Low levels of relatedness on black grouse leks despite male philopatry

In lekking species, males cluster on specific areas for display (the leks) and females generally prefer to copulate with males on large aggregations. The maintenance of leks in which only a few males reproduce might be explained if subordinate males gain indirect fitness benefits. By joining a lek on which relatives are displaying, subordinates might attract more females to the lek thereby increasing the mating opportunities of their kin. In black grouse, a genetic structure among leks has previously been found suggesting that relatives could display together. Using 11 microsatellite loci, we extended this result by testing for the presence of kin structures in nine black grouse leks (101 males). The genetic differentiation among flocks was higher in males than in females, suggesting female-biased dispersal and male philopatry. Because of this genetic structure, males were more related within than among leks. However, the mean relatedness within each lek hardly differed from zero. The lekking males were not more related than random assortments of males from the winter flocks and there were no kin clusters within leks. Thus, black grouse males do not choose to display with and close to relatives. Male philopatry alone was not sufficient to induce elevated levels of relatedness on the leks either because of male partial dispersal or a rapid turnover of the successful males. The indirect fitness benefits associated with males' settlement decision are probably limited compared to the direct benefits of joining large aggregations such as increased current and future mating opportunities.     

Genotyping faeces reveals facultative kin association on capercaillie’s leks

The role that kin selection might play in the evolution of lekking in birds remains controversial. Recent molecular data suggest that males displaying on leks are related. Here we investigated the genetic structure and pattern of relatedness on leks of a declining population of capercaillie (Tetrao urogallus) using microsatellite genetic markers. Since the species is highly sensitive to disturbance, we adopted a non-invasive method by using faecal samples collected in the field. Based on a dataset of 50 males distributed in 6 sub-populations, we found significant genetic structuring among sub-populations, and a significant pattern of isolation by distance among leks. Estimates of relatedness showed that males displaying on the same lek were related, even when controlling for the effects of genetical differentiation among sub-populations. In addition, the frequency distribution of relatedness values indicated that leks contain a mixture of close kin and unrelated individuals (34 and 66%, respectively). This pattern is consistent with the hypothesis that leks often contain kin associations, which might be due to very restricted dispersal of some of the males or to joint dispersal of kin. The results are discussed with respect to their implication for the conservation of endangered populations.     

Determinants and costs of natal dispersal in a lekking species

Avoidance of competition and inbreeding have been invoked as the major ultimate causes of natal dispersal, but proximate factors such as sex, body condition or birth date can also be important. Natal dispersal is expected to be of particular importance to understanding the ecological and evolutionary implications of dispersal strategies, since 1) numerous evidences suggest that individual differences in dispersal strategies are expressed early in life (i.e. at the onset of dispersal movement), 2) ultimate and proximate factors are more likely to act during this stage and 3) this stage is associated with the highest mortality rates in most vertebrates. We analysed the natal dispersal (hereafter, dispersal) behaviour in 100 marked individuals of a lekking species, the North African houbara bustards Chlamydotis undulata undulata, during four years. We investigated the effects of proximate factors on dispersal pattern and distance, as well as the mortality cost associated with movement using multievent models, allowing uncertainty in sex assignment and mixture of live recaptures and dead recoveries. Overall, males exhibited longer dispersal distances than females, contrary to the common pattern in birds. Moreover, males in poorer body condition moved further than those in better condition, whereas distance was independent of body condition in females. Finally, survival rates during dispersal were lower for females than for males and were negatively correlated with the distances covered with a similar distance‐survival slope in the two sexes. Collectively, our results suggest that 1) there is substantial dispersal cost in both sexes, 2) dispersal is strongly male‐biased, 3) this bias is unlikely to be explained by differential movement costs of each sex, and 4) dispersal differences found across different categories of individuals are in broad agreement with both the inbreeding avoidance and intraspecific competition mechanisms for dispersal.     

Male mate choice, sexual conflict and strategic allocation of copulations in a lekking bird

The males of lekking species are not expected to be choosy about mating because a reduced reproductive rate due to lost mating opportunities should outweigh any benefits of male choice. Females have traditionally not been expected to be competitive in this system since their reproduction has usually been assumed to be unconstrained by male availability. Here we show that, in contrast to these predictions, males are choosy and females may be competitive in the lekking great snipe Gallinago media. Males preferred by many females often refused to copulate with and even chased away females that the male had already copulated with, whereas females seemed to compete for repeated copulations. We conclude that choosiness may sometimes pay for popular males in those lekking species where females copulate repeatedly. Apparently, evolutionary conflicts of interest between individuals may cause a richer repertoire of behavioural adaptations than, to our knowledge, hitherto realized.     

