Affect Mating Success Research Articles

Variation in developmental time affects mating success and Allee effects

A fundamental question in biological conservation and invasion biology is why do some populations go extinct? Allee effects, notably those caused by mate location failure, are potentially key factors leading to the extinction of sparse populations. Several previous studies have focused on the inability of males and females to locate each other in space when populations are at low densities but here we investigate the effects of differences in the timing of male and female maturation on mating success. We develop a generalized model to clarify the role of protandry (the appearance of males before female emergence) and variability in adult maturation times. We show that temporal asynchrony can substantially reduce the probability of successful mating. We then apply this generalized model to estimate mating success in invading populations of the gypsy moth in North America in relation to local climate and its associated seasonality. Considerable geographic heterogeneity was observed in simulated mating success and this variability was not correlated with previous evaluations of bioclimatic requirements and habitat suitability. Furthermore, we found that the generalized model of temporal asynchrony provided reliable predictions and that detailed modeling of gypsy moth development was not necessary.

Effects of gamete behavior and density on fertilization success in marine green algae: insights from three-dimensional numerical simulations

We developed a numerical simulation of mating experiment to study effects of phototactic gamete behavior and density on fertilization success, using the C++ programming language, and pseudo-parallelization methods with input parameters based on experimental data. In our experiments, we found that gametes with positive phototaxis are favored, particularly in shallow water, because they can search for potential mates on the two-dimensional (2-D) water surface rather than randomly in three dimensions. We also found evidence that sperm (male gametes) limitation might not be the dominant selective force in the evolution of isogamous or slightly anisogamous marine green algae because almost all of female gametes can be fertilized on the 2-D water surface meaning they might not be under sperm limited conditions. Gamete density also appears to affect mating success seriously. These findings were produced by some technical progress made recently to rapidly and correctly count the numbers of zygotes formed calculating the locations of huge numbers of male and female gametes in the test tank. Both gamete behavior and density might be determined by environmental conditions of habitat, particularly the depth of water.

Antler Size of Alaskan Moose Alces Alces Gigas: Effects of Population Density, Hunter Harvest and Use of Guides

Moose Alces alces gigas in Alaska, USA, exhibit extreme sexual dimorphism, with adult males possessing large, elaborate antlers. Antler size and conformation are influenced by age, nutrition and genetics, and these bony structures serve to establish social rank and affect mating success. Population density, combined with anthropogenic effects such as harvest, is thought to influence antler size. Antler size increased as densities of moose decreased, ostensibly a density-dependent response related to enhanced nutrition at low densities. The vegetation type where moose were harvested also affected antler size, with the largest-antlered males occupying more open habitats. Hunts with guides occurred in areas with low moose density, minimized hunter interference and increased rates of success. Such hunts harvested moose with larger antler spreads than did non-guided hunts. Knowledge and abilities allowed guides to satisfy demands of trophy hunters, who are an integral part of the Alaskan economy. Heavy harvest by humans was also associated with decreased antler size of moose, probably via a downward shift in the age structure of the population resulting in younger males with smaller antlers. Nevertheless, density-dependence was more influential than effects of harvest on age structure in determining antler size of male moose. Indeed, antlers are likely under strong sexual selection, but we demonstrate that resource availability influenced the distribution of these sexually selected characters across the landscape. We argue that understanding population density in relation to carrying capacity (K) and the age structure of males is necessary to interpret potential consequences of harvest on the genetics of moose and other large herbivores. Our results provide researchers and managers with a better understanding of variables that affect the physical condition, antler size, and perhaps the genetic composition of populations, which may be useful in managing and modelling moose populations.

