Number Of Matings Research Articles

Effects of γ-Irradiation on Mating Behavior of Red Palm Weevil, Rhynchophorus ferrugineus (Olivier, 1790) (Coleoptera: Dryophthoridae).

Red palm weevil (RPW) Rhynchophorus ferrugineus (Olivier 1790) is a highly invasive species originating from Southeast Asia and Melanesia. Over the past 30 years, this alien pest has spread extensively in the Middle East and the Mediterranean basin. Its endophagous larvae feed on various palm species, causing significant damage that leads to the death of palm trees. Controlling RPW infestations is challenging due to their gregarious nature and the lack of detectable early symptoms. Systemic insecticides are effective means of control, but their use in urban areas is prohibited and resistance can develop. Considering alternative options with minimal environmental impact, the Sterile Insect Technique (SIT) has been explored. Previous research has shown that male RPWs irradiated at 80 Gy or higher achieve full sterility. This study aimed to investigate in laboratory conditions whether RPW sterile males (irradiated at 60 and 80 Gy) could compete sexually with non-irradiate males. Laboratory bio-assays under both no-choice and choice conditions assessed sexual performance in terms of number of matings, mating duration and time elapsed until the first mating. The results confirmed that irradiation does not negatively affect the mating performance of sterile males, demonstrating their ability to compete successfully with non-irradiated males in both experimental setups.

A matter of time: Bateman's principles and mating success as count and duration across social strata in contemporary Finland.

Bateman's principles heavily influence the understanding of human reproductive behaviour. Yet, few rigorous studies on Bateman's principles in contemporary industrialized populations exist. Most studies use small samples, exclude non-marital unions, and disregard recent insights on within-population heterogeneity in mating strategies. We assess mating success and reproductive success using population-wide Finnish register data on marital and non-marital cohabitations and fertility. We examine variability across social strata in the Bateman principles and analyse the mate count, the cumulated duration with a mate, and the association with reproductive success. Results support Bateman's first and second principles. Regarding Bateman's third principle, the number of mates is more positively associated with reproductive success for men than women, but this association is driven by ever having a mate. Having more than one mate is on average associated with lower reproductive success. However, for men in the lowest income quartile, having more than one mate positively predicts reproductive success. Longer union duration is associated with higher reproductive success, and more so for men. We note that sex differences in the relationship between mating success and reproductive success differ by social strata, and argue that mate duration may be an important component of mating success alongside mate count.

Model on Impingement and consequences of Alzheimer’s disease in community‐ introductory study.

AbstractBackgroundAlzheimer disease demands salutation and envisioning the cause for the disease. Despite the evolving scientific discoveries, the inhabitation among the global population reminds hiking alarmingly. The track of ways the spread of disease should leave a hint for the further research on the origin of the disease.MethodThis is a speculation much closure to current environment, to analyze effect and the pace of spread over a community. Penna model of biological aging [1] and model of colonization (lattice model) [2] are primitive base. For the model both inherited and non‐ inherited Alzheimer disease is taken into account and is obtruded into the lattice simulated on external factors such as age, genome, genetic mutation, mating partner, offspring and visualizing the change in population, symptoms and progress of the disease.ResultOutcome helps in providing an introductory knowledge on the impact Alzheimer creates in the society. It shows the growth on the level of symptoms in the population, the influence of the inheritance on the population and their progress during the course of time. The symptom to analyze the level of disease at respective age of the individual is monitored. The executions for variations in the input arguments are studied to determine the effect of disease from different perspectives.ConclusionThe Preliminary results show reasonable changes on the level of symptoms for the inherited Alzheimer’s disease. The results shell out some introductory ideas about growth of the level of symptoms of AD in the population during the course of the disease increasing number of offspring and number of mating will give a greater view of the consequences in the model and is predictable for the current scenario.1. Stauffer, D. (2007). The Penna model of biological aging. Bioinformatics and Biology Insights, 1, 117793220700100005.2. Mroz, I., &Pękalski, A. (1999). Model of populations colonizing a new habitat. The European Physical Journal B‐Condensed Matter and Complex Systems, 10(1), 181‐186.

Sex-specific selection patterns in a dioecious insect-pollinated plant.

