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1.
Zebra finches evolved in arid areas of Australia. Their reproduction is stimulated by water availability, which is unpredictable. Cheng (Poult. Sci. Rev. 5 (1993) 37) hypothesized that the primary mechanism controlling reproduction in species relying on unpredictable cues should be inhibitory. The onset of stimulatory environmental conditions terminates the inhibition, allowing rapid initiation of reproduction. As the primary hormone regulating water balance in birds, arginine vasotocin (AVT) appears a likely candidate to modulate reproduction in finches. Drought conditions cause sustained AVT release, which in other species inhibits androgen production. To determine whether increased AVT inhibits reproductive behavior, intact males were tested with females and divided into three groups matched for courtship behavior. Osmotic minipumps containing (a) saline, (b) 264 ng AVT, or (c) 1320 ng AVT in saline were implanted subcutaneously and males tested 48 h later. AVT-treated males socialized with females, but the high dose significantly reduced singing and courtship displays. To determine whether AVT acted by depressing androgen secretion, additional males were given subcutaneous androgen implants and divided into two groups matched for courtship behavior. Males were then implanted with minipumps containing (a) saline or (b) the high AVT dose. Males treated with AVT plus androgen showed no deficits in courtship behavior. These data suggest that AVT secretion during periods of drought may inhibit reproduction by inhibiting androgen production. Inhibition of reproductive behavior by AVT may be a more general phenomenon. Large quantities of AVT or, in mammals the closely-related peptide vasopressin (VP), are released when animals are stressed, and high levels of AVT/VP may inhibit reproductive behavior. The extremely short half-life of these peptides means that once proximal factors become more favorable, the gonads should rapidly be released from the peptides' inhibitory actions.  相似文献   

2.
Investigating individual differences in sexual performance in unmanipulated males is important for understanding natural relationships between behavior and morphology, and the mechanisms regulating them. Among male green anole lizards, some court and copulate frequently (studs) and others do not (duds). To evaluate potential factors underlying differences in the level of these behaviors, morphology and androgen receptor expression in neuromuscular courtship and copulatory structures, as well as in the preoptic area and amygdala, were compared in males displaying varying degrees of sexual function. This study revealed that individual differences in behavior among unmanipulated males, in particular the extension of a throat fan (dewlap) used during courtship, were positively correlated with the size of fibers in the associated muscle and with soma size in the amygdala. The physiological response to testosterone, as indicated by the height of cells in an androgen-sensitive portion of the kidney, was also correlated with male sexual behavior, and predicted it better than plasma androgen levels. Androgen receptor expression was not related to the display of courtship or copulation in any of the tissues examined. The present data indicate that higher levels of male courtship behavior result in (or are the result of) enhanced courtship muscle and amygdala morphology, and that androgen-sensitive tissue in studs may be more responsive to testosterone than duds. However, some mechanism(s) other than androgen receptor expression likely confer this difference in responsiveness.  相似文献   

3.
Recent evidence indicates that aromatizable androgens are more effective than nonaromatizable androgens in restoring normal levels of sexual behavior in castrated male zebra finches (Poephila guttata). To determine whether the efficacy of treatment with aromatizable androgens, is in part due to their conversion to estrogens, castrated male finches were treated with androstenedione (AE), an aromatizable androgen, and their sexual and aggressive behavior was compared with that of castrates treated with AE plus 1,4,6-androstatriene-3,17-dione (ATD), an aromatization inhibitor. Males treated with AE + ATD showed less courtship activity and less copulatory behavior than AE-treated males, and were unlikely to have nests. Estradiol (E), when given concurrently with AE + ATD, reversed the inhibitory effects of ATD and restored levels of courtship and copulation to those observed in AE-treated males. Only AE- and AE + ATD + E-treated males displayed aggressive behaviors, but the frequency of such behaviors was so low that there were no significant differences across groups. These data affirm the importance of estrogen in the control of reproductive activities in male zebra finches and indicate that aromatization may be an obligatory step for maintaining normal levels of sexual and aggressive behavior.  相似文献   

