Mate choice for major histocompatibility complex(MHC)complementarity in the Yellow-rumped Flycatcher(Ficedula zanthopygia)

Background:Genes of the major histocompatibility complex(MHC)are an important component of the vertebrate immune system and play a significant role in mate choice in animal populations.However,the MHC genetic targets of female mate choice have not been clearly identified,and whether female mate choice is based on neutral genetic characteristics remains an open question.Here,we focus on the effects of morphological traits and genetic similarity among individuals in MHC class IIB(MHC IIB)exon 2 on mating in a sexually dimorphic songbird that exhibits social monogamy with extra-pair paternity(EPP).Methods:We sequenced 64 parent-offspring triads sampled over a 3-year period using two MHC class II loci to detect disassortative mating in the Yellow-rumped Flycatcher(Ficedula zanthopygia).Results:We found that MHC similarity in social pairs was lower than that in random pairs.Extra-pair mate choice according to MHC IIB was observed,in which females’extra-pair mates had fewer MHC alleles than their within-pair mates,but there was no significant band-sharing between extra-pair sires and potential extra-pair mates.However,the interaction between the MHC diversity of females and that of the social males affected the occurrence of EPP.Conclusions:Our results support the“optimality hypothesis”of MHC-based social and extra-pair choice.Female choice probably maintains a certain level of MHC diversity in offspring in the Yellow-rumped Flycatcher.

Can simple songs express useful signals for mate choice?

Background:As one of the most elaborate and diverse sexual signals,bird songs are prominent among mate choice criteria.Females generally prefer mates with larger repertoire size,which promotes the evolution of song complex?ity.However,there are also some songbirds that have far simpler and less diverse vocalizations,which have not been the focus of scientific scrutiny.Most Phylloscopus warblers are accomplished singers with complex songs.In contrast,Hume's Warbler(P.humei) has extremely simple songs.In order to explore the song's function,its evolutionary sig?nificance and particularly to assess its possible relationship with parental investment,we studied mate choice of the subspecies P.h.mandellii in Lianhuashan National Nature Reserve,Gansu,China.Methods:We recorded body measurements and songs of breeding males and then explored their relationships with the date of clutch initiation,reasoning that the characteristics of males that are involved with early nesting activities reflect female mate preferences.We also recorded egg size and body measurements of nestlings to assess the rela?tionship between parental investment and mate choice.Results:We found that male wing and tail lengths were positively correlated with early clutch initiation as were songs characterized by short duration and rapid rise to maximum amplitude.We also found that early?breeding females did not lay large eggs,but produced more surviving young,which grew up faster.Conclusions:Female mate choice criteria in this bird include both visual signals and song characteristics.Our study supports the hypothesis that females may judge male quality from quite subtle differences.In order to reduce the risk of predation,a preference for such inconspicuous male characteristics may be partially driven by high vulnerability of this warbler to predators as a ground?nesting species.

Mate choice is affected by parasite infestation rate of the choosing individual as well as of potential mating partners

Parasites are known to be a key driving force in mate choice and are important for the expression and evolution of ornaments and behavioral traits being used.However,there is little experimental evidence on how the parasite’s burden of the choosing individual is integrated into the mate-choice process and how it affects decision-making,especially in relation to parasite infestation of potential mates.Thus,the aim of our study was to determine whether female house sparrows Passer domesticus adjust their mate preference according to their own as well as the parasite load of prospective partners.To do this,we experimentally manipulated female parasite load and determined their mate preferences prior to and after parasite treatment.We manipulated the chronic coccidian parasite burden of females either by initiating the acute infection phase via re-infecting them with coccidian or by temporally reducing the parasite load of coccidia.We then measured the effect of this manipulation on mate preference by presenting females with a choice of four stimuli:three males with similar ornaments,but unmanipulated,naturally varying chronic coccidiosis levels,and an unmanipulated control female.Additionally,we recorded some males’behavior in relation to their infection status pointing toward an increased or reduced interest in mating.We found that females preferred highly infested males prior to manipulation,regardless of their own infestation level.However,after manipulation,infested females avoided highly infested males probably in response to the deterioration of their health condition by parasites.Our study suggests that mate-choice decisions are more complex when they are mediated by parasites.The implications of parasites for evolutionary theories of sexual signaling and mate choice are discussed.

