Risk of sperm competition does not influence copulatory behavior in the promiscuous meadow vole (<Emphasis Type="Italic">Microtus pennsylvanicus</Emphasis>)

It is not clear whether males in all mammalian species adjust their copulatory behavior when faced with risk of sperm competition (RSC). Previous work on meadow voles, Microtus pennsylvanicus, indicated that males increase their sperm expenditure but not the number of ejaculations in the presence of odors of a conspecific male. The present study follows up on this work and asks whether male meadow voles modify any aspect of their copulatory behavior when they face a RSC. We examined 46 variables of copulatory behavior and found that the presence of odors from a conspecific male did not affect any of these variables. Thus, male meadow voles, unlike some other species of mammals, do not adjust their copulatory behavior when exposed to cues associated with an elevated RSC.     

Effects of variations in male copulatory behavior on ovulation and implantation in prairie voles, Microtus ochrogaster

The relationships between parameters of male copulatory behavior and ovulation and implantation were examined for Microtus ochrogaster. One ejaculatory series is sufficient for induction of ovulation and implantation, and a second series does not elicit any increase in either the probability of ovulation or the number of corpora lutea and implanted embryos. Within the first ejaculatory series, the probability of ovulation increases with increased numbers of intromissions and intravaginal thrusts. Mounting without vaginal penetration is not sufficient to induce ovulation. It is suggested that Microtus species display a coadaptation of male copulatory behavior and stimulation requirements of the female reporductive system.     

Sexual selection,genital morphology,and copulatory behavior in male Galagos

Variations in penile morphology among galago species are pronounced and complex. Comparative studies of galagos and other primate species show that elongation of the baculum (os penis)is associated with copulatory patterns involving a prolonged period of intromission. The enlarged penile “spines” of male galagos may be important in maintaining a genital “lock” during copulation. In primate species where females mate with a number of partners, sexual selection may have favored the rapid evolution of such features of penile morphology and masculine copulatory behavior. It is suggested that evolution of complex penile morphologies in galagos has been influenced by sexual selection and that such morphological variations are extremely useful in taxonomic studies.     

Differences in responsiveness to testosterone of penile reflexes and copulatory behavior of male rats

The display of penile reflexes and copulatory behavior appears to reflect the activity of two different underlying neuronal system, both of which are modulated by systemic testosterone (T) concentration. To indirectly compare the two systems, the responsiveness to T of penile reflexes and copulatory behavior was examined. In the first experiment castrated spinal male rats were given penile reflex tests while receiving replacement T through Silastic capsule implants filled with T (50 mm T). After capsule removal the number of penile erections and flips declined within 24 hr and gradually decreased for 12 days. Subjects were then reimplanted with new 50-mm T capsules. The number of penile flips and erections increased within 6 and 12 hr. respectively. This is a much more rapid response rate to T than has been established for copulatory behavior. In the second experiment castrated spinal male rats were tested for penile reflexes with a 50-mm T capsule, which was then replaced with a 10-, 5-, or 2-mm T or an empty capsule. The number of penile reflexes declined in a dose-response fashion. In the third experiment, castrated sexually experienced male rats were tested for copulatory behavior with two 25-mm T capsules which were then replaced with a 10 or 2-mm T or an empty capsule. Only males with empty capsules had decrements in copulatory behavior, revealing that a low level of T can maintain virtually normal sexual behavior despite a marked decline in penile reflex activity. The neuronal system underlying penile reflexes (spinal neurons) is apparently much more responsive to changes in T concentrations than the neuronal system underlying motivational and appetitive aspects of copulatory behavior (brain neurons).     

Mating Behavior, Sexual Selection, and Copulatory Courtship in a Promiscuous Beetle

The function of male movements during copulation is unclear. These movements may be a result of the necessary mechanics of insemination, or they may also have further function, for instance, stimulating or courting a female during mating, perhaps influencing female mate choice. We present data from three experiments exploring the mating behavior and copulatory movements of the highly promiscuous beetle Psilothrix viridicoeruleus. Male mating success in the struggle over mating was not related to male or female size (measured by weight) but successful males were more vigorous in terms of copulatory movements. These males took longer to mount females but copulated longer and remained mounted longer. We discuss these results in terms of the mating system of Psilothrix and also in terms of observations of the timing of insemination during copulation. We suggest that copulatory movements in this species are best understood as copulatory courtship.     

