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PubMed1992

Male sexual signaling is defective in mutants of the apterous gene of Drosophila melanogaster.

The apterous (ap) gene of Drosophila melanogaster exhibits extreme pleiotrophy: its functioning is essential for life, normal wing structure, juvenile hormone production, female fertility, and normal development of female sexual receptivity. Four mutant ap alleles (ap4, ap56f, apc, and apblt) were characterized for three additional phenotypes: male mating success, courtship behavior, and immature male sex appeal (the ability of males to stimulate homosexual courtship). Mating success with mature wild-type virgin females is reduced in males mutant for the ap gene, the extreme case being ap4/ap4 males, which are behaviorally sterile. In ap mutants, nonwing courtship elements are qualitatively like those of ap+/ap+ males. However, the mean rate of nonwing courtship directed toward virgin wild-type females (i.e., the mean temporal frequency of these displays) is reduced in males homozygous for ap4, ap56f, or apc alleles. In contrast, the apblt allele makes for wild-type rates of nonwing courtship. Immature male sex appeal persists for at least 3 days in males homozygous for apc and, to a lesser extent, in ap56f or ap4 homozygotes; apblt/apblt and wild-type males lose immature male sex appeal after 1 day. All three male phenotypes map to the ap locus, which is therefore essential for the development of normal levels of male courtship and male mating success and for the timely loss of immature male sex appeal. For each phenotype, ap+ is dominant to ap alleles making for behavioral abnormalities, with a single exception (for rate of nonwing courtship, ap+/apc was low). For mating success and frequency of nonwing courtship, each allele pair exhibits at least partial complementation, except for ap4 and ap56f, which fail to complement. For immature male sex appeal, apc, ap4, and ap56f fall into the same complementation group. Juvenile hormone production is not correlated with effects on male reproductive behavior.

Animals↗
PubMed2004

Chemical signaling in a wolf spider: a test of ethospecies discrimination.

Chemical signals from female wolf spiders that elicit exploratory behavior and courtship in males are often assumed to be species-specific, but males of some species court in response to silk cues deposited by closely related heterospecific females. Such is the case with the wolf spiders Schizocosa ocreata and S. rovneri, ethospecies reproductively isolated on the basis of differences in behavioral mechanisms during courtship. We explored whether male S. ocreata and S. rovneri reciprocally discriminate species-specific chemical or mechanical cues associated with female silk by using male behavioral response as an assay. Males were exposed to stimulus treatment categories including silk, washed silk, silk extract, and appropriate controls within conspecific or heterospecific female stimulus categories. Male S. ocreata and S. rovneri did not discriminate between conspecific or heterospecific female stimuli, and courtship intensity was greatest on untreated silk. There were no differences in latency to begin courtship or in rates of courtship behaviors attributed to species origin of silk. However, silk treatment (washed silk, extract) had a significant effect on display and exploratory behaviors (e.g., chemoexplore) in both species. Methanol extraction of female silk successfully removed or inactivated a component necessary to elicit active courtship, but extraction did not significantly reduce exploratory behavior, suggesting that a separate compound may be responsible for releasing this behavior. Together, these experiments support the characterization of S. ocreata and S. rovneri as ethospecies reproductively isolated only by female discrimination of species-specific male courtship, and indicate that chemical, but not mechanical cues associated with silk are critical for eliciting male courtship in both species.

Animal Communication↗
PubMed2003

Multiple male traits interact: attractive bower decorations facilitate attractive behavioural displays in satin bowerbirds.

