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[Acoustic communication and sexual selection in Orthoptera (Insecta)].

Comparison of calling and courtship songs and mating strategies in different groups of Orthoptera shows that acoustic signals in bush crickets (Tettigonioidea) are used for searching conspecific mates at a distance, and song evolution is primarily driven by the acoustic surroundings and simultaneously singing other species. The role of sexual selection in the evolution of acoustic signals in bush crickets is much less important than in the evolution of other nonacoustic signals employed during direct contact. Acoustic signals of crickets (Grylloidea) are involved in both distant and short-range communication. Acoustic courtship signals, along with other courtship components, may offer the material for sexual selection, although, essentially, evolution of acoustic signals in crickets is determined by the acoustic surroundings. Acoustic communication in the grasshoppers of the subfamily Gomphocerinae is mainly a short-distance communication. Acoustic signals of Gomphocerinae are highly variable and elaborate in temporal parameters, and therefore can serve for evaluation of the mate "quality". Song evolution in this group is to a greater extent driven by sexual selection than by the acoustic surroundings and, therefore, could proceed faster than in other groups of Orthoptera and play a major role in speciation.

Acoustic Stimulation↗
PubMed2005

Mating success of males with and without wing patch in Drosophila biarmipes.

Some males of D. biarmipes--synonym of D. rajasekari and D. raychaudhuri have a black patch on the wing. The patch extends from the apical margin of wing to the third longitudinal vein. Field and laboratory studies have been carried out in D. biarmipes to study role of male's wing patch in mating success. The field study shows that nature favors D. biarmipes males with patch. Although males without patch mated, males with patch have higher mating success suggesting the role of wing patch during courtship. Further, among mating males, males with patch had longer wings than males without patch. During courtship, males with patch oriented and mated faster; performed courtship acts such as tapping, scissoring, vibration, licking and twist dance more times than males without patch in both competitive and non-competitive situations. The results indicate that there is a casual relationship between the presence of wing patch, mating speed and success. Also there is a correlation between presence of wing patch, size of the flies and mating success.

Animals↗
PubMed1990

[Effect of individual chromosomes on sex behavior of Drosophila].

Dependence of intensity of Drosophila virilis male sexual behaviour on age-related differences was studied. Most active proved to be those age periods which correlated with the time of S-esterase elevated activity. Courtship displays were compared in strains 101 and 160, interstrain differences correlating with the S-esterase activity level. As S-esterase plays an important role in fertilization, this relationship seems to be non-random. It is quite possible that the level of S-esterase activity regulates male sexual activity in natural populations. Some variations in male courtship display in interspecies hybrids (D. virilis x D. littoralis) were demonstrated which depended on the gene dose of respective species. It may well be that in the bk and dt gene regions those genes are localized which are responsible for courtship behaviour. The analysis of sexual behaviour in interstrain and interspecies hybrids proved to be successful approach to elucidating possible role of separate chromosomes in sexual behaviour determination.

Animals↗
PubMed1983

Dynamics of the platyhelminth fauna of wood ducks in relation to food habits and reproductive state.

The dynamics of the intestinal helminth fauna of wood ducks (Aix sponsa) and the relationship between changes in food habits and helminth populations during the bird's reproductive cycle were studied in southeast Missouri. A total of 11 species of helminths, comprised of four species of trematodes and seven species of cestodes, were recovered from the digestive tracts of 155 wood ducks. All species except one were found in both sexes. Significant differences were found in parasite numbers by season (spring vs. fall), sex, and stage of the reproductive cycle. Helminth infection in both sexes was higher in the spring than during fall courtship; however, the magnitude of the seasonal difference was considerably greater in females. Females contained significantly more helminths than males during spring, but no sex-related differences were detected in the fall. Seasonal changes and sex-related differences in parasite numbers corresponded closely with the consumption of invertebrates that serve as intermediate hosts. The average number of parasites in females was similar during fall courtship and pre-egg-laying, suggesting that little or no new infection occurred during winter. The most intensive infections were found in laying females and were attributed to hyperphagia and increased invertebrate consumption during egg production. A large decrease in the parasite numbers in females between incubation and fall courtship indicated that most of the helminths acquired by laying females were lost during summer; therefore, the long-term effects of the increased infection are probably negligible.

Animals↗
PubMed2001

New reproductive anomalies in fruitless-mutant Drosophila males: extreme lengthening of mating durations and infertility correlated with defective serotonergic innervation of reproductive organs.

