Divergence in Multiple Courtship Song Traits between Drosophila santomea and D. yakuba

The courtship song of Drosophila is useful for species recognition and sexual selection. A new species of the melanogaster group of Drosophila , D. santomea , has recently been described from the island of São Tomé in the Gulf of Guinea. We describe the courtship song of D. santomea and compare it with that of its sibling species D. yakuba . Both species have a relatively unusual song pattern for melanogaster-group species, in that they have two types of pulse song but no sine song. There are large differences in the inter-pulse interval of both types of song, but no major differences in pulse shape or intrapulse frequency between the species. The song of D. yakuba is similar in lines from the African mainland (allopatric to D. santomea ) and from São Tomé (sympatric). We test if song pattern might influence sexual isolation by examining the mating success of wingless males with homo- and hetero-specific females. We show that song pattern contributes to sexual stimulation, but the differences in song patterns alone are unlikely to explain patterns of sexual isolation such as the asymmetrical isolation seen between species.     

果实蝇求偶行为与求偶歌

果实蝇Bactrocera是危害经济作物的一类重要农业害虫,研发有效的果实蝇防控技术是现代农业产业发展的迫切需求。雄性不育技术是防控果实蝇高效绿色的防控方法。深入研究果实蝇求偶行为是雄性不育技术顺利开展的前提,也能为开发新防控技术提供有效的生物学靶标。本文将以果蝇研究作为对照,对果实蝇求偶行为与求偶歌的研究相关进展进行总结。果实蝇求偶行为基本属于预交配求偶行为,但其求偶歌中是否具有物种特异性的特征参数还有待验证。这为下一步开展果实蝇求偶行为与求偶歌的研究工作提供了基本依据与方向性引导。     

Courtship song genes and speciation in sand flies

Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae: Phlebotominae) is a vector of visceral leishmaniasis in the Americas and it might represent a complex of sibling species. Reproductive isolation between closely related species often involves differences in courtship behaviour. cacophony (cac) and period (per) are two Drosophila genes that control features of the "lovesong" males produce during courtship that has been implicated in the sexual isolation between closely related species. We are using gene fragments from L. longipalpis' homologues of these two genes to study the speciation process in this putative species complex.     

Insertional mutagenesis in Drosophila. II. P element mediated transformation of Drosophila yakuba.

Drosophila yakuba, a member of melanogaster subgroup being free of P element, acquired resistance to an antibiotic neomycin by the transformation utilizing P element. In this species, the transformation frequency was comparable to that of D. melanogaster. Further, the occurrence of 8 base pairs duplication upon the insertion of the element was confirmed. These facts suggest that the P element could be inserted into the genome in the same manner, even in D. yakuba. Any consensus for preferential insertion could not be found on the nucleotide sequence as in D. melanogaster. However, it is noticeable that a series of the short palindromic stretches was common around the insertion sites in both species. It suggests that a structural feature of DNA plays a role as a landmark for P element insertion.     

Substrate Vibrations during Courtship in Three Drosophila species

While a plethora of studies have focused on the role of visual, chemical and near-field airborne signals in courtship of Drosophila fruit flies, the existence of substrate-borne vibrational signals has been almost completely overlooked. Here we describe substrate vibrations generated during courtship in three species of the D. melanogaster group, from the allegedly mute species D. suzukii, its sister species D. biarmipes, and from D. melanogaster. In all species, we recorded several types of substrate vibrations which were generated by locomotion, abdominal vibrations and most likely through the activity of thoracic wing muscles. In D. melanogaster and D. suzukii, all substrate vibrations described in intact males were also recorded in males with amputated wings. Evidence suggests that vibrational signalling may be widespread among Drosophila species, and fruit flies may provide an ideal model to study various aspects of this widespread form of animal communication.     

