Role Of Female Choice Research Articles

IMPACTS OF CHELIPED MORPHOLOGY ON MATE SELECTION OF AN INVASIVE CRAYFISH, THE RED SWAMP CRAYFISH (PROCAMBARUS CLARKII)

Abstract The red swamp crayfish, Procambarus clarkii, is a large-bodied crayfish that is native to northeastern Mexico and the south-central United States. The extensive breeding season and the r-selected characteristics of this species allow it to produce a large number of offspring. Despite the extensive research on the invasive potential of this organism, some behavioral aspects of the mating system have not been well-studied. We investigated how cheliped morphology impacts female choice and copulation behavior by manipulating three male traits: chela presence, function, and chela-body size ratio. Females showed no preference for males based on any of the visual traits examined, and copulations were infrequent and not indicative of female preference for a male phenotype. Chela function and chela-body size ratio impacted male copulation attempts, suggesting male dominance and aggression as a potentially significant component in the mating system of P. clarkii. Finally, our we encourage further research to include other visual and chemical stimuli to truly understand the crayfish mating system and the role of female choice.

Environment and mate attractiveness in a wild insect.

The role of female choice in sexual selection is well established, including the recognition that females choose their mates based on multiple cues. These cues may include intrinsic aspects of a male's phenotype as well as aspects of the environment associated with the male. The role of the spatial location of a potential mate has been well studied in territorial vertebrates. However, despite their role as laboratory models for studies of sexual selection, the potential for insects to choose their mates on the basis of location has scarcely been studied. We studied a natural population of individually tagged crickets (Gryllus campestris) in a meadow in Northern Spain. Adults typically move between burrows every few days, allowing us to examine how pairing success of males can be predicted by the burrow they occupy, independent of their own characteristics. We observed the entirety of ten independent breeding seasons to provide replication and to determine whether the relative importance of these factors is stable across years. We find that both male ID and the ID his burrow affect the likelihood that he is paired with a female, but the burrow has a consistently greater influence. Furthermore, the two factors interact: the relative attractiveness of an individual male depends on which burrow he occupies. Our finding demonstrates a close interaction between naturally and sexually selected traits. It also demonstrates that mate choice studies may benefit from considering not only obvious secondary sexual traits, but also more cryptic traits such as microhabitat choice.

Motorway age is linked to larger body size, but not song carrier frequency, in male grasshoppers from roadside populations

Producing calls with increased minimum carrier frequency is well documented in sound communicating species confronted with noise pollution, possibly helping them to avoid acoustic masking of low-frequency signals. However, the lack of studies on invertebrates limits our understanding of the potentially adverse effects of anthropogenic noise on natural populations. While males of the grasshopper Chorthippus biguttulus are known to produce courtship signals with elevated low-frequency local maxima (LFLM) in roadside populations, previous studies provided no insight into morphological traits underlying LFLM shifts. Although developmental plasticity was identified as one main factor accounting for elevated LFLM, an additional role for a more hard-wired trait architecture was proposed, possibly as a result of adaptation to traffic noise. Our current study therefore aims to assess (1) whether the position of LFLM is related to male body size, (2) whether body size is correlated with motorway age, and (3) whether the position of LFLM is correlated with motorway age in C. biguttulus males from roadside populations. In addition to substantial variation in LFLM among C. biguttulus males, we found that larger males produced signals with lower LFLM, suggesting a potential role in female choice as a predictor of male quality. While we found no significant correlation between LFLM and motorway age, C. biguttulus males were larger near older motorway sections. This positive correlation may be due to several reasons, including: (1) higher nutrient concentration and availability in plant tissues due to eutrophication of roadside habitats; (2) temporal succession of male size phenotypes during colonization processes; and/or (3) selection for larger body size in roadside populations. Our results highlight the multifaceted and often complex nature of the relationships between morphology, signal traits and anthropogenic pressures on sound communication in invertebrates.

