The effect of B chromosomes on mating success of the grasshopper Eyprepocnemis plorans

The mating ability of E. plorans was tested in laboratory conditions in six experimental units composed of ten males and fifteen females during 31 days. When significant differences were found (three from the six cages, and in totals) they involved a decrease of matings involving males with B chromosomes. The same tendency seems to exist in females, but to a lesser extent, so that a significant effect is only detected when the totals are considered. Accessory chromosomes also delay, in both sexes, the occurrence of the first mating. No mating preferences depending on the number of Bs were detected.     

Male life history and intergroup mobility among ringtailed lemurs (Lemur catta)

Lemur catta shares a male-biased dispersal pattern with most primate species and the majority of mammals. Individuals in a free-ranging population of ringtailed lemurs were captured, marked, released, and monitored for a 40-month period. Sixty-four percent of the males (43 of 67) migrated or were missing within this period and all nine censused groups were affected by migration. Males migrate from their natal group and then may migrate again after reaching full adult body weight. Full-sized adult males migrate at a rate of 0.28 per year or once every 3.5 years and may change groups a number of times during their life. Migrations occurred within a 6-month period, ending just after the mating season. However, there is no direct connection between mating success and male migration. Females mate with transferring males, with group males, and with visitors from adjacent groups. The age-related pattern of male migration and the occurrence of extragroup mating inLemur catta is similar to that described for several species of macaques.     

Starvation and the Mating Success of Wild Male Mediterranean Fruit Flies (Diptera: Tephritidae)

Recent evidence suggests that the nutritional state of male Mediterranean fruit flies, Ceratitis capitata (Wied.) (medfly), is an important influence on various components of their reproductive biology, including mating success. The objective of the present study was to examine experimentally the effect of temporary starvation on the mating success of wild male C. capitata. Males were maintained on protein–sugar or sugar-only diets, and for each diet we compared the mating success of continuously fed males versus males starved for 18 or 24 h immediately before testing. In trials conducted on field-caged, host trees, males starved for 24 h obtained only about half as many matings as fed males for both diets. However, when the starvation period was 18 h, starved males reared on the protein–sugar diet mated significantly less frequently than fed males, whereas starved males reared on sugar mated as often as fed males. Measurements of male pheromone calling and female attraction revealed that reduced mating success likely reflected the decreased signaling activity of starved males.     

Body size,male aggression,and male mating success in the cottonwood borer,Plectrodera scalator (Coleoptera: Cerambycidae)

The natural history and mating system ofPlectrodera scalator exhibit several unusual characteristics. Larvae and adults feed on the wood and foliage, respectively, of the same plant,Populus deltoides. The population sex ratio, based on censuses of oviposition areas, is female-biased. Females are significantly larger than males, yet males are intensely aggressive. Larger males tend to win escalated battles, which involve grasping of antennae with mandibles, but smaller males can defeat larger males if they grasp their opponent's antenna first. Most escalated fights involve possession of a female, but prior possession does not play a role in determining the outcome of these fights. The size-dependent fighting advantage does not translate into a mating advantage for larger males. There is no significant difference in elytron length or body mass between mating and single males. Larger females are not preferred as mates. The mating system appears to be a mixture of female-defense and scramble-competition tactics. One advantage to males of aggression may be in its effect on sperm precedence. Males appear to be able to remove previously deposited sperm from a female's reproductive tract.     

Intraspecific competition and mating between fungal strains of the anther smut Microbotryum violaceum from the host plants Silene latifolia and S. dioica

Abstract We studied intraspecific competition and assortative mating between strains of the anther smut fungus Microbotryum violaceum from two of its host species, Silene latifolia and S. dioica . Specifically, we investigated whether strains from allopatric host populations have higher competitive ability on their native host species and show positive assortative mating. In general, strains isolated from S. latifolia outcompeted strains isolated from S. dioica on both host species, but in female hosts, heterotypic dikaryons (i.e., dikaryons composed of a haploid strain originating from S. latifolia and a haploid strain originating from S. dioica ) were most successful in competition. Furthermore, the latency period was significantly shorter for heterokaryons that contained at least one strain originating from S. latifolia , compared to heterokaryons that only contained strains originating from S. dioica . The frequencies of conjugations between strains originating from S. latifolia were much higher than conjugation frequencies between strains originating from S. dioica . A significant positive correlation was detected between the relative success of strains in competition and in conjugation, suggesting that success of a strain in competition might be partly determined by its swiftness of mating. In addition, reciprocal differences within heterotypic crosses revealed a significant effect of fungal mating type, with mating type a₁ being the main determinant of mating pace. The observed differences in infection success, conjugation rate, and latency period in favor of strains from S. latifolia relative to strains from S. dioica on both host species are discussed in an evolutionary context of opportunities for the maintenance of differentiation between different formae speciales upon secondary contact.     

