Copulatory Interactions Research Articles

Characterizing Physical Interactions between Male and Female Mosquitoes (Aedes aegypti) in Relation to Female Receptivity and Insemination Outcomes Using a Hydrophobic Fluorescent Dye.

Aedes aegypti, the yellow fever mosquito, presents a major threat to human health across the globe as a vector of disease-causing pathogens. Females of this species generally mate only once. From this single mating event, the female stores sufficient sperm to fertilize the multiple clutches of eggs produced during her lifetime. Mating causes dramatic changes in the female's behavior and physiology, including a lifetime suppression of her mating receptivity. Female rejection behaviors include male avoidance, abdominal twisting, wing-flicking, kicking, and not opening vaginal plates or extruding the ovipositor. Many of these events occur on a scale that is too miniscule or fast to see by eye, so high-resolution videography has been used to observe these behaviors instead. However, videography can be labor intensive, require specialized equipment, and often requires restrained animals. We used an efficient, low-cost method to record physical contact between males and females during attempted and successful mating, determined by recording spermathecal filling after dissection. A hydrophobic oil-based fluorescent dye can be applied to the abdominal tip of one animal and can be subsequently transferred to the genitalia of animals of the opposite sex when genital contact occurs. Our data indicate that male mosquitoes make high levels of contact with both receptive and unreceptive females and that males attempt to mate with more females than they successfully inseminate. Female mosquitoes with disrupted remating suppression mate with and produce offspring from multiple males, transferring dye to each. These data suggest that physical copulatory interactions occur independently of the female's receptivity to mate and that many of these interactions represent unsuccessful mating attempts that do not result in insemination.

Examining the shape and size of female and male genitalia in snakes using three-dimensional geometric morphometrics

Abstract Quantification of genital variation in males and females can inform our understanding of likely copulatory interactions and evolution of genital diversity. However, no studies have quantified genital shape variation within a single snake species or examined the shape and size of both the vaginal pouch and hemipenes. Here, we examine the shape and size of the genitalia of female and male diamondback water snakes, Nerodia rhombifer, using a three-dimensional automated landmark geometric morphometric approach on models of the lumen of the vaginal pouch and inflated hemipenes, applying these techniques for the first time to the genital shape of vertebrates. Vaginal pouch shape is significantly associated with body size and reproductive status. As females grow larger and become reproductive, the vaginal pouch enlarges, widens and becomes more bifurcated. In reproductive males, the shape of the hemipenes is also significantly associated with body size. As males grow larger, the hemipenes enlarge and widen; their bifurcation becomes more defined and the spines at the base become more prominent. Vaginal pouch and hemipenial centroid size are isometric with respect to body length. The centroid sizes of the hemipenes and vaginal pouch are not significantly different from one another, hence the genitalia match in size. Reproductive females and males covary in the degree of bifurcation and size of their genitalia. We demonstrate the utility of three-dimensional analysis in studies of the shape of soft tissues and advocate its use in future studies of genitalia.

Experimental sexual selection reveals rapid evolutionary divergence in sex-specific transcriptomes and their interactions following mating.

Post copulatory interactions between the sexes in internally fertilizing species elicits both sexual conflict and sexual selection. Macroevolutionary and comparative studies have linked these processes to rapid transcriptomic evolution in sex‐specific tissues and substantial transcriptomic post mating responses in females, patterns of which are altered when mating between reproductively isolated species. Here, we tested multiple predictions arising from sexual selection and conflict theory about the evolution of sex‐specific and tissue‐specific gene expression and the post mating response at the microevolutionary level. Following over 150 generations of experimental evolution under either reduced (enforced monogamy) or elevated (polyandry) sexual selection in Drosophila pseudoobscura, we found a substantial effect of sexual selection treatment on transcriptomic divergence in virgin male and female reproductive tissues (testes, male accessory glands, the female reproductive tract and ovaries). Sexual selection treatment also had a dominant effect on the post mating response, particularly in the female reproductive tract – the main arena for sexual conflict – compared to ovaries. This effect was asymmetric with monandry females typically showing more post mating responses than polyandry females, with enriched gene functions varying across treatments. The evolutionary history of the male partner had a larger effect on the post mating response of monandry females, but females from both sexual selection treatments showed unique patterns of gene expression and gene function when mating with males from the alternate treatment. Our microevolutionary results mostly confirm comparative macroevolutionary predictions on the role of sexual selection on transcriptomic divergence and altered gene regulation arising from divergent coevolutionary trajectories between sexual selection treatments.

