Sexual selection and female fitness in Drosophila simulans

AbstractThe traditional view of sexual selection via female mate choice is that female preference for certain males either has no net fitness cost or is beneficial to overall female fitness. A more contemporary view is that preferred males can at times reduce female fitness. This view has arisen from the realisation that conflict between the sexes is an inevitable feature of sexual reproduction, as each sex necessarily has a different agenda for maximizing fitness. Despite the hailing of sexual conflict as a paradigm shift and its prevalence in the recent sexual selection literature, compelling evidence that attractive males reduce female fitness remains taxonomically restricted. Here we review the findings of a series of investigations into the fitness consequences of female preference in the fly Drosophila simulans and compare them with its sibling species, D. melanogaster. We show that there are stark differences in the fitness consequences of mating with preferred males in the two species and discuss this contrast with reference to the current debates in the sexual selection literature.

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Natural selection increases female fitness by reversing the exaggeration of a male sexually selected trait

Nature Communications ◽

10.1038/s41467-021-23804-7 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Kensuke Okada ◽

Masako Katsuki ◽

Manmohan D. Sharma ◽

Katsuya Kiyose ◽

Tomokazu Seko ◽

...

Keyword(s):

Sexual Selection ◽

Natural Selection ◽

Experimental Evolution ◽

Genetic Correlations ◽

Lifetime Reproductive Success ◽

Fundamental Theory ◽

Female Fitness ◽

Male Trait ◽

Flour Beetles ◽

Male Specific

AbstractTheory shows how sexual selection can exaggerate male traits beyond naturally selected optima and also how natural selection can ultimately halt trait elaboration. Empirical evidence supports this theory, but to our knowledge, there have been no experimental evolution studies directly testing this logic, and little examination of possible associated effects on female fitness. Here we use experimental evolution of replicate populations of broad-horned flour beetles to test for effects of sex-specific predation on an exaggerated sexually selected male trait (the mandibles), while also testing for effects on female lifetime reproductive success. We find that populations subjected to male-specific predation evolve smaller sexually selected mandibles and this indirectly increases female fitness, seemingly through intersexual genetic correlations we document. Predation solely on females has no effects. Our findings support fundamental theory, but also reveal unforseen outcomes—the indirect effect on females—when natural selection targets sex-limited sexually selected characters.

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The physical environment mediates male harm and its effect on selection in females

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2017.0424 ◽

2017 ◽

Vol 284 (1858) ◽

pp. 20170424 ◽

Cited By ~ 38

Author(s):

Li Yun ◽

Patrick J. Chen ◽

Amardeep Singh ◽

Aneil F. Agrawal ◽

Howard D. Rundle

Keyword(s):

Drosophila Melanogaster ◽

Sexual Selection ◽

Physical Environment ◽

Selective Advantage ◽

Laboratory Studies ◽

Male Choice ◽

Female Fitness ◽

High Quality ◽

Evolutionary Consequences ◽

Natural And Sexual Selection

Recent experiments indicate that male preferential harassment of high-quality females reduces the variance in female fitness, thereby weakening natural selection through females and hampering adaptation and purging. We propose that this phenomenon, which results from a combination of male choice and male-induced harm, should be mediated by the physical environment in which intersexual interactions occur. Using Drosophila melanogaster , we examined intersexual interactions in small and simple (standard fly vials) versus slightly more realistic (small cages with spatial structure) environments. We show that in these more realistic environments, sexual interactions are less frequent, are no longer biased towards high-quality females, and that overall male harm is reduced. Next, we examine the selective advantage of high- over low-quality females while manipulating the opportunity for male choice. Male choice weakens the viability advantage of high-quality females in the simple environment, consistent with previous work, but strengthens selection on females in the more realistic environment. Laboratory studies in simple environments have strongly shaped our understanding of sexual conflict but may provide biased insight. Our results suggest that the physical environment plays a key role in the evolutionary consequences of sexual interactions and ultimately the alignment of natural and sexual selection.

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Do metrics of sexual selection conform to Bateman's principles in a wind-pollinated plant?

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2019.0532 ◽

2019 ◽

Vol 286 (1905) ◽

pp. 20190532 ◽

Cited By ~ 6

Author(s):

Jeanne Tonnabel ◽

Patrice David ◽

John R. Pannell

Keyword(s):

Spatial Distribution ◽

Sexual Selection ◽

Reproductive Success ◽

Pollen Dispersal ◽

Male Fitness ◽

Female Fitness ◽

Dioecious Plant ◽

Common Gardens ◽

Mate Acquisition ◽

Mercurialis Annua

Bateman's principles posit that male fitness varies more, and relies more on mate acquisition, than female fitness. While Bateman's principles should apply to any organism producing gametes of variable sizes, their application to plants is potentially complicated by the high levels of polyandry suspected for plants, and by variation in the spatial distribution of prospective mates. Here we quantify the intensity of sexual selection by classical Bateman metrics using two common gardens of the wind-pollinated dioecious plant Mercurialis annua . Consistent with Bateman's principles, males displayed significantly positive Bateman gradients (a regression of fitness on mate number), whereas the reproductive success of females was independent of their ability to access mates. A large part of male fitness was explained by their mate number, which in turn was associated with males' abilities to disperse pollen. Our results suggest that sexual selection can act in plant species in much the same way as in many animals, increasing the number of mates through traits that promote pollen dispersal.