Evaluating the post‐copulatory sexual selection hypothesis for genital evolution reveals evidence for pleiotropic harm exerted by the male genital spines of Drosophila ananassae

The contemporary explanation for the rapid evolutionary diversification of animal genitalia is that such traits evolve by post‐copulatory sexual selection. Here, we test the hypothesis that the male genital spines of Drosophila ananassae play an adaptive role in post‐copulatory sexual selection. Whereas previous work on two Drosophila species shows that these spines function in precopulatory sexual selection to initiate genital coupling and promote male competitive copulation success, further research is needed to evaluate the potential for Drosophila genital spines to have a post‐copulatory function. Using a precision micron‐scale laser surgery technique, we test the effect of spine length reduction on copulation duration, male competitive fertilization success, female fecundity and female remating behaviour. We find no evidence that male genital spines in this species have a post‐copulatory adaptive function. Instead, females mated to males with surgically reduced/blunted genital spines exhibited comparatively greater short‐term fecundity relative to those mated by control males, indicating that the natural (i.e. unaltered) form of the trait may be harmful to females. In the absence of an effect of genital spine reduction on measured components of post‐copulatory fitness, the harm seems to be a pleiotropic side effect rather than adaptive. Results are discussed in the context of sexual conflict mediating the evolution of male genital spines in this species and likely other Drosophila.     

EVIDENCE FOR WIDESPREAD COURTSHIP DURING COPULATION IN 131 SPECIES OF INSECTS AND SPIDERS,AND IMPLICATIONS FOR CRYPTIC FEMALE CHOICE

Male courtship behavior is generally thought to function prior to copulation, as an inducement to the female to allow the male to copulate with her; this study indicates however, that male courtship during and following copulation (“copulatory courtship”) is common in insects and spiders (81% of 131 species in 102 genera and 49 families, mostly Coleoptera, Hemiptera, Diptera, and Araneioidea). Copulatory courtship is apparently evolutionarily labile, as expected if it is under sexual selection; intrageneric variation occurred in all 17 genera in which more than one species was observed. In 81% of 94 species with copulatory courtship, the male abandoned the female soon after copulation ended; thus, copulatory courtship appears not to function generally to induce acceptance of further copulatory attempts. The most likely explanation for copulatory courtship is that it represents attempts by males to influence cryptic female choice. This suggests that an aspect of sexual selection by female choice not considered by Darwin may be more important than previously appreciated and that the common practice in evolutionary studies of measuring male reproductive success by counting numbers of copulations may sometimes be misleading because of cryptic female choice during and after copulation.     

Paternity analyses in wild‐caught and laboratory‐reared Caribbean cricket females reveal the influence of mating environment on post‐copulatory sexual selection

Polyandry is ubiquitous in insects and provides the conditions necessary for male‐ and female‐driven forms of post‐copulatory sexual selection to arise. Populations of Amphiacusta sanctaecrucis exhibit significant divergence in portions of the male genitalia that are inserted directly into the female reproductive tract, suggesting that males may exercise some post‐copulatory control over fertilization success. We examine the potential for male–male and male–female post‐copulatory interactions to influence paternity in wild‐caught females of A. sanctaecrucis and contrast our findings with those obtained from females reared in a high‐density laboratory environment. We find that female A. sanctaecrucis exercise control by mating multiple times (females mount males), but that male–male post‐copulatory interactions may influence paternity success. Moreover, post‐copulatory interactions that affect reproductive success of males are not independent of mating environment: clutches of wild‐caught females exhibit higher sire diversity and lower paternity skew than clutches of laboratory‐reared females. There was no strong evidence for last male precedence in either case. Most attempts at disentangling the contributions of male–male and male–female interactions towards post‐copulatory sexual selection have been undertaken in a laboratory setting and may not capture the full context in which they take place – such as the relationship between premating and post‐mating interactions. Our results reinforce the importance of designing studies that can capture the multifaceted nature of sexual selection for elucidating the role of post‐copulatory sexual selection in driving the evolution of male and female reproductive traits, especially when different components (e.g. precopulatory and post‐copulatory interactions) do not exert independent effects on reproductive outcomes.     

