Pushy males and choosy females: courtship disruption and mate choice in the lekking great snipe

We studied the effects of male disruptive behaviour on female mate choice and male mating success in the great snipe, Gallinago media, a lekking bird. Harassment from neighbouring males, a widespread behaviour in lekking animals, was the most prevalent cause of females leaving a male territory. Several lines of evidence show that females did not prefer to mate with males able to protect them from harassment. Males that obtained mating success were no less likely to suffer disruptions and females were no less likely to be disrupted when with their preferred male. Females returned to the male they later mated with, despite being repeatedly chased away by neighbours. The probability that an individual female returned and solicited mating from a male was 15 times higher for the male she was chased away from compared to the neighbour that chased her away. Females returned as often or more to the territory owner after being disrupted, compared to after leaving the territory without being harassed. Our results suggest that female great snipes are extremely choosy, but also that females do not gain direct benefits (harassment avoidance) by mating with certain males. Females appear to have neither direct nor indirect preferences for dominance that could give them such benefits: females appeared choosy despite, not because of, harassment. If females gain indirect benefits (genetically superior offspring) by being choosy, this is also likely to be unrelated to any dominance among males.     

Females prefer the scent of outbred males: good-genes-as-heterozygosity?

Background  

There is increasing interest to determine the relative importance of non-additive genetic benefits as opposed to additive ones for the evolution of mating preferences and maintenance of genetic variation in sexual ornaments. The 'good-genes-as-heterozygosity' hypothesis predicts that females should prefer to mate with more heterozygous males to gain more heterozygous (and less inbred) offspring. Heterozygosity increases males' sexual ornamentation, mating success and reproduction success, yet few experiments have tested whether females are preferentially attracted to heterozygous males, and none have tested whether females' own heterozygosity influences their preferences. Outbred females might have the luxury of being more choosey, but on the other hand, inbred females might have more to gain by mating with heterozygous males. We manipulated heterozygosity in wild-derived house mice (Mus musculus musculus) through inbreeding and tested whether the females are more attracted to the scent of outbred versus inbred males, and whether females' own inbreeding status affects their preferences. We also tested whether infecting both inbred and outbred males with Salmonella would magnify females' preferences for outbred males.     

Female tawny-bellied seedeaters do not prefer more colorful males in choice experiments

Plumage coloration has long been studied as a sexually selected character. The tawny-bellied seedeater, Sporophila hypoxantha, is a sexually dichromatic species, with adult males the more colorful sex and juvenile males indistinguishable from females. We did choice experiments to evaluate female preferences for males that differ in age or plumage coloration. Females were evaluated in three experiments: (1) choice between males with similar breast brightness that differed in age, (2) choice between males of 2 years of age that differed in breast brightness, and (3) choice between males of 3 or more years of age that differed in breast brightness. We also repeated the latter experiment with estradiol-treated females. We did not find a clear female preference for brighter or older males, as females spent the same proportion of time with males of similar breast brightness that differed in age or with males of similar age that differed in breast brightness. Our results do not support the hypothesis that breast brightness is a cue used by female tawny-bellied seedeaters at the time of choosing males. We propose that, in this species, male plumage coloration might play a role in intrasexual competition.     

Females prefer to associate with males with longer intromittent organs in mosquitofish

Sexual selection is a major force behind the rapid evolution of male genital morphology among species. Most within-species studies have focused on sexual selection on male genital traits owing to events during or after copulation that increase a male''s share of paternity. Very little attention has been given to whether genitalia are visual signals that cause males to vary in their attractiveness to females and are therefore under pre-copulatory sexual selection. Here we show that, on average, female eastern mosquitofish Gambusia holbrooki spent more time in association with males who received only a slight reduction in the length of the intromittent organ (‘gonopodium’) than males that received a greater reduction. This preference was, however, only expressed when females chose between two large males; for small males, there was no effect of genital size on female association time.     