4.
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.  相似文献   

5.
This study investigated the effects of social environment on gonadal recrudescence and sexual behavior in male and female Little Striped Whiptail lizards (Cnemidophorus inornatus). The presence of sexually active males facilitates ovarian recrudescence in conspecific females. Similarly, the presence of reproductively active females facilitates testicular recrudescence in conspecific males. Males housed with females, however, had lower average circulating concentrations of testosterone and dihydrotestosterone, and higher average concentrations of corticosterone compared to intact males housed in isolation. In other studies, the presence of reproductively active females partially restored courtship behavior in castrated males compared to castrated males housed in isolation. Despite the stimulatory effects of females on castrates, exogenous androgens are required for complete restoration of all components of sexual behavior in male C. inornatus. Females are receptive to male courtship and copulatory behavior only during the vitellogenic stages; females in previtellogenic or postovulatory ovarian stages aggressively reject male courtship advances. These findings demonstrate reciprocal effects of sexual behaviors of males and females upon each other's reproductive behavior and physiology.  相似文献   

6.
In this study we examined the mating behavior of Dryas iulia and the acceptance and rejection mechanisms of females during courtship activity. An ethogram of mating behavior was organized on the basis of 100 h of observation in an insectarium. Several different behaviors were catalogued and separated into two behavioral repertoires (pre-coupling, post-coupling). The behavioral sequence of mating behavior was also analyzed using a total of 53 pairs of D. iulia. The courtship activities involved interactions between the sexes in three sequential phases—the aerial, air-ground, and ground phases. In 49% of observations the courtship activities led to copulation. The mean time to the occurrence of the first interaction between males and females did not differ between interactions with and without copulation. The behavior of females and males in the two groups were analyzed and differences were found between behavioral activities of both sexes. The results indicate that males’ insistence on courtship does not affect their copulatory success, and that females play a decisive role in copulation occurrence. Analysis of behavioral transitions showed there are many alternative behavioral routines in interactions with and without copulation. The number of behavioral transitions recorded was smaller in the group in which copulation occurred, indicating that males with copulatory success modified their behavior less frequently. Successful males recorded more transitions with a probability of occurrence greater than 0.4, and their behavioral activity was also less reticulated. Analysis using the stereotyping index showed that situations in which copulations occurred were more stereotyped than those in which it did not.  相似文献   

7.
Males of many animal species engage in courtship behaviours during and after copulation that appear to be solely aimed at stimulating the female. It has been suggested that these behaviours have evolved by cryptic female choice, whereby females are thought to impose biases on male postmating paternity success. Males of the red flour beetle Tribolium castaneum rub the lateral edges of the females' elytra with their tarsi during copulation. We manipulated female perception of this behaviour by tarsal ablation in males, thus preventing males from reaching the edge of the female elytra with their manipulated legs, and by subsequently performing a series of double-mating experiments where the copulatory behaviour was quantified. We found a positive relationship between the intensity of the copulatory courtship behaviour and relative fertilization success among unmanipulated males. This pattern, however, was absent in manipulated males, where female perception of male behaviour differed from that actually performed. Thus, female perception of male copulatory courtship behaviour, rather than male behaviour per se, apparently governs the fate of sperm competing over fertilizations within the female, showing that copulatory courtship is under selection by cryptic female choice.  相似文献   