Several features of male reproductive behavior are under the neural control of fruitless (fru) in Drosophila melanogaster. This gene is known to influence courtship steps prior to mating, due to the absence of attempted copulation in the behavioral repertoire of most types of fru-mutant males. However, certain combinations of fru mutations allow for fertility. By analyzing such matings and their consequences, we uncovered two striking defects: mating times up to four times the normal average duration of copulation; and frequent infertility, regardless of the time of mating by a given transheterozygous fru-mutant male. The lengthened copulation times may be connected with fru-induced defects in the formation of a male-specific abdominal muscle. Production of sperm and certain seminal fluid proteins are normal in these fru mutants. However, analysis of postmating qualities of females that copulated with transheterozygous mutants strongly implied defects in the ability of these males to transfer sperm and seminal fluids. Such abnormalities may be associated with certain serotonergic neurons in the abdominal ganglion in which production of 5HT is regulated by fru. These cells send processes to contractile muscles of the male's internal sex organs; such projection patterns are aberrant in the semifertile fru mutants. Therefore, the reproductive functions regulated by fruitless are expanded in their scope, encompassing not only the earliest stages of courtship behavior along with almost all subsequent steps in the behavioral sequence, but also more than one component of the culminating events.

Animals↗
PubMed2007

Copulation behavior within one-male groups of wild Rhinopithecus roxellana in the Qinling Mountains of China.

This study was conducted using focal animal sampling on the west ridge group of the Sichuan snub-nosed monkey (Rhinopithecus roxellana) located in the Zhouzhi National Nature Reserve on the north slope of the Qinling Mountains, from 8 July 2003 to 24 May 2004. The difference in the average frequency of copulations for each focal male for each month was significant (F=3.068, P=0.016, one-way ANOVA test) with the majority of copulations occurring between September and November. Duration of intromission ranged from 2 to 39 s, with a mean of 16.0+/-0.4 s. Females initiated 627 courtship attempts (96.2%), while males only initiated 3.8%. Both adult females (72.8%) and sub-adult females (27.2%) were involved in sexual interference acts. Females who gave birth in 2004 performed more sexual interference acts than would be expected by chance in the reproductive period of 2003 (X2=13.73>X2(0.005,2), df=2, P<0.005). Male response to female interference was equally divided into "solicitor mounting" and "interrupter mounting". The resident males of one-male units were not observed to mount both the solicitor and the interrupter or mount neither following female solicitation interruptions. Three post-conception copulations were also observed in this study. These results suggest a skewed sexual competition, with multiple females competing for a single male, which was shown by courtship attempts and female interference.

Altitude↗
PubMed2006

Experimental manipulation of male behaviour during copulation in Stenomacra marginella (Heteroptera: Largidae): effect on copula duration, female remating and oviposition.

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.

Animals↗
PubMed2006

Inhibition of cytochrome p450 brain aromatase reduces two male specific sexual behaviours in the male Endler guppy (Poecilia reticulata).

In mammalian and avian vertebrate groups, androgens act as controlling agents on male aggression and courtship behaviour by their conversion to oestrogens by cytochrome P450 aromatase in well-defined brain regions. Despite the fact that bony fishes have exceptionally high brain aromatase activity, little is known about it's possible regulatory effects on the reproductive behaviours of teleosts. In this study, Endler guppy males (Poecilia reticulata) were subjected to 26-29 days of 24-h exposure to two different concentrations (15 and 100 microg/L) of the aromatase inhibitor fadrozole in the water. Compared with the control males, two of three courtship activities in males exposed to the higher concentration were reduced when they were paired with receptive stimulus females. Reduction in brain aromatase activity was confirmed in both exposed groups with the use of the tritiated water assay.

Animals↗
PubMed2004

Effects of central vasotocin and mesotocin manipulations on social behavior in male and female zebra finches.

Male and female zebra finches (Taeniopygia guttata; total n = 40) were fitted with chronic guide cannulae directed at the lateral ventricle and were tested for aggression, affiliation, and partner preference following infusions of mesotocin (MT), vasotocin (VT), their antagonists, and vehicle control. Aggressive behavior was tested in a mate competition paradigm and tests of intersexual affiliation and partner preference were conducted following 1 day of cohabitation with an opposite-sex individual. These tests also provided data on male courtship singing. The results demonstrate a modest dose-dependent facilitation of aggression by VT, but not MT, in both male and female finches. However, only males were sensitive to infusions of a vasopressin antagonist, suggesting that endogenous VT is more important for behavioral modulation in males. Peptide effects were specific to aggression, as no treatments influenced intersexual affiliation, partner preference, or male courtship singing. Thus, in contrast to rodents, partner preference is not readily induced by VT or MT in this species. However, the potential necessity of endogenous VT and MT for natural pair-bond formation remains to be tested.

Aggression↗
PubMed1988

Isolation-dependent enhancement of 2-[14C]deoxyglucose uptake in the forebrain of zebra finch males.

