An introduction to genetic quality in the context of sexual selection

Sexual selection theory predicts that males should be promiscuous to maximize their reproductive success, while females should be choosy. Yet females of many taxa often produce progeny sired by multiple males, indicating that promiscuity can be important for the reproductive success of females. Promiscuity may enhance the fitness of females if it increases the genetic quality, or the genetic variety, and thus the viability of their offspring. We quantified the number of sires per clutch in a population of Northern Map Turtles (Graptemys geographica (LeSueur, 1817)) in Lake Opinicon, Ontario, Canada, and tested whether the number of sires affects several metrics of viability in hatchlings. Based on the most conservative estimate, at least 71% of clutches in this population are sired by multiple males, but there was no evidence that larger clutches are sired by more males. Clutches sired by more males had higher hatching success and survival, but the differences were not statistically significant. We did not find any effect of the number of sires on hatchling morphology or locomotor performance. Collectively, our results partially support the hypothesis that promiscuity can increase the reproductive success of female Northern Map Turtles.

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Avian egg colour and sexual selection: does eggshell pigmentation reflect female condition and genetic quality?

Ecology Letters ◽

10.1046/j.1461-0248.2003.00505.x ◽

2003 ◽

Vol 6 (9) ◽

pp. 803-806 ◽

Cited By ~ 193

Author(s):

Juan Moreno ◽

Jose Luis Osorno

Keyword(s):

Sexual Selection ◽

Genetic Quality ◽

Female Condition ◽

Eggshell Pigmentation ◽

Egg Colour ◽

Avian Egg

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Offspring viability benefits but no apparent costs of mating with high quality males

Biology Letters ◽

10.1098/rsbl.2010.0976 ◽

2010 ◽

Vol 7 (3) ◽

pp. 419-421 ◽

Cited By ~ 25

Author(s):

Leigh W. Simmons ◽

Rebecca Holley

Keyword(s):

Sexual Selection ◽

Sexual Conflict ◽

Alternative Hypothesis ◽

Dung Beetle ◽

Male Courtship ◽

High Quality ◽

Female Resistance ◽

Genetic Quality ◽

Onthophagus Taurus ◽

Courtship Signals

Traditional models of sexual selection posit that male courtship signals evolve as indicators of underlying male genetic quality. An alternative hypothesis is that sexual conflict over mating generates antagonistic coevolution between male courtship persistence and female resistance. In the scarabaeine dung beetle Onthophagus taurus , females are more likely to mate with males that have high courtship rates. Here, we examine the effects of exposing females to males with either high or low courtship rates on female lifetime productivity and offspring viability. Females exposed to males with high courtship rates mated more often and produced offspring with greater egg–adult viability. Female productivity and lifespan were unaffected by exposure to males with high courtship rates. The data are consistent with models of sexual selection based on indirect genetic benefits, and provide little evidence for sexual conflict in this system.

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A model of the interaction between ‘good genes’ and direct benefits in courtship-feeding animals: when do males of high genetic quality invest less?

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2001.0922 ◽

2002 ◽

Vol 357 (1419) ◽

pp. 309-317 ◽

Cited By ~ 24

Author(s):

L. F. Bussière

Keyword(s):

Sexual Selection ◽

Simple Model ◽

Parental Investment ◽

Good Genes ◽

High Quality ◽

Genetic Quality ◽

Individual Female ◽

Female Partners ◽

Direct Benefits ◽

Courtship Feeding

Conflict between mates over the amount of parental investment by each partner is probably the rule except in rare cases of genetic monogamy. In systems with parental care, males may frequently benefit by providing smaller investments than are optimal for individual female partners. Females are therefore expected to choose males that will provide the largest amounts of parental investment. In some species, however, the preferred males provide less care than their rivals. Focusing on species in which males invest by feeding their mates, I use a simple model to demonstrate the conditions under which males preferred by females may have optimal donations that are smaller than those of less–preferred rivals. Pre–mating female choice may sufficiently bias the perception of mate availability of preferred males relative to their rivals such that preferred males gain by conserving resources for future matings. Similarly, ‘cryptic’ biases in favour of high–quality ejaculates by females can compensate for smaller than average donations received from preferred males. However, post–fertilization cryptic choice should not change the optimal donations of preferred males relative to their rivals. I discuss the implications of this work for understanding sexual selection in courtship–feeding animals, and the relevance of these systems to understanding patterns of investment for animals in general.