Competition for mate acquisition is the hallmark of any sexual organism. In insect-pollinated plants, competition to attract pollinators is expected to result in pollinator-mediated selection on attractive floral traits. This could overlap with sexual selection if the number of mating partners increases with pollinator attraction, resulting in an improved reproductive success. In this study, we measured a set of floral traits and estimated individual fitness in male and female Silene dioica in an experimental population. Results align with the predictions of Bateman's principles, in the absence of pollen limitation. In females, natural selection acted on traits that are typically linked with fertility (number of flowers and number of gametes), and selection strength was similar in open- and hand-pollinated females, suggesting a limited role of pollinator-mediated selection. In males, flowering duration and corolla width were positively associated with both reproductive success and number of mates, suggesting that sexual selection has played a role in the evolution of these traits. The use of Bateman's metrics further confirmed stronger sexual selection in males than in females. Taken together, our results shed light on the occurrence of sex-specific patterns of selection in an insect-pollinated plant population.

An Agent-Based Model of Sex and Sexual Orientation Differences in Short-Term Mating Behaviors as a Result of Mating Preferences

ABSTRACT Sex differences in short-term mating behaviors are well-documented in human sexuality research. Existing studies usually explain sex differences in sexual behaviors through differences in mating preferences, which is theoretically problematic. Using an agent-based model, we investigated the circumstances under which males’ and females’ differential preferences for short-term mating would result in sex differences in short-term mating behaviors. The model showed that when all individuals in a closed heterosexual population were considered, males and females had the same average number of short-term mating experiences and short-term mates even when males had stronger preferences for short-term mating. Males (vs. females) had a higher average number of both experiences and mates when analyses were limited to only heterosexual males and females who successfully participated in the mating pool (i.e., those with a non-zero number of short-term mating experiences). Moreover, when males (vs. females) had stronger preferences for short-term mating, gay males had a higher average number of experiences and mates compared to both lesbian females and heterosexual males. These results suggest that even when sex differences in mating preferences exist, the sex differences in short-term mating behaviors only occur among particular populations, or when males’ preferences for short-term mating are not constrained by those of females. Suggestions for future research in human mating psychology and behaviors were provided.

Feeding, mating and animal wellbeing: new insights from phylogenetic comparative methods.

Feeding, mating and animal wellbeing: new insights from phylogenetic comparative methods.

Hidden impacts of conservation management on fertility of the critically endangered kākāpō.

Animal conservation often requires intensive management actions to improve reproductive output, yet any adverse effects of these may not be immediately apparent, particularly in threatened species with small populations and long lifespans. Hand-rearing is an example of a conservation management strategy which, while boosting populations, can cause long-term demographic and behavioural problems. It is used in the recovery of the critically endangered kākāpō (Strigops habroptilus), a flightless parrot endemic to New Zealand, to improve the slow population growth that is due to infrequent breeding, low fertility and low hatching success. We applied Bayesian mixed models to examine whether hand-rearing and other factors were associated with clutch fertility in kākāpō. We used projection predictive variable selection to compare the relative contributions to fertility from the parents' rearing environment, their age and previous copulation experience, the parental kinship, and the number of mates and copulations for each clutch. We also explored how the incidence of repeated copulations and multiple mates varied with kākāpō density. The rearing status of the clutch father and the number of mates and copulations of the clutch mother were the dominant factors in predicting fertility. Clutches were less likely to be fertile if the father was hand-reared compared to wild-reared, but there was no similar effect for mothers. Clutches produced by females copulating with different males were more likely to be fertile than those from repeated copulations with one male, which in turn had a higher probability of fertility than those from a single copulation. The likelihood of multiple copulations and mates increased with female:male adult sex ratio, perhaps as a result of mate guarding by females. Parental kinship, copulation experience and age all had negligible associations with clutch fertility. These results provide a rare assessment of factors affecting fertility in a wild threatened bird species, with implications for conservation management. The increased fertility due to multiple mates and copulations, combined with the evidence for mate guarding and previous results of kākāpō sperm morphology, suggests that an evolutionary mechanism exists to optimise fertility through sperm competition in kākāpō. The high frequency of clutches produced from single copulations in the contemporary population may therefore represent an unnatural state, perhaps due to too few females. This suggests that opportunity for sperm competition should be maximised by increasing population densities, optimising sex ratios, and using artificial insemination. The lower fertility of hand-reared males may result from behavioural defects due to lack of exposure to conspecifics at critical development stages, as seen in other taxa. This potential negative impact of hand-rearing must be balanced against the short-term benefits it provides.

