Differences In Female Preferences Research Articles

Testing sensory drive speciation in cichlid fish: Linking light conditions to opsin expression, opsin genotype and female mate preference.

Ecological speciation is facilitated when divergent adaptation has direct effects on selective mating. Divergent sensory adaptation could generate such direct effects, by mediating both ecological performance and mate selection. In aquatic environments, light attenuation creates distinct photic environments, generating divergent selection on visual systems. Consequently, divergent sensory drive has been implicated in the diversification of several fish species. Here, we experimentally test whether divergent visual adaptation explains the divergence of mate preferences in Haplochromine cichlids. Blue and red Pundamilia co‐occur across south‐eastern Lake Victoria. They inhabit different photic conditions and have distinct visual system properties. Previously, we documented that rearing fish under different light conditions influences female preference for blue versus red males. Here, we examine to what extent variation in female mate preference can be explained by variation in visual system properties, testing the causal link between visual perception and preference. We find that our experimental light manipulations influence opsin expression, suggesting a potential role for phenotypic plasticity in optimizing visual performance. However, variation in opsin expression does not explain species differences in female preference. Instead, female preference covaries with allelic variation in the long‐wavelength‐sensitive opsin gene (LWS), when assessed under broad‐spectrum light. Taken together, our study presents evidence for environmental plasticity in opsin expression and confirms the important role of colour perception in shaping female mate preferences in Pundamilia. However, it does not constitute unequivocal evidence for the direct effects of visual adaptation on assortative mating.

Female preference functions drive interpopulation divergence in male signalling: call diversity in the bushcricket Ephippiger diurnus.

Female preferences play a major role in the elaboration and diversification of male traits: as a selective pressure on males, variation in female preferences can generate population divergence and ultimately, speciation. We studied how interpopulation differences in the shape of female mate preference functions may have shaped male advertisement signals in the bushcricket Ephippiger diurnus. This species is distributed as geographically isolated populations with striking interpopulation variation in male acoustic signals, most notably in the number of syllables per call. Here, we asked whether differences in the shape of preference functions exist among populations and whether those differences may have driven male signal evolution resulting in the observed differences in syllable numbers. Our results reveal fundamental differences in female preferences among populations, with differences in the overall preference function shape corresponding to differences in male signals. These differences in female preferences best explain the major differences in male signals among populations. The interpopulation variation in signals and preferences potentially reflects the evolutionary history of the species and may contribute to further divergence among populations and subsequent speciation.

The Role of Vibrations in Population Divergence in the Red Mason Bee, Osmia bicornis

Differences in female preference for certain male characteristics can be a driving force for population divergence and speciation [1-4]. During precopulation, females of the red mason bee, Osmia bicornis, choose suitable males based on, among other criteria, their thoracic vibrations [5]. These vibrations are thought to be a signal of a male's fitness with females choosing the strongest males that can vibrate for the longest time [5]. The precise role of such vibrational signals, however, has not been determined by bioassays, and the vibrations might also play a role in species recognition [6]. There are two main subspecies of O. bicornis in Europe distinguishable only by a single morphological trait [7] (Figure S1). We therefore developed a new bioassay allowing us to impose the vibrations of one live male onto another in order to discern possible selective mate choice by females from O. bicornis originating from different regions of Europe. Females showed strong preference for males from their own region, and male vibrations were the main signal involved in this choice. Thus, vibrational signals encode not only fitness but also information about the region of origin indicating that divergence exists between the different European O. bicornis populations, which might ultimately lead to speciation. These results provide new insights into the scope of vibrational communication in bees, a group previously considered to rely predominantly on chemical signals [8, 9]. Our newly developed method should shed further light on many exciting questions concerning vibrational communication in bees and other animal taxa.

