evolution.
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25.01.2020 by Mezijin:

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