Drosophila Courtship Research Articles

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.

The Effects of Ectopic White and Transformer Expression on Drosophila Courtship Behavior

The sex determining genes of Drosophila males and females function to establish the potential for sex-specific behaviors. Previous studies suggest that ectopic GAL4-directed misexpression of the female-specific isoform of the sex-determining gene transformer (tra) in specific sub-domains of an otherwise male brain can lead to bisexual courtship behavior, thus identifying brain domains that may mediate sex-specific behavior. However, expression of mini-white, the marker gene used in both P{GAL4} and P{UASG} constructs, also induces males to court other males, questioning whether GAL4-mediated tra expression alone can induce bisexual behavior. Here we demonstrate the consequences of inducing mutations in the mini-white genes within P{GAL4} and P{UASG} constructs to generate flies in which a white mutant phenotype is revealed. In these mini-white mutant strains, P{GAL4}-mediated transformer expression alone is both sufficient and necessary to generate bisexual behavior. In addition, using RT-PCR, we reveal the presence of female transcripts of doublesex and fruitless in the brains of otherwise male (XY) flies exhibiting P{GAL4}-directed tra-expression, demonstrating that P{GAL4}-directed tra is functional at the molecular level. We conclude that P{GAL4}-directed misexpression of tra is responsible for the bisexual behavior previously described and that this is mediated via sex-specific splicing of dsx and fru. Our results support the validity of such strategies for identifying regions of the fly brain that underlie sex-specific behaviors.

Is the heritability for courtship and mating speed in Drosophila (fruit fly) low?

Empirical studies indicate that heritable variation for courtship behaviour in Drosophila is often not detectable, whereas mating speed has a low heritability. These patterns have been used to make inferences about the association between mating behaviours and fitness. However, mating behaviours have been scored as single events, which can lead to underestimates of heritability values relevant to the lifetime fitness of an organism. To test this, repeated measurements on the same individuals were undertaken for time to courtship and mating in Drosophila melanogaster in both parental and offspring generations. Although there was no detectable heritable variation for both traits when parent-offspring comparisons were based on single events, heritabilities were significant and intermediate when the behaviour of each individual was averaged over several events. Estimates for mating behaviours relevant to the fitness of organisms are therefore much higher than indicated by single-event experiments.

A female nervous system is necessary for normal sperm storage in Drosophila melanogaster: a masculinized nervous system is as good as none

A male Drosophila melanogaster deposits many more sperm in a female's bursa copulatrix than are stored in her ventral receptacle or paired spermathecae soon after copula has ended. The remaining sperm are expelled by the female. These observations suggest a sexual conflict over the processes involved in sperm storage. We used genetically manipulated flies to study the role of the central nervous system in sperm storage. Flies with female bodies but masculinized nervous systems, or isolated female abdomens, stored significantly fewer sperm than did control females. Furthermore, compared with control flies, there were relatively more sperm in the ventral receptacle and relatively fewer in the spermathecae. These results suggest that the female nervous input counteracts the male's attempts to force sperm into the ventral receptacle during copula and promotes active transport of sperm to the spermathecae during and after copula. The female is clearly a very active partner in influencing processes involved in sperm competition, especially as only stored sperm can be used later to fertilize eggs. To our knowledge, this is the first study to show directly the involvement of the female nervous system in sperm storage.

Preparation & Use of an Easily Constructed, Inexpensive Chamber for Viewing Courtship Behaviors of Fruit Flies, Drosophila sp.

Courtship behaviors by males and responses to those behaviors by females have been described for a number of species of fruit flies in the genus Drosophila (reviews by Ehrman 1978; Charalambos et al. 1992). These behaviors are particularly useful for teaching students behavioral observation techniques because courtship in Drosophila can be easily categorized and quantified using simple equipment and recording techniques. Several laboratory manuals on animal behavior have described such exercises and the dimensions and construction of observation chambers (e.g. Ehrman 1975; Hansell & Aitken 1977; DeCoursey 1980). Indeed, a number of researchers who have investigated courtship behaviors of several species of Drosophila have employed observation chambers that are very similar in design to those described for educational purposes. For example, Liimatainen et al. (1992) observed Drosophila courtship and mating behaviors in a circular plastic cell that was 40 mm in diameter and 8 mm high. Hoikkala & Kaneshiro (1993) and Hoikkala & Welbergen (1995) used a 5 x 3.5 x 1.5-cm balsawood mating chamber with a glass roof for their observations. Clear plastic boxes (15 x 12 x 5.5 cm) that are available commercially as 24-oz.

Sexual behaviour: Secrets and flies

Recent studies of Drosophila courtship mutants provide a molecular foundation for sexual orientation and behaviour.

Courtship anomalies caused by doublesex mutations in Drosophila melanogaster.

