Higher Mating Research Articles

Evolution of female choosiness and mating frequency: effects of mating cost, density and sex ratio

Choice for mate quality and number of mates are key components of female mating strategies. We investigated how selection on female choosiness also influences number of matings in various ecological conditions. In our individual-based model, females choose their first mate according to an evolving acceptance threshold and then mate with males of increasing quality (trade-up choice). We simulated evolution of this threshold under various conditions of density, sex ratio and mating cost. Thresholds rapidly evolve towards a small set of values that depend on the tested parameters. Consistent with intuitive predictions, choosier females are selected when either number of encounters with males or mating cost is high. Selection results in most females sharing the same threshold. Variation in female mating patterns remains because some variation in thresholds is maintained, at least by mutations, and because of random events affecting number of matings. Our model indicates that mating cost strongly affects evolution of female choosiness and mating frequency. Moreover, it influences the relative importance of other factors: when mating cost is low, selection on acceptance thresholds is weak and relatively more females use thresholds that differ from the norm. In that context, mate quality is therefore the most important factor affecting female reproductive success. When mating cost is high, females evolve thresholds such that both the cost of multiple mating and the risk of remaining unmated become as important as mate quality. High mating cost, by selecting for high choosiness, also leads to females mating with fewer males.

Sexual isolation between North American and Bogota strains of Drosophila pseudoobscura

Sexual isolation, the reduced ability of organisms of different species to successfully mate, is one of the reproductive barriers that prevent gene flow between different taxa. Various species-specific signals during courtship are attributed to the sexual isolation between them. Drosophila pseudoobscura has been widely used to study the behavioral and genetic mechanisms underlying selection for sexual isolation, as a model system for speciation. D. pseudoobscura and its sibling species, D. persmilis, live together in many locations but are reproductively isolated from one another. North American geographic strains of D. pseudoobscura from the American West mate at random. Several decades ago, D. pseudoobscura was collected in the vicinity of Bogota, Colombia, and later named the subspecies D. pseudoobscura bogotana. Nearly 5,000 matings were observed in this study. We analyzed mating behavior and cuticular hydrocarbon profiles as well as courtship within and between North American and Bogota strains of D. pseudoobscura. Here we report for the first time that Bogota strains of D. pseudoobscura do show statistically significant sexual isolation from North American strains. In addition, there are quantitative variations in cuticular hydrocarbons as well as in courtship behavior between Bogota and North American strains, and females of both North American and Bogota strains show strong preference for North American strain males having high mating propensities, suggesting that the Bogota strains are at an early stage that could lead to a separate species.

Sex-ratio control erodes sexual selection, revealing evolutionary feedback from adaptive plasticity

Female choice is a powerful selective force, driving the elaboration of conspicuous male ornaments. This process of sexual selection has profound implications for many life-history decisions, including sex allocation. For example, females with attractive partners should produce more sons, because these sons will inherit their father's attractiveness and enjoy high mating success, thereby yielding greater fitness returns than daughters. However, previous research has overlooked the fact that there is a reciprocal feedback from life-history strategies to sexual selection. Here, using a simple mathematical model, we show that if mothers adaptively control offspring sex in relation to their partner's attractiveness, sexual selection is weakened and male ornamentation declines. This weakening occurs because the ability to determine offspring sex reduces the fitness difference between females with attractive and unattractive partners. We use individual-based, evolutionary simulations to show that this result holds under more biologically realistic conditions. Sexual selection and sex allocation thus interact in a dynamic fashion: The evolution of conspicuous male ornaments favors sex-ratio adjustment, but this conditional strategy then undermines the very same process that generated it, eroding sexual selection. We predict that, all else being equal, the most elaborate sexual displays should be seen in species with little or no control over offspring sex. The feedback process we have described points to a more general evolutionary principle, in which a conditional strategy weakens directional selection on another trait by reducing fitness differences.