Do males choose their mates in the lekking moth Achroia grisella？ Influence of female body mass and male reproductive status on male mate choice

Lekking males aggregate to attract females and contribute solely to egg fer- tilization, without any further parental care. Evolutionary theory therefore predicts them to be nonchoosy toward their mates, because any lost mating opportunities would out- weigh the benefits associated with such preferences. Nevertheless, due to time costs, the production of energetically costly sexual displays, and potential sperm limitation, the mat- ing effort of lekking males is often considerable. These factors, combined with the fact that many females of varying quality are likely to visit leks, could favor the evolution of male mate preferences. Here, we show that males of the lekking lesser wax moth, Achroia grisella, were indeed more likely to mate with heavier females in choice experiments, even at their virgin mating （i.e., when their reproductive resources have not yet been depleted by previous matings）. This differential female mating success could not be attributed to female behavior as heavy and light females showed similar motivation to mate （i.e., la- tency to approach the males） and time to copulate. Males seem to benefit from mating with heavier females, as fecundity positively correlated with female mass. This new em- pirical evidence shows that male mate choice may have been tmderestimated in lekking species

Major histocompatibility complex and mate choice in the polygynous primate:the Sichuan snub-nosed monkey(Rhinopithecus roxellana)

The highly polymorphic genes within the major histocompatibility complex(MHC)not only play a major role in immunity resistance,but also seem to provide hints for mate choice in some animal populations.In the pres­ent study we investigated MHC-related mate choice in a small natural population(group size 40-55 individuals)of a polygynous primate,the Sichuan snub-nosed monkey(Rhinopithecus roxellana).We found that there was no evidence either for MHC-disassortative mating,or for females to mate with males based on MHC hetero­zygosity or specific alleles.Nevertheless,of the 11 alleles identified,we found that the frequencies of 2 alleles,Rhro-DRB2(P<0.01)and Rhro-DRB5(P<0.05)were higher in offspring than in their parents.These findings suggest that MHC-DRB in this population of R.roxellana is unlikely to be associated with mating preferences.Limited female opportunities for mate choice are likely due,in part,to the harem breeding structure present in R.roxellana,and the relatively small number of resident adult males in our study band(N=4-6).In addition,we suggest that differences in the frequency of particular alleles across generations may be linked to parasite resis­tance in a fluctuating environment;however,confirmation of this finding requires further study.

Chromatic and achromatic differences of melanin-and carotenoid-based plumage coloration in five minivet species(Pericrocotus spp.)under conspecific and predator visual systems

Adaptive mate choice has been accepted as the leading theory to explain the colorful plumage of birds.This theory hypothesizes that conspicuous colors act as signals to advertise the qualities of the owners.However,a dilemma arises in that conspicuous colors may not only attract mates,but also alert predators.The"private channels of communication"hypothesis proposes that some intraspecific signals may not be visible to heterospecific animals because of different visual systems.To better understand the evolution of plumage colors and sexual selection in birds,here we studied the chromatic difference and achromatic differences of melanin-and carotenoid-based plumage coloration in five minivet species(Pericrocotus spp.)under conspecific and predator visual systems.We found that either the chromatic or achromatic difference among male or female minivets’plumage was consistently higher under conspecific vision than under predator vision for all five studied species of minivets.This result indicated that individual differences in plumage colors of minivets were visible to the conspecific receivers and hidden from potential predators as a result of evolution under predation risk and conspecific communication.However,males were under a higher risk of predation because they were more conspicuous than females to the vision of a nocturnal predator.

Nonlinear Phenomena Conveying Body Size Information and Improving Attractiveness of the Courtship Calls in the Males of Odorrana tormota

Nonlinear phenomena are commonly shown in the vocalization of animals and exerts different adaptive functions.Although some studies have pointed out that nonlinear phenomena can enhance the individual identification of male Odorrana tormota,whether the nonlinear phenomena play a specific role in the sexual selection of O.tormota remain unclear.Here we presented evidence that there was a significant negative correlation(Pearson:n=30,r=0.65,P<0.001)between the nonlinear phenomena content and snout-vent length in the male O.tormota,and two-choice amplexus experiments showed that female O.tormota preferred male with smaller body size containing higher nonlinear phenomena content in its calls.Phonotaxis experiments also revealed that females preferred calls with higher nonlinear phenomena content.Additionally,compared to the calls with lower nonlinear phenomena content and higher fundamental frequency,there was shorter response time in phonotactic behaviour of female induced by the calls with higher nonlinear phenomena content and lower fundamental frequency.We argue that the nonlinear phenomena content in the calls of male O.tormota can convey its body size information and may provide important clues for female frogs in darkened surroundings to identify males’body size during mate choice,meanwhile,higher nonlinear phenomena content in males’calls may increase the attractiveness of males to females.The results of this study provide confirmation that,for O.tormota,nonlinear phenomena have specific function in mate choice.