Evidence for de novo evolution of testis-expressed genes in the Drosophila yakuba/Drosophila erecta clade

The mutational origin and subsequent evolution of de novo genes, which are hypothesized to be genes of recent origin that are not obviously related to ancestral coding sequence, are poorly understood. However, accumulating evidence suggests that such genes may often function in male reproduction. Here we use testis-derived expressed sequence tags (ESTs) from Drosophila yakuba to identify genes that have likely arisen either in D. yakuba or in the D. yakuba/D. erecta ancestor. We found several such genes, which show testis-biased expression and are often X-linked. Comparative data indicate that three of these genes have very short open reading frames, which suggests the possibility that a significant number of testis-biased de novo genes in the D. yakuba/D. erecta clade may be noncoding RNA genes. These data, along with previously published data from D. melanogaster, support the idea that many de novo Drosophila genes function in male reproduction and that a small region of the X chromosome in the melanogaster subgroup may be a hotspot for the evolution of novel testis-biased genes.     

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.     

Threshold-Based Ordering of Sequential Actions during Drosophila Courtship

1. Download high-res image (215KB)
2. Download full-size image

     

Juvenile Hormone Is Required in Adult Males for Drosophila Courtship

Juvenile Hormone (JH) has a prominent role in the regulation of insect development. Much less is known about its roles in adults, although functions in reproductive maturation have been described. In adult females, JH has been shown to regulate egg maturation and mating. To examine a role for JH in male reproductive behavior we created males with reduced levels of Juvenile Hormone Acid O-Methyl Transferase (JHAMT) and tested them for courtship. JHAMT regulates the last step of JH biosynthesis in the Corpora Allata (CA), the organ of JH synthesis. Males with reduced levels of JHAMT showed a reduction in courtship that could be rescued by application of Methoprene, a JH analog, shortly before the courtship assays were performed. In agreement with this, reducing JHAMT conditionally in mature flies led to courtship defects that were rescuable by Methoprene. The same result was also observed when the CA were conditionally ablated by the expression of a cellular toxin. Our findings demonstrate that JH plays an important physiological role in the regulation of male mating behavior.     

A technique for characterizing the development of rhythms in bird song

The developmental trajectory of nervous system dynamics shows hierarchical structure on time scales spanning ten orders of magnitude from milliseconds to years. Analyzing and characterizing this structure poses significant signal processing challenges. In the context of birdsong development, we have previously proposed that an effective way to do this is to use the dynamic spectrum or spectrogram, a classical signal processing tool, computed at multiple time scales in a nested fashion. Temporal structure on the millisecond timescale is normally captured using a short time Fourier analysis, and structure on the second timescale using song spectrograms. Here we use the dynamic spectrum on time series of song features to study the development of rhythm in juvenile zebra finch. The method is able to detect rhythmic structure in juvenile song in contrast to previous characterizations of such song as unstructured. We show that the method can be used to examine song development, the accuracy with which rhythm is imitated, and the variability of rhythms across different renditions of a song. We hope that this technique will provide a standard, automated method for measuring and characterizing song rhythm.     

Analysis of locomotor activity rhythms in Drosophila

The genetic, molecular and anatomical dissection of the circadian clock in Drosophila and other higher organisms relies on the quantification of rhythmic phenotypes. Here, we introduce the methods currently in use in our laboratories for the analysis of fly locomotor activity rhythms. This phenotype provides a relatively simple, automated, efficient, reliable and robust output for the circadian clock. Thus it is not surprising that it is the preferred readout for measuring rhythmicity under a variety of conditions for most fly clock laboratories. The procedure requires at least 10 days of data collection and several days for analysis. In this protocol we advise on fly maintenance and on experimental design when studying the genetics of behavioral traits. We describe the setup for studying locomotor activity rhythms in the fruit fly and we introduce the statistical methods in use in our laboratories for the analysis of periodic data.     