Sexually selected male courtship displays often involve multiple behavioural and physical traits, but little is known about the function of different traits in mate choice. Here, we examine female courtship behaviours to learn how male traits interact to influence female mating decisions. In satin bowerbirds (Ptilonorhynchus violaceus), successful males give highly aggressive, intense behavioural displays without startling females. Males do this by modulating their displays in response to female crouching, which signals the display intensity that females will tolerate without being startled. Females typically visit multiple males for multiple courtships before choosing a mate, and females show differing tolerance for intense displays during their first courtship with each male. We test three hypotheses that may explain this: (i) familiarity with the courting male; (ii) the order of the courtship in mate-searching; and (iii) the attractiveness of the courting male. We found that females are more tolerant of intense displays during first courtships with attractive males; this increased female tolerance may allow attractive males to give higher intensity courtship displays that further enhance their attractiveness. We then examined why this is so, finding evidence that females are less likely to be startled by males with better physical displays (bower decorations), and this reduced startling then contributes to male courtship success. This role of physical displays in facilitating behavioural displays suggests a novel mechanism by which multiple physical and behavioural traits may influence female choice.

Animals↗
PubMed2002

Novel memory mutants in Drosophila: behavioral characteristics of the mutant nemyP153.

BACKGROUND: Starting from Benzer's initiative, the approach of forward genetics has been widely used to isolate mutations affecting learning and memory. For this aim, mainly the odor-shock conditioning was employed. We have isolated P insertional mutations affecting memory after courtship conditioning - another form of classical conditioning in Drosophila. Here we report the behavioral characteristics of one of these mutants, which we have called nemy (no extended memory). RESULTS: The courtship activity of Drosophila males is reduced when a male has a previous experience of courting a fertilized female. In the wild-type strain C-S (K), this conditioned courtship inhibition lasts for 1-3 h in the test with a virgin female, and at least for 8 h in the test with a subsequent fertilized female. The mutant males nemyP153 display distinct memory deficiency in both tests already 0.5 h after training. The mutant males show an increased level of locomotor activity unrelated to courtship, and spend more time in such an element of courtship as pursuit. This, however, seems to be a pleiotropic effect of the mutation, independent from its influence on the courtship conditioning. The mutation reduces also memory performance after the odor-shock classical conditioning. At the same time, the sensory and motor functions involved in this type of learning seem to be normal. CONCLUSIONS: Insertion of P-lacW vector into 49B region of the second chromosome (mutation nemyP153) causes an increased level of locomotor activity, memory deficiency after the courtship conditioning and subnormal acquisition after the odor-shock conditioning.

Animals↗
PubMed1991

Reassessment of the effect of biological rhythm mutations on learning in Drosophila melanogaster.

A link between learning deficits and circadian period-lengthening mutations in Drosophila melanogaster previously has been reported. Mutant long-period males performed poorly in two learning assays involving experience-dependent courtship inhibition. In one, normal males that have courted fertilized females subsequently show courtship inhibition with virgin females. In the other, normal males that have courted sexually immature males subsequently fail to court other immature males. Those results have been reassessed in an extended study of genetic variants involving the period gene. 1. Long-period perL1 males demonstrated poor conditioned courtship inhibition when exposed to fertilized females; they showed normal courtship conditioning when exposed to immature males. This could be due to a perL1-associated olfactory deficit with fertilized females, since perL1 males were unable to discriminate behaviorally between fertilized and virgin females. 2. Other long-period males, including perL2 males and transgenic perL1 males bearing a truncated form of the per+ gene, were conditioned normally by fertilized females. Thus, the courtship inhibition defect is specific to the perL1 mutant strain. 3. perL1 (and other per mutant) flies showed normal acquisition and retention of a classically conditioned olfactory avoidance response. 4. Results from a new conditioned courtship inhibition experiment are presented; males exposed to fertilized females during training showed further courtship inhibition during subsequent exposure to fertilized females. From the perspective of learning theory, this can be viewed as a savings experiment.

Animals↗
PubMed1999

Interactions between behavior and plasma steroids within the scramble mating system of the promiscuous green turtle, Chelonia mydas.