Sexual selection in hermit crabs: a review and outlines of future research

AbstractThe information currently available on sexual selection in hermit crabs is reviewed to identify the role of males and females before, during and after mating. According to this information, possible mechanisms of male–male competition, female choice and/or sexual conflict are suggested. Important male components that may affect mating success include dragging the female shell, rotations of the female's shell and male cheliped palpations, and male size and/or shell characteristics (species and size). Possible female determinants of male mating/fertilization success include size (as an indicator of egg production capacity), signalling of sexual receptivity to males, delay from mate guarding to copulation and mating duration. Avenues for deeper exploration in males include the role of the number and morphometry of male sexual tubes during sperm transfer, and whether ejaculate size and sperm number can be adjusted with variable situations of sperm competition intensity and risk. In females it would be interesting to investigate the chemical and behavioural mechanisms affecting spermatophore breakage for sperm release and the variable duration from sperm transfer to spawning. Given these possibilities, and that sperm is externally deposited on the female's body but inside her shell (except for those species that do not use shells, e.g. Birgus, or species where shells are rather small and do not cover the body totally, e.g. Parapagurus), we conclude that hermit crabs are unique subjects for separating male and female effects, particularly with respect to the applicability of current ideas in sexual selection such as female choice and sexual conflict. Some practical ideas are provided to disentangle both hypotheses using these animals.

The genetic basis of prezygotic reproductive isolation between Drosophila santomea and D. yakuba due to mating preference.

Sexual isolating mechanisms that act before fertilization are often considered the most important genetic barriers leading to speciation in animals. While progress has been made toward understanding the genetic basis of the postzygotic isolating mechanisms of hybrid sterility and inviability, little is known about the genetic basis of prezygotic sexual isolation. Here, we map quantitative trait loci (QTL) contributing to prezygotic reproductive isolation between the sibling species Drosophila santomea and D. yakuba. We mapped at least three QTL affecting discrimination of D. santomea females against D. yakuba males: one X-linked and one autosomal QTL affected the likelihood of copulation, and a second X chromosome QTL affected copulation latency. Three autosomal QTL also affected mating success of D. yakuba males with D. santomea. No epistasis was detected between QTL affecting sexual isolation. The QTL do not overlap between males and females and are not disproportionately concentrated on the X chromosome. There was some overlap in map locations of QTL affecting sexual isolation between D. santomea and D. yakuba with QTL affecting sexual isolation between D. simulans and D. mauritiana and with QTL affecting differences in pigmentation between D. santomea and D. yakuba. Future high-resolution mapping and, ultimately, positional cloning, will reveal whether these traits do indeed have a common genetic basis.

Mating success of the endemic Des Murs’ Wiretail (Sylviorthorhynchus desmursii, Furnariidae) in fragmented Chilean rainforests

Abstract: We studied the effects of fragment size, vegetation structure and presence of habitat corridors on the reproductive success of the Des Murs’ Wiretail (Sylviorthorhynchus desmursii Des Murs, Furnariidae), a small (10 g) understorey bird, endemic to South American forests. In a rural landscape of Chiloé Island, southern Chile (42°S; 70°W), we determined the mating and nesting success of wiretails in 28 territories distributed in seven small (1–20 ha) and two large (>300 ha) forest fragments during the 1997–1998 breeding season. Wiretails inhabited dense bamboo thickets in the understorey of forest patches, dense shrublands covering old fields, and dense early successional forest vegetation. Wiretails avoided open pastures. Reproductive success depended solely on the probability of finding mates, and the main factor affecting mating success was the presence of corridors. Mated individuals occupied 72% of the territories in forest patches <20 ha connected by corridors, 73% of the territories in large (>300 ha) fragments, but only 20% of territories in isolated fragments surrounded by pastures. Because of the rapid expansion of pastures in southern Chile, the conservation of wiretails and other understorey birds will depend on the maintenance of travel corridors with dense understorey vegetation between forest fragments.