Females adopt sexual catalepsy to facilitate mating

Theory predicts that males and females of dioecious species typically engage in an evolutionary sexual conflict over the frequency and choice of mating partner.Female sexual cannibalism,a particularly dramatic illustration of this conflict,is widespread in certain animal taxa including spiders.Nevertheless,females of some funnel weaving spiders that are generally aggressive to conspecifics enter a cataleptic state after male courtship,ensuring the males can mate without risk of attack.In this study,we demonstrated that the physical posture and duration,metabo-lites,and central neurotransmitters of females of Aterigena aculeata in sexual catalepsy closely resemble females in thanatosis but are distinct from those in anesthesia,indicating that the courted females feign death to eliminate the risk of potentially aggressive responses and thereby allow preferred males to mate.Unlike the taxonomically widespread thanatosis,which generally represents a deceptive visual signal that acts against the interest of the receivers,sexual catalepsy of females in the funnel weaving spiders may deliver a sexual-receptive signal to the courting males and thereby benefit both the signal senders and receivers.Therefore,sexual catalepsy in A.aculeata may not reflect a conflict butrather a confluence of interest betweenthe sexes.

Natural variation in social conditions affects male mate choosiness in the amphipod Gammarus roeselii

The extent of male mate choosiness is driven by a trade-off between various environmental factors associated with the costs of mate acquisition,quality assessment and opportunity costs.Our knowledge about natural variation in male mate choosiness across different populations of the same species,however,remains limited.In this study,we compared male mate choosiness across 10 natural populations of the freshwater amphipod Gammarus roeselii(Gervais 1835),a species with overall high male mating investments,and evaluated the relative influence of population density and sex ratio(both affecting mate availability)on male mate choosiness.We investigated amplexus establishment after separating mating pairs and presenting focal males with a novel,size-matched female from the same population.Our analysis revealed considerable effects of sex ratio and(to a lesser extent)population density on time until amplexus establishment(choosiness).Male amphipods are able to perceive variable social conditions(e.g.,sex ratio)and modify their mating strategy accordingly:We found choosiness to be reduced in increasingly male-biased populations,whereas selectivity increases when sex ratio becomes female biased.With this,our study expands our limited knowledge on natural variations in male mate choosiness and illustrates the importance of sex ratio(i.e.,level of competition)for male mating decisions in natural environments.Accounting for variation in sex ratios,therefore,allows envisioning a distinctive variation of choosiness in natural populations and highlights the importance of considering social background information in future behavioral studies.

Male courtship signal modality and female mate preference in the wolf spider Schizocosa ocreata: results of digital multimodal playback studies

Females must be able to perceive and assess male signals,especially when they occur simultaneously with those of other males.Previous studies show female Schizocosa ocreata wolf spiders display receptivity to isolated visual or vibratory courtship signals,but increased receptivity to multimodal courtship.It is unknown whether this is true when females are presented with a choice between simultaneous multimodal and isolated unimodal male courtship.We used digital playback to present females with a choice simulating simultaneous male courtship in different sensory modes without variation in information content:1)isolated unimodal visual versus vibratory signals;2)multimodal versus vibratory signals;and 3)multimodal versus visual signals.When choosing between isolated unimodal signals(visual or vibratory),there were no significant differences in orientation latency and number of orientations,approaches or receptive displays directed to either signal.When given a choice between multimodal versus vibratory-only male courtship signals,females were more likely to orient to the multimodal stimulus,and directed significantly more orients,approaches and receptivity behaviors to the multimodal signal.When presented with a choice between multimodal and visual-only signals,there were significantly more orients and approaches to the multimodal signal,but no significant difference in female receptivity.Results suggest that signal modes are redundant and equivalent in terms of qualitative responses,but when combined,multimodal signals quantitatively enhance detection and/or reception.This study confirms the value of testing preference behavior using a choice paradigm,as female preferences may depend on the context(e.g.,environmental context and social context)in which they are presented with male signals.

