Effects of Courtship Song in Interspecific Crosses Among the Species of the Drosophila auraria Complex (Diptera: Drosophilidae)

The courtship behavior and the effects of courtship song in inter- and intraspecific crosses were studied in the four sympatric species of the Drosophila auraria complex: D. auraria, D. biauraria, D. subauraria, and D. triauraria. Orientation, tapping, and vibration (the repertoires of male courtship) were observed in both inter- and intraspecific crosses, suggesting that signals from heterospecific females were enough to elicit such male behaviors. The crossability tests with wingless or winged heterospecific males (tests for wing effects) revealed that winged heterospecific males copulated less than wingless ones in all four species but not all the pairwise cases. Since the crossability tests with aristaless females (deaf) or normal females showed essentially the same results as the tests for wing effects, we concluded that the sound produced by wing vibration plays an important role and that the wing movement itself is less important. These findings suggest that courtship songs are of great importance in mate discrimination and the sexual isolation between the species of this complex.     

Substrate influences mating success and transmission of courtship vibrations for the parasitoid Cotesia marginiventris

The influences of artificial and natural rearing substrates on mating success were investigated for the parasitoid wasp Cotesia marginiventris (Cresson) (Hymenoptera: Braconidae), a candidate for augmentative biological control of various lepidopteran pests. Five rearing substrates were tested: plastic, glass, chiffon fabric, and leaves of two host plants, bean [Vigna unguiculata (L.) (Fabaceae)] and maize [Zea mays L. (Poaceae)]. Mating success was highest on chiffon, lowest on plastic and glass, and intermediate on maize and bean. The transmission characteristics of one component (buzz 1) of the courtship vibrations produced by male wing fanning were investigated using laser vibrometry. The duration of buzz 1 was longer on maize, bean, and chiffon than on plastic and glass. The fundamental frequency of buzz 1 (~300 Hz) was lowest on bean and highest on glass, and intermediate among other substrates. The relative amplitude of buzz 1 was higher on chiffon than on plastic, glass, or bean, and intermediate on maize. The relative importance of airborne sound and substrate vibration as courtship signals was also investigated with experiments that manipulated the production of courtship vibrations and the mating substrates. The amplitude of courtship vibrations on chiffon was significantly higher for winged males than for dealated males. The mating success of males was impacted by both the presence of wings and the mating substrate. These findings suggest that mating success and transmission of courtship vibrations are influenced by the rearing substrate, and that courtship vibrations are critical to mating success in C. marginiventris. Future efforts to mass rear this parasitoid and other insects should consider the potential influences of rearing substrates on mating.     

Patterns of inheritance of mating signals in interspecific hybrids between sailfin and shortfin mollies (Poeciliidae: Poecilia: Mollienesia)

Differences in male morphology and mating behaviors are thought to confer species sexual isolation between sailfin and shortfin species of mollies. This study used interspecific crosses between the sailfin molly, P. latipinna, and the shortfin molly, P. mexicana, to investigate patterns of inheritance of morphological traits and behavioral rates of three mating behaviors in F1 hybrid males. The two parental species showed clear species differences with respect to the length of the dorsal fin and dorsal fin ray number. First generation hybrid males were intermediate between the two parental species for dorsal fin length and fin ray number, suggesting autosomal control of this trait with little effect of dominance by genes from either parental species. Parental species showed clear species differences in their rates of courtship displays. Unlike the pattern for dorsal fin morphology, F1 hybrid males showed a clear distinction in display rates with respect to the direction of the interspecific cross. Male hybrids whose sires were P. latipinna had courtship display rates that were up to three times higher than the rates of displays performed by hybrid males whose fathers were P. mexicana. The distribution of phenotypes between the parental species and that of hybrid males sired by that parental species was nearly identical. Such a pattern suggests the influence of Y-linked genes on the inheritance of courtship display rates in mollies.     