Females prefer males with larger first dorsal fins in the common freshwater goby

Males of the common freshwater goby Rhinogobius brunneus , which provide paternal care, have a first dorsal fin (FDF) that is markedly longer and more elaborate in colour and shape than that of females. Females showed a clear preference for males with longer FDFs, but mated randomly with respect to male body size ( L _s) and nest size. They were individually consistent in their choice of mates, and the strength of preference increased with inter-male differences in FDF length. During courtship, despite the unequivocal preference, females seem not to rely on FDF size in choosing a mate, but the leading display of males appears to play an important role in female choice. The results of this study suggest that intersexual selection probably contributes to the evolution of the elaborate FDF.     

Female choice and male humoral immune response in the lekking great snipe (Gallinago media)

Parasites and diseases constitute major evolutionary forcesin many natural populations, and thus having an efficient immunedefense to resist infections is crucial for many organisms.Properties of the immune response may also influence mate choicedecisions in many animals. Theory predicts several advantagesfor females when choosing males with superior immune systems.These benefits can be both direct (e.g. increased paternal careand reduced disease transmission) and indirect (good genes).We have investigated female choice with respect to antibodyresponse to two novel antigens in males of a lekking bird, thegreat snipe (Gallinago media). Because of the lek mating system,female choice probably mainly incurs indirect (genetic) ratherthan direct benefits. Males responded to vaccination with diphtheriaand tetanus toxoids by producing specific antibodies to bothantigens. Triggering the immune system had no negative impacton display activities or survival. Males that were chosen byfemales as mates had on average higher antibody response tothe tetanus antigen than their neighbors. We did not, however,find any covariance between the strength of the antibody responseand male mating success.     

Reduced sexual size dimorphism in a pipefish population where males do not prefer larger females

Within a species' distribution, populations are often exposed to diverse environments and may thus experience different sources of both natural and sexual selection. These differences are likely to impact the balance between costs and benefits to individuals seeking reproduction, thus entailing evolutionary repercussions. Here, we look into an unusual population (Baltic Sea) of the broadnosed pipefish, Syngnathus typhle, where males do not seem to select females based on size and hypothesize that this pattern may derive from a reduction in direct benefits to the male. We further hypothesize that if larger females do not persistently secure a higher reproductive success, either through pre‐ or postcopulatory sexual selection, a decrease in sexual size dimorphism in the Baltic population should be apparent, especially when contrasted with a well‐studied population, inhabiting similar latitudes (Swedish west coast), where males prefer larger females. We found that, in the Baltic population, variation in female quality is low. We were unable to find differences in abortion rates or protein concentration in oocytes produced by females of contrasting sizes. Direct benefits from mating with large partners seem, thus, reduced in the Baltic population. We also found no evidence of any postcopulatory mechanism that could favor larger mothers as embryo development was unrelated to female size. While female size can still be selected through intrasexual competition or fecundity selection, the pressure for large female body size seems to be lower in the Baltic. Accordingly, we found a noticeable decrease in sexual size dimorphism in the Baltic population. We conclude that, although far from negating the significance of other selective processes, sexual selection seems to have a decisive role in supporting pipefish sexual size asymmetries.     

Major histocompatibility complex variation and mate choice in a lekking bird, the great snipe (Gallinago media)

Genes of the major histocompatibility complex (MHC) play a major part in the activation of the vertebrate immune system. In addition, they also appear to function as cues for mate choice. In mammals especially, several kinds of MHC-dependent mate choice have been hypothesized and observed. These include choice of mates that share no or few alleles with the choosing individual, choice of mates with alleles that differ as much as possible from the choosing individual, choice of heterozygous mates, choice of certain genotypes and choice of rare alleles. We investigated these different aspects of mate choice in relation to MHC in a lekking bird species, the great snipe (Gallinago media). We found no evidence for MHC disassortative mating, no preference for males with many MHC alleles and no preference for rare alleles. However, we did find that some allelic lineages were more often found in males with mating success than in males without mating success. Females do not seem to use themselves as references for the MHC-dependent mate choice, rather they seem to prefer males with certain allele types. We speculate that these alleles may be linked to resistance to common parasites.     