Influência da idade da fêmea na performance reprodutiva e longevidade de Argyrotaenia sphaleropa (Lepidoptera, Tortricidae)

Argyrotaenia sphaleropa (Meyrick, 1909) é uma praga generalista de fruteiras na América do Sul. A influência da idade da fêmea na performance reprodutiva e longevidade foi investigada sob condições laboratoriais. Fêmeas virgens com 1, 3, 5 e 8 dias de idade foram pareadas com machos virgens com idade entre 0 e 3 dias. Longevidade, sucesso no acasalamento, padrão de oviposição, fecundidade e fertilidade, foram avaliados diariamente. O retardo na cópula não influenciou o período de oviposição e longevidade, entretanto, afetou o período de pré-oviposição, sucesso no acasalamento, fecundidade e fertilidade. A percentagem de acasalamento foi 25% inferior em fêmeas de 8 dias de idade, comparadas às fêmeas pareadas com 1 dia após a emergência. A maior fecundidade foi observada nas fêmeas de 1 dia de idade. Fêmeas pareadas com 3, 5 e 8 dias, apresentaram redução na fertilidade de 57, 82 e 99%, respectivamente. As implicações destes resultados em relação às estratégias de controle de A. sphaleropa, são discutidas.

Reproductive ageing and sexual selection on male body size in a wild population of antler flies (Protopiophila litigata)

Little is known about the importance of trade-offs between ageing and other life history traits, or the effects of ageing on sexual selection, particularly in wild populations suffering high extrinsic mortality rates. Life history theory suggests that trade-offs between reproduction and somatic maintenance may constrain individuals with higher initial reproductive rates to deteriorate more rapidly, resulting in reduced sexual selection strength. However, this trade-off may be masked by increased condition dependence of reproductive effort in older individuals. We tested for this trade-off in males in a wild population of antler flies (Protopiophila litigata). High mating rate was associated with reduced longevity, as a result of increased short-term mortality risk or accelerated ageing in traits affecting viability. In contrast, large body size was associated with accelerated ageing in traits affecting mating success, resulting in reduced sexual selection for large body size. Thus, ageing can affect sexual selection and evolution in wild populations.

Is political correctness damaging science?

Science is hardly unique in relying on peer review to determine merit and success. But for science, the reliance on peers to referee both submissions for publication and applications for grants involves greater dangers than in some other disciplines. It brings the triple risk of conformity, cronyism and plagiarism, which together can smother innovation. At a broader level, there is a tendency for researchers to fall in line with a particular point of view, especially in the more politically charged branches of science such as ecology or climatology. Those who oppose the prevailing orthodoxy risk being branded ‘flat earthers’ and cast into a wilderness where funding and publications are hard to obtain. According to Bruce Beutler, professor of immunology at the Scripps Research Institute (La Jolla, CA, USA), peer pressure in its various forms is a particular problem for science. “It is not unique to research, but in science it goes very much against the grain of what's trying to be accomplished,” he said. Yet scientists themselves must take some of the blame for perpetuating a system that can stifle original thinking, Beutler contends. “Scientists like to present an image to the outside world as being very iconoclastic and sceptical. Yet they have a complete conformity of opinion on certain things, and they do victimize people who differ from them.” By way of example, Beutler cited the atmosphere surrounding the recent US presidential election, in which any scientist who argued in favour of George W. Bush attracted severe ridicule. More worryingly though, such political correctness can distort research, with consequences not just for scientific direction but also for public matters such as health policy. “I think the best example of conformity of science is the influenza vaccine,” said Tom Jefferson, an independent researcher in the UK who specializes in immunology. …

Behavioural Elements Influencing Mating Success ofSymmorphus Allobrogus(Hymenoptera: Eumeninae)

Elements of the predatory wasp Symmorphus allobrogus mating behaviour are described, their influence on mating success is assessed based on laboratory observations. The analysis revealed that in the premounting phase activities of males, abdomen extension and substrate antennation, in particular, play a decisive role in predetermining mating success. In the precopulatory phase, activities of both sexes are nearly equal in importance. Struggle of female individuals negatively affects mating success, while their shaking increases the likelihood of copulation. Antennation and stroking of the abdomen are the most important elements of male behaviour, stimulating copulation. In the copulatory phase of mating visible activities of males have little influence on the duration of copulation, whilst shaking and struggle of females induce an earlier termination of it.