Pronounced reproductive skew in a natural population of green swordtails, Xiphophorus helleri

For many species in nature, a sire's progeny may be distributed among a few or many dams. This poses logistical challenges--typically much greater across males than across females--for assessing means and variances in mating success (number of mates) and reproductive success (number of progeny). Here we overcome these difficulties by exhaustively analyzing a population of green swordtail fish (Xiphophorus helleri) for genetic paternity (and maternity) using a suite of highly polymorphic microsatellite loci. Genetic analyses of 1476 progeny from 69 pregnant females and 158 candidate sires revealed pronounced skews in male reproductive success both within and among broods. These skews were statistically significant, greater than in females, and correlated in males but not in females with mating success. We also compare the standardized variances in swordtail reproductive success to the few such available estimates for other taxa, notably several mammal species with varied mating systems and degrees of sexual dimorphism. The comparison showed that the opportunity for selection on male X. helleri is among the highest yet reported in fishes, and it is intermediate compared to estimates available for mammals. This study is one of a few exhaustive genetic assessments of joint-sex parentage in a natural fish population, and results are relevant to the operation of sexual selection in this sexually dimorphic, high-fecundity species.     

Nest‐site fidelity in parental male bluegill Lepomis macrochirus: spatial patterns and the influence of prior mating success

A 4 year mark–recapture study examined the pattern of nesting site fidelity of parental‐type male bluegill Lepomis macrochirus. The study results indicated that iteroparous male L. macrochirus choose new nest sites near their own previously used sites. The scale of site fidelity varied, but generally males choose to renest within shoreline areas rather than specific or exact nest locations (94% within‐year, 86% among‐years). Iteroparous males also displayed no preference to nest in proximity to neighbouring males from previous colonies to suggest social fidelity. Contrary to expectation, manipulating males' reproductive success had no significant effect on the pattern or scale of male reproductive site fidelity.     

The unexpected mating system of the androdioecious barnacle Chelonibia testudinaria (Linnaeus 1758)

Androdioecy was first described by Darwin in his seminal work on barnacle diversity; he identified males and hermaphrodites in the same reproductive population. Today, we realize that many androdioecious plants and animals share astonishing similarities, particularly with regard to their evolutionary history and mating system. Notably, these species were ancestrally dioecious, and their mating system has the following characteristics: hermaphrodites self‐fertilize frequently, males are more successful in large mating groups, and males have a mating advantage. A male mating advantage makes androdioecy more likely to persist over evolutionary times. Androdioecious barnacles, however, appear to persist as an outlier with a different evolutionary trajectory: they originate from hermaphroditic species. Although sexual systems of androdioecious barnacles are known, no information on the mating system of androdioecious barnacles is available. This study assessed the mating system of the androdioecious barnacle Chelonibia testudinaria. In contrast to other androdioecious species, C. testudinaria does not self‐fertilize, males do not have a mating advantage over hermaphrodites, and the average mating group is quite small, averaging only three individuals. Mating success is increased by proximity to the mate and penis length. Taken together, the mating system of C. testudinaria is unusual in comparison with other androdioecious plants and animals, and the lack of a male mating advantage suggests that the mating system alone does not provide an explanation for the maintenance of androdioecy in this species. Instead, we propose that sex‐specific life history equalizes male and hermaphroditic overall fitness.     

Puddling in butterflies: sodium affects reproductive success in Thymelicus lineola*

ABSTRACT. Adults of many species of Lepidoptera, principally the males, frequent mud puddles, edges of streams, carrion and animal excreta where they imbibe moisture, an activity referred to as 'puddling' Sodium ions are the only known stimulus present which cause males of at least two lepidopteran species to drink for extended periods. In the European skipper Thymelicus lineola (Ochsenheimer) (Lepidoptera: Hesperiidae), only males puddle, even though they have concentrations of abdominal sodium 2–3 times that of females at emergence. During their first mating, males transfer 32% of their abdominal sodium to females. This could be of considerable importance given that an average egg complement contains >50% of the total body sodium of females at emergence. Virgin females, as well as having reduced fecundity, have reduced longevity. This is attributed to virgins not obtaining important nutrients which males transfer to females during mating. Access to sodium ions increases the total number of matings by c. 50% for males living >15 days. Access to sodium ions by once-mated males increases the percentage of males which re-mate on the day following first mating; the percentage of females, mated to the twice-mated males, which lay >50% fertile eggs; and the drought resistance of eggs laid by those females.     

Variable microsatellite loci isolated from the azure damselfly,Coenagrion puella (L.) (Zygoptera; Coenagrionidae)

We isolated and characterized 10 polymorphic microsatellite loci from the azure damselfly Coenagrion puella (Zygoptera; Coenagrionidae) as part of a study assessing reproductive success and genetic structure in an isolated population of this species. Levels of genetic diversity were assessed in 50 individuals collected from Queen Elizabeth Country Park, Hampshire, UK. The number of alleles per microsatellite loci ranged from three to 22 and the observed and expected heterozygosities varied between 0.26 and 0.84 and between 0.23 and 0.91, respectively. Two loci showed significant (P < 0.05) heterozygote deficits, likely because of null (non‐amplifying) alleles; one pair of loci was in linkage disequilibrium.     