Dispersal of phlebotomine sand flies (Diptera: Psychodidae) in a Colombian focus of Leishmania (Viannia) braziliensis.

Dispersal of five species of phlebotomine sand flies was studied in a coffee plantation near Arboledas, Colombia, by mark-release-recapture studies using fluorescent powders. The estimated recapture rate for males of Lutzomyia shannoni marked and released during the day was 28.1%, significantly higher than that for all other species (p < 0.05). Recapture rate of female Lu. shannoni was 9.5%, and no females of the other four species were recovered. This suggests either that Lu. shannoni is a more sedentary species than the others, or that the large trees on which these insects were captured and recaptured function as foci of lekking behaviour in males. The high recapture rates of females of this species may indicate that oviposition occurs in close proximity to the bases of these trees. Although most marked sand flies were recaptured within 200 m of their release point, a single female Lu. gomezi was recovered 960 m away 36 h after release. This suggests that the dispersal capacity of Lutzomyia species may be greater than has been thought, an important consideration in future control programs directed against these insects in Leishmania-endemic areas.     

Absence of male reproductive skew,along with high frequency of polyandry and conspecific brood parasitism in the lekking Houbara bustard Chlamydotis undulata undulata

Behavioural studies have led to the perception that lekking species experience a high male reproductive skew as a consequence of females’ selective mate choice. In addition, observations suggest that females copulate only once and therefore polyandry seems unlikely as females are supposed to choose the best male available. In order to analyse the mating strategy of the Houbara bustard, an endangered lekking species under reinforcement in eastern Morocco, we used microsatellite data to perform paternity analyses. None of our observations followed common expectations under a lek mating system: we found no male reproductive skew suggesting no apparent selective female mate choice and no apparent male benefit from lekking. In contrast, a high level of polyandry (60 % of the nests) was recorded suggesting that sperm competition may operate. In addition, we present another case of conspecific brood parasitism in a lekking species and this was an unexpected alternative strategy for a species presenting high parental cost and low fecundity. The increasing number of studies contradicting common assumptions on lekking species suggests that alternative breeding strategies such as males pursuing an off‐lek mating strategy, female polyandry and even conspecific brood parasitism might be more widespread in lekking species than previously thought.     

Nutritional reserves regulate male participation in Mediterranean fruit fly leks

1. The mating system of Mediterranean fruit flies ( Ceratitis capitata , Diptera: Tephritidae), is based on male leks that form on the foliage of trees. Following observations that not all males participate in leks, the hypotheses that (a) small males are absent from leks and (b) males with inadequate nutrient reserves are unable to participate in leks were examined.
2. The size and weight of lekking males ( n = 183) and resting males captured at the same time in the vicinity of leks ( n = 148) were established. In addition, using biochemical techniques, the amounts of sugar, glycogen, lipid and protein in each individual were established quantitatively.
3. There was no significant size difference between lekking and resting males. However, lekking males were significantly heavier and contained significantly more sugars and protein than resting males.
4. In conclusion, leks are exclusive, and only males with adequate nutritional reserves may join. Thus, in this species, reproductive success is closely linked to foraging success.     

Experimental Evidence for Male Sequential Mate Preference in a Lekking Species

In lekking species females visit male aggregations solely to copulate or have their eggs fertilized. Because lekking males do not contribute to parental care, evolutionary theory does not expect them to be choosy. However, we show here that in the cichlid fish Astatotilapia flaviijosephi the lekking males exhibit sequential mate preference that strongly suggests a trade‐off between present and future reproductive effort. We tested mate preferences of A. flaviijosephi males by sequentially presenting them with two images of a gravid female, differing only in size. Previously, males were shown to prefer larger, more fecund females in simultaneous preference tests. The sequential presentation experiment reported here indicates that even in the absence of simultaneous presentation, males spent more time courting larger female images, and stayed longer in their vicinity. Thus, our study suggests that lekking males may be much choosier than previously appreciated. Furthermore, considering the intense competition among lekking males we also suggest that male choosiness, combined with other factors, may help to solve the ‘paradox of the lek’. It can make less attractive females more available to subordinate males, thereby increasing the contribution of the latter to the population gene pool and keeping genetic variability among males at a level that justifies female choice.     