We measured plasma androgen (combined testosterone and 5alpha-dihydrotestosterone) (A) and corticosterone (B) in the promiscuous green turtle (Chelonia mydas) during courtship in the southern Great Barrier Reef. This study examined if reproductive behaviors and intermale aggression induced behavioral androgen and adrenocortical responses in reproductively active male and female green turtles. Associations between reproductive behavior and plasma steroids were investigated in green turtles across the population and within individuals. Levels across a range of both asocial and social behaviors were compared including (a) free swimming behavior; (b) initial courtship interactions; (c) mounted behavior (male and female turtles involved in copulatory activities); (d) intermale aggression (rival males that physically competed with another male turtle or mounted males recipient to these aggressive interactions); and (e) extensive courtship damage (male turtles that had accumulated excessive courtship damage from rival males). Behavioral androgen responses were detected in male turtles, in that plasma A was observed to increase with both attendant and mounted behavior. Male turtles who had been subjected to intermale aggression or who had accumulated severe courtship damage exhibited significantly lower plasma A than their respective controls. No pronounced adrenocortical response was observed after either intermale aggression or accumulation of extensive courtship damage. Female turtles exhibited a significant increase in plasma B during swimming versus mounted behavior, but no change in plasma A. We discuss our results in terms of how scramble polygamy might influence behavioral androgen interactions differently from more typical combative and territorial forms of male polygamy.

Aggression↗
PubMed2000

The transvestite serpent: why do male garter snakes court (some) other males?

In large mating aggregations of red-sided garter snakes, Thamnophis sirtalis parietalis, in Manitoba, male courtship is directed not only to females, but also to other males with female-like skin lipids ('she-males'). We show that 'she-maleness' is an intrinsic property of a male rather than an artefact of lipid transfer from females, and that male-male courtship is very common in the field. She-males were distinctive in terms of appearance (they were heavier than other males and more often covered with mud), behaviour (they were inactive and rarely courted females) and performance (they were slow crawlers, ineffective courters and easily outcompeted by other males in mating trials). 'She-maleness' was not a characteristic of a particular subset of males, as envisaged in previous work; instead, it was a transitory phase that most (perhaps all) male snakes passed through soon after they first emerged from the winter den. Recently emerged males spent their first day or two relatively inactive, while restoring physiological functions (including locomotor performance and courtship ability). Experimental application of female skin lipids on to males dramatically decreased courtship levels of the recipient snakes. Thus, recently emerged males may derive two kinds of benefit from mimicking female skin lipids. First, female mimicry 'switches off' the male's own (energetically expensive) courtship at a time when that courtship would be unproductive. Second, it may disadvantage his rivals by distracting them from females, and increasing their energy expenditure. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1990

Dissociation of sexual arousal and sexual proclivity in the garden snail, Helix aspersa.

Sexual arousal (intensity of courtship) and sexual proclivity (tendency to court) in Helix aspersa can be reliably measured using externally observable correlates. Snails with sexual proclivity are significantly more likely to turn toward an anesthetized conspecific after contacting it than are sexually unreceptive snails. Sexual arousal can be inferred from the stage of a snail's genital eversion, which appears only during courtship. The higher the stage of the eversion, the shorter the time required to complete introductory courtship behavior and the higher the rate of successful copulation, the fewer the number of breaks and pauses during courtship, and the longer the time a snail will spend in contact with an anesthetized conspecific. Sexual proclivity has no effect on feeding or locomotory behavior; however, sexual arousal inhibits feeding and increases locomotor activity. Snails that were allowed daily contact with conspecifics required less time to complete introductory courtship behavior relative to snails that were isolated from conspecifics for 1 week. This suggests that daily contact increases sexual arousal. A greater percentage of isolated snails exhibited courtship behavior than did snails which had experienced daily conspecific contact. This suggests that isolation increases sexual proclivity. These differences indicate that sexual arousal is not merely due to an increase in sexual proclivity.

Animals↗
PubMed1997

Ovulation and the suppression of mating in Drosophila melanogaster females: behavioral basis.