Causes of variability in male vibratory signals and the role of female choice in Mantophasmatodea

Communication systems that involve substrate vibrations are increasingly a focus of research since this communication mode - recently termed biotremology - has been found to be remarkably widespread in the animal kingdom. Vibrational signals are often used during courtship and therefore underlie both natural and sexual selection. Mantophasmatodea use species- and sex-specific substrate vibrational signals during courtship. We explored whether male vibrational signals of the South African heelwalker Karoophasma biedouwense vary with temperature, body condition and age, and tested female preference towards various signal pattern combinations. We recorded male signals under varying temperatures and over 3.5 weeks after onset of signaling. Our results show that the temporal structure of male signals is modified by changes in temperature, and changes with male age. Other characteristics, especially duty cycles, are less affected, but correlate with body condition. Females responded along a broad spectrum of signaling patterns, indicating that they do not favor signals of males of a certain age or condition. They were selective towards the fine structure of vibratory signals, suggesting that pulse repetition times carry species-specific information. Mantophasmatodea thus use vibrational signals to identify and localize a mating partner, but presumably not for precopulatory mate selection.

Male bull-headed shrikes use food caches to improve their condition-dependent song performance and pairing success

Food caching is common in many animal species and is thought to have evolved largely by natural selection. We propose that sexual selection also plays an important role in the evolution of food caching. The sexual trait promotion (STP) hypothesis predicts that if male food caches provide supplemental nutrition allowing males to improve their sexual traits (e.g. song) serving a role in female choice, then sexual selection would act on male food caching. To test this idea, we investigated correlations between the number of caches that males retrieved, male song and pairing success, in the bull-headed shrike, Lanius bucephalus. Our field observations showed that the number of food caches males retrieved was positively correlated with male singing tempo (i.e. the number of notes uttered per second), not with other song characteristics (e.g. repertoire size). The bull-headed shrike's singing tempo has been found to reflect the nutritional condition of the singer and females choose their mates based on the tempo. Food supplementation experiments showed that males with artificially augmented food caches sang at higher speeds and mated with females earlier than controls; conversely, cache removal experiments showed that males with depleted food caches sang at lower speeds and were more likely to fail to mate than controls. Our results suggest that the food caches of male bull-headed shrikes provide them with supplementary nutrition allowing them to improve a condition-dependent song characteristic, which in turn serves the function of female attraction. We therefore conclude that sexual selection is an important evolutionary force acting on male food caching.

Female genitalia can evolve more rapidly and divergently than male genitalia

Male genitalia exhibit patterns of divergent evolution driven by sexual selection. In contrast, for many taxonomic groups, female genitalia are relatively uniform and their patterns of evolution remain largely unexplored. Here we quantify variation in the shape of female genitalia across onthophagine dung beetles, and use new comparative methods to contrast their rates of divergence with those of male genitalia. As expected, male genital shape has diverged more rapidly than a naturally selected trait, the foretibia. Remarkably, female genital shape has diverged nearly three times as fast as male genital shape. Our results dispel the notion that female genitalia do not show the same patterns of divergent evolution as male genitalia, and suggest that female genitalia are under sexual selection through their role in female choice.

Assessing the use of wing ornamentation and visual display in female choice sexual selection

Conspicuous sexual dimorphism is often ascribed to sexual selection. When the differences between the sexes are ornamental, this is thought to indicate a role for female choice. In spotted winged Drosophila species courtship, a male positioned in front of a female waves his wings, which have a patch of melanization on the exterior margin. In this study, we examine both female preference for wing spots and the role of vision in mating success in three species of the suzukii group: Drosophila biarmipes, D. suzukii, and D. subpulchrella. To assess female preference for wing spot, we removed the spot with a novel, non-invasive method, and competed spotless males with males with two spots. Phenotype did not affect mating success in any species. To eliminate the potential effect of competitive behavior on male mating success, we also ran a no-choice analysis. Mating frequency and timing was not different between phenotypes within these species. The effect of vision on mating success was assessed by comparing mating success of spotted males between light and dark conditions, both for frequency of mating, as well as timing of multiple courtship parameters. Species varied in the extent that lack of vision negatively affected mating success. Though vision is important for mating success, the spot itself may not be providing the signal that females use to make mating decisions.