Environmental enrichment improves mating success in fruit flies

Environmental enrichment, defined as housing conditions that include a combination of complex inanimate and social stimulation, has strong positive effects on brain and behaviour in various species. We extended previous studies to evaluate how enrichment affects mating success. In a series of experiments, we found that male fruit flies, Drosophila melanogaster, reared in an enriched environment were twice as successful in acquiring mates as were males from standard rearing conditions. The dominant factor increasing mating success was the larger space available per fly. Flies from enriched and standard environments showed no significant behavioural differences, leading us to suggest that different social environments at high and low per capita spaces are associated, on average, with either subtle behavioural differences or distinct pheromonal profiles to which females are sensitive while choosing mates.

Sexual selection on morphological and physiological traits and fluctuating asymmetry in the yellow dung fly.

Previous univariate studies of the yellow dung fly (Scathophaga stercoraria) have demonstrated strong sexual selection, in terms of mating success, on male size (estimated as hind tibia length). To identify specific target(s) of selection on body size and possible conflicting selection pressures on particular body parts, two multivariate field studies of sexual selection were conducted. In one study using point samples from three populations, we assessed several morphological traits, including genital traits and measures of fluctuating asymmetry (FA) of all paired traits. There was sexual selection for large male size in general, confirming previous, univariate studies. With the possible exception of thorax width, which was selected in the opposite direction, no main target of selection was identified, as most morphological traits were highly correlated. There was no detectable sexual selection on the male external genital structures assessed. In a second study using multiple samples from one population, we included physiological measures of energy reserves (lipids, glucose and glycogen) known to affect mating success, in addition to trait size and FA of wings and legs. Inclusion of physiological traits is rare in phenomenological studies of selection. This study again confirmed the mating advantage of large males, and additionally showed independent positive influences of lipid and glucose but not glycogen levels. FA in paired traits generally did not affect male mating success, but was negatively correlated with energy reserves. Our study suggests that inclusion of physiological measures and genital traits in phenomenological studies of selection would be fruitful in other species.

Off-season maturation and spawning of Penaeus semisulcatus by eyestalk ablation and/or temperature–photoperiod regimes

In this study, nine different treatments were tested on off-season reproductive performance of Penaeus semisulcatus for 60 days in a recirculating system, in round tanks (1.2-m diameter) situated in a greenhouse. A combination of raised temperature (28 °C) and shortened (10 h) or increased day length (14 h) was not sufficient to induce maturation in unablated females of P. semisulcatus. Unablated females showed no sign of ovarian development at a constant low temperature of 20 °C. Cyclic fluctuation (period of 10 days) of water temperature (20–28 °C) at local winter photoperiod regime (10-h illumination) induced successful maturation and even multiple spawnings within the same moulting period. Natural daylight supplementation (14-h illumination) did not produce any advantage over natural illumination (10 h). Unilateral eyestalk ablation had the most profound effect on the induction of ovarian development and spawning in this species. Even at a temperature of 20 °C, eyestalk-ablated females developed their ovaries up to the 4th stage but with still no spawning. It appears that P. semisulcatus requires not only optimal environmental conditions but also a certain stimulus such as ablation or temperature fluctuation for successful maturation and spawning in captivity during the winter season. Small tank size (1.2 m in diameter) did not inversely affect mating success of P. semisulcatus at the sex ratio of 1:2 male/female and 10 shrimp/m 2 stocking density. The present results have demonstrated that eyestalk ablation or cyclic temperature fluctuation techniques can successfully be applied to obtain off-season spawning from P. semisulcatus broodstock in the sub-tropics.

Sunny‐side up: flower heliotropism as a source of parental environmental effects on pollen quality and performance in the snow buttercup,Ranunculus adoneus(Ranunculaceae)