Is more always better when it comes to mating?

Fitness usually increases when a male mates with more females, but is the same true for females? A new meta-analysis in PLOS Biology shows that females, like males, tend to have a positive relationship between the number of mates and their reproductive output. But why?

Costs and benefits of polyandry in a sexually cannibalistic mantis.

Mating with more than one male often provides direct or indirect benefits to female fitness but can also increase the chance of injury and death. Costs of mating are expected to increase linearly with increasing mating number. But how such costs interact with benefits to determine the net payoff of mating multiply is not well understood. Using the highly cannibalistic Springbok mantis, Miomantis caffra, a species where females are stabbed in the abdomen by males during violent premating struggles that males initiate to avoid being cannibalized, we took an experimental approach to assess the economics of polyandry under the risk of external, male-inflicted injury. We predicted that females that mate multiply would be more likely to show abdominal injuries, have higher prereproductive mortality, produce fewer offspring and be more likely to engage in pre-mating cannibalism to avoid unwanted matings. In line with our predictions, we found that the likelihood of abdominal injury was highest among females that mated at least once, and prereproductive death was highest among females that mated twice or three times. Virgin females completely avoided these costs and produced some offspring parthenogenetically but not enough to provide a net benefit. Although mating was better than not mating, there was no singularly optimal mating number: females that mated once and three times produced similarly high numbers of offspring from the first ootheca, which resulted in an intermediate trough in offspring production at two matings. We also found little evidence that cannibalism was deployed as a mate-avoidance strategy: females consistently attacked and consumed males regardless of how many times they mated or how long they were housed with males. Our results suggest the possibility of two distinct mating strategies in M. caffra, where females either mate at a lower frequency to minimize costs or at a higher frequency to maximize benefits. We discuss possible explanations for this bimodal pattern in offspring production.

Pre- and post-copulatory sexual selection increase offspring quality but impose survival costs to female field crickets.

Whether sexual selection increases or decreases fitness is under ongoing debate. Sexual selection operates before and after mating. Yet, the effects of each episode of selection on individual reproductive success remain largely unexplored. We ask how disentangled pre- and post-copulatory sexual selection contribute to fitness of field crickets Gryllus bimaculatus. Treatments allowed exclusively for (i) pre-copulatory selection, with males fighting and courting one female, and the resulting pair breeding monogamously, (ii) post-copulatory selection, with females mating consecutively to multiple males and (iii) relaxed selection, with enforced pair monogamy. While standardizing the number of matings, we estimated a number of fitness traits across treatments and show that females experiencing sexual selection were more likely to reproduce, their offspring hatched sooner, developed faster and had higher body mass at adulthood, but females suffered survival costs. Interestingly, we found no differences in fitness of females or their offspring from pre- and post-copulatory sexual selection treatments. Our findings highlight the potential for sexual selection in enhancing indirect female fitness while concurrently imposing direct survival costs. By potentially outweighing these costs, increased offspring quality could lead to beneficial population-level consequences of sexual selection.

Polyandrous females but not monogamous females vary in reproductive ageing patterns in the bean bug Riptortus pedestris

BackgroundIn general, reproductive performance exhibits nonlinear changes with age. Specifically, reproductive performance increases early in life, reaches a peak, and then declines later in life. Reproductive ageing patterns can also differ among individuals if they are influenced by individual-specific strategies of resource allocation between early-life reproduction and maintenance. In addition, the social environment, such as the number of available mates, can influence individual-specific resource allocation strategies and consequently alter the extent of individual differences in reproductive ageing patterns. That is, females that interact with more partners are expected to vary their copulation frequency, adopt a more flexible reproductive strategy and exhibit greater individual differences in reproductive ageing patterns.MethodsIn this study, we evaluated the effect of mating with multiple males on both group- and individual-level reproductive ageing patterns in females of the bean bug Riptortus pedestris by ensuring that females experienced monogamous (one female with one male) or polyandrous conditions (one female with two males).ResultsWe found that group-level reproductive ageing patterns did not differ between monogamy-treatment and polyandry-treatment females. However, polyandry-treatment females exhibited among-individual variation in reproductive ageing patterns, while monogamy-treatment females did not.ConclusionOur findings provide the first empirical evidence regarding the influence of the social environment on individual variation in reproductive ageing patterns. We further suggest that the number of potential mates influences group- and individual-level reproductive ageing patterns, depending on which sex controls mating. We encourage future studies to consider interactions between species-specific mating systems and the social environment when evaluating group- and individual-level reproductive ageing patterns.