Gene expression and alternative splicing dynamics are perturbed in female head transcriptomes following heterospecific copulation

BackgroundDespite the growing interest in the female side of copulatory interactions, the roles played by differential expression and alternative splicing mechanisms of pre-RNA on tissues outside of the reproductive tract have remained largely unknown. Here we addressed these questions in the context of con- vs heterospecific matings between Drosophila mojavensis and its sister species, D. arizonae. We analyzed transcriptional responses in female heads using an integrated investigation of genome-wide patterns of gene expression, including differential expression (DE), alternative splicing (AS) and intron retention (IR).ResultsOur results indicated that early transcriptional responses were largely congruent between con- and heterospecific matings but are substantially perturbed over time. Conspecific matings induced functional pathways related to amino acid balance previously associated with the brain’s physiology and female postmating behavior. Heterospecific matings often failed to activate regulation of some of these genes and induced expression of additional genes when compared with those of conspecifically-mated females. These mechanisms showed functional specializations with DE genes mostly linked to pathways of proteolysis and nutrient homeostasis, while AS genes were more related to photoreception and muscle assembly pathways. IR seems to play a more general role in DE regulation during the female postmating response.ConclusionsWe provide evidence showing that AS genes substantially perturbed by heterospecific matings in female heads evolve at slower evolutionary rates than the genome background. However, DE genes evolve at evolutionary rates similar, or even higher, than those of male reproductive genes, which highlights their potential role in sexual selection and the evolution of reproductive barriers.

Glans inflation morphology and female cloaca copulatory interactions of the male American alligator phallus†.

The phallic glans of the American alligator (Alligator mississippiensis) is the distal termination of the semen-conducting sulcus spermaticus and during copulation has the closest, most intimate mechanical interactions with the female urodeum, the middle cloacal chamber that contains the opening to the vaginal passages and oviducts. However, the details of this interface leading to insemination and gamete uptake are unclear. Here, we: (1) histologically characterize the underlying tissue types and morphologically quantify the shape changes associated with glans inflation into the copulatory conformation, (2) digitally reconstruct from MRI the 3D shape of functional tissue compartments, and (3) diffusible iodine-based contrast-enhanced computed tomography image the copulatory fit between male phallus and female cloaca. We discuss these results in relation to tissue type material properties, the transfer on intromittent forces, establishing potential copulatory lock, inflated glans volume scaling with body mass/length, the mechanics of semen targeting and insemination, and potential female cryptic choice impacting multiple clutch paternity. In part, this study further clarifies the phallic morphological variation observed among crocodylians and begins to investigate the role(s) these divergent male forms play during copulation interacting with female cloacal forms to increase reproductive success.

Pubertal stress decreases sexual motivation and supresses the relation between cerebral theta rhythms and testosterone levels in adult male rats

This study evaluated the effect of stress during puberty on sexual motivation and the correlation between serum testosterone levels (T) and the absolute power of the theta electroencephalographic rhythms, recorded in the medial prefrontal cortex (mPFC) and basolateral amygdala (BLA) of adult male rats. Thirty males of the stressed group (SG, housed 1 per cage from days 25–50) and 30 controls (CG, housed 5 per cage), were tested in copulatory interactions at 90 days of age. The above mentioned physiological parameters were obtained during the awake-quiet state in a sub-group without sexual motivation (WSM, n = 15, stimulated with a nonreceptive female) and a sub-group with sexual motivation (SM, n = 15, stimulated with a receptive-female). Pearson correlations (r) between these parameters were calculated for each sub-group and brain structure and then compared between sub-groups. SG presented higher mount and intromission latencies than CG. While CG-WSM showed a positive r between T levels and theta band (0.23-0.59), those CG-SM presented a negative r (−0.23 to −0.67). An r that tended towards zero (−0.31 to 0.29) was obtained in both stressed sub-groups. This study shows that pubertal stress suppresses the relation between serum T levels and theta rhythms in the mPFC and BLA in adult male rats. This is one of the first studies evaluating the association between these two physiological parameters specifically in the context of sexual motivation; thus increasing our understanding of the effect of pubertal stress on prefrontal-amygdaline functioning during the sexually-motivated state in male rats.