8.
To elucidate the mechanisms of amphibian gonadal sex differentiation, we examined the expression of aromatase and androgen receptor (AR) mRNAs for days 17-31 after fertilization. The effects of inhibitors and sex steroid hormones were also examined. In ZZ males, expression of AR decreased after day 19, while aromatase expression was low throughout the sampling period. Males treated with 17beta-estradiol (E2) showed increasing aromatase expression after day 21, and formed ovaries. AR antagonist treatment also induced high-level aromatase expression and ovarian differentiation. In males co-treated with an aromatase inhibitor and E2, the undifferentiated gonads developed into testes despite high-level aromatase expression. Males treated with androgen and E2 before and during an estrogen sensitive period, respectively, also formed testes. In ZW females, AR expression persisted at a low-level, while aromatase expression increased after day 18. Short-term treatment with an aromatase inhibitor was ineffective in preventing ovarian differentiation, whereas long-term treatment resulted in testes developing from ovarian structure. Compared with the ZZ males and ZW females, WW females did not exhibit detectable expression of AR, suggesting that the active AR gene(s) itself, or a putative gene regulating AR gene expression, is located on Z chromosomes. From the time lag of aromatase expression between ZW females and ZZ males treated with E2 and the effect of AR antagonist, it was found that in males elevated AR expression suppresses aromatase expression directly or indirectly. Consequently, endogenous androgens, accumulated by blocking estrogen biosynthesis, induced testicular differentiation. The gonadogenesis of males is dependent on sex hormone, whereas that of females has evolved to hormone-independence.  相似文献   

9.
Though cooperative behavior has long been a focus of evolutionary biology, the proximate hormonal mechanisms underlying cooperative interactions remain poorly understood. Lance-tailed manakins (Chiroxiphia lanceolata) are tropical passerines that form long-term male-male partnerships and cooperate in paired male courtship displays. To elucidate patterns of natural hormonal variation in relation to cooperation and reproductive behavior, we examined circulating androgen levels of male lance-tailed manakins in relation to social status, display behavior, and time of year. We found significantly higher circulating androgen levels in alpha-ranked (breeding) males compared to non-alpha adult males in the population. Beta males, which participated in courtship displays but did not copulate, had androgen levels indistinguishable from those of unpaired adult males that never displayed for females, suggesting that an elevated concentration of plasma testosterone in tropical lekking birds may be associated primarily with copulatory behavior or other status-specific traits, and not the performance of courtship display. Androgens decreased throughout the breeding season for males of all status categories. Interestingly, alphas that displayed for females in the observation session prior to sampling had lower androgen levels than alphas that did not display for females. This pattern may result from female discrimination against alpha males at display areas with high levels of social conflict among males, as social disruption is linked to elevated testosterone in many species. However, recent change of a display partner was not related to alpha androgen levels. We discuss alternative explanations and the possible implications of these results, and generate several testable predictions for future investigations.  相似文献   

10.
Androgenized females, Day 1 male castrates, normal males, and normal females were tested for mounting behavior as adults following TP administration (1 mg/day). Genital anesthetization was used to eliminate all intromission and ejaculation behavior. Results showed that sexually-naive normal males and androgenized females mounted significantly more then Day 1 male castrates, while the Day 1 male castrates mounted significantly more than normal females. Sexually-experienced normal males and androgenized females displayed a significant facilitation of mounting behavior as compared to the sexually-naive animals. Tests of masculine copulatory behavior without genital anesthetization also were conducted with androgenized females and normal males. In these tests, androgenized females were indistinguishable from normal males in all aspects of the complete masculine pattern. The present results provide evidence that during perinatal development androgen acts directly on neural systems which will later regulate adult masculine sexual behavior.  相似文献   

11.
Variation in male courtship behavior may be due to inherent differences among males or may arise from males adjusting their courtship displays according to female responsiveness. Female veiled chameleons, Chamaeleo calyptratus , exhibit two distinctive suites of body coloration and behavior patterns that vary according to receptive and non-receptive stages of their reproductive cycle. We presented male chameleons with both receptive and non-receptive females, and recorded differences in their mating frequency, courtship intensity and courtship behavior patterns. As expected, males were more likely to court and attempt mating with receptive females. Although fewer males courted non-receptive females, their courtship displays were significantly longer than those directed towards receptive females. Males also adjusted the contents of their displays according to female reproductive condition. Certain behavior patterns were unique to courtship displays directed towards each class of females. Males exhibited the behavior pattern `head roll' only when paired with receptive females, and `chin rub' was displayed only during courtship of non-receptive females. We hypothesize that these differences in male courtship frequency, intensity and content reflect differences in female reproductive value. Although males may benefit from mating with both receptive and non-receptive females, the costs associated with courtship may depend on female responsiveness. Thus, males adjust their courtship tactics accordingly.  相似文献   