Multiple mating by both sexes in an invasive insect species, Aethina tumida (Coleoptera: Nitidulidae).

Multiple mating by both sexes is common among sexually reproducing animals. Small hive beetles (SHB), Aethina tumida, are parasites of bee nests endemic to sub-Saharan Africa and have become a widespread invasive species. Despite the considerable economic damages they can cause, their basic biology remains poorly understood. Here we show that male and female small hive beetles can mate multiple times, suggesting that costs for mating are low in this species. In an invasive A. tumida population in the United States, a combination of laboratory experiments for males and paternity analysis with eight polymorphic DNA microsatellite markers for field-caught females were used to estimate the number of mating by both sexes. The data show that females and males can mate multiple times-females mated with up to eight males, whereas males mated with at least seven females. The results also showed that A.tumida displayed a skewed paternity, although this was not consistent among the tested females. Thus, first or last male advantage seem to be unlikely in A.tumida. Our observations that individuals of both sexes of A. tumida can mate multiple times opens new research avenues for examining drivers of multiple mating and determining the role it may play in promoting biological invasions.

African wild dogs (Lycaon pictus) from the Kruger National Park, South Africa are currently not inbred but have low genomic diversity

African wild dogs (Lycaon pictus) have undergone severe population reductions and are listed as endangered on the International Union for Conservation of Nature Red List. Small, isolated populations have the potential to suffer from threats to their genetic diversity that may impact species viability and future survival. This study provides the first set of population-wide genomic data to address conservation concerns for this endangered species. Whole genome sequencing data were generated for 71 free-ranging African wild dogs from the Kruger National Park (KNP), South Africa, and used to estimate important population genomic parameters. Genomic diversity metrics revealed that variation levels were low; however, this African wild dog population showed low levels of inbreeding. Very few first- and second-order relationships were observed in this cohort, with most relationships falling into the third-order or distant category. Patterns of homozygosity could have resulted from historical inbreeding or a loss in genome variation due to a population bottleneck. Although the results suggest that this stronghold African wild dog population maintains low levels of inbreeding, likely due to their cooperative breeding system, it may lead to a continuous population decline when a reduced number of suitable mates are available. Consequently, the low genomic variation may influence species viability over time. This study highlights the importance of assessing population genomic parameters to set conservation priorities. Future studies should include the investigation of the potential of this endangered species to adapt to environmental changes considering the low genomic diversity in this population.

Sterility of Cydia pomonella by X ray irradiation as an alternative to gamma radiation for the sterile insect technique.

The codling moth Cydia pomonella is a major pest of global significance impacting pome fruits and walnuts. It threatens the apple industry in the Loess Plateau and Bohai Bay in China. Sterile insect technique (SIT) could overcome the limitations set by environmentally compatible area-wide integrated pest management (AW-IPM) approaches such as mating disruption and attract-kill that are difficult to suppress in a high-density pest population, as well as the development of insecticide resistance. In this study, we investigated the effects of X-ray irradiation (183, 366, 549 Gy) on the fecundity and fertility of a laboratory strain of C. pomonella, using a newly developed irradiator, to evaluate the possibility of X-rays as a replacement for Cobalt60 (60Co-γ) and the expanded future role of this approach in codling moth control. Results show that the 8th-day is the optimal age for irradiation of male pupae. The fecundity decreased significantly as the dosage of radiation increased. The mating ratio and mating number were not influenced. However, treated females were sub-sterile at a radiation dose of 183 Gy (20.93%), and were almost 100% sterile at a radiation dose of 366 Gy or higher. Although exposure to a radiation dose of 366 Gy resulted in a significant reduction in the mating competitiveness of male moths, our radiation biology results suggest that this new generation of X-ray irradiator has potential applications in SIT programs for future codling moth control.