Quantifying Reproductive Barriers in a Sympatric Pair of Darter Species

Quantifying and comparing the strengths of different reproductive barriers between diverging lineages is especially useful for determining the evolutionary mechanisms driving speciation. Etheostoma barrenense and Etheostoma zonale are closely related sympatric species of darters that are sexually dimorphic and exhibit clear differences in male nuptial coloration. Prior studies demonstrated that these species exhibit complete behavioral isolation, and that both intraspecific and interspecific variation in male coloration play a role in female choice, all consistent with speciation by sexual selection on male nuptial color. Remaining unclear, however, is whether behavioral isolation is the strongest reproductive barrier between these species or, alternatively, whether additional reproductive barriers are equally strong, which could implicate mechanisms other than sexual selection in speciation. Here, we compare the relative strengths of multiple reproductive barriers between the two focal species, measuring: (1) ecological isolation, (2) gametic incompatibility, (3) hybrid inviability, (4) conspecific sperm precedence, and comparing these measures to a previously estimated strength of behavioral isolation. We find that behavioral isolation is the strongest reproductive barrier measured to date and suggest it may be the only barrier that has evolved to completion. This result provides additional empirical evidence for speciation driven by sexual selection and provides insight into the maintenance of sympatric species in nature.

Moderators, Mates, and Matchmakers: Effects of Oral Contraceptives on Sexual Desire May Also Depend on Partners’ Behavior and the Role of Female Choice

Moderators, Mates, and Matchmakers: Effects of Oral Contraceptives on Sexual Desire May Also Depend on Partners’ Behavior and the Role of Female Choice

Concordant female mate preferences in the cichlid fish Tropheus moorii

Discriminating female mate preferences enhance the variance in reproductive success among males of a population and create a potential for sexual selection, which can account for trait evolution and diversification. Fish color patterns are among the prime targets of mate choice-driven sexual selection. Populations of the cichlid Tropheus from Lake Tanganyika display remarkable geographic color pattern variation, but the role of female choice in their rapid and rich phenotypic diversification is unclear. Males and females establish a pair bond prior to spawning monogamously, but as brood care is strictly maternal, female investment in reproduction is high and the operational sex ratio is male-biased. Therefore, variance in male reproductive success can accrue if individual males succeed repeatedly in securing a mate. To test this prediction in the red colored Tropheus moorii “Chimba”, four pairs of males were presented to a series of females and female mate preferences were inferred from pairwise interactions. There was a significant difference in mating success between the males of each pair (P < 0.001 over all trials), as—with one exception—females shared preferences for the same males. Male courtship activity was strongly correlated with female choice. Our experiment suggests that female choice contributes to the variance in male reproductive success in the tested population.

Is female mate preference based on the interaction between static and dynamic signals in bearded reedlings?

In many animal species ornaments and display behaviours are used together in intersexual communication. Few studies, however, have simultaneously explored how the static and dynamic components interact. We examined the significance of behaviour (e.g. dominance status) in comparison with beard length for the mate choice process in a bird species, the bearded reedling, Panurus biarmicus. In choice experiments, females were confronted with two males of varying beard length (artificially shortened or elongated) and status (dominant/subdominant). The results suggest that female choice is primarily based on beard length whereas dominance seems to be less important. Our results indicate that the beard length plays an important role in female choice in this species, as previously reported. Nevertheless, dominance status has a slight complementary effect. Beard length and behaviour seem to inform the female about the same aspect of male condition but with a different error probability. However, additional studies in which display rates and song properties are directly manipulated are needed.

Determinants of Paternity Success in a Group of Captive Vervet Monkeys (Chlorocebus aethiops sabaeus)