12.
The mating of the Neotropical lycosid Schizocosa malitiosa is long and complex, involving intense genital stimulation and copulatory courtship. This suggests functions other than just insemination. Previous data indicated that mated females of this species are less sexually receptive than virgins. We hypothesise that copulatory characteristics presented by males during prolonged copulations could be responsible for subsequent female sexual reluctance, and may be selected by cryptic female choice. Our objective was to examine the influence of copulatory behaviour on subsequent female sexual receptivity in S. malitiosa, isolating it from the effects of sperm transfer per se. For this purpose, we obtained males without sperm in their copulatory organs (palpal bulbs), and prevented them from charging their palps by sealing their genital pores immediately after their last moult (treated males). Virgin females were separated into three groups: (i) females exposed once to normal males, (ii) females exposed twice to normal males, and (iii) females exposed first to treated and second to normal males. The results showed that, 3 d after their first mating, females first mated with untreated males were frequently refractory to remating, whereas all those first mated with treated males were receptive. Copulations performed by treated males showed some differences from those performed by normal males, but maintained the basic behavioural pattern with abundant sexual stimulation. The presence of sperm fluids in the female receptacles appears to be the most likely factor generating female remating reluctance. Males may manipulate female responses using receptivity inhibiting substances in their sperm, like those described for insects. Females would first ensure sperm supply, becoming more choosy afterwards. All females, whether mated once or twice, generated similar numbers of progeny, indicating no relationship between number of matings and number of spiderlings.  相似文献   

13.
Mating is critical for species survival and is profoundly regulated by neuromodulators and neurohormones to accommodate internal states and external factors. To identify the underlying neuromodulatory mechanisms, we investigated the roles of dopamine receptors in various aspects of courtship behavior in Drosophila. Here, we report that the D1 dopamine receptor dDA1 regulates courtship drive in naïve males. The wild‐type naïve males actively courted females regardless their appearance or mating status. On the contrary, the dDA1 mutant (dumb) males exhibited substantially reduced courtship toward less appealing females including decapitated, leg‐less and mated females. The dumb male's reduced courtship activity was due to delay in courtship initiation and prolonged intervals between courtship bouts. The dampened courtship drive of dumb males was rescued by reinstated dDA1 expression in the mushroom body α/β and γ neurons but not α/β or γ neurons alone, which is distinct from the previously characterized dDA1 functions in experience‐dependent courtship or other learning and memory processes. We also found that the dopamine receptors dDA1, DAMB and dD2R are dispensable for associative memory formation and short‐term memory of conditioned courtship, thus courtship motivation and associative courtship learning and memory are regulated by distinct neuromodulatory mechanisms. Taken together, our study narrows the gap in the knowledge of the mechanism that dopamine regulates male courtship behavior.  相似文献   