Dead or alive? Sexual conflict and lethal copulatory interactions in long-jawed Tetragnatha spiders

Dead or alive? Sexual conflict and lethal copulatory interactions in long-jawed Tetragnatha spiders

Copulatory Fit of Common Bottlenose Dolphin (Tursiops truncatus) Genitalia

Sexual selection is the primary force that drives gross morphological variation of male genitalia in many species. Less information is known about how male and female genitalia fit together during copulation or how sexual selection and mechanical constraints during copulation interact and shape reproductive organs. Marine mammals offer important insights into evolutionary forces that act on genital morphology in both sexes because of adaptations to extreme environmental constraints (e.g., hydrodynamic drag forces acting on the penis during copulation while swimming, the necessity to prevent seawater from entering the uterus, and the challenge of successful intromission while moving in a 3‐D space). Cetaceans (whales, dolphins, and porpoises) have a fibroelastic penis type and their vaginas have muscular folds, both characteristics that are rare among mammals and unique to cetartiodactlys. We used excised male and female reproductive tracts from deceased adult common bottlenose dolphins (Tursiops truncatus) to assess how deep the penis penetrates the vagina, which anatomical landmarks of male genitalia contact morphological features of females, and how genital shape influences copulatory interactions. Frozen‐thawed vaginas remained flaccid and were stained with iodine, while penises were mechanically inflated and formalin‐fixed to maintain rigidity. Female and male reproductive tracts were ct‐scanned independently. The penis was then inflated inside the vagina in a position that approximates real intromission and the reproductive tracts were ct‐scanned together. Resulting images were reconstructed in transverse and sagittal planes. In conjunction with video observations of copulations by free‐swimming dolphins, our results suggest that the tip of the bottlenose dolphin penis navigates around the female's single vaginal fold to achieve successful insemination. Understanding the coevolution of male and female reproductive anatomy under extreme environmental constraints has broad applications to conservation and captive breeding programs. Copulatory fit can provide clues of how genitals interact to influence fertility and improve artificial insemination techniques.

Functions of vocalization in sociosexual behaviors in rats (Rattus norvegicus) in a seminatural environment.

Both male and female rats produce vocalizations in the presence of a potential sexual partner. In this study, we evaluated the role of vocalizations in sociosexual behaviors in an ecologically valid procedure. Three males and 4 females were housed in a seminatural environment. In each group, 1 or 2 males and females were devocalized, and the other subjects were sham operated. Sociosexual interactions between males and females were recorded for a period of 1 hr when all 4 females were receptive so that the males had the choice to interact either with vocalizing or with silent females. Devocalized and sham-operated males displayed very similar behavioral patterns. There was no difference in any of the male sexual behavior patterns nor in male-initiated nonsexual social interaction. Female vocalizations do not contribute to the regulation of sociosexual interaction. Devocalized males received as much attention from females as sham-operated males, with the exception of paracopulatory behaviors with short duration, which were more frequently directed toward the sham-operated males than to the devocalized males. This was the case for both silent and vocalizing females. It appears, then, that devocalized males are inferior to sham males with regard to the capacity to induce female paracopulatory behaviors. However, this has no consequence for sexual interaction because devocalized and sham males copulated equally based on the number of mounts, intromissions, and ejaculations. In sum, these data show that vocalizations play a very limited role in rat sociosexual behavior in a seminatural environment. Furthermore, this indicates that vocalizations have no evident function during copulatory interactions. (PsycINFO Database Record

Studying Genital Coevolution to Understand Intromittent Organ Morphology.

Male intromittent organs are exceedingly diverse, yet we know comparatively little about female genital diversity. However, the most direct mechanical interaction between males and females occurs during copulation, and therefore, genital coevolution is expected to be widespread. This means that diversification of male structures must influence diversity of female genital features and vice versa. As we expand our understanding of coevolutionary interactions between the sexes, we need to expand our knowledge of three basic areas: First, we need quantitative data, on morphological variation of female genitalia. Second, we need to study the mechanics of copulatory interactions, and third, we need to use this understanding to determine which features of genital morphology are under selection, and how their variable morphology and function may affect fitness. Though studying coevolution is certainly difficult, this knowledge is crucial to our understanding of diversity in morphology of the male intromittent organ.

