Male territoriality and mating system in the European beewolf Philanthus triangulum F. (Hymenoptera: Crabronidae): evidence for a “hotspot” lek polygyny

The evolution of the mating system of a species is strongly influenced by the spatial and temporal distribution of females and/or resources. Here, we describe aspects of the territorial behavior of males of a solitary digger wasp, the European beewolf (Philanthus triangulum) and characterize the mating system. We show that beewolf males establish small territories that do not contain any resources essential to females. These territories are intensively scent-marked with a pheromone from a cephalic gland and are defended against intruders in combat flights. We provide evidence that scent-marking constitutes a chemical display and that the pheromone serves to attract receptive females and, thus, represents a sex pheromone. Using spatial statistics, we show that beewolf territories are clumped in space both with respect to other male territories and, more importantly, with respect to female nesting sites. Additionally, the proportion of days a territory is occupied by a male is correlated with the number of female nests in the vicinity. Taking into account that beewolf males do not defend or provide resources essential to females, but merely display chemically to attract females for mating in an aggregation of territories close to female nesting sites, we conclude that the European beewolf exhibits a hotspot lek polygyny with female nesting sites constituting “hotspots” for lek formation.     

Are Centrally Displaying Males Always the Centre of Female Attention? Acoustic Display Position and Female Choice in a Lek Mating Subterranean Insect

Several conceptual models seek to explain patterns of male display and factors that influence female mate choice in lek mating systems. The central advantage model predicts that males displaying at or near the lek centre should be more attractive to females than are males positioned along the lek periphery. Females may exhibit biases toward these centrally displaying males based on either spatial or display‐related cues. We tested the prediction of the central advantage model in investigating the importance of male display position in the subterranean and lek mating prairie mole cricket (Gryllotalpa major). Gryllotalpa major males form mating aggregations in the early spring and produce an acoustic advertisement signal from a constructed calling chamber at the soil surface. Pair formation occurs in the calling chamber, and males typically maintain these structures for the duration of the reproductive season. To assess whether G. major females exhibit a preference for males calling from centrally located acoustic burrows, we documented the spatial position and number of female attractions for all advertising males across the focal lek. Six spatial attributes related to display position were reduced using principal component analysis and examined for an association with male attractiveness. We found that in general, female attractions were distributed randomly across the lek; male attractiveness was not related to proximity to the lek centre nor to any factor associated with display position. The most highly attractive males, however, were located further from the lek centre and from nearest calling neighbours than other attractive males. Advertising males that segregate themselves within the aggregation and locate nearer the lek margin may gain a geometric advantage resulting in the increased probability of attracting a searching female.     

Effects of avian malaria on male behaviour and female visitation in lekking blue‐crowned manakins

Avian malaria, the infection by blood parasites of the genus Plasmodium, can reduce host fitness not only through mortality, but also by impairing the expression of sexual selection traits. Although different studies highlight the association of parasitism with a decrease in host reproductive success, few studies have addressed the role of parasites in honest signalling by lekking species. Hence, it is still uncertain which fitness components are affected by parasites in these species. We investigated whether avian malaria is associated with a decrease in mating behaviour of male blue‐crowned manakins Lepidothrix coronata and whether it affects female visitation in leks of a population in the central Amazon. Through behavioural observations, we estimated the rates of total male activity and social interaction, as well as the frequency of female visits at individual perches. We then examined if individuals were infected with Plasmodium spp. using molecular techniques. Avian malaria was associated with a decrease in male mating behaviour in each lek, and mating behaviour correlated with female visitation. Although rates of social interaction were not correlated with avian malaria among males, we observed that interacting with several individuals within a lek may be advantageous for males, as they also vocalized and displayed more, thus increasing their chances of being visited by females. Although female visitation was not associated with avian malaria in individuals or leks, it is still possible that female visitation is indirectly affected by avian malaria through the latter's effects on male activity. We suggest a role for male activity as an honest sexual signal for females. Thus, male display rate could be used by females as cue for the probability of a male being infected.     