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Sexual selection can reduce mutational load in Drosophila subobscura

Genetika ◽

10.2298/gensr1302537v ◽

2013 ◽

Vol 45 (2) ◽

pp. 537-552 ◽

Cited By ~ 3

Author(s):

Marija Savic-Veselinovic ◽

Sofija Pavkovic-Lucic ◽

Zorana Kurbalija-Novicic ◽

Mihailo Jelic ◽

Marko Andjelkovic

Keyword(s):

Sexual Selection ◽

Sexual Conflict ◽

Male Mating ◽

Mutational Load ◽

Genetic Quality ◽

Genetic Structure Of Populations ◽

Deleterious Alleles ◽

Theoretical Predictions ◽

Set Up ◽

Genetic Pool

According to theoretical predictions sexual selection can reduce mutational load through male mating success. Males of good genetic quality should be more successful in matings, compared to the males of low genetic quality, thus in this way females can prevent deleterious alleles to be transmitted to the next generation. We tested this hypothesis through set up of two experimental groups from same genetic pool, where in one group genetic quality was manipulated by ionizing radiation. Within each group opportunity for choosing mates was imposed: males and females had no choice or had multiple choice. Mutational load was measured through the variability of different fitness components: fecundity and egg-to-adult viability. Our results indicate that sexual selection can reduce mutational load, only for fecundity. Group with the presence of female choice exhibited higher fecundity than group in which sexual selection was experimentally eliminated, but only in ?irradiated? group. There was no overall difference in egg-to-adult viability between different sexual selection regimes in any of the group. It should be considered that sexual selection can cause sexual conflict, and potential opposite effects of sexual selection and sexual conflict on fitness. Genetic structure of populations, in terms of the level of mutational load, is an important factor which can determinate the role of sexual selection.

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No evidence of positive assortative mating for genetic quality in fruit flies

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2019.1474 ◽

2019 ◽

Vol 286 (1912) ◽

pp. 20191474

Author(s):

Nathaniel P. Sharp ◽

Michael C. Whitlock

Keyword(s):

Sexual Selection ◽

Assortative Mating ◽

Genetic Variance ◽

Genetic Load ◽

Fruit Fly ◽

Genetic Quality ◽

Mating Patterns ◽

Disassortative Mating ◽

Deleterious Alleles ◽

Positive Assortative Mating

In sexual populations, the effectiveness of selection will depend on how gametes combine with respect to genetic quality. If gametes with deleterious alleles are likely to combine with one another, deleterious genetic variation can be more easily purged by selection. Assortative mating, where there is a positive correlation between parents in a phenotype of interest such as body size, is often observed in nature, but does not necessarily reveal how gametes ultimately combine with respect to genetic quality itself. We manipulated genetic quality in fruit fly populations using an inbreeding scheme designed to provide an unbiased measure of mating patterns. While inbred flies had substantially reduced reproductive success, their gametes did not combine with those of other inbred flies more often than expected by chance, indicating a lack of positive assortative mating. Instead, we detected a negative correlation in genetic quality between parents, i.e. disassortative mating, which diminished with age. This pattern is expected to reduce the genetic variance for fitness, diminishing the effectiveness of selection. We discuss how mechanisms of sexual selection could produce a pattern of disassortative mating. Our study highlights that sexual selection has the potential to either increase or decrease genetic load.

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The efficacy of good genes sexual selection under environmental change

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2018.2313 ◽

2019 ◽

Vol 286 (1896) ◽

pp. 20182313 ◽

Cited By ~ 7

Author(s):

Ivain Martinossi-Allibert ◽

Claus Rueffler ◽

Göran Arnqvist ◽

David Berger

Keyword(s):

Sexual Selection ◽

Environmental Change ◽

Mating Systems ◽

Good Genes ◽

Genetic Quality ◽

Changing Environments ◽

Sexually Selected Traits ◽

Deleterious Alleles ◽

Selected Traits ◽

Mechanistic Basis

Sexual selection can promote adaptation if sexually selected traits are reliable indicators of genetic quality. Moreover, models of good genes sexual selection suggest that, by operating more strongly in males than in females, sexual selection may purge deleterious alleles from the population at a low demographic cost, offering an evolutionary benefit to sexually reproducing populations. Here, we investigate the effect of good genes sexual selection on adaptation following environmental change. We show that the strength of sexual selection is often weakened relative to fecundity selection, reducing the suggested benefit of sexual reproduction. This result is a consequence of incorporating a simple and general mechanistic basis for how sexual selection operates under different mating systems, rendering selection on males frequency-dependent and dynamic with respect to the degree of environmental change. Our model illustrates that incorporating the mechanism of selection is necessary to predict evolutionary outcomes and highlights the need to substantiate previous theoretical claims with further work on how sexual selection operates in changing environments.

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