Persistent Copulation in Asexual Female Potamopyrgus antipodarum: Evidence for Male Control with Size-Based Preferences

Transitions from sexual to asexual reproduction provide a useful context for investigating the evolutionary loss of nonfunctional traits. It is often assumed that useless behaviors or structures will degrade, but this process is poorly understood. Potamopyrgus antipodarum is an ancestrally sexual New Zealand freshwater snail characterized by numerous independent transitions to asexual all-female lineages. The availability of multiple independently-derived asexual lineages of various time since derivation from sexual ancestors means that the P. antipodarum system is well-suited for the study of trait loss related to mating behavior and copulation. Here, we asked whether mating behavior in asexual female P. antipodarum degrades with increasing asexual lineage age. While copulation frequency did not differ in females from old versus young asexual lineages, post hoc analyses indicated that it was instead positively associated with mean lineage female size. We observed that female P. antipodarum take a passive physical role in copulatory interactions, indicating that female behavior may not be a useful variable for detection of sex-related vestigialization in this system. Instead, males seem to be in proximate control of copulation frequencies, meaning that male mating behavior may be a primary determinant of the expression of mating behavior in asexual female P. antipodarum.

Why Do Columbian Ground Squirrels Copulate Underground?

Abstract Columbian ground squirrels (Spermophilus columbianus) usually copulate underground in a burrow. Underground copulations might be associated with 2 nonexclusive benefits: reducing probability of predation during copulation and reducing interference by conspecific males. We tested whether either of these benefits was involved in determining if the copulation site was underground or aboveground. In 2006 and 2007, we obtained detailed information on the copulatory behavior and social interactions of free-ranging individuals in southwestern Alberta, Canada. During the 3-week annual breeding period, we also recorded the activity of predators of Columbian ground squirrels such as ravens, foxes, and hawks. Squirrels that lived on the periphery of the population were more susceptible to predation than squirrels in the center. Despite this risk, aboveground copulations usually occurred on peripheral territories. In addition, aboveground copulations were not further removed in time from predator attacks or ...

6-Hydroxydopamine Lesions in Female Hamsters (Mesocricetus auratus) Abolish the Sensitized Effects of Sexual Experience on Copulatory Interactions With Males.

This study examined the effects of sexual experience in female hamsters (Mesocricetus auratus) on copulatory interactions with male hamsters. Female sexual experience improved the copulatory efficiency of sexually naive males, an effect that persisted for at least 6 weeks without further sexual behavior testing. In a 2nd study, dopamine lesions made in the region of the nucleus accumbens prior to sexual experience specifically blocked the effects of the female's sexual experience on the hit rate of naive males. These results suggest that sexual experience in female hamsters increases the efficiency of copulatory interactions with males, that these effects persist in the absence of further sexual experience, and that dopamine neurotransmission in the basal forebrain underlies this effect of sexual experience.

Male condition, female choice, and extreme variation in repeated mating in a scaly cricket, Ornebius aperta (Orthoptera: Gryllidae: Mogoplistinae).

Mating in the scaly cricket Ornebius aperta often includes the transfer of many spermatophores to individual females during extended copulatory interactions. We manipulated male condition in staged matings to determine whether this could explain variation in the number of repeated copulations seen across pairs. Males on a high nutrient diet were in good condition, were more likely to mate repeatedly, and transferred more spermatophores on average than low-diet males (in poor condition). High-diet males were more likely to produce a vibratory signal that increased female receptivity to repeated mating attempts. Courtship and copulatory interactions were always terminated by females, and in every case males had already formed a spermatophore when deserted by females. We conclude that variation in male repeated mating success may be due to female choice rather than an inability or unwillingness of low-diet males to produce spermatophores.

Increased Fos expression in oxytocin neurons following masculine sexual behavior.