Antelope mating strategies facilitate invasion of grasslands by a woody weed

Intra and interspecific variation in frugivore behaviour can have important consequences for seed dispersal outcomes. However, most information comes from among‐species comparisons, and within‐species variation is relatively poorly understood. We examined how large intraspecific differences in the behaviour of a native disperser, blackbuck antelope Antilope cervicapra, influence dispersal of a woody invasive, Prosopis juliflora, in a grassland ecosystem. Blackbuck disperse P. juliflora seeds through their dung. In lekking blackbuck populations, males defend clustered or dispersed mating territories. Territorial male movement is restricted, and within their territories males defecate on dung‐piles. In contrast, mixed‐sex herds range over large areas and do not create dung‐piles. We expected territorial males to shape seed dispersal patterns, and seed deposition and seedling recruitment to be spatially localized. Territorial males had a disproportionately large influence on seed dispersal. Adult males removed twice as much fruit as females, and seed arrival was disproportionately high on territories. Also, because lek‐territories are clustered, seed arrival was spatially highly concentrated. Seedling recruitment was also substantially higher on territories compared with random sites, indicating that the local concentration of seeds created by territorial males continued into high local recruitment of seedlings. Territorial male behaviour may, thus, result in a distinct spatial pattern of invasion of grasslands by the woody P. juliflora. An ex situ experiment showed no beneficial effect of dung and a negative effect of light on seed germination. We conclude that large intraspecific behavioural differences within frugivore populations can result in significant variation in their effectiveness as seed dispersers. Mating strategies in a disperser could shape seed dispersal, seedling recruitment and potentially plant distribution patterns. These mating strategies may aid in the spread of invasives, such as P. juliflora, which could, in turn, negatively influence the behaviour and ecology of native dispersers.     

Choosy males in a haplochromine cichlid: first experimental evidence for male mate choice in a lekking species

Current theories of mate choice predict that the level of choosiness of males and females will depend on their relative investment in parental care. Males often invest less than females and are expected to be less choosy, especially in lekking species where males contribute only sperm. Our study of the haplochromine cichlid fish Astatotilapia flaviijosephi, a maternal mouthbrooder, provides the first experimental evidence for male mate choice in a lekking species. In this species the number of eggs spawned is positively correlated with female weight, thus making larger females potentially better mates. In the laboratory, we conducted a simultaneous choice experiment where males had the opportunity to associate with, and court, each of two females that differed in size. Males preferred to court the larger female and spent more time courting during experimental trials involving larger females. This selective allocation of courtship effort to more attractive (i.e. heavier) females suggests that there may be constraints on males in fertilizing multiple females, thus compelling them to be choosy.Copyright 2003 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.      

Local genetic structure in a white-bearded manakin population

Local genetic structure was studied in lekking white-bearded manakins in a study area on northern Trinidad, West Indies. The study population consisted of nine leks, at which a total of 238 birds were caught. By genotyping the individuals at eight polymorphic microsatellite loci we inferred some males on leks to be related (r = 0.25) as we found an average number of 14.8 half-sib relationships and two full-sib relationships per lek. We found that the sampled birds belonged to one genetic population that was slightly inbred (FIS and FIT = 0.02). Kinship coefficients decreased with increasing geographical distance, indicating that related birds displayed at the same or nearby leks. However, leks did not consist of only one family group because the average genetic distance (aij) between males within leks was higher than when comparing males on leks within close proximity. These patterns suggest limited male dispersal, that some type of kin recognition process between individuals may exist in this species and that males on leks may be more likely to establish themselves as territory-holding birds if a relative is already present.     

Microsatellite DNA analysis shows that greater sage grouse leks are not kin groups

The spectacular social courtship displays of lekking birds are thought to evolve via sexual selection, but this view does not easily explain the participation of many males that apparently fail to mate. One of several proposed solutions to this 'lek skew paradox' is that kin selection favours low-ranking males joining leks to increase the fitness of closely related breeders. We investigated the potential for kin selection to operate in leks of the greater sage grouse, Centrocercus urophasianus, by estimating relatedness between lekking males using microsatellite DNA markers. We also calibrated these estimates using data from known families. Mean relatedness within leks was statistically indistinguishable from zero. We also found no evidence for local clustering of kin during lek display, although males tended to range closer to kin when off the lek. These results make kin selection an unlikely solution to the lek skew paradox in sage grouse. Together with other recent studies, they also raise the question of why kin selection apparently promotes social courtship in some lekking species, but not in others.     