The best of both worlds:cicada males change costly signals to achieve mates while females choose a mate based on both calling and courtship songs

Cicadas usually sing and mate in the higher parts of trees.Studies addressing the effects of different acoustic signals on mate choice in Cicadidae are very limited.We investigated the effects of both acoustical features and morphological traits on mate choice in an East Asian cicada Platypleura kaempferi.Males produce high-rate calling songs that attract females,then produce low-rate courtship songs to secure mating when a female is attracted.Higher calling song rate(CR),shorter single-pulse duration,and shorter pulse period of the calling song,together with lower courtship song rate and longer echeme period of the courtship song,are the most desirable traits used by females to choose a mate.These traits indicate that the more amale can raise the rate of song production,the higher the probability he is sexually selected by the female.No correlation was found between morphological traits and mating success.After mating,a minority of males started emitting calling songs again,but the CR was significantly lower than before mating and none of them attracted a new mate later.This promotes females mating with unmated males.We hypothesize that P.kaempferi may have the best of both worlds due to the unique song modulation and the mechanism of female mate choice:males change energetically,costly acoustic signals to achieve mates,while females choose a mate based on males’acoustic properties.Our results contribute to better understanding the diversity of mating preference and enrich the mechanism of mate choice in acoustic insects.

Wild bacterial probiotics fed to larvae of mass-reared Queensland fruit fly[Bactrocera tryoni(Froggatt)]do not impact long-term survival,mate selection,or locomotor activity

Queensland fruit fly[Bactrocera Uyoni(Froggatt),Diptera,Tephritidae]is the most devastating insect pest impacting Australian horticulture.The Sterile Insect Technique(SIT)is an important component of tephritid pest management programs.However,mass-rearing and irradiation(to render insects sterile)may reduce the fitness and performance of the insect,including the ability of sterile males to successfully compete for wild females.Manipulation of the gut microbiome,including the supplementation with bacterial probiotics shows promise for enhancing the quality of mass-reared sterile flies,however there are fewer published studies targeting the larval stage.In this study,we supplemented the larval stage of mass-reared B.tryoni with bacterial probiotics.We tested several individual bacteria that had been previously isolated and characterized from the gut of wild B.tryoni larvae including Asaia sp.,Enterobacter sp.,Lactobacillus sp.,Leuconostoc sp.We also tested a consortium of all four of these bacterial isolates.The fitness parameters tested included adult survival in field cages,laboratory mate selection of bacteria supplemented males by bacteria nonsupplemented females,and laboratory locomotor activity of adult flies.None of the bacterial probiotic treatments in the current study was significantly different to the control for field survival,mate selection or locomotor activity of adult B.Uyoni,which agree with some of the other studies regarding bacterial probiotics fed to the larval stage of tephritids.Future work is needed to determine if feeding the same,and/or other probiotics to adults,as opposed to larvae can positively impact survival,mating performance,mating competitiveness and locomotor activity of B.tryoni.The bacterial group(s)and function of bacterial species that increase fitness and competitiveness is also of interest to tephritid mass-rearing programs.

Mismatch between calf paternity and observed copulations between male and female reindeer:Multiple mating in a polygynous ungulate?

In polygynous systems,such as that exhibited by reindeer Rangifer tarandus,mate choice can be difficult to disentangle from male intrasexual competition because male behavior may constrain female choice.Multiple mating may provide an avenue for female mate choice,though it is difficult to identify using behavioral estimators alone.Molecular techniques address this issue by affording ecologists an opportunity to reassess mating systems from a genetic perspective.We assessed the frequency and possible explanations for multiple mating in reindeer using a genetic approach to determine the success of observed copulations in a semi-domesticated herd in Kaamanen,Finland.Behavioral and genetic data were synthesized with population characteristics over a 7-year period to test the hypothesis that,if present,polyandry in reindeer is driven by sexual harassment from sub-dominant males.We observed multiple mating in 42%of females,with as many as 60%exhibiting multiple mating in certain years.We found no evidence that multiple mating resulted from sexual harassment by sub-dominant males,suggesting that it is likely a deliberate strategy among females.Conversion rate of copulations into paternities varied with male size,with smaller males more likely to experience mismatch than larger males.Female preference for larger males persisted despite the occurrence of multiple mating,possibly suggesting a mechanism for cryptic post-copulatory selection.We suggest further research to delineate the possible influence of cryptic post-copulatory selection and multiple mating to defend against infertility in exhausted males.