Natural Genetic Variation in Social Niche Construction: Social Effects of Aggression Drive Disruptive Sexual Selection inDrosophila melanogaster

Social niche construction (SNC) occurs when animals actively shape their social environments. Currently the fitness consequences of SNC are poorly understood, and no study has examined whether variation in SNC has a genetic basis. Here we report the first instance of genetic variation in SNC by showing that Drosophila male aggression shapes the social environment. We allowed flies of different genotypes to interact in complex arenas; we measured the number and sex of individuals in the groups that formed and counted instances of mating. Arenas containing more aggressive male genotypes formed groups with fewer males, demonstrating that aggressive male genotypes experienced different social environments than nonaggressive genotypes. Further, genotypes with highest mating success were those whose SNC behavior generated the social environment in which they were most adept at mating: genotypes who mate most often after winning aggressive encounters benefit from aggressive SNC, while genotypes who mate most often after losing achieve high mating rates by forgoing aggression. The presence of these alternative strategies-which were robust across eight population densities-revealed that selection on aggression and context-dependent mating was disruptive, consistent with the hypothesis that SNC can maintain genetic variation in multiple behaviors.

No Country for Young Men: Deteriorating Labor Market Prospects for Low-Skilled Men in the United States

The labor market fate of the nation’s male teens and young adults (ages 20—29) has deteriorated along most employment, weekly wages, and annual earnings dimensions in recent decades. The employment rates reached new post—World War II lows in 2009, with the less well educated faring the worst. The deterioration in the labor market well-being of these young men has had a number of adverse consequences on their social behavior. Less-educated young men, especially high school dropouts, are far more likely to be incarcerated than their peers in earlier decades. They are considerably less likely to be married and more likely to be absent fathers, with gaps in marriage rates across educational groups widening substantially since the 1970s. The decline in marriage among less-educated young adults, high assortative mating among younger married couples, and growing gaps in earnings across educational groups have contributed to a substantial widening in income and wealth disparities among the nation’s young families.

Assortative mating in fallow deer reduces the strength of sexual selection.

BackgroundAssortative mating can help explain how genetic variation for male quality is maintained even in highly polygynous species. Here, we present a longitudinal study examining how female and male ages, as well as male social dominance, affect assortative mating in fallow deer (Dama dama) over 10 years. Assortative mating could help explain the substantial proportion of females that do not mate with prime-aged, high ranking males, despite very high mating skew. We investigated the temporal pattern of female and male matings, and the relationship between female age and the age and dominance of their mates.ResultsThe peak of yearling female matings was four days later than the peak for older females. Younger females, and especially yearlings, mated with younger and lower-ranking males than older females. Similarly, young males and lower-ranking males mated with younger females than older males and higher-ranking males. Furthermore, the timing of matings by young males coincided with the peak of yearling female matings, whereas the timing of older male matings (irrespective of rank) coincided with the peak of older female matings.ConclusionsAssortative mating, through a combination of indirect and/or direct female mate choice, can help explain the persistence of genetic variation for male traits associated with reproductive success.

실기간 소음제거를 위한 IGC Algorithm의 LabVIEW FPGA 구현

The LMS(Least Mean Square) algorithm is generally used because of tenacity, high mating spots and simplicity of realization. But the LMS algorithm has trade-off between nonuniform collect and EMSE(Excess Mean Square Error). To overcome this weakness, variable step size is used widely but it needs a lot of calculation load. In this paper we consider new algorithm, which can reduce calculations and adapt in case of environment changes, uses original signal and noise signal of IGC(Instantaneous Gain Control). For the real time processing of IGC algorithm, we remove the logarithmic function. The performance of proposed algorithm is tested to adaptive noise canceller in automobile. We show implemented LabVIEW FPGA system of IGC algorithm is more efficient than others.