Virgin females of Drosophila melanogaster that are ectopically expressing the sex-peptide gene show a high level of ovulation and are unreceptive to males. However, if they are genetically deprived of eggs, receptivity is considerably restored (Fuyama, 1995). These females, whether they have eggs or not, extrude their ovipositors toward courting males as frequently as do fertilized females. However, this rejection behavior was ineffective in suppressing male courtship. Of females with eggs, about half of them could suppress male courtship. Females lacking eggs could not suppress male courtship and continued to elicit vigorous courtship. This difference seems to account for the increased mating frequency in sterilized females. Courtship behavior by mutant males defective in olfaction or learning suggested that females are capable of repelling males by emitting a volatile pheromone(s) with an inhibitory effect on male courtship.

Animals↗
PubMedDate not supplied

The effect of thermal stress on the mating behavior of three Drosophila species.

Selection may act on the weakest link in fitness to change how a species adapts to an environmental stress. For many species, this limitation may be reproduction. After adult Drosophila melanogaster, Drosophila simulans, and Drosophila mojavensis males were exposed to varying levels of thermal stress well below those that endanger life, courtship and mating frequency declined. The regression coefficients of both courtship and mating success did not differ significantly between D. melanogaster and D. simulans males. In contrast, significant differences were present between the two cosmopolitan species and D. mojavensis. Courtship frequency decreased at a much slower rate in D. mojavensis than in D. melanogaster and D. simulans, and while heat-stressed D. mojavensis males continued to court, many did not mate. In the cosmopolitan species, courting males almost always mated successfully. Courtship behaviors, including wing waving, were observed in D. mojavensis at temperatures that prohibited flight, while flight, courtship, and mating were knocked out simultaneously in D. melanogaster. One possible explanation for decreased flight ability and courtship success may be the reduced heat shock response in the flight muscle tissue because Hsp70 expression was lowest in the thoracic tissue of both D. melanogaster and D. mojavensis.

Adaptation, Physiological↗
PubMed2000

Annual social behaviour of basking sharks associated with coastal front areas.

Comparatively little is known about reproductive behaviour in wild sharks as it has proved extremely difficult to study, especially in large pelagic sharks. Here we describe annual courtship-like behaviour in the second-largest fish species, the basking shark (Cetorhinus maximus), from 25 separate episodes observed and tracked during a five-year study period (1995-1999) off south-west England. Social behaviours observed between paired, or three or four, sharks were consistent with courtship behaviours seen in other shark species, namely nose-to-tail following, close following, close flank approach, parallel and echelon swimming. Mature individuals between 5 and 8 m total body length (L(T)) exhibited these behaviours whereas smaller sharks (3-4 m L(T)) did not. Lead individuals were identified as female on a number of occasions and interactions were prolonged; the longest continuous observation of socializing was 1.8 h, although intermittent track data indicates bouts may last for up to 5-6 h. Locations of courtship-like behaviour events were not distributed randomly and were significantly associated with thermal fronts. Our results indicate that putative courtship behaviour occurs between May and July along oceanographic fronts, probably as a consequence of individuals aggregating to forage in rich prey patches before initiating courtship. Thus, locating the richest prey patches along fronts may be important for basking sharks to find mates as well as food in the pelagic ecosystem. As courtship-like behaviours occur annually off south-west England we speculate that this region may represent an annual breeding area for this protected species, but mating itself probably takes place at depth as it was not seen at the surface.

Animals↗
PubMedDate not supplied

The role of 5alpha-reductase activity in sexual behaviors of the green anole lizard.