Females lay fewer eggs for males with greater courtship success in a lekking Drosophila

The evolutionary basis for female mate choice in lek mating systems has been a common subject of research in animal behaviour. Because males apparently provide only gametes to females in lekking species, most research has focused on possible indirect (genetic) benefits that females might gain by discriminating among males. Despite the emphasis on indirect benefits, it has been recognized that females in non-resource-based systems such as leks could potentially gain direct benefits via mate choice if males varied in fertilization abilities, for example. Previous evidence has shown that females of a lekking Hawaiian Drosophila, D. grimshawi, vary in fecundity when mated to certain males, and that females possess preferences for vigorously courting males. This study tests the hypothesis that D. grimshawi females gain direct benefits by preferentially mating with more sexually vigorous males. Male courtship vigour (performance of wing and head-under-wing displays) and the consequences of female choice on offspring production were evaluated separately using different females. Unexpectedly, matings involving more vigorously courting males resulted in fewer offspring being produced. Reduced offspring number resulted because females laid fewer eggs when mating with males having greater courtship success. These results are discussed in light of sexual conflict and possible multiple mating by females. Females also demonstrated considerable variation in mating behaviour and behavioural variation was correlated with mating benefits. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.      

Correlates of male mating success in the lekking great snipe (Gallinago media): results from a four-year study

To investigate behavioral or morphological traits importantas mate choice cues, we measured selection differentials (s)as the covariances between each trait and male mating success,and directional selection gradients (J3) from multiple linearregression of the standardized traits on male mating success.Data from two leks in four consecutive years were included,and the annual data were analyzed separately. The main findingsare: (1) the distribution of male mating success proved to beless skewed than those found in many other lekking species,(2) only a few traits yielded significant selection gradients,(3) the importance of age on male mating success changed acrossyears, (4) females may use traits with a high variance as matechoice cues, and (5) individual males achieved similar matingsuccesses between years. Attendance and age were the traitsmost consistently correlated with male mating success, but notraits showed significant selection gradients in all years.Our results indicate that variable sexual selection pressuresexisted between years, but the high correlation found betweenthe mating success of individual males in successive seasonsalso indicates that permanent differences in male traits areimportant. Key words: lek, mate choice, sexual selection.     

Mate selection in Litoria chloris and Litoria xanthomera: Females prefer smaller males

It is generally accepted that high quality males are those that succeed in male–male competition: in either aggression or rivalry to attract and be selected by females. Previous studies of amphibians have suggested that the main characters influencing male mating success include variation in call characteristics (e.g. call rate, call intensity), calling behaviour, body condition, age and chorus tenure. In the present paper, several of the characters influencing female mate choice (male body size, body condition, call rate, call frequency and chorus tenure) are investigated in two closely related, explosive breeding frog species Litoria chloris and Litoria xanthomera. Smaller males of both species are shown to be more successful than larger males and this success is attributed to the increased chorus tenure of smaller males in L. xanthomera. This increased chorus tenure was attributed to the lower total energy used per call by a small male calling at a higher frequency. Whether increased chorus tenure explains female mate choice in L. chloris is uncertain but is highly probable given the strong similarity between the two species in both ecology and call characteristics.     

Females prefer mating males in the carmine triplefin,Axoclinus carminalis,a paternal brood-guarder

Synopsis This study investigates the role of male mating status in female choice patterns in the carmine triplefin, Axoclinus carminalis, a tripterygiid fish that exhibits paternal care. The distribution of daily reproductive activity is clumped, with many males receiving no mates and some receiving three or more. Females in this species do not prefer larger males, and characteristics of the oviposition site appear to have minimal effects on male mating success. When a female is removed from a male early in the daily spawning period, that male attracts fewer additional females for the remainder of the spawning period than does a control male. These changes in mating success are temporary, and do not affect mating success on subsequent days. A preference for mating males or males that are guarding eggs could provide asymmetric benefits for males to defend oviposition sites. This preference for males with eggs could be acting alone or with other factors such as high variance in oviposition site quality to favor the evolution of paternal care in fishes.     