Asymmetric reinforcement in Lucania killifish:assessing reproductive isolation when both sexes choose

Reinforcement can occur when maladaptive hybridization in sympatry favors the evolution of con-specific preferences and target traits that promote behav ioral isolation(BI).In many systems,enhanced BI is due to increased female preference for conspecifics.In others,BI is driven by male preference,and in other systems both sexes exert preferences.Some of these patterns can be atributed to classic sex-specific costs and benefits of preference.Alternatively,sex differences in conspecific preference can emerge due to asymmetric postzygotic isolation(e.g.,hybrid offspring from female A × male B have lower fitness than hybrid offspring from female B × male A),which can lead to asymmetric BI(e.g.,female A and male B are less likely to mate than female B and male A).Understanding reinforcement requires understanding how conspecific preferences evolve in sympatry.Yet,estimating conspecific preferences can be difficult when both sexes are choosy.In this study,we use Lucania killifish to test the hypothesis that patterns of reinforcement are driven by asymmetric postzygotic isolation between species.If true,we predicted that sympatric female Lucania goodei and sympatric male L.parva should have lower levels of BI compared with their sympatric counterparts,as they produce hybrid offspring with the highest fitness.To address the problem of measuring BI when both sexes are choosy,we inferred the contribution to BI of each partner using assays where one sex in the mating pair comes from an allopatric population with potentially low preference,whereas the other comes from a sympatric population with high prefer-ence.For one hybrid cross direction,we found that both female L.parva and male L.goodei have high contributions to BI in sympatry.In the other hybrid cross direction,we found that only female L.goodei contribute to BI.Sympatric male L.parva readily engaged in hybrid spawnings with allo-patric L.goodei females.These results indicate that both asymmetric postzygotic isolation and the traditional sex-specific costs to preference likely affect the nature of selection on conspecific prefer-ences and target traits.

Is bigger better？ Male body size affects wing-borne courtship signals and mating success in the olive fruit fly, Bactrocera oleae （Diptera： Tephritidae）

Variations in male body size are known to affect inter- and intrasexual selection outcomes in a wide range of animals. In mating systems involving sexual signaling before mating, body size often acts as a key factor affecting signal strength and mate choice. We evaluated the effect of male size on courtship displays and mating success of the olive fruit fly, Bactrocera oleae （Diptera： Tephritidae）. Wing vibrations performed during successful and unsuccessful courtships by large and small males were recorded by high-speed videos and analyzed through frame-by-frame analysis. Mating success of large and small males was investigated. The effect of male-male competition on mating success was evaluated. Male body size affected both male courtship signals and mating outcomes. Successful males showed wing-borne signals with high frequencies and short interpulse intervals. Wing vibrations displayed by successful large males during copulation attempt had higher frequencies over smaller males and unsuccessful large males. In no-competition conditions, large males achieved higher mating success with respect to smaller ones. Allowing large and small males to compete for a female, large males achieve more mating success over smaller ones. Mate choice by females may be based on selection of the larger males, able to produce high-frequency wing vibrations. Such traits may be indicative of ＂good genes,＂ which under sexual selection could means good social-interaction genes, or a good competitive manipulator of conspecifics.

Sexual selection for bright females prevails under light pollution

The functions of sexually selected traits are particularly sensitive to changes in the environment because the traits have evolved to increase mating success under local environmental conditions(Rosenthal and Stuart-Fox 2012).When environmental conditions change,previously reliable signals may become less reliable or harder to detect and evaluate.Because the correct expression,transmission,and interpretation of sexual signals typically influence mate choice outcomes,impediments to sexual signals can change both the strength and the direction of sexual selection(Rosenthal and Stuart-Fox 2012).Artificial light is a major anthropogenic disturbance that is intensifying around the world and has high potential to negatively impact wildlife,for example by hampering the expression and detection of sexual signals.

Female preferences for male golden snub-nosed monkeys vary with male age and social context

Age is a key factor affecting sexual selection,as many physical and social traits are age-related.Although studies of primate mate choice often consider particular age-related traits,few consider the collective effects of male age.We tested the hypothesis that female golden snub-nosed monkeys Rhinopithecus roxellana prefer prime aged males(10-15 years)over younger and older males.We examined a habituated,provisioned troop during a 3-year study in the Qinling Mountains,China.Prime age males were more likely to be resident males of 1-male units(OMUs)than males of other ages.Since females are free to transfer between OMUs,the number of females per OMU can be indicative of female preferences.We examined the number of females per OMU,and found that it increased with resident male age up to 7-8 years,and declined after 12 years,such that prime age resident males had more females than other resident males.Females also initiated extra-unit copulations with high-ranking prime age males at significantly higher rates than with other males.Nevertheless,females tended to transfer from OMUs with high-ranking,older resident males to those with low-ranking,younger resident males.Thus,females appear to use different strategies when choosing social mates and extra-unit mates(i.e.,different social contexts).We speculate that females may perceive early signs of aging in males and trade off the benefits and costs of high rank versus male senescence.This study lays the groundwork for future studies that examine possible direct and indirect benefits of such strategies.