Virgin females compete for mates in the male lekking species Ceratitis capitata

Abstract. Aggressive behaviour occurring in intrasexual competition is an important trait for animal fitness. Although female intrasexual aggression is reported in several insect species, little is known about female competition and aggressive interactions in polygynous male lekking species. The interactions of female Mediterranean fruit flies, Ceratitis capitata (a male lekking species), with other females and mating pairs under laboratory conditions are investigated. Mature, unmated (virgin) females are aggressive against each other and against mating pairs, whereas immature females are not. Female aggression against other females decreases dramatically after mating; however, mated females maintain aggression against mating pairs. In addition, higher intrasexual aggression rates are observed for mature, virgin females than for virgin males of the same age. The results show that female aggressiveness is virginity related, suggesting female competition for mates. These findings have important implications for understanding the physiological aspects of a complex social behaviour such as aggression and should stimulate further research on female agonistic behaviour in male lekking mating systems.     

Male Lekking duration and Mating Benefits in a Lek-Forming Hawaiian Drosophila

Variation in lekking duration of males of a Hawaiian Drosophila, D. grimshawi, was examined in laboratory enclosures. The relationship between variation in male lekking activity and number of eggs laid by females, proportion of eggs hatching, and total offspring production was investigated. Females mating highly active males laid fewer eggs and thus had lower offspring production than females mating less active males, even though other studies have shown that D. grimshawi females prefer more active males as mates. These results are discussed in terms of conflict between males and females over mating benefits and in trade-offs faced by males between lekking duration and offspring production per mating. Testis mass was not related to lekking activity levels, but males with heavier testes produced more offspring per mating, suggesting that males may vary in other ways that correlate with possible direct fitness gains for females.     

Sex-ratio-distorting Wolbachia causes sex-role reversal in its butterfly host

Sex-role-reversed mating systems in which females compete for males and males may be choosy are usually associated with males investing more than females in offspring. We report that sex-role reversal may also be caused by selfish genetic elements which distort the sex ratio towards females. Some populations of the butterflies Acraea encedon and Acraea encedana are extremely female biased because over 90% of females are infected with a Wolbachia bacterium that is maternally inherited and kills male embryos. Many females in these populations are virgins suggesting that their reproductive success may be limited by access to males. These females form lekking swarms at landmarks in which females exhibit behaviours which we interpret as functioning to solicit matings from males. The hypothesis that female A. encedon swarm in order to mate is supported by the finding that, in release recapture experiments, mated females tend to leave the swarm while unmated females remained. This behaviour is a sex-role-reversed form of a common mating system in insects in which males form lekking swarms at landmarks and compete for females. Female lekking swarms are absent from less female-biased populations and here the butterflies are instead associated with resources in the form of the larval food plant.     

Dual reproductive cost of aging in male Medflies: dramatic decrease in mating competitiveness and gradual reduction in mating performance

Although age-based effects on the reproductive success of males have been reported in several animal taxa the cost of aging on male mating success in lekking species has not been fully explored. We used the Mediterranean fruit fly, a lekking species, to investigate possible cost of aging on male reproductive success. We performed no choice and choice mating tests to test the hypothesis that aging does not affect the mating performance (mating success in conditions lacking competition) or the mating competitiveness (mating success against younger rivals) of males. The mating probability of older males decreased significantly when competing with younger males. Aging gradually reduced the mating performance of males but older males were still accepted as mating partners in conditions lacking competition. Therefore, older males are capable of performing the complete repertoire of sexual performance but fail to be chosen by females in the presence of young rivals. Older males achieved shorter copulations than younger ones, and female readiness to mate was negatively affected by male age. Older and younger males transferred similar amount of spermatozoids to female spermathecae. Females stored spermatozoids asymmetrically in the two spermathecae regardless the age of their mating partner. Aging positively affected the amount of spermatozoids in testes of both mated and nonmated males. No significant differences were observed on the amount of spermatozoids between mated and nonmated males.     