In a previous study (H. J. Bischof & K. Herrmann (1986), Behavioral Brain Research, 21, 215-221) we demonstrated that four forebrain areas of the zebra finch male are activated in situations which arouse the animal, for example when the birds are chased around the cage or when they are exposed to a female. These areas, the hyperstriatum accessorium-dorsale (HAD), a part of the medial neo-hyperstriatum (MNH), the lateral neo-hyperstriatum (LNH), and a portion of the caudal archi-neostriatum (ANC), show enhanced 2-[14C]deoxyglucose (2-DG) uptake according to the experimental situation. On the basis of these experiments, we examined whether the activation of the areas is correlated with motor activity and is influenced by different isolation times prior to a 2-DG experiment, where courtship of the male birds is elicited by exposing them to a female zebra finch. For this purpose, we isolated male zebra finches for 1 day, 1 week, or 8 weeks, respectively, before we injected the 2-DG and exposed the birds to a female. During the experiment, besides other activities, the number of song motifs performed by the bird and the frequency of changing perches was recorded. Our experiments demonstrate that there is a weak negative correlation between motor activity and 2-DG uptake, and a positive correlation between isolation time and 2-DG uptake. We suggest that long isolation blocks courtship behavior by some unknown mechanisms, and that the "internal drive" of the animal, which possibly corresponds with the activity of the four forebrain areas, is enhanced by isolation and by the fact that the birds do not perform the consummatory behavior. Our results also demonstrate that the 2-DG method can show up small differences in the internal state of an animal, which cannot easily be detected by behavioral measurements.

Animals↗
PubMed1997

Sexual activity among junior secondary school girls in Zambia.

This paper proposes a causal model of sexual activity among a randomly selected sample of 305 Junio secondary school girls in Zambia. The results indicate that liberal sexual attitudes influence romantic involvement with boys. Emotional involvement is likely to result in sexual activity. Traditional courtship forms are slowly being replaced by modern patterns of courtship behaviour. Policy and programme implications are discussed.

Adolescent↗
PubMed2003

Pheromonally mediated sexual isolation among denning populations of red-sided garter snakes, Thamnophis sirtalis parietalis.

Utilizing behavioral experiments and chemical analyses, we examined whether pheromonally mediated sexual isolation exists between denning populations of red-sided garter snakes (Thamtnophis sirtalis parietalis) in Manitoba, Canada. Simultaneous choice tests conducted during the breeding season revealed that adult males from a hibernaculum in central Manitoba displayed a strong courtship preference for females from their own population over females from a hibernaculum in western Manitoba, whereas males from the western Manitoba hibernaculum showed no such preference. In addition. trailing experiments testing the response of males from the two hibernacula to familiar and unfamiliar female trails showed similar results, demonstrating that the observed male preference is mediated through chemical cues. Subsequent chemical analysis of the female sexual attractiveness pheromone. a homologous series of long-chain saturated and (omega-9 cis-unsaturated methyl ketones responsible for eliciting male courtship behavior and trailing behavior in garter snakes, showed significant variation in the composition of the pheromone between the two populations. Specifically, the two populations varied in the relative concentrations of individual unsaturated methyl ketones expressed by females. These results suggest that sexual isolation exists to a degree among denning populations of red-sided garter snakes due to variation in the expression of the female sexual attractiveness pheromone.

Animals↗
PubMed2001

Towards a resolution of the lek paradox.

Genetic benefits in the shape of 'good genes' have been invoked to explain costly female choice in the absence of direct fitness benefits. Little genetic variance in fitness traits is expected, however, because directional selection tends to drive beneficial alleles to fixation. There seems to be little potential, therefore, for female choice to result in genetic benefits, giving rise to the 'lek paradox'. Nevertheless, evidence shows that genetic variance persists despite directional selection and genetic benefits of female choice are frequently reported. A theoretical solution to the lek paradox has been proposed on the basis of two assumptions: that traits are condition-dependent, and that condition shows high genetic variance. The observed genetic variability in sexual traits will be accounted for, because a proportion of the genetic variance in condition will be captured and expressed in the trait. Here we report results from experiments showing that male courtship rate in the dung beetle Onthophagus taurus is a condition-dependent trait that is preferred by females. More importantly, male condition has high genetic variance and is genetically correlated with courtship rate. Our results thereby represent a significant step towards a resolution of the lek paradox.

Animals↗
PubMed2005

Fruitless specifies sexually dimorphic neural circuitry in the Drosophila brain.