Density‐dependent changes of mating system and family structure in Brandt's voles (Lasiopodomys brandtii)

AbstractA mating system is an important life history for animals dealing with changing environments. Population density affects the plasticity of a mating system and subsequently the family structure of animals, but its impacts on mating systems and social structures are rarely investigated by using molecular markers in field conditions. In this study, using microsatellite genetic markers, we examined the changes in the social and genetic mating system and family structure of Brandt's voles in the grassland of Inner Mongolia, China, under low‐, medium‐, and high‐density enclosures (each enclosure 0.48‐ha with 4 replicates.) We found, with the increase in population density of the founder voles introduced into the enclosure in early spring, both sexes increased their number of genetic mating partners, while males increased their social partners, resulting in a more promiscuous mating system. The number of genetic fathers and mothers per family, the number of social offspring per founder male or female, and the proportion of extra‐group offspring increased with increased density, indicating that the response of the family structure to density change, which is consistent with the change in mating system observed in our study. Both male and female voles had multiple mates, but males had a larger number of social and genetic mates, the number of social and genetic offspring, and the number of social and genetic families. Our study highlights the significance of density‐dependent plasticity of a mating system and family structure in affecting the population change of small mammals.

Juvenile socio-sexual experience determines lifetime sperm expenditure and adult survival in a polygamous moth, Ephestia kuehniella.

Male animals often adjust their sperm investment in response to sperm competition environment. To date, only a few studies have investigated how juvenile sociosexual settings affect sperm production before adulthood and sperm allocation during the first mating. Yet, it is unclear whether juvenile sociosexual experience (1) determines lifetime sperm production and allocation in any animal species; (2) alters the eupyrene : apyrene sperm ratio in lifetime ejaculates of any lepidopteran insects, and (3) influences lifetime ejaculation patterns, number of matings and adult longevity. Here we used a polygamous moth, Ephestia kuehniella, to address these questions. Upon male adult emergence from juveniles reared at different density and sex ratio, we paired each male with a virgin female daily until his death. We dissected each mated female to count the sperm transferred and recorded male longevity and lifetime number of matings. We demonstrate for the first time that males ejaculated significantly more eupyrenes and apyrenes in their lifetime after their young were exposed to juvenile rivals. Adult moths continued to produce eupyrene sperm, contradicting the previous predictions for lepidopterans. The eupyrene : apyrene ratio in the lifetime ejaculates remained unchanged in all treatments, suggesting that the sperm ratio is critical for reproductive success. Male juvenile exposure to other juveniles regardless of sex ratio caused significantly shorter adult longevity and faster decline in sperm ejaculation over successive matings. However, males from all treatments achieved similar number of matings in their lifetime. This study provides insight into adaptive resource allocation by males in response to juvenile sociosexual environment.

Sex-specific movement ecology of the shortest-lived tetrapod during the mating season

Sex-specific reproductive strategies are shaped by the distribution of potential mates in space and time. Labord’s chameleon (Furcifer labordi) from southwestern Madagascar is the shortest-lived tetrapod whose life-time mating opportunities are restricted to a few weeks. Given that these chameleons grow to sexual maturity within about three months and that all individuals die soon after breeding, their mating strategies should be adapted to these temporal constraints. The reproductive tactics of this or any other Malagasy chameleon species have not been studied, however. Radio-tracking and observations of 21 females and 18 males revealed that females exhibit high site fidelity, move small cumulative and linear distances, have low corresponding dispersal ratios and small occurrence distributions. In contrast, males moved larger distances in less predictable fashion, resulting in dispersal ratios and occurrence distributions 7–14 times larger than those of females, and males also had greater ranges of their vertical distribution. Despite synchronous hatching, males exhibited substantial inter-individual variation in body mass and snout-vent length that was significantly greater than in females, but apparently unrelated to their spatial tactics. Females mated with up to 6 individually-known mates, but frequent encounters with unmarked individuals indicate that much higher number of matings may be common, as are damaging fights among males. Thus, unlike perennial chameleons, F. labordi males do not seem to maintain and defend territories. Instead, they invest vastly more time and energy into locomotion for their body size than other species. Pronounced variation in key somatic traits may hint at the existence of alternative reproductive tactics, but its causes and consequences require further study. This first preliminary study of the mating system of a Malagasy chameleon indicates that, as in other semelparous tetrapods, accelerated life histories are tied to a mating system with intense contest and scramble competition among males.