Floral traits affect mating success via their influence on the microenvironment in which sexual reproduction occurs as well as their impact on pollinator attraction. Here we investigate the importance of flower heliotropism as a source of parental environmental effects on pollen quality and performance. Flowers of the snow buttercup, Ranunculus adoneus, closely track the sun's rays. We experimentally restrained flowers to test for effects of heliotropism on pollen quality and performance after pollination. When equivalent amounts of pollen were transferred to recipient pistils, pollen from solar-tracking donor flowers exhibited a 32% advantage in germination compared to pollen from stationary (tethered) donor flowers. By the end of anthesis, pistils of tracking flowers contained 40% more germinating pollen grains and 44% more pollen tubes midway down the style than pistils of stationary ones. Solar tracking had no direct effect on pollen tube growth. The greater amount of germinating pollen in tracking flowers accounted for the treatment effect on pollen tube density. A survey of pollen receipt and pollen germination in naturally tracking flowers indicated that solar tracking primarily affects pollen tube density by promoting pollen germination rather than pollen deposition. We conclude that flower heliotropism, by enhancing the paternal environment for pollen development and the maternal environment for pollen germination, represents a source of positive parental environmental effects on pollen performance in snow buttercups.

Disentangling Female Mate Choice and Male Competition in the Rainbow Darter, Etheostoma caeruleum

Sexual selection via female choice is assumed to be common in darters despite few studies demonstrating the phenomenon. This study examines the breeding behaviors of the rainbow darter, Etheostoma caeruleum, and addresses the following four questions: Do females exhibit mating preferences? Which behavioral variables are good measures of female mating preferences? Which male behaviors are used in the context of mating? How do female choice and male competition affect mating success? In dichotomous choice tests, where females could choose between males from two different populations, females performed a precopulatory behavior (nosedigs) significantly more often in front of males from Prairieville Creek than they did in front of males from Seven Mile Creek. However, no pattern of choice was detected when preference was measured as the amount of time spent associated with each male. When the animals were allowed to interact freely, males competed aggressively over the female by chasing and attacking each other. Group spawns occurred where two males mated simultaneously with the female. Male spawning success was positively correlated with male guarding ability (the ability to prevent a competing male from coming between himself and the female). However, there were no significant correlations between overt aggression (chases and attacks) and male spawning success or between female preference (measured in dichotomous choice tests) and male spawning success. Male interactions, in the form of guarding, appear to play a larger role in determining male mating success than does female choice.

INFLUENCE OF MALE DIET ON MALE MATING SUCCESS AND LONGEVITY AND FEMALE REMATING IN THE MEDITERRANEAN FRUIT FLY (DIPTERA: TEPHRITIDAE) UNDER LABORATORY CONDITIONS

The purpose of the present study was to investigate the effect of dietary protein on the mating behavior and survival of male Mediterranean fruit flies (medflies), Ceratitis capitata (Wied.), as a means of enhancing the effectiveness of mass-reared males in sterile release programs to suppress wild populations. Conducted in the laboratory, our study addressed three main questions: 1) Does the inclusion of protein in the adult diet affect mating success of wild and mass-reared males? 2) Are copulation duration and remating tendency of wild females affected by the strain (wild versus mass-reared) and diet (protein-fed versus protein-deprived) of their initial mating partner? 3) Does the inclusion of protein in the adult diet affect the longevity of mass-reared males? In mating trials involving wild flies, protein-fed males had a mating advantage over protein-deprived males. However, the addition of protein to the diet did not boost the mating success of mass-reared males in competition with wild or mass-reared males for wild females. The inclusion of protein in the male diet had no apparent effect on female remating tendency, copulation duration, or male longevity. Independent of male diet, we found no difference between wild and mass-reared males in the duration of copulations with wild females, and wild females mated initially to wild and mass-reared males displayed similar remating propensity. The implications of these findings for SIT are discussed.

Path analysis and the relative importance of male–female conflict, female choice and male–male competition in water striders