Exploring the influence of individual courtship behaviors on male mating success in a blow fly

Male courtship behavior and displays influence female mating decisions, and therefore affect mating success in a diverse range of organisms. While there is substantial evidence confirming that females prefer males who invest more in courtship, less attention has been paid to the relative importance of individual behaviors, and the discrete sequences of courtship that result in mating success. The small hairy maggot blow fly, Chrysomya varipes, performs stereotyped courtship behaviors, involving orienting, tapping, waving, arching, wing vibration and mounting. This study aimed to quantify male investment in specific courtship behaviors, and compare courtship investment and behavioral transitions between males who gained mating success (successful males) and those that did not (unsuccessful males). Our results show that mating success was influenced by the behaviors orienting, tapping, arching and mounting. Behavioral transitions revealed a distinct pattern of behaviors leading to a mating attempt, and some differences were observed between successful and unsuccessful males. Overall, our findings suggest that female mating decisions were based on differences in specific male courtship behaviors. This detailed observational study has quantified multiple courtship behaviors for the first time in C. varipes, and highlights the importance of considering multiple behavioral traits when exploring the influence of male courtship on mating success.     

Six cryptic species on a single species of host plant: morphometric evidence for possible reproductive character displacement

Abstract 1. Diversification of some highly host‐specific herbivorous insects may occur in allopatry, without shifts in host use. Such allopatric divergence may be accelerated by sexual selection operating on courtship displays. Wing size and shape may affect visual and vibrational courtship displays in tephritid fruit flies. Geometric morphometric methods were used to examine wings of six sympatric cryptic species in the neotropical genus Blepharoneura. All six species feed on flowers of the same species of host (Gurania spinulosa), a neotropical vine in the Cucurbitaceae. Three of the fly species court and mate in close proximity on the host. Thus, courtship behaviours could serve as important reproductive isolating mechanisms. Two sets of hypotheses were tested: (i) species differ in wing shape and wing size; and (ii) species are sexually dimorphic in wing size and wing shape. Wing size differed among a few species, but wing shape differed significantly among all six species. Sexual dimorphism in wing size was found in only one species, but sexual dimorphism in wing shape was found in two of the three species known to court on the same host plant. In the two sexually dimorphic species, wing shape differed among males, but not among females. This suggests that selection for reproductive character displacement might accelerate divergence in wing shape.     

Evidence for sexual isolation as a prezygotic barrier to gene flow between morphologically divergent species of Rhagoletis fruit flies

1. Certain groups of fruit flies in the genus Rhagoletis (Diptera: Tephritidae) are exemplars for sympatric speciation via host plant shifting. Flies in these species groups are morphologically similar and overlap in their geographic ranges, yet attack different, non‐overlapping sets of host plants. Ecological adaptations related to differences in host choice and preference have been shown to be important prezygotic barriers to gene flow between these taxa, as Rhagoletis flies mate on or near the fruit of their respective host plants. Non‐host‐related assortative mating is generally absent or present at low levels between these sympatrically diverging fly populations. 2. However, some Rhagoletis taxa occasionally migrate to ‘non‐natal’ plants that are the primary hosts of other, morphologically differentiated fly species in the genus. These observations raise the question of whether sexual isolation may reduce courtship and copulation between morphologically divergent species of Rhagoletis flies, contributing to their prezygotic isolation along with host‐specific mating. 3. Using reciprocal multiple‐choice mating trials, we measured sexual isolation among nine species pairs of morphologically differentiated Rhagoletis flies. Complete sexual isolation was observed in eight of the nine comparisons, while partial sexual isolation was observed in the remaining comparison. 4. We conclude that sexual isolation can be an effective prezygotic barrier to gene flow contributing to substantial reproductive isolation between many morphologically distinct Rhagoletis species, even in the absence of differential host plant choice and host‐associated mating.     

