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Current Topics in Developmental Biology 2021Sexual interactions negatively impact health and longevity in many species across the animal kingdom. C. elegans has been established as a good model to study how mating... (Review)
Review
Sexual interactions negatively impact health and longevity in many species across the animal kingdom. C. elegans has been established as a good model to study how mating and intense sexual interactions influence longevity of the individuals. In this chapter, we review the most recent discoveries in this field. We first describe the phenotypes caused by intense mating, including shrinking, fat loss, and glycogen loss. We then describe three major mechanisms underlying mating-induced killing: germline activation, seminal fluid transfer, and male pheromone-mediated toxicity. Next, we summarize the current knowledge of genetic pathways involved in regulating mating-induced death, including DAF-9/DAF-12 steroid signaling, Insulin/IGF-1 signaling (IIS), and TOR signaling. Finally, we discuss the possible fitness benefits of mating-induced death. Throughout this review, we compare and contrast mating-induced death between the sexes and among different species in an effort to discuss this phenomenon and underlying mechanisms from the evolutionary perspective. Further investigation using mated C. elegans will improve our understanding of sexual antagonism, as well as the coordination between reproduction and somatic longevity in response to various external signals. Due to the evolutionary conservation in many aspects of mating-induced death, what we learn from a short-lived mated worm could provide new strategies to improve our own fitness and longevity.
Topics: Animals; Caenorhabditis elegans; Female; Male; Sexual Behavior, Animal
PubMed: 33992158
DOI: 10.1016/bs.ctdb.2020.08.004 -
Ecology and Evolution Jun 2020Ungulates exhibit diverse mating systems that range from monogamous pair territories to highly polygynous leks. We review mating systems and behaviors across ungulates... (Review)
Review
Ungulates exhibit diverse mating systems that range from monogamous pair territories to highly polygynous leks. We review mating systems and behaviors across ungulates and offer a new approach synthesizing how interacting factors may shape those mating systems. Variability exists in mating systems among and within species of ungulates and likely is affected by predation risk, availability of resources (food and mates), habitat structure, and sociality. Ungulate mating systems may be labile as a consequence of the varying strength of those interacting factors. In addition, degree of polygyny and sexual dimorphism in size are associated with the evolution of mating systems. Neither male-male combat nor paternal care, however, can completely explain differences in sexual size dimorphism for ungulates, a necessary component in understanding the development of some mating systems. Whatever the evolutionary pathway, sexual segregation limits paternal care allowing more intense male-male competition. Selection of habitat structure, because it modifies risk of predation, is a major determinant of sociality for ungulates. Likewise, ruggedness and steepness of terrain limit the types of mating systems that can occur because of limitations in group size and cohesiveness, as well as the ability of males to herd even small groups of females effectively. The quality and defensibility of resources affect mating systems, as does the defensibility of females. Population density of females also may be a critical determinant of the types of mating systems that develop. Size of groups likewise constrains the types of mating tactics that males can employ. Our aim was to use those relationships to create a broad conceptual model that predicts how various environmental and social factors interact to structure mating systems in ungulates. This model provides a useful framework for future tests of the roles of both ecological and social conditions in influencing the social systems of ungulates.
PubMed: 32551090
DOI: 10.1002/ece3.6246 -
Biology Letters Nov 2021Humans often mate with those resembling themselves, a phenomenon described as positive assortative mating (PAM). The causes of this attract broad interest, but there is... (Review)
Review
Humans often mate with those resembling themselves, a phenomenon described as positive assortative mating (PAM). The causes of this attract broad interest, but there is little agreement on the topic. This may be because empirical studies and reviews sometimes focus on just a few explanations, often based on disciplinary conventions. This review presents an interdisciplinary conceptual framework on the causes of PAM in humans, drawing on human and non-human biology, the social sciences, and the humanities. Viewing causality holistically, we first discuss the proximate causes (i.e. the 'how') of PAM, considering three mechanisms: stratification, convergence and mate choice. We also outline methods to control for confounders when studying mate choice. We then discuss ultimate explanations (i.e. 'the why') for PAM, including adaptive and non-adaptive processes. We conclude by suggesting a focus on interdisciplinarity in future research.
Topics: Animals; Mating Preference, Animal; Reproduction
PubMed: 34813721
DOI: 10.1098/rsbl.2021.0463 -
Science (New York, N.Y.) Jan 2022Darwin's theory of sexual selection fundamentally changed how we think about sex and evolution. The struggle over mating and fertilization is a powerful driver of... (Review)
Review
Darwin's theory of sexual selection fundamentally changed how we think about sex and evolution. The struggle over mating and fertilization is a powerful driver of diversification within and among species. Contemporaries dismissed Darwin's conjecture of a "taste for the beautiful" as favoring particular mates over others, but there is now overwhelming evidence for a primary role of both male and female mate choice in sexual selection. Darwin's misogyny precluded much analysis of the "taste"; an increasing focus on mate choice mechanisms before, during, and after mating reveals that these often evolve in response to selection pressures that have little to do with sexual selection on chosen traits. Where traits and preferences do coevolve, they can do so whether fitness effects on choosers are positive, neutral, or negative. The spectrum of selection on traits and preferences, and how traits and preferences respond to social effects, determine how sexual selection and mate choice influence broader-scale processes like reproductive isolation and population responses to environmental change.