Three major behavioural mechanisms underlying sexual selection in many systems are male–male competition, female choice and male–female conflict. We used path analysis to evaluate the relative importance of these mechanisms in generating sexual selection on a suite of male traits in the stream-dwelling water strider, Aquarius remigis. To gather data for the analysis, we quantified the morphology (total length, limb length, forefemur width, genital length), behaviour (activity), mating frequency, mean mating duration and overall mating success of 96 adult males over a 10-day period. Males varied considerably in mating success. Over the 10 days, individual males mated 0–14 times, spending 0–67% of their time in copula. Path analysis showed that male–male competition was important in favouring larger males with longer limbs that tended to be more active. Active males should encounter females more frequently. In water striders, almost all male–female encounters result in intense premating struggles pitting female resistance to mating against male insistence. This male–female conflict favoured larger males with longer genitalia. These traits help males overcome female resistance. Female choice was expressed via female-controlled variation in mate-guarding durations. Female choice favoured smaller males perhaps because they are lighter, less expensive ‘shields’ against harassment by other males. Male size thus affected mating success via all three behavioural mechanisms. Weak, overall sexual selection favouring larger males was the product of conflicting effects: male–female conflict strongly favouring larger males and male–male competition weakly favouring larger males, offset by female choice favouring smaller males. Separate analyses for warmer versus colder days showed that on colder days (daily high below 20°C), male–male competition was the main mechanism generating variation in mating frequency, while on warmer days, both male–male competition and male–female conflict were important. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.

Analysis of tufted capuchin (Cebus apella) courtship and sexual behavior repertoire: changes throughout the female cycle and female interindividual differences.

Sexual solicitations and initiative (proceptivity, sensu Beach [1976] Horm Behav 7:105-138) are important components of the sexuality of females of many primate species. In the tufted capuchin (Cebus apella), female proceptivity characterizes the species' mating system. In study 1, we defined and discussed 20 behavioral patterns based on the observation of 6 females and 5 males living in two social groups. In study 2, each behavior, including mounting activity, was quantitatively assessed during the periovulatory and nonperiovulatory cycle phases of 4 females, detected on the basis of urinary progestin levels (N = 20 ovulatory cycles, 5 for each female); moreover, we monitored changes in females' social interactions (agonism, grooming activity, and play). Nine of the behaviors typically used by the female during courtship and in sexual interactions showed a dramatic increase during the periovulatory phase. Though males mounted females at an apparently higher rate during the periovulatory than the nonperiovulatory phase, the difference was not significant. However, when adult male mounting is separated into those which occur within play and nonplay contexts, there is a significant periovulatory phase effect for mounts not associated with play. Females groomed adult males at the same rate throughout the cycle. Agonism and play did not show any phase effect; however, females' avoidance of adult males significantly increased during the periovulatory phase. Finally, each female made a statistically different use of the behavioral repertoire by performing some behaviors more than others. This variability among females during courtship calls for further research into whether it affects mating success.

Mating success and mating behaviour of the aphid, Myzus persicae (Hemiptera: Aphididae)

In this study, aspects of the reproductive performance and behaviour of male Myzus persicae (Sulzer) (Hemiptera: Aphididae) were investigated. We report that males of clones possessing an autosomal 1,3 translocation conferring insecticide resistance show a weak trend for a reduction in reproductive potential. Clones with the translocation that can produce males but no mating females (androcyclic clones) did not have an additional disadvantage. The age of virgin males and females affected mating success. Young males and females, 0-5 days old, were the most successful with respect to the number of females mated and number of eggs produced. There was a decline in reproductive potential after 9-10 days into adult life for males and after 4-5 days for females. Mating behaviour was observed in the laboratory and described. Some pre-copulatory stroking behaviour by the fore and hind legs of the male was observed. Females occasionally walked in copula sometimes resulting in the disengagement of the male before the termination of mating. Average mating duration in the experimental conditions was 10.5 ± 4.0 minutes and both males and females readily mated more than once.

Male size does not affect mating success (of Anopheles gambiae in São Tomé).

For malaria control, the utility of transgenic vector Anopheles mosquitoes (Diptera: Culicidae) refractory to Plasmodium transmission, will depend on their interbreeding with the wild vector population. In many species, larger males are more successful in obtaining mates. In São Tomé island, we determined that size did not affect mating success of male Anopheles gambiae Giles sensu stricto, the main malaria vector in tropical Africa. Also we showed that larval intraspecific competition is probably insignificant in this population of An. gambiae. Thus, the potential success of transgenic An. gambiae is unlikely to be affected by size selection under field conditions.