14.
The resistance of courtship behavior and communicative sound production to heat shock (37 degrees C, 30 min) was studied in wild-type Canton S (CS) male Drosophila melanogaster and males of two strains with defects in the kynurenine pathway of tryptophan metabolism (KPTM) caused by mutations cinnabar (block at the level of kynurenine-3-hydroxylase leading to accumulation of kynurenic acid, a neuroprotective metabolite, in the brain) and cardinal (block at the level of phenoxazinone synthetase causing accumulation of 3-hydroxykynurenine, an oxidative stress generator, in the brain). Males of each strain were divided into four groups. Males from control groups were not exposed to heat shock. The other groups were exposed to heat shock at the late embryonic/early larval (the first instar) developmental stage, when mushroom bodies are formed (HS1 groups); at the prepupal stage, when the brain central complex develops (HS2 groups); or at the imago stage 1 h before the experiment (HS groups). All males were tested at an age of five days. Virgin and fertilized five-day-old CS females served as courtship objects. The courtship behavior and singing of control CS and cinnabar males were similar. Control cardinal males also had high motivation, but their courtship efficiency was lower because of less precise movements (wing vibration was often not accompanied by sound production) and hyperexcitability. Exposure of first-instar larvae to heat shock had almost no effect on behavior or singing of adult males of any strain. In cardinal males exposed to heat shock at the prepupal stage or, especially, at the imago stage 1 h before the test (the HS2 and HS groups), courtship was strongly impaired, and various distortions appeared in their sound signals, which indicated disturbance of coordination between elements of the song center and their interaction with pacemakers. These effects were much milder or absent altogether in HS2 and HS wild-type males and, especially, cinnabar males. Thus, permanent excess of 3-hydroxykynurenine in the male brain dramatically decreased their stress resistance. In contrast, excess of kynurenic acid alleviated the consequences of stress.  相似文献   

15.
Activities associated with courtship are often in conflict with avoiding elevated predation risk. In polygamous species with temporally restricted mating seasons, males should be less responsive to interruption of courtship by detection of elevated predation risk compared to females. We tested this prediction with the hermit crab Clibanarius vittatus. Courting males continued to execute pre‐copulatory behavior patterns when exposed to predator odors. However, in the presence of predator odors, fewer pairs were established. Exposing previously paired males and females to predator cues showed that males were unaffected in their motivation to form pairs, whereas females were no longer attractive to males following exposure to predator cues.  相似文献   

16.
《Animal behaviour》1986,34(4):1099-1108
Male Drosophila subobscura provide females with a drop of regurgitated food during courtship. Males that were physically prevented from producing this drop (1) had reduced courtship success with starved, but not with fed, females; (2) positioned themselves in front of the female less frequently than males providing drops; and (3) had a smaller proportion of frontal displays which led to copulation. Males that produced small or watery drops also had reduced courtship success with starved, but not with fed, females. The starved females moved away from such males more frequently than from males providing large or yeasty drops. Evidence is presented in support of the hypothesis that the drops of food offered by males during courtship slow the moving female down, making it easier for the male to complete a frontal display, and to circle and attempt to mount before the female moves away after taking the food. The effectiveness of the drop in this role depends on its attractiveness to the female, which is influenced by the drop's size and content and by the female's nutritional status.  相似文献   

17.
Females can affect male probabilities of paternity success through behavioural, morphological and/or physiological processes occurring during or after copulation. These processes under female-control include the acceptance or rejection of mating attempts by subsequent males. Leucauge mariana is an orb weaving spider that shows male mate guarding of penultimate females, male–male competition on female webs and copulatory plugs, suggesting a polyandric mating system. The aim of the present study was to ascertain whether male behaviour during courtship and copulation in L. mariana relate with female re-mating decisions. Forty-three virgin females were exposed to up to three males until they mated. In 24 cases, the copulatory plug was absent after mating and females were exposed the next day to up to three other males. Eighteen females accepted a second mating. Relatively larger females were more receptive to second matings and were more likely to copulate if the second male was smaller. Longer duration of female tapping and abdominal bobbing during courtship, and first copulations with less short insertions and more flubs, were associated with increased female acceptance to second matings. The results indicate cryptic female choice on male courtship and copulatory performance and suggest female-control over the determination of male mating success in this spider species.  相似文献   