High mating frequency and variation with lineage ratio in dependent-lineage harvester ants

Explaining the evolution of multiple mating is a challenge because of the associated costs. For social insects, mating frequency may have fitness consequences due to effects on social interactions or genetic diversity within colonies. Here, we investigated the evolution of mating frequency in a social insect species with a unique genetic system that requires multiple mating. In certain populations of Pogonomyrmex harvester ants, there are two interbreeding yet genetically distinct mitochondrial lineages. Queens must mate with males of the opposite lineage to produce workers and with males of the same lineage to produce reproductive females. We expected queens of the dependent-lineage system to exhibit high mating frequencies relative to other social insects. Furthermore, we expected queens from populations of highly asymmetric lineage ratios to exhibit even higher mating frequencies, to adequately sample the population and successfully mate with males of the less common lineage. To test these predictions, we estimated the mating frequency of 16 P. barbatus queens, and compared these mating frequencies between two populations, one with relatively equal lineage ratio (60:40) and a second with a highly asymmetrical lineage ratio (96:4). Overall, observed mating frequency exceeded 10, which is high in comparison to other social insects, and our estimates of effective mating frequency were among the highest of Pogonomyrmex species. Mating frequency at the site with the asymmetrical lineage ratio was also significantly higher than the site with the more even ratio. Our results suggest that obligate multiple mating as well as lineage ratio contribute to the evolution of high mating frequency in dependent-lineage populations.

Male attractiveness is negatively genetically associated with investment in copulations

In species with high male mating effort, there is a trade-off between mating effort spent in a current mating and resources left for future matings. Males are therefore expected to allocate resources prudently across successive matings. Attractive males that will have a high mating success might therefore be forced to decrease mating investment in comparison with less-attractive males. Furthermore, if there is genetic variation in attractiveness, one might expect to find a negative genetic correlation between attractiveness and mating investment. Here, this genetic prediction is tested using the scorpionfly Panorpa cognata (Insecta: Mecoptera). In this species, males offer costly salivary secretions as nuptial gifts to females. By producing large secretions, males increase copulation duration and sperm transfer, thus gaining an advantage in sperm competition. I used a full-sib breeding design and found that both attractiveness and mating investment showed considerable heritability. Most importantly, there was a significant negative genetic correlation between attractiveness and mating investment: In families with attractive individuals, males produced smaller salivary secretions than in those with less-attractive males. The results thus demonstrate an important evolutionary trade-off between mating success and sperm competition success.

Toward a Developmental Taxonomy of Adult Sexual Aggressors of Women: Antisocial Trajectories in Youth, Mating Effort, and Sexual Criminal Activity in Adulthood

Recent studies suggest that sexual aggressors of women are characterized by early- and late-onset antisocial trajectories. However, these studies have not examined the role of mating effort and its role on sexual offending in adulthood. This study examined differences in the level of mating effort of early- and late-onset offenders and the association between mating effort and sexual offending in adulthood. Factor analysis identified two latent constructs of sexuality: mating effort and high sexual drive. Early-onset offenders exhibited significantly higher levels of mating effort and sexual drive. Furthermore, high mating effort and high sexual drive were more strongly associated with an earlier onset and a higher frequency of sexual crimes in adulthood than group membership. This study provided empirical evidence that a developmental taxonomy of early and late onset distinguishes the sexual activity and sexual criminal activity of adult sexual aggressors. The findings are discussed in light of a developmental taxonomy of sexual aggressors of women.

Benefits of a risky life for fallow deer bucks (Dama dama) aspiring to patrol a lek territory

Summary Little is known about the relation between male ungulates’ ability to adopt a successful mating strategy during the rut and certain foraging strategies before the rut. In highly polygynous species such as many cervids, males are regarded as pure capital breeders, in that they allocate the energy stored in spring and summer to reproduction. According to the predation risk hypothesis, best foraging strategies adopted before the rut may imply a risk because, in order to invest in body size, males exploit the best feeding areas, even though characterized by higher predation risk. We performed a 9-year research through monitoring 31 fallow bucks in the lekking population of San Rossore, Italy. Among the mating strategies adopted by males, defence of the lek territory was repeatedly shown to be the most successful one. A sector of the study area was characterized by the highest meadow productivity and the highest predation risk. We showed that only those males that exploited the best feeding and yet risky areas before the rut to a greater extent, hereby investing in body size, were subsequently more likely to defend a lek territory. Males that during their life reduced the use of best feeding areas before the rut, were less likely to defend a lek territory during the rut. Among territorial males, which adopted the same spatial and foraging strategies before the rut, only few achieved a high mating success during the rut, suggesting that many other factors (phenotype, experience from previous mating seasons, and that gained as subadult males) along with foraging strategies may simultaneously contribute to explain the variability of mating success among territorial males in a lek.