Topics: Animals; Biological Evolution; Female; Humans; Male; Mating Preference, Animal; Perception; Sensation; Sex Characteristics; Sexual Behavior; Sexual Behavior, Animal; Sexual Selection; Social Environment
PubMed: 35050648
DOI: 10.1126/science.abi6308 -
Ecology and Evolution Jul 2022Sexual selection influences the evolution of phenotypic traits and contributes to patterns of biodiversity. In many animals, mating involves sequential steps. Often,...
Sexual selection influences the evolution of phenotypic traits and contributes to patterns of biodiversity. In many animals, mating involves sequential steps. Often, individuals must secure resources that are essential for mating (nests, territories, food), and then after securing a resource, individuals engage in competition for access to limited opposite sex mates and gametes. A large body of empirical research and some verbal models have illustrated that resource acquisition can influence sexual selection. In general, though, we lack predictions of when and how resource acquisition will influence sexual selection. Here, we use a mathematical framework to explore the link between resource acquisition and sexual selection on an advantageous mate-acquisition trait across biologically relevant trade-off scenarios. Our findings provide a set of testable predictions of how resource acquisition can influence sexual selection on mating traits. In general, selection on mate-acquisition traits is expected to be heavily influenced by: (1) the episode of selection considered, and in particular, whether one considers selection associated with the mating pool only or selection associated with both the mating pool and pre-mating pool; (2) whether resource-acquisition and mate-acquisition traits are positively associated or whether they trade off; and (3) the proportion of males with the resource- and mate-acquisition traits.
PubMed: 35898422
DOI: 10.1002/ece3.9137 -
Journal of Evolutionary Biology Feb 2021When the reproductive interests of males and females conflict, males can evolve traits that are harmful to females, and females can coevolve traits to resist this harm....
When the reproductive interests of males and females conflict, males can evolve traits that are harmful to females, and females can coevolve traits to resist this harm. In the fruit fly, Drosophila melanogaster, there is genetic variation in female resistance traits, which can affect the pre- and post-mating success of males that try to mate with them. However, it is not clear to what extent the expression of these phenotypes can be modified by environmental factors such as sociosexual experience. Here, we tested how the genetic background of a female and her previous mating experience interact to affect the mating success of focal males. In the experience phase, we placed females from 28 distinct genetic backgrounds individually either with a single male (low conflict) or with three males (high conflict) for 48 hr. In the subsequent test phase, we measured the mating and post-mating fertilization success of focal males paired individually with each female. We found that focal males paired with females from the high-conflict treatment were less successful at mating, took longer to mate when they were successful, and had a lower proportion of paternity share. Furthermore, we identified significant female genetic variation associated with male mating success. These results indicate that female experience, along with intrinsic genetic factors, can independently influence different fitness components of her subsequent mates and has implications for our understanding of plastic female mating strategies and the evolution of sexually antagonistic traits in males and females.
Topics: Adaptation, Physiological; Animals; Drosophila melanogaster; Female; Male; Reproduction; Sexual Behavior, Animal
PubMed: 33128417
DOI: 10.1111/jeb.13729 -
Archives of Sexual Behavior Jan 2022Researchers have highlighted numerous sociocultural factors that have been shown to underpin human appearance enhancement practices, including the influence of peers,... (Review)
Review
Researchers have highlighted numerous sociocultural factors that have been shown to underpin human appearance enhancement practices, including the influence of peers, family, the media, and sexual objectification. Fewer scholars have approached appearance enhancement from an evolutionary perspective or considered how sociocultural factors interact with evolved psychology to produce appearance enhancement behavior. Following others, we argue that evidence from the field of evolutionary psychology can complement existing sociocultural models by yielding unique insight into the historical and cross-cultural ubiquity of competition over aspects of physical appearance to embody what is desired by potential mates. An evolutionary lens can help to make sense of reliable sex and individual differences that impact appearance enhancement, as well as the context-dependent nature of putative adaptations that function to increase physical attractiveness. In the current review, appearance enhancement is described as a self-promotion strategy used to enhance reproductive success by rendering oneself more attractive than rivals to mates, thereby increasing one's mate value. The varied ways in which humans enhance their appearance are described, as well as the divergent tactics used by women and men to augment their appearance, which correspond to the preferences of opposite-sex mates in a heterosexual context. Evolutionarily relevant individual differences and contextual factors that vary predictably with appearance enhancement behavior are also discussed. The complementarity of sociocultural and evolutionary perspectives is emphasized and recommended avenues for future interdisciplinary research are provided for scholars interested in studying appearance enhancement behavior.