18.
Despite having detailed information on mechanisms mediating sex-typical behavior in many species, we have little understanding of whether the same mechanisms regulate these behaviors when they are performed in the same species under different social contexts. In the five field experiments of this study of bluehead wrasses (Thalassoma bifasciatum), a sex-changing fish, we examined the roles of arginine vasotocin (AVT) and the potent teleost androgen 11-ketotestosterone (11KT) in mediating sexual and aggressive behaviors typical of dominant males. We demonstrated that AVT appears necessary for the assumption of dominant territorial status in males and females, but is sufficient only in the socially dominant terminal phase (TP) male phenotype. Specifically, an AVP V(1) receptor antagonist prevented both TP males and females from gaining dominance over recently vacated territories. However, unlike TP males in a previous study, neither females nor initial phase males responded to AVT treatment with increases in display of TP male typical behaviors when under social conditions that inhibit sex change. Treating females with 11KT did not alter responsiveness to AVT, but did induce male coloration and courtship behavior that was not observed in oil-treated females. Combined with the results of a previous study, these results indicate that the ability of AVT to induce male-typical behavior differs among sexual phenotypes and that this differential responsiveness appears to be dependent on social context and not directly on exposure to 11KT. Furthermore, since 11KT can induce courtship behavior in females that is not affected by AVT, there may be different hormonal mechanisms mediating courtship behavior under different social contexts.  相似文献   

19.
Apparently stimulatory male copulatory behaviour (MCB) is widespread among arthropods and it could help males to increase their fitness by inducing favourable behavioural and physiological changes in females. The empirical study of female responses to MCB is hindered because its experimental manipulation is difficult. We have developed a technique for reducing, with minimal disturbance, the frequency of MCB in the true bug Stenomacra marginella. Here, we test the idea that, in a polygamous species like S. marginella, sexual selection favours males whose MCB induces females to increase copula duration (thereby increasing the amount of sperm and accessory substances transferred), reduce their sexual receptivity to additional males and increase their rate of oviposition. Males prevented from performing MCB increased their rate of attempts to perform MCB. Copulations with previously mated females were of longer duration than those with virgin females, probably as a male adaptation for sperm competition, and MCB could have played a role in inducing this effect. Partial or total experimental reduction of MCB frequency had no effect on remating rates, because most females accepted remating at the first opportunity (1 day after their first copula). The probability of egg laying was reduced in females whose first mate was partially prevented from performing copulatory courtship, but not in females whose first mate was completely prevented from performing copulatory courtship. This is an intriguing result and further experiments are needed to understand its causes. We hypothesize that MCB evolved as a result of sexual selection.  相似文献   

20.
Environmental microbes have the potential to be involved in nearly all behavioural processes. For example, mating systems where males use intromittent organs to transfer sperm to females represent a means by which environmental microbes collected by males can breach entry into females' body cavities during mating. However, the degree to which the acquisition of environmental microbes onto important sex structures alters courtship behaviours remains unknown. Here, we collected bacteria from the copulatory organs of Agelenopsis pennsylvanica funnel‐weaving spiders in situ to test whether exposure to bacteria on copulatory organs can alter hosts' courtship behaviour, reproductive success and survival. We used a standardized assay to repeatedly measure each spider's aggressiveness, a behavioural component of both male courtship and female sexual receptivity. Then, we experimentally altered the bacteria present on male and female spiders' copulatory organs with an application of either (a) a mixture of bacteria collected from conspecifics to increase bacterial presence, (b) an antibiotic to reduce bacterial presence or (c) a procedural control. Each spider was paired with a size‐matched spider of the opposite sex whose copulatory organs were unaltered, and we measured the latency until the onset and the duration of courtship. Spiders were then isolated, and we measured each individual's time until death and female fecundity over the next 40 days. We found that female exposure to bacteria had multiple effects on mating dynamics. Males took over four times longer to begin courting females that had been exposed to bacteria compared to unexposed and antibiotic‐treated females. Only when courting these bacteria‐exposed females, males began courtship sooner when females were more aggressive. Lastly, females whose mate had been exposed to bacteria experienced reduced survival. These data suggest that bacteria present on animals' copulatory organs can alter courtship behaviours, female survivorship, and may potentially play a role in mating dynamics.  相似文献   

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