Drosophila free-running rhythms require intercellular communication

Robust self-sustained oscillations are a ubiquitous characteristic of circadian rhythms. These include Drosophila locomotor activity rhythms, which persist for weeks in constant darkness (DD). Yet the molecular oscillations that underlie circadian rhythms damp rapidly in many Drosophila tissues. Although much progress has been made in understanding the biochemical and cellular basis of circadian rhythms, the mechanisms that underlie the differences between damped and self-sustaining oscillations remain largely unknown. A small cluster of neurons in adult Drosophila brain, the ventral lateral neurons (LN_vs), is essential for self-sustained behavioral rhythms and has been proposed to be the primary pacemaker for locomotor activity rhythms. With an LN_v-specific driver, we restricted functional clocks to these neurons and showed that they are not sufficient to drive circadian locomotor activity rhythms. Also contrary to expectation, we found that all brain clock neurons manifest robust circadian oscillations of timeless and cryptochrome RNA for many days in DD. This persistent molecular rhythm requires pigment-dispersing factor (PDF), an LN_v-specific neuropeptide, because the molecular oscillations are gradually lost when Pdf⁰¹ mutant flies are exposed to free-running conditions. This observation precisely parallels the previously reported effect on behavioral rhythms of the Pdf⁰¹ mutant. PDF is likely to affect some clock neurons directly, since the peptide appears to bind to the surface of many clock neurons, including the LN_vs themselves. We showed that the brain circadian clock in Drosophila is clearly distinguishable from the eyes and other rapidly damping peripheral tissues, as it sustains robust molecular oscillations in DD. At the same time, different clock neurons are likely to work cooperatively within the brain, because the LN_vs alone are insufficient to support the circadian program. Based on the damping results with Pdf⁰¹ mutant flies, we propose that LN_vs, and specifically the PDF neuropeptide that it synthesizes, are important in coordinating a circadian cellular network within the brain. The cooperative function of this network appears to be necessary for maintaining robust molecular oscillations in DD and is the basis of sustained circadian locomotor activity rhythms.     

Sleep and biological rhythms of Drosophila

Sleep and Biological Rhythms -     

New synonym of Drosophila yakuba Burla, 1954 (Diptera: Drosophilidae)

New biological and bibliographic information confirms that the widely accepted name Drosophila yakuba Burla, 1954 and the unused name Drosophila opisthomelaina are synonymous. The latter was coined by Nolte & Stoch in a 1950 work containing a disclaimer and is unavailable by strict application of Article 8b of the International Code of Zoological Nomenclature (3rd edn, 1985). In a previously overlooked publication, Nolte (1958) cites D.opisthomelaina as a senior synonym; the work also contains diagnostic information. Synonymy is not disputed but before 1958 the name was unavailable. Thus D. opisthomelaina Nolte, 1958 is treated as a junior rather than a senior synonym of D.yakuba. These nomenclatural corrections remove confusion concerning records of this species in southern Africa and will probably be met with general approval. The distribution in southern Africa and Madagascar of D.yakuba and closely related species: D.melanogaster Meigen, 1830, D.simulans Sturtevant, 1919 and D.teissieri Tsacas, 1971, are summarized.     

The courtship song of African Drosophila melanogaster

For many years it was thought that Drosophila melanogaster was relatively panmictic, without differentiation in the Mate Recognition System. Recent studies have demonstrated that flies from Africa vary in pheromones and assortative mating. Strains from Zimbabwe show strong sexual isolation from others. We show that the interpulse interval (IPI) of courtship song, an important mating signal, is unusually short among African flies. Zimbabwean flies have the shortest IPI, but there is no correlation with assortative mating, suggesting little direct role in sexual isolation. Chromosome replacements show that the IPI difference is largely due to genes on chromosome III, with significant interactions involving other chromosomes. Several traits potentially influencing sexual isolation among the melanogaster group of Drosophila seem to be localized to this chromosome. A concentration of important genetic differences might mean that the interaction effects reflect secondary coadaptation of the genetic background to changes associated with chromosome III.