Lek size variation and its consequences in the ochre-bellied flycatcher, Mionectes oleagineus

Several hypotheses suggest that the costs and benefits of displayin aggregations of different sizes play a major role in boththe evolution of leks and in the distribution of males acrossleks of different sizes. We examined the consequences of variationin lek size for both males and females in a study of the ochre-belliedflycatcher, Mionectes oleagineus. We observed 41 solitary displaysites and leks, ranging in size from 1 to 5 mates, over 3 breedingseasons. Although mean visitation rate by females was positivelycorrelated with lek size, female visitation rate per male remainedconstant across lek sizes. The rate at which females visitedthe male who had the highest female visitation rate at eachlek was positively correlated with lek size as predicted bythe hotshot hypothesis. Neither mean nor per capita intrusionrates were correlated with lek size. For the top-ranked male,however, there was a significant correlation between intrusionrates and the size of the lek at which he displayed. Intrusionat leks may be costly, as 28% of female visits were interruptedby intruders. Solitary mates suffered no such interference.Females show no preferences for larger leks, visiting and matingat solitary sites as well as at leks. However, females preferentiallyvisit males with high singing rates, and this male trait maydetermine visitation patterns. Our data argue that preferencesfor larger leks are not important in the evolution of lekkingin this species, nor do they affect lek size. Instead, the dataare in accordance with the predictions of both the hotshot andhot-spot models. These processes may be operating simultaneouslyin this species     

Correlates of male mating success in a lekking bird with male-male cooperation

Correlates of male mating success were examined in a population of long-tailed manakins, Chiroxiphia linearis, that included 270 colour-banded individuals. Long-tailed manakins have a lek mating system and male-male cooperation in courtship display. Multivariate analysis of behavioural variables indicated that female visitation correlated with the number of unison ‘toledo’ calls given by male partners. Given a female vist, copulatory success was correlated with the ‘butterfly’ display component of the dual-male dance. Both ‘toledo’ output and dance display differed significantly between perch-zones. Only six to eight partnerships in a local population of as many as 55 males per season performed call displays at a level (75–335 toledos per h) that was correlated with any female visitation. Data on crown plumage of female visitors suggested that younger females may have been less discriminating than were older females. The relationship between variance in mating success and the evolution of cooperative male display is discussed.     

The social organization of feral peafowl

Peafowl are usually reported to have a mating system based on harem defence by adult males. In a small feral population near Oxford, males defended small (<1 ha) territories while females remained in one flock that ignored male territory boundaries. After mating, females become solitary. At no time did a female associate selectively with one male or remain within his territory, nor did males attempt to follow or guard female groups. Two out of four males were seen to mate. These differed from the other two in being neither very old nor very young; they held territories smaller than that of the young male and were no larger or longer-tailed. However, they spent more time displaying. We suggest that peafowl have a mating system similar to a lek: males defending small, clumped territories visited by females for mating.     

No peace for estrous topi cows on leks

Male coercion, such as harassment, may be considered the thirdmain component in sexual selection alongside male competitionand female choice. In this study on lek-breeding topi antelopes(Damaliscus lunatus), I investigate whether female mating preferenceshave consequences for male investment in harassment and whetherharassing males are more likely to succeed in mating. I thenaddress the question of whether lek evolution in topi can beexplained by harassment avoidance. Judging from mating rate,I found that female topi antelopes in estrus preferred lek malesto resource defenders. In contrast to lek males, resource defendersdemonstrated significantly higher harassment rates before theysucceeded in mating than when they did not, and the precopulatoryharassment rate was significantly higher on resource territoriesthan on lek territories. After mating on resource territories,harassment dropped to low levels. Thus, resource defenders,but not lek males, seem to employ harassment as a strategy tocoerce females to mate against their preference. However, byusing various measures of harassment intensity, overall estrousfemales were found to experience higher harassment levels onlek, and chases by intruders were relatively rare on all territorytypes. These findings suggest that harassment avoidance is unlikelyas an explanation for lek evolution.     

Flower-feeding affects mating performance in male oriental fruit flies Bactrocera dorsalis

1. Males of the oriental fruit fly Bactrocera dorsalis are attracted to and feed on flowers of the golden shower blossom Cassia fistula. Flowers of this plant contain methyl eugenol, the metabolites of which apparently function in the synthesis of male sex pheromone. 2. The goal of the study reported here was to determine whether feeding on C. fistula flowers enhanced male mating success. Mating frequencies of unfed (control) and fed (treated) males were compared in trials conducted 0 (same day), 2, 7, or 21 days after treated males were exposed to the flowers. Trials were performed using flowers from three trees of C. fistula to investigate whether the effects of floral feeding were similar among different plants. 3. For all three trees, treated males accounted for a disproportionately large number of matings in trials performed 0, 2, and 7 days after floral feeding by the treated males. For two of the trees, treated males also had a mating advantage 21 days after flower‐feeding. 4. Additional tests were conducted to compare female attraction to perch sites of control and treated males. When at a lek, males exhibit rigorous wing‐fanning behaviour, presumably to increase dispersal of the sex pheromone. Floral feeding had no significant effect on the level of wing‐fanning. Significantly more female sightings were recorded for perches of treated than control males, however, suggesting that the treated males produced a pheromone more attractive to females than did control males.     