The role played by the sex-determining gene doublesex (dsx) and its influence on Drosophila courtship were examined. Against a background of subnormal male-like behavior that is reported to be an attribute of haplo-X flies homozygous for the original dsx mutation, and given that a sex-specific muscle is unaffected by genetic variation at this locus, analyses of several reproductive behaviors and control for genetic background effects indicated that XY dsx mutants are impaired in their willingness to court females. When they did court, certain behavioral actions were normal, including components of courtship song. However, these mutants never produced courtship humming sounds. Mature XY dsx flies elicited anomalously high levels of courtship; that this occurs merely because of a delay in imaginal development was experimentally discounted. The current analysis reconciled two ostensibly conflicting reports involving the courtship-stimulating qualities of this mutant type. Such experiments also uncovered a new behavioral anomaly: dsx mutations caused chromosomal males to court other males at abnormally high levels. These results are discussed from the perspective of doublesex's influence on internal tissues of adult Drosophila involved in the triggering and neural control of male- and female-like elements of courtship, reproductive pheromone production, or a combination of such factors.

811 Homosexual courtship in Drosophila is induced by a mutation of the neural sex-determination gene fruitless that encodes a novel zinc finger protein with a BTB domain

811 Homosexual courtship in Drosophila is induced by a mutation of the neural sex-determination gene fruitless that encodes a novel zinc finger protein with a BTB domain

Misexpression of the white (w) gene triggers male-male courtship in Drosophila.

We report here that the general ectopic expression of a tryptophan/guanine transmembrane transporter gene, white (w), induces male-male courtship in Drosophila. Activation of a hsp-70/miniwhite (mini-w) transgene in mature males results in a marked change in their sexual behavior such that they begin to vigorously court other mature males. In transformant populations containing equal numbers of both sexes, most males participate, thus forming male-male courtship chains, circles, and lariats. Mutations that ablate the w transgene function also abolish this inducible behavior. Female sexual behavior does not appear to be altered by ectopic w expression. By contrast, when exposed to an active homosexual courtship environment, non-transformant males alter their behavior and actively participate in the male-male chaining. These findings demonstrate that, in Drosophila, both genetic and environmental factors play a role in male sexual behavior.

The mating of a fly.

Courtship in Drosophila is influenced by a wide variety of genes, in that many different kinds of pleiotropic mutations lead to defective courtship. This may seem to be a truism, but the broad temporal and spatial expression of most of the fly's "neuro genes" makes it difficult to exclude elements of such genes' actions as materially underlying reproductive behavior. "Courtship genes" that seem to play more particular roles were originally identified as sensory, learning, or rhythm mutations; their reproductive abnormalities have been especially informative for revealing components of male or female actions that might otherwise have gone unnoticed. Further behavioral mutations seemed originally to be courtship-specific, turned out not to have that property, and have led to a broadened perspective on the nature and action of Drosophila's sex-determination genes.

Artificial neural network classification of Drosophila courtship song mutants.

Courtship songs produced by Drosophila males--wild-type, plus the cacophony and dissonance behavioral mutants--were examined with the aid of newly developed strategies for adaptive acoustic analysis and classification. This system used several techniques involving artificial neural networks (a.k.a. parallel distributed processing), including learned vector quantization of signals and non-linear adaption (back-propagation) of data analysis. "Pulse" song from several individual wild-type and mutant males were first vector-quantized according to their frequency spectra. The accumulated quantized data of this kind, for a given song, were then used to "teach" or adapt a multiple-layered feedforward artificial neural network, which classified that song according to its original genotype. Results are presented on the performance of the final adapted system when faced with novel test data and on acoustic features the system decides upon for predicting the song-mutant genotype in question. The potential applications and extensions of this new system are discussed, including how it could be used to screen for courtship mutants, search novel behavior patterns or cause-and-effect relationships associated with reproduction, compress these kinds of data for digital storage, and analyze Drosophila behavior beyond the case of courtship song.

Drosophila courtship song cycles in normal andperiod mutant males revisited

Courtship songs of normal males and those expressing short-period, long-period, and arrhythmic mutations at the period (per) locus of Drosophila melanogaster have been reanalyzed for rhythmic components, using spectral treatments of the fluctuating rates of tone pulse production that occur during courtship. It was concluded, as in previous studies, that such songs are strongly rhythmic, except for courtships performed by per01 males. Songs produced by males expressing this and other per alleles were compared to computer-generated "random" ones. Interpulse interval variations influenced by per01 and songs stimulated to be arrhythmic both were found to be associated with cryptic rhythmicities; several such period values, extracted by the spectral analyses, defined very short cycle durations. We discuss the implications of these findings and of some recently reported results that have challenged the existence of rhythmicity in Drosophila songs.

Spectral analysis of Drosophila courtship song rhythms

Crossley (1988, Anim. Behav., 36, 1098–1109) and Ewing (1988, Anim. Behav., 36, 1091–1097), have criticized the use of non-linear regression in testing for song cycles in Drosophila courtship songs. In the present study a large body of data was reanalysed with appropriate time series analyses. The results confirm the original conclusions based on regression. Evidence suggests that the apparent discrepancies between our results may arise from: (1) the size of mating cell used by Ewing (1988) to record songs; (2) the way the song traces are interpreted; (3) the way mean inter-pulse intervals are assessed, especially when there are missing data points; and (4) the method used to assign statistical significance.