Copulatory behavior in relation to anatomical characteristics of three macaques

Anatomy of copulatory organs and patterns of copulatory behavior were studied in three species of Macaca. The copulatory behavior of the rhesus monkey (M. mulatta) and crab-eating macaque (M. fascicularis) were similar. Mounting time was longer in stump-tailed macaque (M. arctoides) (48 seconds) than in the rhesus monkey or crab-eating macaque (8.5 seconds). Species differences were correlated with anatomical differences in the female and male reproductive organs. In the stump-tailed macaque the male has a relatively long penis, and the female has an elaborate vestibular colliculus in the vestibule. Both rhesus and crab-eating macaques have a short penis, and the female has no vestibular colliculus. Under scanning electron microscope, cone-like projections (3–4 mm) were observed on the surface of the glans and corpus penis of M. arctoides. In M. fascicularis shorter projections (0.05–0.1 mm) were observed on the glans penis but not the corpus penis.     

Copulatory Courtship in Drosophila: Behavior and Songs of D. birchii and D. serrata

D. birchii and D. serrata, two endemic Australian Drosophila species, have a copulatory courtship. The males of these species begin to court the female after mounting her and often go on with the courtship after the copulation is over. In the present paper we have described behavioral interactions between the male and the female and analyzed acoustic signals produced by the flies during courtship. Species differences were more pronounced in female than in male behavior. Variation within the species was obvious in the relative proportions of time the flies spent in different behaviors. Even though courtship took place nearly solely during copulation, some remains of precopulatory courtship were observed in both species. It is suggested that copulatory courtship exhibited by D. birchii and D. serrata flies is a derived rather than a primitive character.     

Annual changes in the copulatory behavior of male rats maintained under constant laboratory conditions

ABSTRACT

The objective of the present study was to evaluate the sexual behavior of male rats kept under constant laboratory conditions for one entire year. A total of 213 sexually-inexperienced, male Wistar rats were maintained in controlled environmental conditions from birth. Depending the month in which they reached the age 3-month-old, the male rats were divided into 12 groups, one for each month of the year, and their sexual behavior was evaluated. Records of their sexual behavior were made from 09:00 to 11:00 hrs am. The following parameters were recorded: mount (latency and number), intromission (latency and number), ejaculation latency, and intromission rate. During the months of March, June, July and September, the rats showed lower mount and intromission latencies than in January, February, April, May and October-to-December. Similarly, in March, June, July and August they had higher copulatory efficiency than in January, February, April and December. Results suggest that male rats exposed to controlled environmental conditions could have endogenous mechanisms that regulate sexual behavior but are independent of seasonal environmental signals. The annual variability in the sexual behavior of male rats maintained under constant laboratory conditions should be considered when planning research and experiments.     

The effects of progesterone on sexual behavior in male green anole lizards (Anolis carolinensis)

It is well known that androgen-dependent sexual behaviors in male mammals and birds are inhibited by exogenous progesterone (P). However, recent research on male whiptail lizards (Cnemidophorus inornatus) indicates that P can stimulate sexual and copulatory behavior. We report here both antiandrogenic and synandrogenic actions of P on sexual behavior in males of another reptile, the green anole lizard (Anolis carolinensis). Earlier reports on birds and mammals are reviewed and discussed in relation to a possible physiological role of P in influencing sexual behavior in male vertebrates.     

Female mate choice in relation to heterozygosity in Tribolium castaneum

Abstract Female mate choice, both before and after copulation, is pervasive among insect species. It is often hypothesized that females would preferentially mate with males that are genetically dissimilar to promote the genetic variability of the offspring. We used various strains of red flour beetle, Tribolium castaneum, and tested the effect of male and female genetic backgrounds on precopulatory and post‐copulatory female mate choice. Simultaneous mate choice experiments using previously well established pheromone assays did not detect female preference for males of different strains. Post‐copulatory female mate choice was examined through paternity analysis. Two parameters were used to measure post‐copulatory female mate choice, including male defence capacity (P₁, proportion of offspring sired by the first male when a female mated with two males consecutively) and offence capacity (P₂, proportion of offspring sired by the second of two males to mate with a female). When female and male beetle strains were same, defence capacity was significantly higher than when female and male strains were different. However, such a pattern was not observed for offence capacity. The results suggest that female precopulatory mate choice is not affected by genetic background, but the outcome of post‐copulatory processes depends on the genetic background of male and female beetles.     