Non-random mating in classical lekking grouse species: seasonal and diurnal trends

This paper is the first to integrate both field and theoretical approaches to demonstrate that fertility benefits can be a direct benefit to females mating on the classical lek. Field data collected for male sharp-tailed grouse (Tympanuchus phasianellus), a classical lekking species, revealed potential fertility benefits for selective females. Adult males and individuals occupying centrally located territories on the lek were found to have significantly larger testes than juveniles and peripheral individuals. Further, using empirical data from previously published studies of classical lekking grouse species, time-series analysis was employed to illustrate that female mating patterns, seasonal and daily, were non-random. We are the first to show that these patterns coincide with times when male fertility is at its peak. Received: 26 February 1999 / Revised: 13 December 1999 / Accepted: 15 March 2000     

Testing predictions for the evolution of lekking in the sandfly, Lutzomyia longipalpis

We carried out a combination of field and laboratory experiments to investigate two possible mechanisms promoting the evolution of lekking in the sandfly, Lutzomyia longipalpis. Males in this species lek on or near hosts that females visit to mate and feed. To test whether the distribution of resources, lek size and female number were positively correlated (a prediction of hotspot models) we manipulated the availability of potential lek sites by varying the numbers of chickens, Gallus gallus domesticus, held in field cages. We then investigated the distribution of males and females across leks formed within these cages and measured males to assess the relationship between male size and lek size. The number of males attracted to a lek increased with the number of hosts present and on average males on larger leks had longer abdomens. The number of females was positively correlated with the number of males present, but the average number of females per male decreased with increasing lek size. In a second experiment, we introduced single females to laboratory leks of different sizes, and compared female latency to mate. Contrary to an explicit prediction of the black hole model, lek size had a direct effect on a female's latency to mate. Females at larger leks encountered and copulated with males sooner than those at smaller aggregations, but the length of time a pair spent courting did not vary with lek size. Our results suggest that the black hole model is unlikely to explain the evolution of lekking in this species. The data instead support the hotspot model as a possible mechanism promoting lekking in L. longipalpis but suggest that female preference for larger leks may need to be invoked to obtain the degree of aggregation observed.     

Restrictive mating by females on black grouse leks

In bird species with pair bonds, extra-pair matings could allow females to choose genetically superior males. This is not needed in lekking species because female choice is not constrained by pairing opportunities. However, polyandry has been reported in most lekking species studied so far. Using 12 microsatellite loci, we determined the paternity of 135 broods of black grouse sampled between 2001 and 2005 (970 hatchlings and 811 adult birds genotyped). The paternity assignments were combined to lek observations to investigate the mating behaviour of black grouse females. About 10% of the matings seemed to take place with males displaying solitarily. Forty per cent of the copulations between males displaying on the studied leks and radio-tagged females were not recorded. This was due to difficulties in identifying the females and because our observations did not cover all the possible time for matings. However, females of the undetected copulations had chosen males that were already known to be successful on the leks. There was a strong consistency between the observations and true paternity, even when the copulation was disturbed by a neighbouring male. Multiple mating and multiple paternities were rare. We can now confidently ascertain that most females mate only once with one male for the whole clutch. This mating behaviour requires that a single insemination is sufficient to fertilize a clutch and that females can determine whether the sperm has been successfully transferred. Grouse Tetraoninae with many lekking species may be the only bird taxon that has evolved these traits.     

Evolution of sexual size dimorphism in grouse and allies (Aves: Phasianidae) in relation to mating competition,fecundity demands and resource division

Sexual size dimorphism (SSD) is often assumed to be driven by three major selective processes: (1) sexual selection influencing male size and thus mating success, (2) fecundity selection acting on females and (3) inter‐sexual resource division favouring different size in males and females to reduce competition for resources. Sexual selection should be particularly strong in species that exhibit lek polygyny, since male mating success is highly skewed in such species. We investigated whether these three selective processes are related to SSD evolution in grouse and allies (Phasianidae). Male‐biased SSD increased with body size (Rensch’s rule) and lekking species exhibited more male‐biased SSD than nonlekking ones. Directional phylogenetic analyses indicated that lekking evolved before SSD, but conclusions were highly dependent on the body size traits and chosen model values. There was no relationship between SSD and male display agility, nor did resource division influence SSD. Although clutch mass increased with female body size it was not related to the degree of SSD. Taken together, the results are most consistent with the hypothesis that lekking behaviour led to the evolution of male‐biased SSD in Phasianidae.