The Terminal Investment Hypothesis and Age-related Differences in Female Preference for Dads vs. Cads

Williams’ (1966) terminal investment hypothesis states that in species showing an age-related decline in reproductive value, reproductive effort should increase with age. Non-human primate studies have supported this hypothesis, though research in humans is lacking, likely due to the restricted age range of participants in typical studies in evolutionary psychology. We hypothesize that older women will decrease mating effort in order to allocate additional resources to parental effort, and that this shift will be manifested in women’s’ mate selection preferences. Because older women are hypothesized to shift resources from mating to parenting, they may show greater preferences for partners with high potential for paternal investment compared to partners with features signaling high potential for genetic investment. We use character sketches of “dad” and “cad” male reproductive strategies to demonstrate the age-related shift in relationship preferences. We found that older women prefer mating strategies that are related with higher paternal investment. In addition, we found that a woman's self-description changes with age, mediating the age-related changes in mate preferences. We suggest that these changes serve the changing needs of an older woman and the transition from investing in future offspring to investment in the current offspring.

Female preference and larval performance of sunflower moth, Homoeosoma electellum, on sunflower pre‐breeding lines

AbstractThe preference–performance hypothesis for insect herbivores predicts that adult females should preferentially choose hosts on which their offspring perform better. We tested this hypothesis for the sunflower moth, Homoeosoma electellum (Hulst) (Lepidoptera: Pyralidae), using 16 sunflower (pre‐breeding) lines, derived from a number of wild species of Helianthus, including Helianthus annuus L., Helianthus deserticola Heiser, Helianthus paradoxus Heiser, Helianthus praecox Engelm. & Gray ssp. hirtus (Heiser) Heiser, Helianthus praecox Engelm. & Gray ssp. runyonii (Heiser) Heiser, Helianthus petiolaris Nutt., Helianthus resinosus Small, and Helianthus tuberosus L. (Asteraceae), that are suitable for introducing wild sunflower germplasm into commercial cultivars. Female moths showed a range of ovipositional preference measures to the various lines. Combined data for three Helianthus species represented by multiple lines showed significant differences in female preference with respect to the parental species. Larval performance, determined by proportion of infested neonate larvae reaching the pupal stage, or mean pupal weight, varied across the lines and, as for the female preference data, also showed significant differences among the three parental Helianthus species represented by multiple lines. These data suggest that the characteristics in the pre‐breeding lines influencing female sunflower moth preference and larval performance likely originate from the parental species and may be consistently transferred to the derived pre‐breeding lines. Of particular note with regard to potential plant resistance mechanisms, lines derived from H. tuberosus showed consistent low preference–performance measures. Female preference and larval performance (for both measures) were strongly correlated, indicating that females preferred plants and lines on which larvae performed better, in support of the preference–performance hypothesis.

Fluctuating mate preferences in a marine fish

According to theory, directional female choice for male sexual ornaments is expected to erode underlying genetic variation. Considerable attention, in this regard, has been given to understanding the ubiquity of heritable genetic variation in both female choice and male sexual traits. One intriguing possibility emerging from this work is that persistent genetic variation could be maintained, over time, by variation in female mate preferences. Here, we report the results of a four-year study showing significant year-to-year fluctuations in mate preferences in a small marine fish, the sand goby, Pomatoschistus minutus. Although the average size of mature fish varied across years, we were unable to find direct evidence linking this variation to differences in female preferences among years. Our results, nevertheless, underscore the importance of temporal fluctuations in female mate preferences, as these can have important consequences for understanding variation in sexual traits and the intensity of sexual selection.

Do peahens not prefer peacocks with more elaborate trains?