Identifying female phenotypes that promote behavioral isolation in a sexually dimorphic species of fish Etheostoma zonale

In sexually dimorphic species characterized by exaggerated male ornamentation,behavioral isola-tion is often attributed to female preferences for conspecific male signals.Yet,in a number of sexu-ally dimorphic species,male mate choice also results in behavioral isolation.In many of these cases,the female traits that mediate species boundaries are unclear.Females in sexually dimorphic species typically lack many of the elaborate traits that are present in males and that are often used for taxonomic classification of species.In a diverse and largely sexually dimorphic group of fishes called darters(Percidae:Etheostoma),male mate choice contributes to behavioral isolation be-tween a number of species;however,studies addressing which female traits males prefer are lack-ing.In this study,we identified the dominant female pattern for two sympatric species,Etheostoma zonale and Etheostoma barrenense,using pattern energy analysis,and we used discriminate func-tion analysis to identify which aspects of female patterning can reliably classify species.We then tested the role of female features in male mate choice for E.zonale,by measuring male preference for computer animations displaying the identified(species specific)conspecific features.We found that the region above the lateral line is important in mediating male mate preferences,with males spending a significantly greater proportion of time with animations exhibiting conspecific female patterning in this region than with animations exhibiting heterospecific female patterning.Our results suggest that the aspects of female phenotypes that are the target of male mate choice are different from the conspicuous male phenotypes that traditionally characterize species.

Heightened condition dependent expression of structural coloration in the faces,but not wings,of male and female flies

Structurally colored sexual signals are a conspicuous and widespread class of ornament used in mate choice,though the extent to which they encode information on the quality of their bearers is not fully resolved.Theory predicts that signaling traits under strong sexual selection as honest indicators should evolve to be more developmentally integrated and exaggerated than nonsexual traits,thereby leading to heightened condition dependence.Here,we test this prediction through examination of the sexually dimorphic faces and wings of the cursorial fly Lispe cana.Males and females possess structural UV-white and golden faces,respectively,and males present their faces and wings to females during close-range,ground-based courtship displays,thereby creating the opportunity for mutual inspection.Across a field-collected sample of individuals,we found that the appearance of the faces of both sexes scaled positively with individual condition,though along separate axes.Males in better condition expressed brighter faces as modeled according to conspecific flies,whereas condition scaled with facial saturation in females.We found no such relationships for their wing interference pattern nor abdomens,with the latter included as a nonsexual control.Our results suggest that the structurally colored faces,but not the iridescent wings,of male and female L.cana are reliable guides to individual quality and support the broader potential for structural colors as honest signals.They also highlight the potential for mutual mate choice in this system,while arguing for 1 of several alternate signaling roles for wing interferences patterns among the myriad taxa which bear them.

Sex differences in the influence of social context, salient social stimulation and amphetamine on ultrasonic vocalizations in prairie voles

Prairie voles(Microtus ochrogaster)are a socially monogamous rodent species and their cooperative behaviors require extensive communication between conspecifics.Rodents use ultrasonic vocalizations(USVs)to com­municate and because a prairie vole breeder pair must engage in extensive cooperation for successful repro­duction,auditory communication may be critical for this species.Therefore,we sought to characterize USVs in adult male and female prairie voles,and to determine how these calls are influenced by social context,salient social stimuli and the psychostimulant drug of abuse amphetamine(AMPH).Here,we characterize prairie vole USVs by showing the range of frequencies of prairie vole USVs,the proportion of various call types,how these call types compare between males and females,and how they are influenced by social stimulation and AMPH.AMPH caused a robust increase in the number of USVs in both males and females and there was a dramatic sex difference in the complexity of call structures of AMPH-induced USVs,with males emitting more elaborate calls.Moreover,we show that novel(i.e.salient)social cues evoked differential increases in USVs across sex,with males showing a much more robust increase in USV production,both with respect to the frequency and complexity of USV production.Exposure to an estrous female in particular caused an extraordinary increase in USVs in male subjects.These data suggest that USVs may be a useful measure of social motivation in this spe­cies,including how social behaviors can be impacted by drugs of abuse.