Induction of the c-fos protein product (Fos) was used to immunocytochemically identify oxytocin (OT) neurons that may be activated during copulatory interactions. Fos induction was quantified in sexually-experienced male rats after either (a) exposure to a testing arena recently vacated by an estrous female, (b) copulatory interactions such as mounting and intromission without ejaculation, or (c) mounting and intromissions culminating in ejaculation. In the parvocellular regions of the paraventricular nucleus of the hypothalamus (PVN), the number of neurons expressing Fos increased following either intromission (53%) or ejaculation (124%). Significant, but less striking, increases in the number of cells expressing Fos were noted in magnocellular regions of the PVN where intromission resulted in a 13% increase and ejaculation in a 49% increase in Fos. The number of perikarya immunoreactive for OT and AVP did not differ as a function of increasing sexual contacts. In control (novel arena) males, 33-73% of the Fos labeling occurred in OT cells. Sexual interactions did not enhance the number of double-labeled cells in most parvocellular regions. However, in lateral parvocellular regions located in the most caudal aspects of the PVN, 31% of the Fos-positive cells occurred in OT neurons in ejaculated males, while in control males none of the OT cells were double-labeled. This PVN subdivision is known to consist of neurons that project to the brain stem and spinal cord at lumbar levels which contain motor neurons that regulate penile reflexes. The present data suggest a possible neurochemical circuit which incorporates oxytocinergic neurons in the mediation of masculine sexual responses.

Patterns of behaviour during postpartum oestrus in prairie voles, Microtus ochrogaster

Social and sexual behaviour during postpartum oestrus in prairie voles was monitored using time-lapse videotaping over a period of at least 24h. Behaviour was measured as a function of the familiarity and social history of the male partner and as a function of the presence or absence of pups. In general, postpartum oestrus was shorter than male-induced oestrus. When pups remained with the pair, the duration and frequencies of copulatory interactions were further reduced. In familiar pairs mountlordosis bouts were more frequent, and durations of male autogrooming and side-by-side contact were longer than in unfamiliar pairs. All pairs successfully reproduced and litter size among groups was similar, even then the frequency of sexual activities was very low. These results suggest that in monogamous species, such as prairie voles, the social history of the pair was well as female reproductive status are strong determinants of sexual and social interactions that occur during postpartum oestrus.

Sexual interactions between estrous female rats and castrated male rats treated with testosterone propionate or estradiol benzoate

Estrous female rats display ‘precopulatory behaviors’ such as ear wiggling and hopping/darting when castrated males treated with testosterone propionate (TP) are placed in their vicinity and before copulatory interactions have taken place. Castrated males treated with estradiol benzoate (EB) do not elicit these precopulatory behaviors in advance of copulatory interactions. It therefore seemed of interest to study females' sexual behavior with castrated males treated with TP or EB when males or females had primary control over the temporal patterning of the behavior. Unrestrained sexual behavior (=male control) with EB-treated males was characterized by large numbers of intromissions and long periods of time preceding ejaculation, as compared with interactions with TP-treated males. The temporal pattern of sexual behavior did not change importantly when the males were tethered (=sexual behavior controlled by females). When given a choice between two sexually active castrated and tethered males, one treated with TP and the other with EB, estrous females ‘preferred’ EB-treated animals in various respects. Fewer interactions occurred with, and less time was spent in the vicinity of, TP-treated males over prolonged observation periods (115–135 min). The preference for EB-treated males disappeared, and TP- and EB-treated animals became equally attractive, when the vaginal opening of the female animals was covered with adhesive tape to prevent the occurrence of penile intromissions during mounting. It is concluded that female control over copulatory behavior does not necessarily change the females' sexual behavior. ‘Preference’ of EB-treated males to TP-treated males seems due to aversive sensory actions, during intromissions, associated with insertion of the androgen-stimulated penis and the ejaculate. Genital stimulation during mating plays an important role in the maintenance of ‘sexual motivation’ in female rats.

Behavioral and Physiological Analyses of Ultrasound Production by Female Hamsters (Mesocricetus auratus)

synopsis. The results of behavioral studies suggest specific roles for high-frequency vocali? zations (ultrasounds) in courtship and copulatory interactions among golden hamsters. In addition, these results, and functional interpretations based on them, can help to guide studies of physiological mechanisms controlling ultrasonic communication. For example, interpretations of rodent ultrasounds as sexual or agonistic signals suggest that ultrasound rates depend on gonadal hormones. This prediction has been verified for several rodent species, including hamsters. Similar reasoning should apply to the analysis of brain mecha? nisms for ultrasound production. In particular, the consideration of hamster ultrasounds as sexual behaviors and vocalizations, as well as hormone-dependent responses, suggests several brain areas as especially likely participants in neural circuits mediating hormonal effects on ultrasonic communication. The preliminary results of a study in which we lesioned one of these areas, the mesencephalic central grey, confirm this structure's involvement in the control of hamster ultrasounds, and, more generally, support the utility of behavioral data in phvsiological studies.