Courtship inDrosophila sechellia: Its structure, functional aspects, and relationship to those of other members of theDrosophila melanogaster species subgroup

The courtship behavior of Drosophila sechelliais described. Male wing displays are mainly vibration and scissoring, with low levels of rowing. As courtship proceeds the proportion of courtship spent in male wing vibration and licking increases, whereas female movement decreases. The male courtship song of sechelliacontains pulse song but no sine song. This species also shows a distinctive “copulation song” associated with mounting and copulation. The main cuticular hydrocarbon in females is 7,11-heptacosadiene. The number of copulations increased when flies were placed in the presence of food. Visual and acoustic stimuli appear to be important for mating. A multidimensional comparison was used to compare members of the melanogaster species subgroup, based upon courtship behavior, song characteristics, and cuticular hydrocarbons. A multidimensional comparison of courtship sequences in sechellia, melanogaster, simulans,and mauritianashowed differences in variability between the two island species as compared to the two cosmopolitan species. The courtship song of D. orenais described: it shows both sine and pulse song; there is also a “copulation song” in this species.

In situ localization of the per clock protein during development of Drosophila melanogaster.

The per locus influences biological rhythms in Drosophila melanogaster. In this study, per transcripts and proteins were localized in situ in pupae and adults. Earlier genetic studies have demonstrated that per expression is required in the brain for circadian locomotor activity rhythms and in the thorax for ultradian rhythmicity of the Drosophila courtship song. per RNA and proteins were detected in a restricted group of cells in the eyes and optic lobes of the adult brain and in many cell bodies in the adult and pupal thoracic ganglia. per products were also found in the pupal ring gland complex, a tissue involved in rhythmic aspects of Drosophila development. Abundant expression was seen in gonadal tissue. No biological clock phenotypes have been reported for this tissue in any of the per mutants, per protein mapped to different subcellular locations in different tissues. The protein accumulated in or around nuclei in some cells and appeared to be cytoplasmic in others.

In Situ Localization of the Per Clock Protein During Development of Drosophila melanogaster

The per locus influences biological rhythms in Drosophila melanogaster. In this study, per transcripts and proteins were localized in situ in pupae and adults. Earlier genetic studies have demonstrated that per expression is required in the brain for circadian locomotor activity rhythms and in the thorax for ultradian rhythmicity of the Drosophila courtship song. per RNA and proteins were detected in a restricted group of cells in the eyes and optic lobes of the adult brain and in many cell bodies in the adult and pupal thoracic ganglia. per products were also found in the pupal ring gland complex, a tissue involved in rhythmic aspects of Drosophila development. Abundant expression was seen in gonadal tissue. No biological clock phenotypes have been reported for this tissue in any of the per mutants, per protein mapped to different subcellular locations in different tissues. The protein accumulated in or around nuclei in some cells and appeared to be cytoplasmic in others.

Failure to confirm rhythms in Drosophila courtship song

The importance of courtship song rhythms in Drosophila to molecular and behaviour genetics led to an attempt to verify them. Two songs considered rhythmic by one of the two workers who first reported this behaviour were found to be arrhythmic because the analysis used earlier was inappropriate for identifying song cycles. Using time series analyses by spectral analysis and autocorrelation, no fly showed the sinusoidal pattern in its song claimed by the earlier workers. These findings require recent research concerned with Drosophila song rhythms to be re-evaluated.

Cycles in the courtship song of male Drosophila melanogaster have not been detected

Cyclical short-term fluctuations in the mean inter-pulse intervals of Drosophila courtship song have been previously described. The failure to repeat these results is reported and it is shown that if such cycles do indeed exist, the methods of analysis employed have been inappropriate and, furthermore, that the sample sizes have been inadequate to demonstrate the phenomenon.

The effects of crowding on courtship and mating success in Drosophila melanogaster.

The mating times of single males and pairs of males were increased by crowding with virgin females but only at very high densities. Mating times were decreased by the presence of a second male. Quantitative analysis of courtship showed that prestimulation of females in crowded conditions influences mating. The pattern of male courtship was highly consistent across moderate levels of crowding. This suggests thatDrosophila courtships evolved in crowded conditions.

The relationship between locomotor activity and courtship in the melanogaster species sub-group of Drosophila

Changes in locomotor activity, courtship latency and mating between 1 and 6 days following eclosion and over the 9 h after ‘dawn’ were measured for six species of the Drosophila melanogaster species sub-group. No consistent change in locomotor activity was found for the six species in relation to age or time of day. Male flies were significantly more active than females, with melanogaster, teissieri and yakuba the most active species. D. melanogaster consistently had the highest proportion of pairs copulating and the shortest latencies. D. erecta consistently showed the lowest levels. No effect of time of day was found for courtship latency. Overall there was a tendency for courtship latencies to decrease between 1 and 2 days, with all species showing an increase in latency between 5 and 6 days after eclosion. Negative correlations were found between locomotor activity and courtship latency in both sexes. In melanogaster, simulans and mauritiana, the three species showing the highest levels of copulation, no significant correlations were found between courtship latency and courtship duration. The implications of these results for models of Drosophila courtship are discussed.