Trade-off between pre and post-copulatory traits depends on locomotor activity in male Tribolium castaneum beetles

Locomotor performance is an indicator of dynamic exercise; thus, it is a central trait in many animal behaviours. Although higher locomotor endurance may increase male reproductive success (e.g., in mate searching and male–male contests), investment in other male reproductive traits (e.g., male attractiveness and sperm competition) may be decreased through energy consumption due to higher activity levels. Here, I investigated male attractiveness, mating success, and paternity success using males of the red flour beetle Tribolium castaneum selected for higher (H) and lower (L) locomotor endurance. Although there was no difference in male attractiveness between the selection regimes, H males had significantly higher mating success than L males. Conversely, L males had significantly higher paternity success than H males. Therefore, there was a trade-off between mating success and paternity success among the selection regimes, suggesting that locomotor endurance affects male reproduction in T. castaneum, and individual variation of locomotor endurance may be maintained within a population.     

Male mating success, reproductive success and multiple paternity in a natural population of sand lizards: behavioural and molecular genetics data

Sand lizard Lacerta agilis females characteristically mate with several males which, in staged mating experiments, results in multiple paternity of the offspring. In order to investigate multiple paternity in a natural population and interpret male reproductive behaviours in terms of sired young, we sampled the blood of females, potential fathers and hatchlings, and determined paternity using multilocus DNA fingerprinting as well as the variation at a single locus detected by the probe (TC) _n . The paternity analyses were preceded by a laboratory experiment in which we established that the parental alleles identified by the single locus probe were inherited in a Mendelian way. Our molecular data demonstrated that 12 out of 13 males (92%) that sired offspring were correctly identified from the 56 sexually mature males in the population. Also smaller males were accepted as sexual partners by the females, but sired fewer young in competition with larger males and were less able to maintain prolonged post-copulatory mate guarding. This may result in that some sexually successful males are only observed inside a female's home range, but never in pair-association with the female.     

Index of intensity of sexual selection: A comment on Nishida's article

An index of intensity of sexual selection proposed by Nishida (1992: Res. Popul. Ecol. 34: 373–382) was examined. Two examples were presented to show that Nishida's index was not free from confounding effect of mortality schedule. Importance of removing the phylogenetic effects in comparative analyses was also discussed.     

Voice pitch predicts reproductive success in male hunter-gatherers

The validity of evolutionary explanations of vocal sexual dimorphism hinges upon whether or not individuals with more sexually dimorphic voices have higher reproductive success than individuals with less dimorphic voices. However, due to modern birth control methods, these data are rarely described, and mating success is often used as a second-rate proxy. Here, we test whether voice pitch predicts reproductive success, number of children born and child mortality in an evolutionarily relevant population of hunter-gatherers. While we find that voice pitch is not related to reproductive outcomes in women, we find that men with low voice pitch have higher reproductive success and more children born to them. However, voice pitch in men does not predict child mortality. These findings suggest that the association between voice pitch and reproductive success in men is mediated by differential access to fecund women. Furthermore, they show that there is currently selection pressure for low-pitch voices in men.     

Nest orientation patterns in Salaria fluviatilis

The entrances of nests established under small stones by male river blennies Salaria fluviatilis in two rivers of the Ebro Basin in eastern Spain were randomly oriented in slow-flowing sites. In fast-flowing stretches or under large stones, however, nest entrances tended to open at an angle of c . 30° relative to current flow direction, i.e. near a south-east direction. As current velocity increased, males positioned their nest entrance closer and closer to the direction of flow. Selective nest entrance orientation reduced significantly the speed of current reaching the nest entrance such that current velocity was similar (5–7 cm s⁻¹) for all nests, regardless of stone size, prevailing current speed, or study site. Male mating success, measured as egg clutch area, however, was not related to current speed at the nest entrance but instead, it increased with nest stone size and decreased with deviations from a south-east direction. The reasons for female river blenny preference for this specific nest orientation are unknown but may be related to patterns of water flow, and hence oxygenation of the eggs, in the nest.     

Lifetime mating success of males in a natural population of the papilionid butterfly,Atrophaneura alcinous (Lepidoptera: Papilionidae)

Lifetime mating success of males in a natural population of the papilionid butterfly, Atrophaneura alcinous, was investigated and causes of the variation were examined. The most successful males mated with 5 females, whereas about 73% of the males failed to mate. Body size of males was not correlated with their eclosion date, longevity and lifetime mating success. There was no trade-off between mating success and longevity, and long-lived males had a disproportionately high mating success. Although number of available females per male per day was not variable among males with different longevities, long-lived males had higher mating efficiency. Time interval between matings by non-virgin males was shorter than that from eclosion to the first mating. High lifetime mating success of long-lived males was strongly related to their mating experience, not to their age per se.     

A field observation on the influence of aggressive behaviour on mating success in the European grayling

The biggest male grayling present on a spawning area was strongly territorial and developed more aggressive behaviours than smaller males. However, its spawning frequency was similar to that of Smaller males.