Ever since Darwin (1871), the peacock’s train has been cited as the icon of an extravagant conspicuous secondary sexual trait that has evolved through female mate choice. However, Takahashi et al. (2008) recently challenged this idea. They monitored female mate choice during 7 years in a feral peafowl, Pavo cristatus, population in Japan and found no correlation between male mating success and three morphological train traits. They concluded that ‘combined with previous results, our findings indicate that the peacock’s train is not currently the universal target of female choice’ and proposed ‘that the peacock’s train is an obsolete signal for which female preference has already been lost or weakened’ (Takahashi et al. 2008, page 1216). We feel that their conclusions are far too strong, particularly since three independent studies have found a relationship between train features and mating success (Petrie et al. 1991; Petrie & Halliday 1994; Yasmin & Yahya 1996; Loyau et al. 2005a). The purpose of this article is therefore to draw attention to alternative explanations and conclusions that are essential for the understanding of the complexity of mate choice. We first suggest some possible nonadaptive and adaptive explanations for the reported differences in female preferences in the peafowl. We then show that plasticity in mate choice is a widespread phenomenon across a large spectrum of species. Therefore, we suggest that findings based on a single

Differences in female preference for male body size in Poecilia latipinna using simultaneous versus sequential stimulus presentation designs

Female sailfin mollies (Poecilia latipinna) were presented simultaneously with a series of dummy male pairs that differed only in male body size (with dorsal fin size held constant). Females showed a significant directional preference for males of larger body size. However, when presented with the same five dummies in sequence, the same females showed a much weaker preference for increased male body size. To our knowledge, this study is the first of its kind to present to the same females the same set of stimuli in both sequential and paired fashion. Our results showed that females exhibit a much stronger preference for larger males presented simultaneously than when presented in sequence. Female sailfin mollies may therefore more strongly prefer larger males when they can make direct and immediate comparisons between them. These results highlight the importance of considering how females encounter potential mates in nature when designing experiments on female preference in a given species. They also emphasize how the distribution and local density of prospective mates and the context in which they are presented may influence mate choice and sexual selection in general.

SYMPATRIC SPECIATION BY SEXUAL SELECTION ALONE IS UNLIKELY

According to Darwin, sympatric speciation is driven by disruptive, frequency-dependent natural selection caused by competition for diverse resources. Recently, several authors have argued that disruptive sexual selection can also cause sympatric speciation. Here, we use hypergeometric phenotypic and individual-based genotypic models to explore sympatric speciation by sexual selection under a broad range of conditions. If variabilities of preference and display traits are each caused by more than one or two polymorphic loci, sympatric speciation requires rather strong sexual selection when females exert preferences for extreme male phenotypes. Under this kind of mate choice, speciation can occur only if initial distributions of preference and display are close to symmetric. Otherwise, the population rapidly loses variability. Thus, unless allele replacements at very few loci are enough for reproductive isolation, female preferences for extreme male displays are unlikely to drive sympatric speciation. By contrast, similarity-based female preferences that do not cause sexual selection are less destabilizing to the maintenance of genetic variability and may result in sympatric speciation across a broader range of initial conditions. Certain groups of African cichlids have served as the exclusive motivation for the hypothesis of sympatric speciation by sexual selection. Mate choice in these fishes appears to be driven by female preferences for extreme male phenotypes rather than similarity-based preferences, and the evolution of premating reproductive isolation commonly involves at least several genes. Therefore, differences in female preferences and male display in cichlids and other species of sympatric origin are more likely to have evolved as isolating mechanisms under disruptive natural selection.

SYMPATRIC SPECIATION BY SEXUAL SELECTION ALONE IS UNLIKELY

According to Darwin, sympatric speciation is driven by disruptive, frequency-dependent natural selection caused by competition for diverse resources. Recently, several authors have argued that disruptive sexual selection can also cause sympatric speciation. Here, we use hypergeometric phenotypic and individual-based genotypic models to explore sympatric speciation by sexual selection under a broad range of conditions. If variabilities of preference and display traits are each caused by more than one or two polymorphic loci, sympatric speciation requires rather strong sexual selection when females exert preferences for extreme male phenotypes. Under this kind of mate choice, speciation can occur only if initial distributions of preference and display are close to symmetric. Otherwise, the population rapidly loses variability. Thus, unless allele replacements at very few loci are enough for reproductive isolation, female preferences for extreme male displays are unlikely to drive sympatric speciation. By contrast, similarity-based female preferences that do not cause sexual selection are less destabilizing to the maintenance of genetic variability and may result in sympatric speciation across a broader range of initial conditions. Certain groups of African cichlids have served as the exclusive motivation for the hypothesis of sympatric speciation by sexual selection. Mate choice in these fishes appears to be driven by female preferences for extreme male phenotypes rather than similarity-based preferences, and the evolution of premating reproductive isolation commonly involves at least several genes. Therefore, differences in female preferences and male display in cichlids and other species of sympatric origin are more likely to have evolved as isolating mechanisms under disruptive natural selection.