Microsatellite analysis of female mating behaviour in lek-breeding sage grouse

We used microsatellite DNA markers to genotype chicks in 10 broods of lek-breeding sage grouse, Centrocercus urophasianus, whose mothers' behaviour was studied by radio-tracking and observing leks. Previous behavioural studies suggested that almost all matings are performed by territorial males on leks and that multiple mating is rare. Two broods (20%) were sired by more than one male. Genetic analyses of the broods of eight females that visited an intensively studied lek were consistent with behavioural observations. Four females observed mating produced singly sired broods and males other than the individual observed copulating were excluded as sires for most or all of their chicks. Territorial males at the study lek were excluded as sires of broods of four other females that visited the lek but were not observed mating there. Radio-tracking suggested that two of these females mated at other leks. Our results confirm the reliability of mating observations at leks, but do not rule out a possible unseen component of the mating system.     

On the cue for male territorial site selection in the dragonfly,Nannophya pygmaea: A field experiment

A field observation of the dragonflyNannophya pygmaea revealed that males prefer some territorial sites to others, and that these same sites attract more females than others (Tsubaki & Ono, 1986, 1987). In this paper, we asked if males choose territorial sites in response to female dispersion or distribution of resources. We conducted 3 types of removal experiments to test the following 2 hypotheses; (1) a male may assess the territory quality by the female encounter rate at his site (learning), (2) a male may assess the resource quality (or quantity) in the territory. The results of our experiments show that males discriminate attractive and less attractive territorial sites without any mating experience within the study area. Moreover, the territorial site preference of males was not affected by the mating experience. Therefore, males probably choose territorial sites by resource quality rather than by female dispersion.     

Elaborate Nests in a Weaverbird: A Role for Female Choice?

Studies on sexual selection have focused on behaviour and morphology, but several groups of animals build elaborate structures associated with acquiring a mate. I investigated female choice for nests built by male baya weavers (Ploceus philippinus). Nest choice by females should be strong, as nests are obvious direct benefits provided by males. I used a field experiment supplemented with correlational information to ask whether females appear to base mate choice decisions on male behaviour, nest architecture, and nest location. When the nests of highly visited males were exchanged with those of poorly visited males, female visits remained highest at the original male and location. I found no relationship between female choice and male display or other behaviour. Correlational analyses show that nest location was a better predictor of female choice than was nest architecture. These data suggest that current female choice is driven more by access to safe nesting sites rather than to well‐built nests, possibly because all males are able to build nests of adequate quality. However, nest architecture is unlikely to be irrelevant to females, and its role deserves further investigation.     

SEXUAL SELECTION THROUGH FEMALE CHOICE IN LAWES' PAROTIA,A LEK-MATING BIRD OF PARADISE

We studied sexual selection in Lawes' Parotia, a lek-mating bird of paradise, during 1981–1983 in Papua New Guinea. There was a high variance in mating success among males, with fewer than half of the individuals mating in any one year. This variance was independent of male-male interactions and disruptions. A role of female choice in sexual selection was suggested by the patterns of female visitation to courts and statistical correlations across males between phenotypic traits and mating success. Females repeatedly visited most males in their home ranges and began visiting males up to six weeks before mating. In one or more years, six aspects of male behavior and one morphological variable were positively correlated with mating success, but the probability values were not significant using a simultaneous inference test. Calculation of combined probability values across all three years revealed that one aspect of male display behavior, the probability of display, positively and significantly influenced mating status. The probability of display was also significantly correlated with relative mating success among males. Females showed strong fidelity to mates, both within and between seasons. Display sites of male Lawes' Parotia are variably dispersed, but mating success did not differ for grouped and solitary males. These data confirm an important role of female choice in sexual selection in birds of paradise but also suggest that female choice may be unrelated to the process of lek-initiation in this species.     