Incubation rhythm in the great snipe Gallinago media

The incubation rhythm of four female great snipe was monitored with telemetric equipment. The mean daily incubation constancy was 90.3 ± 2.0 (SD) per cent, and the mean daily time off the nest amounted to 139.8 ± 28.8 min. The number of recesses per day averaged 8.7 ± 1.9, with a mean duration of 15.7 ± 6.1 min. Generally, the birds incubated for long bouts during the night, and left the nest frequently during the daylight hours.
Recesses were concentrated in the warmest part of the day in cool periods, but were more evenly distributed throughout the day in warmer periods. Recess duration decreased with decreasing temperature. These adjustments minimize egg cooling when the bird is off the nest, and thus allow the incubating bird more time to feed without lowering the mean egg temperature.
Calculations of the cooling rates of eggs indicate that the bird minimizes incubation energy expenditure as far as possible, but without letting the eggs cool beyond the temperature of no embryonic development.     

Food supply and breeding occurrences: the West European population of the lekking great snipe Gallinago media (Latham, 1787) (Aves)

For species with very high energetic costs during reproduction we expect occurence during the reproduction season to be dramatically affected by the availability of energy. Recent studies have shown very high energetic costs of lekking for great snipe males, Gallinago media (Latham, 1787) and that breeding great snipes prefer to feed in soft soil with a high abundance of earthworms. We here evaluate the hypothesis that the breeding occurrence of great snipe is restricted to areas with very high availability of food. All the 125 registered great snipe leks in Scandinavia were situated in open habitats along the tree line. The occurrence of leks were analysed in relation to bedrock quality, soil chemistry and earthworm biomass. There was a strong positive relationship between soil pH and earthworm biomass. High pH values were found on or in the close vicinity of base-rich bedrocks. No great snipe leks were documented in areas with acid soil, even if the extent of acid bedrocks along the tree line predicts that 31% of the leks should be situated on acid soils. Hypotheses, including both natural and sexual selection, for why breeding occurrence of great snipe is restricted to areas with high abundance of high quality food are evaluated, and we find indications for this to be a consequence of the very high energetic costs for the lekking males. These costs have probably evolved through female mate choice and indicate that sexual selection may have important consequences for a species distribution. Population-level effects of sexual selection have previously received little attention. The stringent habitat demands here documented may also make great snipes vulnerable to environmental changes and can contribute to explain the dramatic reduction in breeding range of this species in western Europe during the past 150 years (Løfaldli et al ., 1989).     

Females prefer males producing a high-rate song with shorter timbal–stridulatory sound intervals in a cicada species

Uncovering mate choice and factors that lead to the choice are very important to understanding sexual selection in evolutionary change. Cicadas are known for their loud sounds produced by males using the timbals. However, males in certain cicada species emit 2 kinds of sounds using respectively timbals and stridulatory organs, and females may produce their own sounds to respond to males. What has never been considered is the mate choice in such cicada species. Here, we investigate the sexual selection and potential impact of predation pressure on mate choice in the cicada Subpsaltria yangi Chen. It possesses stridulatory sound-producing organs in both sexes in addition to the timbals in males. Results show that males producing calling songs with shorter timbal–stridulatory sound intervals and a higher call rate achieved greater mating success. No morphological traits were found to be correlated with mating success in both sexes, suggesting neither males nor females display mate preference for the opposite sex based on morphological traits. Males do not discriminate among responding females during mate searching, which may be due to the high energy costs associated with their unusual mate-seeking activity and the male-biased predation pressure. Females generally mate once but a minority of them re-mated after oviposition which, combined with the desirable acoustic traits of males, suggest females may maximize their reproductive success by choosing a high-quality male in the first place. This study contributes to our understanding mechanisms of sexual selection in cicadas and other insects suffering selective pressure from predators.     

Attractive males do not sire superior daughters

Much of the recent work on the evolution of female choice has focused on the relative influence of direct and indirect benefits, and particularly whether direct costs can be offset by indirect benefits. Studies investigating whether attractive males benefit females by increasing the viability of their offspring often report mating advantages to sons consistent with the Fisher process, while detecting no or weak viability benefits. One potential reason for this is that sons may trade-off viability benefits with investment in costly traits that enhance mating success, leading to the suggestion that viability benefits may be better detected by examining daughters’ fitness. Here we investigate the relationship between male attractiveness and daughters’ fitness in Drosophila simulans. We measured daughter (and dam) lifetime reproductive success and longevity. We found no evidence that attractive males sire high fitness daughters. Additionally, neither daughters nor dams gained direct benefits from mating with attractive males. However, aspects of daughters’ fitness were related to dam characters.