Environmental Predictors of Geographic Variation in Human Mating Preferences

Sexual selection theory classically posits consistent and directional mate‐preferences for male traits that provide benefits to females. However, flexible mate‐choice tactics may persist within a species when males display multiple desirable features that confer different benefits to females under variable environmental conditions. Ecological factors such as population density, resource demand, and sex ratio can influence the value that female animals place on certain male characteristics across mating environments. In this study, I used human mate‐preference data from `lonely hearts' advertisements in the newspapers of 23 cities in the USA to assess geographic differences in female preferences for male traits (e.g. physical attributes, resource‐holding potential, emotional characteristics, personal interests) in relation to these ecological parameters. I found that females placed more emphasis on the resource‐accruing ability of prospective mates in densely populated cities and cities having greater resource demands (higher cost of living). In contrast, women from densely populated or resource‐demanding cities placed less emphasis on the emotional aspects or personal interests of males. Preferences for physical features were not environmentally linked, but instead were a function of the degree to which females advertised their own physical attractiveness. Collectively, these results suggest that certain mate‐choice criteria employed by women are sensitive to variation in local environmental conditions and that variable levels of resource or mate availability may favor different mating tactics across human populations.

Drosophila song as a species-specific mating signal and the behavioural importance of Kyriacou & Hall cycles in D. melanogaster song

‘Species-specific’ mating signals may not make a significant contribution to sexual isolation if differences between species are not matched by narrowly tuned differences in female preferences. The courtship song of the melanogaster species group of Drosophila has been studied by several researchers as a potential factor in sexual isolation, but there are few clear demonstrations that species differences are behaviourally significant. We played synthetic song with typical pulse interval parameters for D.melanogaster, D.simulans orD.sechellia to D.melanogaster or D.simulans females in the presence of mute males. Females mated most quickly when stimulated by song typical of their own species, confirming that song can influence sexual isolation between these species. This effect was greater in D.melanogaster than D.simulans, which correlates with reduced variability in mean interpulse interval within D.melanogaster. We also examined the role of ‘Kyriacou & Hall cycles’ (periodic cycling of mean interpulse intervals) in D.melanogaster. Contrary to some predictions, the presence of the Kyriacou & Hall cycle was more important in increasing mating speed than the increased variability of interpulse intervals that is inevitably present in song containing a cycle. The large stimulatory effect of cycles on mating speed is curious, given that the periodicity of cycles would probably be difficult for females to detect during courtship in field conditions.

Male advertisement call and female preference in sympatric and allopatric midwife toads

Advertisement calls and female preferences in allopatric populations of midwife toads,Alytes obstetricansandA.cisternasiiwere compared with those in a sympatric population. These species have simple tonal advertisement calls which overlap substantially in frequency and duration. In both species, the duration of male advertisement calls did not differ between an allopatric and a sympatric population. Playback tests suggested that females in allopatric populations preferentially approach low frequency calls and long calls, exerting directional selection for larger males and males with longer calls. FemaleA.cisternasiifrom the sympatric zone did not prefer low frequency calls, which could be made by males ofA.obstetricansSimilarly, femaleA.obstetricansfrom the sympatric zone did not preferentially approach long calls, which could be made byA.cisternasiimales. The differences in female preference between sympatry and allopatry follow the expected direction of reproductive character displacement. Within each species, female preferences differed clearly between sympatry and allopatry while male call characteristics did not.