The genetic architecture of sexual conflict: male harm and female resistance inCallosobruchus maculatus
Laura GayEric W. BrownTom TregenzaDaniel Pincheira‐DonosoPaul E. EadyRam VasudevJohn HuntDavid J. Hosken
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Abstract:
Males harm females during mating in a range of species. This harm is thought to evolve because it is directly or indirectly beneficial to the male, despite being costly to his mate. The resulting sexually antagonistic selection can cause sexual arms races. For sexually antagonistic co-evolution to occur, there must be genetic variation for traits involved in female harming and susceptibility to harm, but even then intersexual genetic correlations could facilitate or impede sexual co-evolution. Male Callosobruchus maculatus harm their mates during copulation by damaging the female's reproductive tract. However, there have been no investigations of the genetic variation in damage or in female susceptibility to damage, nor has the genetic covariance between these characters been assessed. Here, we use a full-sib/half-sib breeding design to show that male damage is heritable, whereas female susceptibility to damage is much less so. There is also a substantial positive genetic correlation between the two, suggesting that selection favouring damaging males will increase the prevalence of susceptible females. We also provide evidence consistent with intralocus sexual conflict in this species.Keywords:
Callosobruchus maculatus
Genetic Variability
Genetic architecture
Abstract Sexual dimorphism — the sex-specific trait expression — may emerge when selection favours different optima for the same trait between sexes, i.e., under antagonistic selection. Intra-locus sexual conflict exists when the sexually dimorphic trait under antagonistic selection is based on genes shared between sexes. A common assumption for sexual-size dimorphism (SSD) is that its presence indicates resolved sexual conflict, but how current sex-specific evolution proceeds under sexual dimorphism remains enigmatic. We investigated whether a sex-specific architecture of adult body size explains sexual conflict resolution under extreme SSD in the African hermit spider, Nephilingis cruentata , where adult female body size greatly exceeds that of males. Specifically, we estimated the sex-specific importance of genetic and maternal effects on adult body size among individuals that we laboratory-reared for up to eight generations. Quantitative genetic model estimates indicated that size variation in females is to a larger extent explained by direct genetic effects than by maternal effects, but in males to a larger extent by maternal than by genetic effects. We conclude that this sex-specific body-size architecture enables body-size evolution to proceed much more independently than under a common architecture to both sexes, thereby mitigating sexual conflict under SSD.
Sexual dimorphism
Trait
Genetic architecture
Sex characteristics
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Observations on the biology of Callosobruchus maculatus( Fab.) were carried out under ambient laboratory conditions. Pattern of oviposition, female adult longevity and F1 progeny emergence in Callosobruchus maculatus ( Fab. ) were observed. The results showed that over 60% of the total number of eggs was laid during the first 72 hours of the commencement of oviposition; however, oviposition rate and F1 adult emergence of the bruchids decreased with time thereafter. The maximum adult C. maculatus survival period was about ten days.Keywords: Callosobruchus maculatus, pattern of oviposition, female adult longevity and F1 adult progeny emergence
Callosobruchus maculatus
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Females are frequently harassed and harmed by males attempting to obtain matings. When these males are also "choosy" with their courtship, there may be negative consequences to the species' ability to adaptively evolve.
Counterintuitive
Mating preferences
Persistence (discontinuity)
Experimental Evolution
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Many years ago, when I began researching young women's aggression, I was struck by the extent to which verbal and physical fights centered—directly or indirectly—on men. At that time, this message ...
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Sexual conflict over the indirect benefits of mate choice may arise when traits in one sex limit the ability of the other sex to freely choose mates but when these coercive traits are not necessarily directly harmful (i.e. forced fertilization per se). Although we might hypothesize that females can evolve resistance in order to retain the indirect, genetic benefits (reflected in offspring attractiveness) of mating with attractive males, up to now it has been difficult to evaluate potential underlying mechanisms. Traditional theoretical approaches do not usually conceptually distinguish between female preference for male mating display and female resistance to forced fertilization, yet sexual conflict over indirect benefits implies the simultaneous action of all of these traits. Here, we present an integrative theoretical framework that draws together concepts from both sexual selection and sexual conflict traditions, allowing for the simultaneous coevolution of displays and preferences, and of coercion and resistance. We demonstrate that it is possible for resistance to coercion to evolve in the absence of direct costs of mating to preserve the indirect benefits of mate choice. We find that resistance traits that improve the efficacy of female mating preference can evolve as long as females are able to attain some indirect benefits of mating with attractive males, even when both attractive and unattractive males can coerce. These results reveal new evolutionary outcomes that were not predicted by prior theories of indirect benefits or sexual conflict.