Pride and prejudice or children and cheating? Jane Austen’s representations of female mating strategies.

Empirical Literary Darwinists investigate how themes and patterns predicted by human evolutionary theory are evident in fictive works. The current study fills an important gap in this emerging literature, and provides additional information in an area currently underrepresented in human evolutionary research in general. Previous research demonstrated how proper and dark male heroes in British Romantic literature represent high paternal investment and high mating effort strategies, respectively. This past work showed that people infer reproductively relevant behaviors from brief character depictions, and report preferring interactions with these characters in ways that would enhance their own reproductive success. We conducted a similar experiment investigating variation in female reproductive strategies depicted by six female characters in novels written by Jane Austen. Three women were described as loyal, quiet, “mother” figures, while three were described as active, boisterous and untamed “lover” figures. Results show that men recognize the distinct strategies, expressing a preference to marry the “mother” and realizing that the “lover” would be more likely to cheat on them. Women recognize that men would prefer the “lover” for sexual relations, and believe that the “mother” would be better with children and a better mother. Once again, people intuitively recognized reproductively relevant behavior from brief character sketches. Austen’s intuitive evolutionary psychology may be one reason why her works remain so popular and well respected nearly 200 years after their publications.

Kemampuan Reproduksi Daphnia magna Jantan Hasil Induksi Logam Berat (Cd, Pb) Dan Pestisida Diazinon <br><i>[Reproductive Ability Of Male Daphnia magna Induction Results Of Heavy Metal (Cd, Pb) And Pesticide Diazinon]<i>

Abstract Daphnia magna is one of the natural food which is used widely in fish hatchery. Generally, Daphnia magna is used widely in larval rearing of fish that are traded in the form of resting eggs called ephipia. Ephipia production can be performed with Daphnia magna culture in conditions that are not optimal, one of which is pollution. If the conditions are not optimal then the parthenogenesis Daphnia magna would produced a male individual. The presence of Daphnia magna males will initiate sexual reproduction, where Daphnia magna males will perform on the female and copulation produce ephipia. Ephipia production is influenced by the efficiency of matting, reproduction ephipia will improve if a high mating eficiency of Daphnia magna. Mating eficiency describes the number of females that successflly fertilized by the male.The purpose of this study is to determine the reproductive capacity of Daphnia magna male’s induction of heavy metals (Cd, Pb) and the Pesticide Diazinon on mating efficiency and quality ephipia produced. The research method used is an experimental method by using completely randomized design with 4 treatments and 5 replications so that was followed by Duncan Multiple Range Test. This study uses the ratio of male to female sex 1:30 for each treatment. The treatments in this study consist of control males mated with females, male induced lead (Pb) were mated with female, males induced cadmium (Cd) were mated with females, the male mated with the induction of pesticide Diazinon female. Results showed that treatments using natural male produced an average value of mates which were the highest efficiency and quality ephipia optimal, with precentage of 88,66 and 88,71. So that in order to produce ephipia in large quantities and quality needed natural male culture can be done in the unpolluted waters.