A redescription of Heterocotyle pastinacae Scott, 1904 (Monogenea: Monocotylidae) from Dasyatis pastinaca (Dasyatididae), with a neotype designation

Heterocotyle pastinacae Scott, 1904 is redescribed and a neotype is designated. H. pastinacae is most easily distinguished from other members of the genus by the elaborate arrangement of sclerotised spines in the vagina. The male copulatory organ also serves to differentiate it from other species in the genus. A possible function for the vaginal spines and unique form of the male copulatory organ is discussed. The use of head organ number as a generic character is considered questionable.     

Histofluorescent labelling of catecholaminergic structures in rotifers (Aschelminthes)

Summary 1. Catecholaminergic structures in the male Brachionus plicatilis were investigated, using aqueous dansylpropranolol as fluorescent label of neurotransmitter receptors. 2. All major organs of the male are innervated by catecholaminergic systems, that may also be involved in the regulation of copulatory behavior. 3. Cryostat-sectioned preparations of the female B. plicatilis were also investigated. They provided additional information to findings on whole animals reported in our previous paper (Keshmirian and Nogrady 1987a).     

Male copulatory patterns in the lesser bushbaby (Galago moholi) in captivity

I observed seven pairs of sexually mature, captiveGalago moholi during the females’ ovarian cycles to determine the pattern of male copulatory behavior and its relationship to female receptivity. In this species, a copulatory lock was not apparent, a variety of thrusting patterns was displayed, and the male was capable of ejaculating following a single mount and intromission and may have ejaculated more than once during the 30-min test. Male mating indices did not differ significantly on consecutive days of the mating period, though declines in certain mating latencies on the second and third days of mating suggested increased female receptivity. Mating indices did not differ notably between the first and the second copulation within a test, though both showed some differences compared to the third copulation. InG. moholi, male copulatory behavior is typical of a prosimian species with a dispersed — nongregarious — mating system, in which copulation has a single prolonged intromission that extends into the postejaculatory period. This is characteristic of species in which more than one male has access to an estrous female.     

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.     

A role for ATP-sensitive potassium channels in male sexual behavior

ATP-sensitive potassium (K⁺_ATP) channels regulate cell excitability and are expressed in steroid-responsive brain regions involved in sexual behavior, such as the preoptic area (POA) and medial basal hypothalamus (MBH). We hypothesized that K⁺_ATP channels serve as a mechanism by which testosterone can control the electrical activity of neurons and consequently elicit male sexual responsiveness. RT-PCR analysis indicated that castration induces, while testosterone inhibits, mRNA expression of the K⁺_ATP channel subunit Kir6.2 in both the POA and MBH of adult male rats. Intracerebral infusion of the pharmacological K⁺_ATP channel inhibitor tolbutamide increased the proportion of long-term castrates displaying sexual behavior and restored mount frequency, intromission frequency, and copulatory efficacy to values observed in testes-intact animals. Infusions of tolbutamide, but not vehicle, also decreased latencies to mount and intromit in castrated males. Unilateral tolbutamide infusion directly into the POA significantly reduced mount latency of castrates; however, it did not affect other copulatory measures, suggesting that blockade of K⁺_ATP channels in additional brain regions may be necessary to recover the full range of sexual behavior. These data indicate that blockade of K⁺_ATP channels is sufficient to elicit the male sexual response in the absence of testosterone. Our observations are consistent with the hypothesis that testosterone modulates male sexual behavior by regulating K⁺_ATP channels in the brain. Decreased channel expression or channel blockade may increase the excitability of androgen-target neurons, rendering them more sensitive to the hormonal, chemical, and somatosensory inputs they receive, and potentially increase secretion of neurotransmitters that facilitate sexual behavior.     

Monoamines and reproduction in Pecten maximus,a preliminary approach

Summary

The distribution of serotonin-like immunoreactivity was studied in the central nervous system and the gonad of Pecten maximus. Cerebral and pedal ganglia contain a well developed serotonin-immunoreactive neuronal subpopulation, whereas positive neurons are scarce in the visceral ganglion. The distribution pattern of immunoreactive elements in the gonad indicate that serotonin is involved in peripheral neurotransmission of this organ. Seasonal variations of monoamines (serotonin, dopamine and noradrenaline) have been investigated in the nervous system using HPLC. Lower concentrations of serotonin are observed during winter in the central nervous system; dopamine levels of the visceral ganglion are correlated to gonadal growth.