The social behaviour of the Pin-tailed Whydah Vidua macroura in northern Ghana

This paper describes the pattern of territory usage by male Pin-tailed Whydahs Vidua macroura , and the display postures used by territorial males, intruding males and visiting females are described. Each territory holder used one or two favoured display sites at which he was visited by, and displayed towards females in groups of one to eight. The frequency of display flights and song output reflected the diurnal pattern of visits by females. Each female was courted by up to six males, but the number of copulations observed was too few to indicate the type of mating system used. The operative sex ratio was estimated at 1:6 (females to territory holders), and the results of a removal experiment suggested that a proportion of males was prevented from breeding.     

Evolution of black grouse leks: female preferences benefit males in larger leks

Leks, communal display grounds in which males display and femalesonly attend to mate, represent one of the most remarkable outcomesof sexual selection. There have been no detailed studies thatcompare the behavior of males and females between leks of differentsizes to test if there is any benefit for male clumping andto test the many hypotheses suggested to explain lekking. Inthe black grouse, Tetrao tetrix, larger leks have many morefemale visits and copulations, leading to a higher average malemating success. Females visiting larger leks are also more likelyto mate, indicating that female preferences of males are importantfor the evolution of leks. Yearling males seldom copulate, buttheir presence on the lek increases the mating success of adultmales, suggesting that lek size per se and not only male qualityaffects female preferences for larger leks. The distributionof males over lek sizes agrees with a game theory model of idealfree distribution with unequal competitors, in which less competitivemales go to smaller leks.     

The lek mating system of the worm pipefish (Nerophis lumbriciformis): a molecular maternity analysis and test of the phenotype‐linked fertility hypothesis

The origin and maintenance of mating preferences continues to be an important and controversial topic in sexual selection research. Leks and lek‐like mating systems, where individuals gather in particular spots for the sole purpose of mate choice, are particularly puzzling, because the strong directional selection imposed by mate choice should erode genetic variation among competing individuals and negate any benefit for the choosing sex. Here, we take advantage of the lek‐like mating system of the worm pipefish (Nerophis lumbriciformis) to test the phenotype‐linked fertility hypothesis for the maintenance of mating preferences. We use microsatellite markers to perform a parentage analysis, along with a mark–recapture study, to confirm that the worm pipefish has an unusual mating system that strongly resembles a female lek, where females display and males visit the lek to choose mates. Our results show that the most highly ornamented females occupy positions near the centre of the breeding area, and males mating with these females receive fuller broods with larger eggs compared to males mating with less‐ornamented females. We also conduct a laboratory experiment to show that female ornaments are condition‐dependent and honestly signal reproductive potential. Overall, these results are consistent with the predictions of a sex‐independent version of the phenotype‐linked fertility hypothesis, as male preference for female ornaments correlates with fertility benefits.     

Uganda kob prefer high-visibility leks and territories

In lekking species, where males provide estrous females withlittle more than sperm, it has been widely supposed that theonly possible benefits to females of mate choice are genetic.We studied female choice of leks and territories in a reduncineantelope, the Uganda kob (Kobus kob thomasi), and found thatfemales consistently preferred high-visibility mating sites.Leks were elevated and had shorter grass and fewer thicketsthan the surrounding areas. Changes in the number of male andfemale kob on 10 leks were correlated with changes in surroundinggrass height, and both females and males preferred leks withexperimentally reduced grass height over neighboring controls.Within a lek, territory popularity was the primary determinantof male daily mating success, and females preferred territoriesrelatively far from thickets, but removal of thickets did notaffect female territory preferences. Because lion hunting successon kob increases with grass height and thicket density, femalesmay benefit directly from these preferences by reducing therisk of predation.     

Responses of Male and Female Black Grouse to Male Vocal Display

The evolution of leks may be explained by several hypotheses. The ‘female preference’ hypothesis, which states that females favour males that have aggregated, has recently gained some empirical support. Low-quality, unattractive males may, however, settle near attractive males, as predicted by the ‘hotshot’ hypothesis. We tested whether black grouse Tetrao tetrix females use auditory cues to find the preferred leks, and whether males respond to vocal display emitted on leks. We conducted a playback experiment with male vocal display (rookooing) on leks, where the visiting females and displaying males were counted. The number of males tended to increase more on playback leks. Specifically, the number of 1-year-old males was greater on playback sites than on control sites. Also, the number of females, in relation to the lek size before the start of the experiment tended to increase. In addition, we used aviary playback trials to test whether females distinguish between single-male and multi-male displays. In a choice test, females showed greater preference for the ‘multi-male’ tape. The tendency for increased male numbers on playback leks resulted from increased visits of young, mobile males which were attracted to leks that they perceived to be large. This suggests a ‘hotshot’-type mechanism in the settlement of young males. Because females also responded to the supplemented auditory advertisement, or directly to the increased number of males, the ‘female preference’ hypothesis is also supported. Females may, at least in part, base their decision of which lek to visit on auditory cues, but visual contact to males may be also needed.     