Mate choice in males with one-shot genitalia: limited importance of female fecundity

Male mate choice is expected in species in which future mating opportunities of males are strongly diminished after their first copulation and mate quality is variable unless the costs of choice exceed the benefits. Males of the spider Argiope bruennichi are mostly monogynous; they damage their paired one-shot genitalia during copulation and fall victim to sexual cannibalism. Even males that are not cannibalized can achieve a maximum of two matings. Such a high mating effort implies that a male’s reproductive success can be increased by selecting the best possible mate. Mate quality may depend on female mating status and/or fecundity. Males should be selected to prefer virgin females over mated ones since previously used female genital ducts can be blocked by genital mating plugs. Fecundity is a common approximation of female quality and in invertebrates is generally correlated with body size and mass. Argiope bruennichi females vary in body size and fecundity, providing a basis for male selectivity. By creating binary choice situations in field and laboratory experiments in which search costs were largely removed, we tested whether males show mate choice. There was weak evidence for a male preference based on female phenotype. However, virgin females were significantly preferred over mated females even if the virgin had a less fecund phenotype. We conclude that selective benefits of mating first with a female override potential benefits of choice based on female fecundity, leading to competition for virgin females.

Sperm Swimming Velocity Predicts Competitive Fertilization Success in the Green Swordtail Xiphophorus helleri

Sperm competition is expected to favour the evolution of traits that influence the performance of sperm when they compete to fertilize a female's eggs. While there is considerable evidence that selection favours increases in sperm numbers, much less is known about how sperm quality contributes towards competitive fertilization success. Here, we determine whether variation in sperm quality influences competitive fertilization success in the green swordtail Xiphophorus helleri, a highly promiscuous livebearing fish. We use artificial insemination as a method of controlled sperm delivery and show that sperm swimming velocity is the primary determinant of fertilization success when ejaculates from two males compete to fertilize a female's eggs. By contrast, we found no evidence that sperm length had any effect on siring success. We also found no evidence that pre- and postcopulatory sexual traits were phenotypically integrated in this species, suggesting that the previous observation that reproductive skew favours males with high mating rates is unlikely to be due to any direct association between sperm quality and male sexual ornamentation.

Costing reproduction: effects of mating opportunity on mating success in male Bicyclus anynana butterflies

It is frequently assumed that males have an almost unlimited reproductive capacity, while access to receptive females is typically limiting. Consequently, sexual selection is expected to favor vigorous courtship behavior in males. If such behavior is associated with non-trivial costs, ample current mating opportunities should be accompanied by a reduction in future mating vigor. To test this hypothesis, three treatments differing in sex ratio were established using the tropical butterfly Bicyclus anynana: 50 males each were housed either with 0, 25, or 50 females. Mating trials involving the competition among males from each treatment for a single virgin female were carried out on days 3, 9, and 15 after allocation to treatments. While there was no difference on day 3, prior mating opportunity clearly reduced mating success on days 9 and 15, being lowest if identical numbers of males and females were housed together. This finding suggests accumulating costs associated with high courtship and/or mating activity. Further, older males were more active and initiated copulation earlier than the younger ones, consistent with the residual reproductive value hypothesis. We found no evidence for a survival or fertility cost of mating.

What affects mating rate? Polyandry is higher in the directly developing generation of the butterfly Pieris napi

Polyandry is common among insects, and female insects in general gain directly from mating multiply in terms of increased lifetime reproductive success. Nevertheless, polyandry is not rampant, suggesting that realized polyandry is the outcome of costs and benefits associated with multiple matings. In the bivoltine green-veined white butterfly, Pieris napi, females gain from mating multiply as males transfer a substantial nuptial gift along with the sperm at mating. None the less, lifetime number of matings varies between one and six, and 12% of females mate only once. We investigated the reason for this variation and tested: (1) whether female polyandry is contingent on environmental conditions (specifically whether females can compensate for adverse conditions by mating more often); and (2) whether the level of polyandry differs between the diapausing generation, which flies after pupal hibernation, and the directly developing generation (specifically whether females in the more time-constrained summer generation are more polyandrous, possibly as a result of selection for early high mating propensity and thereby shorter prereproductive period). Results showed that: (1) females did not compensate for adverse conditions by mating more often; and (2) the level of polyandry was higher in the directly developing generation than in the diapause generation. Hence, we argue that differences in time stress and mating propensity between generations interplay in shaping mating frequency, and that the difference in polyandry between generations highlights the importance of integrating developmental pathway and life history.