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Transgenerational effects of sexual interactions and sexual conflict: non-sires boost the fecundity of females in the following generation

Biology Letters ◽

10.1098/rsbl.2015.0067 ◽

2015 ◽

Vol 11 (3) ◽

pp. 20150067 ◽

Cited By ~ 17

Author(s):

Francisco Garcia-Gonzalez ◽

Damian K. Dowling

Keyword(s):

Sexual Selection ◽

Life Histories ◽

Direct Effects ◽

Female Fitness ◽

Transgenerational Effects ◽

Female Fecundity ◽

Sexual Interaction ◽

Offspring Fitness ◽

Generational Effects ◽

Simple Production

The consequences of sexual interactions extend beyond the simple production of offspring. These interactions typically entail direct effects on female fitness, but may also impact the life histories of later generations. Evaluating the cross-generational effects of sexual interactions provides insights into the dynamics of sexual selection and conflict. Such studies can elucidate whether offspring fitness optima diverge across sexes upon heightened levels of sexual interaction among parents. Here, we found that, in Drosophila melanogaster , components of reproductive success in females, but not males, were contingent on the nature of sexual interactions experienced by their mothers. In particular, maternal sexual interactions with non-sires enhanced female fecundity in the following generation. This highlights the importance of non-sire influences of sexual interactions on the expression of offspring life histories.

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Female Choice in the Midwife Toads (Alytes Obstetricans and a. Cisternasii)

Behaviour ◽

10.1163/156853995x00342 ◽

1995 ◽

Vol 132 (1-2) ◽

pp. 151-161 ◽

Cited By ~ 31

Author(s):

Rafael Márquez

Keyword(s):

Sexual Selection ◽

Hatching Success ◽

Female Preference ◽

Dominant Frequency ◽

Female Fitness ◽

Significant Preference ◽

Male Size ◽

Low Frequencies ◽

Behavioural Mechanism ◽

Alytes Obstetricans

AbstractA previous study reported that large males had greater mating success than small males in two species of midwife toads. A behavioural mechanism that would explain such a pattern is sought. Dominant frequency is inversely correlated with male size in Alytes obstetricans and A. cisternasii. In both cases, two-speaker playback tests with synthetic calls show that females have a significant preference for calls with low frequencies. The results shows that female preference may impose directional sexual selection upon a static acoustic character that is correlated with male size. Male Alytes tend their eggs on land, but male size is not correlated with hatching success. Therefore female preference for larger males does not appear to directly increase female fitness.

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How multiple mating by females affects sexual selection

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2012.0046 ◽

2013 ◽

Vol 368 (1613) ◽

pp. 20120046 ◽

Cited By ~ 39

Author(s):

Stephen M. Shuster ◽

William R. Briggs ◽

Patricia A. Dennis

Keyword(s):

Sexual Selection ◽

Life History ◽

Multiple Mating ◽

Female Offspring ◽

Relative Fitness ◽

Male Mating ◽

Female Fitness ◽

Offspring Number ◽

Reproductive Life ◽

Sperm Utilization

Multiple mating by females is widely thought to encourage post-mating sexual selection and enhance female fitness. We show that whether polyandrous mating has these effects depends on two conditions. Condition 1 is the pattern of sperm utilization by females; specifically, whether, among females, male mating number, m (i.e. the number of times a male mates with one or more females) covaries with male offspring number, o . Polyandrous mating enhances sexual selection only when males who are successful at multiple mating also sire most or all of each of their mates' offspring, i.e. only when Cov ♂ ( m , o ), is positive. Condition 2 is the pattern of female reproductive life-history; specifically, whether female mating number, m , covaries with female offspring number, o . Only semelparity does not erode sexual selection, whereas iteroparity (i.e. when Cov ♀ ( m , o ), is positive) always increases the variance in offspring numbers among females, which always decreases the intensity of sexual selection on males. To document the covariance between mating number and offspring number for each sex, it is necessary to assign progeny to all parents, as well as identify mating and non-mating individuals. To document significant fitness gains by females through iteroparity, it is necessary to determine the relative magnitudes of male as well as female contributions to the total variance in relative fitness. We show how such data can be collected, how often they are collected, and we explain the circumstances in which selection favouring multiple mating by females can be strong or weak.

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