Behavioral Sequence Leading to Sexual Isolation Between <Emphasis Type="Italic">Drosophila ananassae</Emphasis> and <Emphasis Type="Italic">D. pallidosa</Emphasis>

Drosophila ananassae and D. pallidosa are closely related, sympatric species that lack postmating isolation. Sexual isolation has been considered important in maintaining them as independent species. To clarify the behavioral processes leading to sexual isolation, we analyzed behavioral sequences and examined the effect of courtship song on mating success and on behaviors of both sexes by surgically removing male wings (song generators), female aristae (song receivers), or female wings (means of fluttering). We found that heterospecific courtship songs evoked female wing fluttering, whereas conspecific courtship song did not. Furthermore, female wing fluttering made courting males discontinue courtship. These findings suggest that strong sexual isolation is achieved through the following behavioral sequence: heterospecific song→female wing fluttering→courtship discontinuation.     

The Influence of Male Body Size and Social Environment on the Mating Behavior of Phallichthys quadripunctatus (Pisces: Poeciliidae)

In some poeciliid fishes, variation in male size is accompanied by differences in mating behavior. Large males are preferred by females and perform courtship displays followed by copulatory thrusts, whereas small males perform copulatory thrusts with few or no displays. This phenomenon has been described in only a few genera and little is known about mating behavior in other poeciliids. Although Phallichthys quadripunctatus males display size dimorphism that has a genetic component, mating behavior of this species has not been documented. We conducted experiments using socially experienced and socially naive males to characterize the mating behavior of this species and to evaluate potential size-dependent differences in behavior. Males were tested with postpartum (presumably receptive) and midcycle (presumably unreceptive) females in different social environments. Whereas neither size class of P. quadripunctatus males performed courtship displays or altered behavior based on female receptivity, large males performed several reproductive behaviors more frequently than small males. This trend was repeatable and occurred in all social environments examined. Some males also attempted to mate with other males, with small males showing a greater tendency to perform this behavior than large males. The manner in which differences in reproductive activity translate into differences in reproductive success must be examined before inferring sexual selection favoring large males in P. quadripunctatus.     

拟环纹豹蛛雄蛛触肢上黑白相间毛饰物的功能

狼蛛科雄蛛附肢上多样化的饰装往往与求偶行为相偶联,这些特殊的饰装通常被认为是雌性选择的结果。拟环纹豹蛛Pardosa pseudoannulata,属狼蛛科豹蛛属,雄蛛触肢胫节密被白毛,跗舟密被黑毛,具有典型的性二型现象;同时,只有成熟的雄蛛才展现触肢黑白相间的毛饰物。推测拟环纹豹蛛雄蛛触肢这种黑白相间的毛饰物可能在物种识别中具重要作用。在室内我们拟通过涂抹操作对拟环纹豹蛛雄蛛触肢黑白相间毛饰物的功能进行分析。实验分为4组,分别是对照组(A组,雄蛛不做任何处理)、雄蛛触肢白色胫节全部涂成黑色(B组)、雄蛛触肢黑色跗舟全部涂成白色(C组)和雄蛛触肢的黑色跗舟被涂成黑色(D组),然后采用雌雄配对进行求偶交配行为测定。实验结果表明,B组雄蛛的交配成功率显著低于A、C和D组的雄蛛,而后3组雄蛛的交配成功率无显著差异。相反,B组雄蛛被雌蛛相食百分率显著高于其它3组。可见拟环纹豹蛛雄蛛触肢上黑白相间毛饰物,尤其是其胫节上的白色饰物在雌蛛种间识别中起重要作用。     

Singing on the wings! Male wing fanning performances affect female willingness to copulate in the aphid parasitoid Lysiphlebus testaceipes (Hymenoptera: Braconidae: Aphidiinae)