Corticosterone, testosterone and life-history strategies of birds

Steroid hormones have similar functions across vertebrates, but circulating concentrations can vary dramatically among species. We examined the hypothesis that variation in titres of corticosterone (Cort) and testosterone (T) is related to life-history traits of avian species. We predicted that Cort would reach higher levels under stress in species with higher annual adult survival rates since Cort is thought to promote physiological and behavioural responses that reduce risk to the individual. Conversely, we predicted that peak T during the breeding season would be higher in short-lived species with high mating effort as this hormone is known to promote male fecundity traits. We quantified circulating hormone concentrations and key life-history traits (annual adult survival rate, breeding season length, body mass) in males of free-living bird species during the breeding season at a temperate site (northern USA) and a tropical site (central Panama). We analysed our original data by themselves, and also combined with published data on passerine birds to enhance sample size. In both approaches, variation in baseline Cort (Cort0) among species was inversely related to breeding season length and body mass. Stress-induced corticosterone (MaxCort) also varied inversely with body mass and, as predicted, also varied positively with annual adult survival rates. Furthermore, species from drier and colder environments exhibited lower MaxCort than mesic and tropical species; T was lowest in species from tropical environments. These findings suggest that Cort0, MaxCort and T modulate key vertebrate life-history responses to the environment, with Cort0 supporting energetically demanding processes, MaxCort promoting survival and T being related to mating success.

German cockroach males maximize their inclusive fitness by avoiding mating with kin

Conventional sex roles imply choosy females and nondiscriminating males. However, growing evidence suggests that male choosiness is more common than expected. While male mate choice is clearly linked to high mating investment in sex role-reversed species, factors promoting male mate choice in conventional sex role species are still debated. We addressed this fundamental issue in the German cockroach, Blattella germanica (L.), a group-living species where members of both sexes exercise mutual mate choice to avoid inbreeding. We focused on (1) male potential reproductive rate, (2) male effective reproductive rate, and (3) male reproductive success in relation to female quality. Males tested in situations with unrestrained female availability were able to mate throughout their life, thus revealing a high potential reproductive rate. However, their effective reproductive rate was much more limited under ecologically realistic conditions with restrained female availability. In contradiction with general predictions of sex role theory, mate choice by B. germanica males occurs despite an apparent low mating investment and a male-biased operational sex ratio. The finding that inbred matings were less fertile than outbred matings reveals that kinship is the key factor promoting male choice in this particular case. In the light of inbreeding avoidance theory, we propose that by being choosy cockroach males avoid imposing inbreeding costs on their sisters, thus maximizing their own inclusive fitness via kin selection.

Aggregation patterns of macroendoparasites in phylogenetically related fish hosts

Macroparasites are generally aggregated within their hosts with infection and aggregation levels resulting from a continuous arms race between maintaining high mating probability and host mortality low for which host and environmentally related factors contribute to some extent. Here, infection and aggregation patterns of the macroendoparasites infecting the flatfish Citharus linguatula, Arnoglossus laterna, Lepidorhombus boscii, Scophthalmus rhombus and Platichthys flesus in 3 areas along the Portuguese coast were analysed. Of the 21 macroendoparasite species found only 1 infected all hosts and most were host or area exclusive. For each host-parasite system, values of the indices varied between areas and macroendoparasites were not always aggregated; in fact, some macroendoparasites were generally uniformly distributed, which can be related to specific density-dependent regulation mechanisms. No general pattern was found for infection or aggregation levels of the 3 species infecting more than 2 hosts along the Portuguese coast, i.e. Lecithochirium rufoviride, Nybelinia lingualis and Anisakis simplex s.l., suggesting that regulation mechanisms are not species specific but are locally determined, with host ecology playing a significant role.