The Drosophila fruitless (fru) gene product Fru has been postulated to be a neural sex determination factor that directs development of the central nervous system (CNS), thereby producing male-typical courtship behaviour and inducing male-specific muscle. Male-specific Fru protein is expressed in small groups of neurons scattered throughout the CNS of male, but not female, Drosophila. Collectively, these observations suggest that Fru 'masculinizes' certain neurons, thereby establishing neural substrates for male-typical behaviour. However, specific differences between neurons resulting from the presence or absence of Fru are unknown. Previous studies have suggested that Fru might result in sexual differences in the CNS at the functional level, as no overt sexual dimorphism in CNS structure was discernible. Here we identify a subset of fru-expressing interneurons in the brain that show marked sexual dimorphism in their number and projection pattern. We also demonstrate that Fru supports the development of neurons with male-specific dendritic fields, which are programmed to die during female development as a result of the absence of Fru. Thus, Fru expression can produce a male-specific neural circuit, probably used during heterosexual courtship, by preventing cell death in identifiable neurons.

Animals↗
PubMed2003

Fitness effects of female mate choice: preferred males are detrimental for Drosophila melanogaster females.

The evolution of female mate choice, broadly defined to include any female behaviour or morphology which biases matings towards certain male phenotypes, is traditionally thought to result from direct or indirect benefits which females acquire when mating with preferred males. In contrast, new models have shown that female mate choice can be generated by sexual conflict, where preferred males may cause a fitness depression in females. Several studies have shown that female Drosophila melanogaster bias matings towards large males. Here, we use male size as a proxy for male attractiveness and test how female fitness is affected by reproducing with large or small males, under two different male densities. Females housed with large males had reduced lifespan and aged at an accelerated rate compared with females housed with small males, and increased male density depressed female fitness further. These fitness differences were due to effects on several different fitness components. Female fitness covaried negatively with male courtship rate, which suggests a cost of courtship. Mating rate increased with male size, whereas female fitness peaked at an intermediate mating rate. Our results suggest that female mate choice in D. melanogaster is, at least in part, a by-product of sexual conflict over the mating rate.

Animals↗
PubMed1998

Neural bases of song preferences in female zebra finches (Taeniopygia guttata).

We examined the neural bases of song preferences in female zebra finches (Taeniopygia guttata). Females performed more courtship displays in response to conspecific songs than to heterospecific songs. Following electrolytic lesion to the HVc (sometimes referred to as high vocal center), females maintained normal song preferences. However, following lesion to cHV (caudal hyperstriatum ventrale, an auditory area) females performed courtship displays at high rates in response to both conspecific and heterospecific song. Thus cHV, but not HVc, must be intact for female zebra finches to exhibit normal song preferences. Differences between this study and those showing HVc lesions disrupting song preferences in female canaries (Serinus canaria) indicate interspecific variation in the function of HVc in female songbirds.

Acoustic Stimulation↗
PubMed1995

Intraventricular prolactin inhibits hypothalamic vasoactive-intestinal polypeptide-expression in doves.

While the role of prolactin in promoting the development of the crop-sac in members of the pigeon family (Columbiformes) is well established, its action in the central nervous system is less well understood. In the present study, prolactin was administered intracerebroventricularily (i.c.v.) in ring doves, and central expression of vasoactive-intestinal polypeptide (VIP) and gonadotropin-releasing hormone (GnRH), and the display of sexual behavior was investigated. Ovine-prolactin (1 microgram in 2 microliters o-prl) was injected daily for six days through chronically implanted cannula either prior to a 2-h period of courtship, or late in incubation. Control subjects were given vehicle injections and were otherwise identical to experimental animals. Prolactin administered prior to courtship resulted in a reduction of sexual behavior, and in a decrease in testicular weight but had no detectable effect on the number of neurons expressing VIP or GnRH. In contrast, i.c.v. prolactin during incubation resulted in a reduced number of infundibular VIP-positive neurons and decreased crop weight. We conclude that during incubation prolactin regulates its own synthesis and/or release by modulating VIP expression in infundibular neurons.

Analysis of Variance↗
PubMed2002

Psychological aggression in dating relationships: predictive models for males and females.

Variables related to the use of physical aggression in dating relationships and conflict management strategies were used to predict the use of psychological aggression in courtship. Individual factors (i.e., variables associated with threat susceptibility) and situational variables (i.e., relationship length and emotional commitment to the partner, conflict management strategies, and weekly alcohol intake) were proposed to be important in the prediction of male's and female's use of psychological aggression with their partners. Our findings suggest that these variables successfully predict the use of psychologically aggressive acts in courtship. Further, interactions with sex of participant suggest that different variables are important in the prediction of males' and females' use of such negative behaviors. These differences in the relationships between the predictors and criteria for males and females suggest not only divergent predictive models but also potential motivational differences in the employment of such tactics.

Adolescent↗