Genetic Factors Influencing Sperm Competition.

Alberto Civetta,José M Ranz

doi:10.3389/fgene.2019.00820

Alberto Civetta, José M Ranz

Open Access

https://doi.org/10.3389/fgene.2019.00820

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Abstract

Females of many different species often mate with multiple males, creating opportunities for competition among their sperm. Although originally unappreciated, sperm competition is now considered a central form of post-copulatory male–male competition that biases fertilization. Assays of differences in sperm competitive ability between males, and interactions between females and males, have made it possible to infer some of the main mechanisms of sperm competition. Nevertheless, classical genetic approaches have encountered difficulties in identifying loci influencing sperm competitiveness while functional and comparative genomic methodologies, as well as genetic variant association studies, have uncovered some interesting candidate genes. We highlight how the systematic implementation of approaches that incorporate gene perturbation assays in experimental competitive settings, together with the monitoring of progeny output or sperm features and behavior, has allowed the identification of genes unambiguously linked to sperm competitiveness. The emerging portrait from 45 genes (33 from fruit flies, 8 from rodents, 2 from nematodes, and 2 from ants) is their remarkable breadth of biological roles exerted through males and females, the non-preponderance of sperm genes, and their overall pleiotropic nature.

Highlights

Sexual selection refers to the differential ability among the members of one sex to compete for access to mates or to choose mates (Darwin, 1871)
The polygenic nature underlying sperm competitive ability and vast non-additive genetic factors have complicated the identification of relevant genes, the necessary experimental methodologies have become increasingly available
Staggering evidence supports that the fertilization bias that results from post-copulatory male–male competition can be exerted by genes whose effects manifest through the males and through the females (Chen et al, 2019)

Summary

Introduction

Sexual selection refers to the differential ability among the members of one sex to compete for access to mates or to choose mates (Darwin, 1871). Not all the genes preferentially expressed in tissues such as the male accessory gland proteins and the female spermatheca show signatures of sexual antagonism (Innocenti and Morrow, 2010), and second, when some of those genes (e.g., Acp63F, Acp95EF, and Acp98A) are tested in SNPassociation studies in relation to sperm competitive phenotypes, no effect was found (Fiumera et al, 2007).

Results

Conclusion