Topics: Biological Evolution; Female; Heterosexuality; Humans; Male; Physical Appearance, Body; Sexual Behavior; Sexual Partners
PubMed: 33025291
DOI: 10.1007/s10508-020-01745-4 -
Cold Spring Harbor Protocols Apr 2022is a powerful model system for cell and developmental biology in part because frogs produce thousands of eggs and embryos year-round. Natural matings are a simple and...
is a powerful model system for cell and developmental biology in part because frogs produce thousands of eggs and embryos year-round. Natural matings are a simple and common method to obtain embryos for injection or other experimental use or to raise to adulthood. This method does not require sacrificing a male as in vitro fertilization (IVF) does. Male and female frogs are injected with an ovulation hormone, placed together in a mating bucket, and left for 4-6 h or overnight to mate. Embryos are then collected, treated with cysteine to remove the sticky jelly coat, and used for injections and/or raised to later stages or adulthood. For embryos raised past free-swimming stages, the cysteine step can optionally be skipped, and tadpoles can be allowed to hatch naturally from the jelly coat. Although there are many similarities between natural mating protocols for and , there are key differences such as hormone dosage, timing of ovulation, and embryo incubation temperature. Here we provide a specific protocol for inducing natural matings in .
Topics: Animals; Female; Fertilization in Vitro; Larva; Male; Ovulation; Xenopus; Xenopus laevis
PubMed: 34031213
DOI: 10.1101/pdb.prot106609 -
Animals : An Open Access Journal From... Nov 2022Mate choice is the attempt of an individual to gain higher reproductive fitness by preferring to mate with some individuals and not with others. We studied the role of...
Mate choice is the attempt of an individual to gain higher reproductive fitness by preferring to mate with some individuals and not with others. We studied the role of mate choice in the mating system of the neotropical toad by assessing male reproductive tactics for mate acquisition and the contribution of female choice for pair formation. In a shallow pond in central Argentina, we estimated male mating success and the corresponding reproductive tactics by focal observation. The variation of phenotypic and genotypic traits (size and shape, longevity, vocalization features, heterozygosity) was related to the observed mating success in 110 males. The phonotactic response of 21 reproductive females to conspecific advertisement call features was tested in arena experiments. Mating success was limited to 32 males, pair formation was size-assortative. The dominant reproductive tactics were advertising from call positions near suitable breeding sites and pre-mating fights with intruding males, whereas the interception of amplectant pairs and the displacement of mated males were never observed. Female phonotaxis was directed to conspecific choruses but complex and simple call structures were not distinguished. We conclude that the mating system is a lek combining pre-mating fights among males and female choice of slightly smaller males. Fights interfere with female choice, undermining size-assortative mating. This is a unique system in the species group, in which interception behavior dominates reproduction.
PubMed: 36496788
DOI: 10.3390/ani12233268 -
Proceedings. Biological Sciences Jun 2021Traumatic mating is the male wounding his mate during mating using specialized anatomy. However, why males have evolved to injure their mates during mating remains...
Traumatic mating is the male wounding his mate during mating using specialized anatomy. However, why males have evolved to injure their mates during mating remains poorly understood. We studied traumatic mating in to determine its effects on male and female fitness. The sharp teeth on male gonostyli penetrate the female genitalia and cause copulatory wounds, and the number of scars on the female genitals is positively related to the number of times females mated. When the injurious teeth were encased with low-temperature wax, preventing their penetration of the female's genitalia during mating, male mating success and copulation duration were reduced significantly, indicating the importance of the teeth in allowing the male to secure copulation, remain in copula and effectively inseminate his mate. The remating experiments showed that traumatic mating had little effect on the female mating refractory period, but significantly reduced female remating duration with subsequent males, probably benefiting the first-mating male with longer copulation duration and transferring more sperm into the female's spermatheca. The copulatory wounds reduced female fecundity, but did not accelerate the timing of egg deposition. This is probably the first report that traumatic mating reduces female remating duration through successive remating experiments in animals. Overall, our results provide evidence that traumatic mating in the scorpionfly helps increase the male's anchoring control during mating and provides him advantage in sperm competition, but at the expense of lowering female fecundity.
Topics: Animals; Copulation; Female; Fertility; Male; Reproduction; Sexual Behavior, Animal; Spermatozoa
PubMed: 34074125
DOI: 10.1098/rspb.2021.0235