Paternity success of high-ranking primate males is affected by the number of males and the number of fertile females and their cycle synchrony. Female vervets in the wild show strong reproductive seasonality and do not advertise the ovulatory period with conspicuous signals or behavior. Because this makes it difficult for males to monopolize fertile females, it can be expected that male reproductive skew in this species is lower than in other cercopithecines living in multimale groups that advertise the ovulatory period. We assessed male reproductive success in a captive vervet group, initially consisting of 4 males and 12 unrelated females. Besides a general low reproductive skew, we predicted paternity success of the alpha males to be dependent on the overlap of synchronously fertile females, month into alpha male tenure, and housing conditions (the subjects were kept in a large park but had to be locked in a small indoor compartment during the winter months). Further, because the number of males reaching their prime increased over time, we predicted a decrease in reproductive success of the alpha male with increasing tenure length of the alpha male. To assess this we collected genetic samples from 27 of 32 offspring born into the group during 3 yr, using 7 polymorphic human microsatellite markers. Contrary to our predictions, reproductive success of the males occupying the alpha position during the study was among the highest found in cercopithecines, with the alpha males siring 78% of all offspring. The degree of overlapping fertile periods did not affect paternity success, nor did paternity success of the alpha male differ between the 2 housing conditions. Only the alpha male’s tenure length had an effect. Alpha male reproductive success decreased over time, which we attribute to either a shift in female mate choice toward younger males or to increased competition among the males in the later stage of the alpha male’s tenure. This study demonstrates the importance of assessing reproductive success of males throughout >1 season and should spawn more research into the role of female choice and postcopulatory mechanisms in this species.

Multiple signals for multiple messages: great tit, Parus major, song signals age and survival

Birdsong is a well-known sexually selected trait that plays a major role in female choice and male – male interactions. Although birdsong has been studied for many years, it has only recently been suggested that it is a multifaceted signal that could encompass multiple sexually selected traits. According to the theories on the evolution and maintenance of multiple sexually selected signals, the different components of birdsong may signal multiple, redundant or unreliable information on male quality. We used a cross-sectional approach to examine whether the expression of song in the great tit was differentially related to any of three measures of quality: age, condition and survival. We analysed several informative characteristics in great tit song concerning diversity, output, performance and consistency to see whether different traits were simultaneously related to the studied quality parameters, or if, in contrast, each song trait was related to only one of the measures of quality. Song consistency and repertoire size were strongly related to only one of the studied parameters (age and survival, respectively), indicating that different song traits signal specific quality characteristics, and providing, therefore, evidence to support the multiple-signal hypothesis. Moreover, measures of song performance and song output (phrase and strophe rate) correlated positively with repertoire size, which might indicate that, at the same time, great tit song is signalling redundant information. In addition, some song characteristics did not correlate with any of the quality parameters measured, suggesting that those song traits might provide unreliable information.

Male song repertoire size and syllable sharing of oriental great reed warblers, acrocephalus orientalis

The size of song repertoires mainly provides evidence for explaining sexual selection for female choice as well as male‐male competition. We investigated the role of oriental great reed warbler songs (Acrocephalus orientalis) of breeding territorial males. Early arrived males possessed larger song repertoires, paired earlier, and tended to become polygynous. No correlation was found between arrival date and territory size, but polygynous males significantly occupied larger territories than non polygynous males. Song sharing was low among males and the degree of similarity did not relate with spatial distance. Our results suggest that song repertoire of the oriental great reed warbler males play a role in female choice, where territory quality may affect male pairing success.

The mechanisms of sexual selection in a lek-breeding anuran, Hyla intermedia

In lek mating systems, sexual selection is thought to operate through two main mechanisms: endurance rivalry and female choice. We investigated the role of these mechanisms in explaining variation in male mating success in a typical lekking anuran, the Italian treefrog, Hyla intermedia. The results suggested that both chorus attendance and calling quality may affect male mating success, and that selection on these traits may indirectly result in selection for males with higher-than-average body condition. Both generalized linear models (GLM) and cubic-spline regressions (CSR) showed a monotonic relationship between mating success and chorus attendance, suggesting open-ended directional selection on male chorus tenure. GLMs on call acoustic properties showed a significant association of mating success with several highly intercorrelated call temporal properties (i.e. call rate, pulse rate and call duration), but not with call spectral properties. In both cases, however, CSRs provided evidence that the relationships of the call properties with mating success are unimodal, with peaks close to (spectral properties) or above (temporal properties) the population means. As often observed in anurans, chorus attendance explained much more variation in mating success than did calling quality. However, contrary to what is often assumed, we argue that the important role of endurance rivalry does not reduce, but rather emphasizes, the role of female choice in sexual selection.