Territorial Advertisement and Mate Attraction in the Bat Pipistrellus pipistrellus

A South Swedish population of the vespertilionid bat Pipistrellus pipistrellus was studied by means of bat boxes from April to the beginning of October in 1984. The mating system of the pipistrelle bat is a “resource defence polygyny”. Three territorial males were studied to determine the relative importance of two potential resources, food and roost sites, for male reproductive success. The day roost was found to be the crucial resource for the male's chances to get access to females. A territorial male advertises the location of his day roost to the females by a songflight display. The male who spent most time in songflight display was visited by the greatest number of females.     

A FIELD STUDY OF THE CALFBIRD PERISSOCEPHALVS TRICOLOR

The Calf bird Perissocephalus tricolor was studied in the Kanuku Mountains of southern Guyana for three months (January-April 1970), during which time almost daily visits were paid to a lek of four adult males. The adult males owned perches about 30 ft up in understorey trees, where they displayed and called throughout much of the day. Four immature males also visited the lek, particularly in the morning and evening. The immatures also wandered, feeding and occasionally calling together, over an area of forest of approximately 3 miles by half a mile. There was a hierarchy among the adult and immature males, the dominant males owning the most coveted perches at the lek. The male's most far-reaching call, the “moo call”, is a co-operative advertising call, in that birds calling together adjust the timing of their calls so as to follow each other and not overlap. The adult males perform a number of silent agonistic displays on their lek perches. Periodically, adult and immature males and sometimes a female invade the vicinity of a lek perch, usually that of the dominant male. Once a female was briefly mounted by the dominant male on his lek perch during an invasion. On other occasions females visited the lek but no mating occurred. The food of the males attending the lek was recorded by the daily collection of a total of 2,500 regurgitated fruit seeds (mostly drupes) from below the perches. Males also regularly take insects, but in smaller quantities. Three nests were found. The nest is an extremely light structure built entirely of fine twigs. A single egg was laid in each nest. All the nests (and two old ones) were within half a mile of the lek. Two of the nests were only 5 yards apart and the eggs were laid in them within 10 days of each other. The incubation period at one nest was 26–27 days and the fledging period approximately 27 days. The chick on hatching was covered in bright orange-chestnut down. It was fed mostly on insects (predominantly Orthoptera) brought by the female in her beak. There was no evidence of a male attending the nest. The Calfbird's nesting and lek behaviour is compared with that of other species of Cotingidae.     

The flexible lek: Phymatopus hecta the gold swift demonstrates the evolution of leking and male swarming via a hotspot (Lepidoptera: Hepialidae)

Leking moths present an evolutionary problem in their apparently simultaneous reversal of male–female attraction. The mating system of Phymatopus (or Hepialus) hecta embraces an unusually wide range of procedures. Both males and females use medium‐range olfactory attractants (also probably visual signals), and both sexes will lure, and both will approach, the other, either when flying or perched. This produces an ‘infinite variety’ which includes the classic moth mating procedure (males fly to sessile female); a typical lek procedure (female flies to sessile male); a mating swarm (hovering male follows passing female); and intermediates such as a mutual courtship dance. Male behaviour includes a flying display, two sessile displays, and an escalating war of attrition. The system is versatile, persistent, and probably evolutionarily stable. The lek site has a high density of perches suitable for copulation which facilitate predator‐escape by means of a dead drop. The whole supports a model for the evolution of resource‐based leks which commence with a concentration of females on a hotspot, leading to a concentration of males; and then an escalating process of sexual selection as males become increasingly attractive over a distance to females, and females use the males as a way of locating the resource. The main stabilizing pressure may be selection for efficient mate acquisition, and as with grouse leking systems, the precondition for evolution was probably having travelling females that actively sought a reproductive resource or a predator free space. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114 , 184–201.