Lysiphlebus testaceipes (Hymenoptera: Braconidae: Aphidiinae) is a generalist endoparasitoid attacking more than 100 aphid species. In L. testaceipes, wing fanning is a main male courtship display evoked by a female‐borne sex pheromone. However, no information is available on the characteristics and behavioral role of male fanning during courtship in this parasitoid. Here, the courtship behavior of a wild strain of L. testaceipes was quantified and the male wing fanning performances were analyzed through high‐speed video recordings and examined in relation to mating success. Courtship sequence of wild L. testaceipes did not substantially differ from that previously reported for other populations mass reared on aphids. We observed that the male courtship duration did not affect mating success. However, video analysis revealed that the males producing high‐frequency fanning signals achieved higher mating success over those that display low‐frequency fanning. Wing fanning before successful and unsuccessful courtship differed in amplitude of wing movements and alignment toward the mate, highlighting that frontal courtship positively influence the female mating decisions. This study increases knowledge on sexual behavior in a key parasitoid of aphids, highlighting the importance of wing fanning among the range of sensory modalities used in the sexual communication of L. testaceipes. From a practical point of view, this information is useful in L. testaceipes‐based biocontrol strategies, since it can help to establish parameters for quality checking of mass‐reared wasps over time.     

A Life History Trade-Off Between Flight Ability and Reproductive Behavior in Male Field Crickets (<Emphasis Type="Italic">Gryllus texensis</Emphasis>)

Male field crickets (Gryllus texensis) that differ in flight ability incur a life history trade-off between flight ability and reproduction, where flight ability comes with a male fitness cost. In courtship trials, flight-capable males produced courtship song, a necessary signal for mating success, with a significantly lower probability than flight-incapable males. The trade-off was evident in young males, and a similar trend occurred in older males. Males that lost the ability to fly through histolysis of flight muscles produced courtship song with a similar probability as males incapable of flight for their entire lives. Time of day did not affect the expression of the trade-off. Neither male morph nor time of day influenced female mating behavior.     

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.     

Courtship inDrosophila sechellia: Its structure,functional aspects,and relationship to those of other members of theDrosophila melanogaster species subgroup

The courtship behavior of Drosophila sechelliais described. Male wing displays are mainly vibration and scissoring, with low levels of rowing. As courtship proceeds the proportion of courtship spent in male wing vibration and licking increases, whereas female movement decreases. The male courtship song of sechelliacontains pulse song but no sine song. This species also shows a distinctive copulation song associated with mounting and copulation. The main cuticular hydrocarbon in females is 7,11-heptacosadiene. The number of copulations increased when flies were placed in the presence of food. Visual and acoustic stimuli appear to be important for mating. A multidimensional comparison was used to compare members of the melanogaster species subgroup, based upon courtship behavior, song characteristics, and cuticular hydrocarbons. A multidimensional comparison of courtship sequences in sechellia, melanogaster, simulans,and mauritianashowed differences in variability between the two island species as compared to the two cosmopolitan species. The courtship song of D. orenais described: it shows both sine and pulse song; there is also a copulation song in this species.     

The behavioural basis of overdominance in competitive mating success at the ebony locus of Drosophila melanogaster

Male files homozygous for the gene ebony¹¹ are partially blind, and at a disadvantage in competitive mating. The courtship of the mutant males is deficient in wing vibration stimulation, which is characterized by a low proportion of sine song and a high intra-pulse frequency. Males heterozygous for ebony have normal vision, but show an increase in courtship song, and are superior in competitive mating to wild type males. The auditory characteristics of courtship song produced by heterozygous males are indistinguishable from those of wild type, and their superiority in competitive mating success is due to overdominance involving this specific element of male courtship behaviour.     