Dawn song in superb fairy-wrens: a bird that seeks extrapair copulations during the dawn chorus

Functional explanations of the dawn chorus in birds remain elusive. One hypothesis suggests that this acoustic display may play a role in female choice of extrapair males. Most young in cooperatively breeding superb fairy-wrens, Malurus cyaneus, are sired by extra-group males. Females initiate extra-group copulations exclusively through predawn forays to males singing in the dawn chorus. We measured variation between males in dawn singing at three levels of song production: song components, structured into songs, which make up recitals. We related this variation to independent measures of male quality and social status. Males sing two distinct categories of songs during the dawn chorus: a complex and variable chatter song and a more repeatable trill song. Dominant males with male subordinate helpers produced chatter songs at a greater rate than either dominant males without helpers or subordinates, suggesting a role in the competition between male group members. However, the trill song is implicated in female choice because older males sing songs with a longer trill component and have greater extrapair success, and trade-offs between phrases within the trill component imply constraints on the length of the trill component in entirety that could enforce honesty. The dawn chorus of the superb fairy-wren may thus have a duel role, involving enforcement of dominance among male group members (male–male competition), and signalling attractiveness to mates (female choice).

The use of chemical and visual cues in female choice in the butterflyBicyclus anynana

Investigating the relative importance of multiple cues for mate choice within a species may highlight possible mechanisms that led to the diversification of closely related species in the past. Here, we investigate the importance of close-range pheromones produced by male Bicyclus anynana butterflies and determine the relative importance of these chemical cues versus visual cues in sexual selection by female choice. We first blocked putative androconial organs on the fore- and hindwings of males, while also manipulating the ability of females to perceive chemical signals via their antenna. We found that male chemical signals were emitted by both fore- and hindwing pairs and that they play an important role in female choice. We subsequently tested the relative importance of these chemical cues versus visual cues, previously identified for this species, and found that they play an equally important role in female choice in our laboratory setting. In addition, females will mate with males with only one signal present and blocking both androconial organs on males seems to interfere with male to male recognition. We discuss the possible functions of these signals and how this bimodal system may be used in intra- and interspecific mate evaluation.

Song repertoire size is correlated with body measures and arrival date in common nightingales, Luscinia megarhynchos

In songbirds, the individual features of a male's song play a role in female choice and male–male interactions. Therefore, it has been hypothesized that the song characteristics of an individual should be correlated with its quality and this has been shown for some species. The species studied so far have only small or medium-sized song repertoires, leaving open the question of whether, in species with large repertoires, song characteristics such as repertoire size are related to male quality. We investigated the correlations between body measures, song characteristics and arrival dates of common nightingales, a songbird species in which males have extraordinarily large song type repertoires. We found that birds with large repertoires had longer wings and were heavier, and arrived earlier, than those with small repertoires. Other song characteristics, such as song diversity and proportion of whistle songs, were not significantly correlated with body measures. When we correlated body measures with arrival date, we found that birds that arrived earlier were heavier and tended to be in better condition. These findings provide supporting evidence that repertoire size is an indicator of a male's quality.

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

AbstractStudies 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.

FemaleBicyclus anynanabutterflies choose males on the basis of their dorsal UV-reflective eyespot pupils

Sexual and natural selection pressures are thought to shape the characteristic wing patterns of butterfly species. Here we test whether sexual selection by female choice plays a role in the maintenance of the male wing pattern in the butterfly Bicyclus anynana. We perform one of the most extensive series of wing pattern manipulations in butterflies, dissecting every component of the 'bulls-eye' eyespot patterns in both ventral and dorsal wing surfaces of males to test the trait's appeal to females. We conclude that females select males on the basis of the size and brightness of the dorsal eyespot's ultraviolet reflecting pupils. Pupil absence is strongly selected against, as are artificially enlarged pupils. Small to intermediate (normal sized) pupils seem to function equally well. This work contradicts earlier experiments that suggest that the size of dorsal eyespots plays a role in female choice and explains why male dorsal eyespots are very variable in size and often have indistinct rings of coloration, as the only feature under selection by females seems to be the central white pupil. We propose that sexual selection by female choice, rather than predator avoidance, may have been an important selective factor in the early stages of eyespot evolution in ancestral Lepidopteran lineages.