Both testosterone (T) and its metabolite, 5alpha-dihydrotestosterone (DHT), can facilitate male sexual behavior in the lizard Anolis carolinensis. The present study addresses the role of DHT synthesis in regulating male sexual behavior by inhibiting 5alpha-reductase, the enzyme that converts T into DHT. In two separate experiments (one replacement and one maintenance paradigm), breeding adult males were castrated and implanted with capsules of T, DHT, or a control capsule (blank, BL). The animals were then injected with the 5alpha-reductase inhibitor, FCE, or with steroid suspending vehicle (SSV) as a control. Both experiments produced similar results. Overall, T was most effective in eliciting courtship and copulatory behaviors above control levels. In both experiments, treatment with FCE attenuated the T-induced effects on courtship behavior, whereas the inhibition of 5alpha-reductase activity resulted in modest and inconsistent effects on the latency to intromission and the proportion of copulating males. DHT treatment did not significantly increase courtship or copulatory behaviors above control levels. These results suggest that (a) 5alpha-reductase activity is necessary but that DHT alone is not sufficient for stimulating courtship in male A. carolinensis; and (b) courtship behavior is more sensitive than copulatory behavior to the activity of the androgen metabolizing enzyme.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1976

Role of mate's previous experience in ring dove hormone-induced incubation.

Progesterone-induced incubation was examined in 40 pairs of adult ring doves, differing in their previous reproductive experience (courtship vs. nest building) and the previous reproductive experience of their mates (courtship vs. nest building) during testing. Only the previous experience of the experimental subject significantly affected the establishment of incubation during the 24-hr test period. More doves experienced with nest building established incubation than did courtship-experienced doves. The latency to enter the nest area and the latency to stand on the nest were affected by both the previous breeding experience of the subject and the previous breeding experience of its mate. Nest-building-experienced mates decreased the latencies of courtship-experienced subjects, and courtship-experienced mates increased the latencies of nest-building-experienced doves. Males were not more affected by their mates' experience than were females. Time spent on the nest was affected only by the subject's previous experience and sex. While the hypothesis that the behavior of the mate can affect a dove's progesterone-induced incubation was not confirmed, the mate's behavior can affect some of the components of nest responsiveness.

Animals↗
PubMed1987

Sexual behavior: its genetic control during development and adulthood in Drosophila melanogaster.

Courtship behavior in Drosophila melanogaster males is an innate behavior pattern. Whether or not a fly will display male courtship behavior is governed by the action of a set of regulatory genes that control all aspects of somatic sexual differentiation. The wild-type function of one of these regulatory genes, transformer-2 (tra-2), is necessary for female sexual differentiation; in the absence of tra-2+ function XX individuals differentiate as males. A temperature-sensitive tra-2 allele has been used to investigate, by means of temperature shifts, when and how male courtship behavior is specified during development. The removal of tra-2ts function in the adult (by a shift of the tra-2ts mutant flies to the restrictive temperature) can lead to the appearance of male courtship behavior in flies that otherwise would not display these behaviors. These experiments suggest that the regulatory hierarchy controlling sexual differentiation is functioning in the adult central nervous system. More importantly, these results suggest that the adult central nervous system has some functional plasticity with respect to the innate behavioral pattern of male courtship and is maintained in a particular state of differentiation by the active control of gene expression in the adult.

Animals↗
PubMed2006

No evidence for learned mating discrimination in male Drosophila pseudoobscura.

BACKGROUND: Since females often pay a higher cost for heterospecific matings, mate discrimination and species recognition are driven primarily by female choice. In contrast, frequent indiscriminate matings are hypothesized to maximize male fitness. However, recent studies show that previously indiscriminate males (e.g., Drosophila melanogaster and Poecilia reticulata) can learn to avoid heterospecific courtship. This ability of males to discriminate against heterospecific courtship may be advantageous in populations where two species co-occur if courtship or mating is costly. RESULTS: Here, we tested whether Drosophila pseudoobscura males learn to discriminate against heterospecific females after being exposed to and rejected by D. persimilis females. In most of our assays, we failed to observe differences in D. pseudoobscura courtship intensity of heterospecific females by males that had previously courted heterospecific females vs. males that had been maintained in isolation. CONCLUSION: We conclude that learning to avoid heterospecific courtship may not be universal, even within the genus Drosophila, and may possibly be dependent on the natural history of the species.

Animals↗
PubMed1998

Temporal manipulation of ejaculate components by newly fertilized Drosophila melanogaster females.