Antagonistic Coevolution
Mating preferences
Parent–offspring conflict
Sexual coercion
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Female mate choice and male–male competition are the typical mechanisms of sexual selection. However, these two mechanisms do not always favour the same males. Furthermore, it has recently become clear that female choice can sometimes benefit males that reduce female fitness. So whether male–male competition and female choice favour the same or different males, and whether or not females benefit from mate choice, remain open questions. In the horned beetle, Gnatocerus cornutus, males have enlarged mandibles used to fight rivals, and larger mandibles provide a mating advantage when there is direct male–male competition for mates. However, it is not clear whether females prefer these highly competitive males. Here, we show that female choice targets male courtship rather than mandible size, and these two characters are not phenotypically or genetically correlated. Mating with attractive, highly courting males provided indirect benefits to females but only via the heritability of male attractiveness. However, mating with attractive males avoids the indirect costs to daughters that are generated by mating with competitive males. Our results suggest that male–male competition may constrain female mate choice, possibly reducing female fitness and generating sexual conflict over mating.
Antagonistic Coevolution
Mating preferences
Courtship display
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The order in which females encounter, or sample, males in a population may have important consequences for mate choice, with the information gathered about males influencing both the preference function and degree of choosiness of females. Sexual selection may be affected as a result. Sampling of particular subsets of males may be a crucial component of individual variation in mate preferences within populations. However, the sequence in which males are sampled may also be important in species without traditional, active mate choice, such as when sexual selection involves sexual conflict over mating. This would occur if the likelihood of a female mating with a male of a certain phenotype changes as a result of previous encounters. We examined the effects of encountering males differing in body size, a sexually selected phenotype, in the seaweed fly Coelopa frigida. Sexual selection occurs in this species as a result of a sexual conflict over mating. We show that the outcome of the sexual conflict is independent of the order in which males are encountered by female seaweed flies, with the overall mating advantage to large males being unaffected. In addition, we explored female preference functions and evaluate the heterogeneity in female willingness to mate. We suggest that consideration of mate sampling theory is valuable when examining mate choice in species in which sexual selection is driven by sexual conflict.
Mating preferences
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Abstract The evolution of female mate choice, broadly defined to include any female behaviour or morphology which biases matings towards certain male phenotypes, is traditionally thought to result from direct or indirect benefits which females acquire when mating with preferred males. In contrast, new models have shown that female mate choice can be generated by sexual conflict, where preferred males may cause a fitness depression in females. Several studies have shown that female Drosophila melanogaster bias matings towards large males. Here, we use male size as a proxy for male attractiveness and test how female fitness is affected by reproducing with large or small males, under two different male densities. Females housed with large males had reduced lifespan and aged at an accelerated rate compared with females housed with small males, and increased male density depressed female fitness further. These fitness differences were due to effects on several different fitness components. Female fitness covaried negatively with male courtship rate, which suggests a cost of courtship. Mating rate increased with male size, whereas female fitness peaked at an intermediate mating rate. Our results suggest that female mate choice in D. melanogaster is, at least in part, a by-product of sexual conflict over the mating rate.
Courtship display
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اثر حشره کشی سه نهشته ایرانی خاک دیاتومه تهیه شده از معدنهای مراغه، ممقان و خراسان جنوبی و یک فرمولاسیون تجاری Sayan® روی حشرات بالغ Callosobruchus maculatus F. (Coleoptera: Bruchidae) بررسی شد. دانههای لوبیا چشم بلبلی با چهار غلظت 200، 600، 1000، و 1500 میلی گرم بر کیلوگرم تیمار شدند و هر غلظت چهار بار تکرار شد. آزمایشها در دمای 1 ± 28 درجه سلسیوس، رطوبت نسبی 5 ± 55 درصد و در شرایط تاریکی انجام شد. تلفات بعد از 2، 5، و 10 روز از تیمار شمارش شد. بعد از گذشت 10 روز، همه حشرات بالغ از ظرفهای آزمایش دور ریخته شد و ظرفها برای بررسی نتاج تولید شده برای 35 روز بیشتر در همان شرایط نگهداری شدند. درصد تلفات با افزایش غلظت و مدت زمان قرارگیری در معرض هر غلظت افزایش یافت. به ترتیب نهشتههای ممقان، خراسان جنوبی و مراغه خاک دیاتومه بیشترین اثر حشره کشی را روی حشرات بالغ، 10 روز بعد از تیمار ایجاد کردند. غلظت 1000 میلی گرم بر کیلوگرم از این نهشته ها برای مانع شدن از تولید نتاج C. maculatus کافی است. بنابراین، می توان نهشتههای ایرانی خاک دیاتومه را به عنوان ابزار مناسب در برنامههای مدیریت آفات محصولات انباری به کار برد.
Callosobruchus maculatus
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Callosobruchus maculatus
Callosobruchus chinensis
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