Automated radio tracking provides evidence for social pair bonds in an obligate brood parasite

Social monogamy predominates in avian mating systems, but this strategy seems unlikely among brood parasites, where the emancipation from parental care should lead to an increase in numbers of mates for both sexes. Despite this, there is great diversity in mating systems in brood parasitic birds. The Screaming CowbirdMolothrus rufoaxillarisis a brood parasite that specializes almost exclusively on one host, the Greyish BaywingAgelaioides badius. Field observations and a radio telemetry study have indicated that male–female pairs spend a great deal of time together through the day, suggesting that they may be socially monogamous. We tested the hypothesis of social monogamy by radio‐tracking male and female Screaming Cowbirds using an array of automated radiotracking receivers to collect data on spatial behaviour and social mating system. Monogamous pair bonds were recorded through social network analysis. These bonds endured throughout the entire breeding season, with males and females remaining associated throughout the day. In accordance with the hypothesis, paired Screaming Cowbirds spent significantly more time in proximity to their mates than to other conspecifics of the opposite sex, and had similar home‐ranges. Social monogamy in the Screaming Cowbird differed markedly from the social polygyny/promiscuity exhibited by the sympatric congener Shiny CowbirdMolothrus bonariensis, a generalist brood parasite.

Optimum contribution selection (OCS) analyses prompted successful conservation actions for Faroese Horse population

The Faroese horse, an endangered indigenous horse breed, is a part of the cultural and societal heritage of the Faroe Islands. Population history describes a severe bottleneck, prompting for quantification of the genetic diversity (level of inbreeding, probability of gene origin, effective population size) and assessment of sustainable conservation potential (Optimum Contribution Selection, OCS) of the Faroese horse population. The pedigree completeness (PCI) of the Faroese horse is adequate for a realistic estimation of the level of inbreeding (PCI5 = 0.96). In concordance with the known population history, the average inbreeding is exceptionally high; in the last cohort, it was equal to 26.8%. An estimate of the effective population size, based on individual increase in inbreeding and coancestry, accounting for the whole population history, was eight. OCS offers a tool to understand and control the increase in the average relationships in the population. Within a fixed number of matings, the repetitive use of stallions resulted in the lowest level of average relationships. Successful follow-up of mating schemes planned together with a holistic assessment of the suitability of an individual as a breeding candidate, will minimize the increase in inbreeding in future generations and maximize the possibility to increase the census size of the Faroese horse population.

Mating Competitiveness of Bactrocera dorsalis (Diptera: Tephritidae) Males From a Genetic Sexing Strain: Effects of Overflooding Ratio and Released Females.

The oriental fruit fly, Bactrocera dorsalis (Hendel), is a global pest that infests a range of fruit and vegetables. Males are attracted to methyl eugenol, and control is often achieved by the Male Annihilation Technique, where methyl eugenol + insecticide dispensers are deployed to eliminate males, preclude matings, and reduce population growth. The Sterile Insect Technique (SIT) has also been used to control B. dorsalis. The SIT involves the release of mass-reared, sterilized males to achieve matings with wild females, who then produce inviable eggs. Two key elements of SIT include the overflooding ratio achieved (sterile: wild males) and the strain type utilized, namely bisexual or genetically sexed (allowing male-only releases). Here, we describe the effects of these two factors on the mating competitiveness of a males from a genetic sexing strain of B. dorsalis, termed DTWP. Mating success was scored for DTWP versus wild males in field cages at ratios of 1:2, 1:1, 2:1, and 10:1 both when DTWP females were or were not concurrently released with DTWP males. Close correspondence was found between observed numbers of matings of particular male-female combinations and expected numbers based on the numbers of flies released of each sex and each strain. As a result, the proportion of total matings achieved by the DTWP across the eight treatments showed a corresponding increase with overflooding ratio. At a given ratio, DTWP males had a higher relative mating success when DTWP females were absent rather than present, although the reason for this was unclear.