Co-evolving wing spots and mating displays are genetically separable traits in Drosophila

The evolution of sexual traits often involves correlated changes in morphology and behavior. For example, in Drosophila, divergent mating displays are often accompanied by divergent pigment patterns. To better understand how such traits co-evolve, we investigated the genetic basis of correlated divergence in wing pigmentation and mating display between the sibling species Drosophila elegans and Drosophila gunungcola. Drosophila elegans males have an area of black pigment on their wings known as a wing spot and appear to display this spot to females by extending their wings laterally during courtship. By contrast, D. gunungcola lost both of these traits. Using Multiplexed Shotgun Genotyping (MSG), we identified a ∼440 kb region on the X chromosome that behaves like a genetic switch controlling the presence or absence of male-specific wing spots. This region includes the candidate gene optomotor-blind (omb), which plays a critical role in patterning the Drosophila wing. The genetic basis of divergent wing display is more complex, with at least two loci on the X chromosome and two loci on autosomes contributing to its evolution. Introgressing the X-linked region affecting wing spot development from D. gunungcola into D. elegans reduced pigmentation in the wing spots but did not affect the wing display, indicating that these are genetically separable traits. Consistent with this observation, broader sampling of wild D. gunungcola populations confirmed that the wing spot and wing display are evolving independently: some D. gunungcola males performed wing displays similar to D. elegans despite lacking wing spots. These data suggest that correlated selection pressures rather than physical linkage or pleiotropy are responsible for the coevolution of these morphological and behavioral traits. They also suggest that the change in morphology evolved prior to the change in behavior.     

Identification of acoustic stimuli that mediate sexual behavior inDrosophila busckii (Diptera: Drosophilidae)

We have shown that D. busckiimales and females, unlike other drosophilids that have been analyzed in this regard, court and copulate as well in relatively dim red light as they do in bright white light. We have also shown that males and females of this species flutter their wings during courtship and that wing fluttering in both sexes is associated with acoustic stimuli. Wingless males perform vigorous courtship but are incapable of mating, suggesting that females must perceive male song to be receptive to copulation. When they are tested with normal males, wingless females stimulate vigorous courtship, but their copulation frequencies are significantly lower than winged females. This observation suggests that perception of the female's song by either or both sexes facilitates mating.     

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.      

Variation in male wing song characters inDrosophila plantibia (Hawaiian picture-wingedDrosophila group)

The males of most species of the HawaiianDrosophila planitibia group produce songs when vibrating their wings during courtship. In four of the most recently evolved species,D. differens, D. planitibia, D. heteroneura, andD. silvestris, these songs are simple in structure and possess a higher and more variable carrier frequency than the songs of the more ancestral species of the group. In the present paper, we studied the variation in wing song production and song characters in aD. planitibia population. Some males vibrated their wings at a very low amplitude or slow speed, producing no detectable sound. Other males produced sound bursts varying in carrier frequency and burst length. The carrier frequency of the song depended mainly on the wing posture of the male during wing vibrations and was consistent for individual males. Variation between males of different isofemale progenies was not significant in any measured song trait. Songs of the males recorded in the present study differed, however, from songs of the males of a laboratory strain recorded earlier.     

Male Wing Fanning Performance During Successful and Unsuccessful Mating in the Parasitic Wasp Lariophagus distinguendus Förster (Hymenoptera: Pteromalidae)

Lariophagus distinguendus Förster (Hymenoptera: Pteromalidae) is a generalist solitary ectoparasitoid that parasitizes the immature stages of at least 11 foodstuff beetles from five families, including species developing in the seeds of Poaceae, Fabaceae and in dried natural products. In L. distinguendus, male wing fanning is a key phase in the courtship sequence and is elicited by a female-borne sex pheromone. However, studies aimed at understanding the role of wing vibration in L. distinguendus during courtship are lacking. In this research, the wing fanning performances of the L. distinguendus male towards other females and males were analyzed through high-speed video recordings and examined in relation to mating success. Only small differences were found between the fanning characteristics displayed toward females and young males, highlighting that young males are really perceived as females by older males. Male mating success was affected by the quality of the wing fanning in the courtship phase. Indeed, both immediately after the female perception and during mating attempts, fanning before a successful courtship differed compared to wing fanning performed prior to an unsuccessful courtship in terms of their mean frequency, but not their amplitude. Overall, our work increases knowledge of the courtship behavior of L. distinguendus and highlights the crucial importance of wing fanning among the range of sensory modalities used in the sexual communication of this parasitic wasp.