Observations of newly mated Drosophila melanogaster females suggest that females control the times at which components of the ejaculate cause behavioural and physiological changes characteristic of fertilized females. Females that were assayed immediately after they mated elicited as much courtship as they did when they were virgins, but were unreceptive to copulation. Within a few minutes of when they disengaged from copulation, most females performed ovipositor extrusion, which has been classified as a rejection behaviour, in response to courting males or males that had previously performed courtship. Most females that were assayed immediately after mating had already ovulated. The females, however, do not begin to lay eggs until 4-6 h after mating, at which time they elicit very little courtship (Scott & Richmond 1985, Anim. Behav., 33, 817-824). Our observations suggest that neither ovipositor extrusion nor male-synthesized pheromones that are transferred to females' cuticles during copulation inhibit males' courtship of newly fertilized females. Thus, males cannot determine that newly fertilized females are unreceptive to copulation. These observations also indicate that the failure of newly fertilized females to mate with males is not a consequence of the females' inability to elicit vigorous courtship. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1996

Courting and noncourting male red-sided garter snakes, Thamnophis sirtalis parietalis: plasma melatonin levels and the effects of pinealectomy.

Previous studies found that pinealectomy of male Canadian red-sided garter snakes (Thamnophis sirtalis parietalis) in the autumn, before prolonged exposure to low temperatures (hibernation), significantly impaired the expression of courtship behavior upon emergence in the spring. Additionally, pinealectomized animals with a disrupted diel cycle of plasma melatonin did not court while those exhibiting a more typical diel pattern did. These results suggested that the pineal gland functions in the transduction of a temperature cue which stimulates courtship. To test this hypothesis, we pinealectomized males in the spring after they had undergone a normal hibernation but were still courting. Pinealectomy of courting males in the spring, in each of the 3 years of study, had no effect on courtship. This result suggests that once the cue is transduced, the pineal gland no longer has a modulatory effect on courtship behavior. Finally, we took advantage of the fact that, in the laboratory, there is always a small percentage of males that do not court upon emergence. Pinealectomy of these noncourters greatly increased the percent of males expressing courtship behavior in each of the study years. Plasma melatonin levels of unmanipulated courting and noncourting males was measured after emergence in successive years. In both years, courters had a typical pattern of melatonin secretion (low in the photophase, high in the scotophase) while persistent noncourters displayed the opposite pattern.

Animals↗
PubMed1989

Hormonal patterns in breeding and nonbreeding kestrels, Falco tinnunculus: field and laboratory studies.

Plasma levels of luteinizing hormone (LH), androgens, and corticosterone (B) were measured in breeding and nonbreeding kestrels, both in the field and in captivity under different food conditions. LH levels in breeding males were elevated from courtship through incubation and androgen concentration peaked during courtship and laying. Seasonal changes in LH and androgens were similar in breeding and nonbreeding males, although androgens declined sharply after laying in breeding males. Egg laying was characterized by marked increases in both female body mass and plasma concentrations of LH and B. In both breeding and nonbreeding females LH and B increased during pair formation and courtship (March-April), although maximum levels were lower in nonbreeders. Two marked differences were found between free-living and captive (paired) birds. First, during winter plasma levels of LH were basal in free-living birds, while significantly elevated in both captive males and females. Second, during courtship androgen levels in breeding males were three-fold higher in the field than in captivity, probably as a result of intermale aggression under natural conditions. Females breeding early, late, or not at all had similar LH concentrations on arrival and during early courtship. Before breeding there were also no differences in LH (males and females) or in androgen levels (males) between pairs fed ad libitum and pairs temporary food rationed. However, captive females with experimentally reduced food intake showed low levels of B until their rations were increased. Nonbreeders showed hormonal changes similar to breeders, except for those changes in females that were associated with laying. These results suggest that at the start of the breeding season both nonbreeding and breeding kestrels have functional reproductive systems. That some breed early, late, or not at all is primarily an effect of food availability and is not due to hormonal modulation of the reproductive cycle.

Androgens↗