Wing Extension Research Articles

The Sex-Determination Genes fruitless and doublesex Specify a Neural Substrate Required for Courtship Song

SummaryCourtship song is a critical component of male courtship behavior in Drosophila, making the female more receptive to copulation and communicating species-specific information [1–6]. Sex mosaic studies have shown that the sex of certain regions of the central nervous system (CNS) is critical to song production [7]. Our examination of one of these regions, the mesothoracic ganglion (Msg), revealed the coexpression of two sex-determination genes, fruitless (fru) and doublesex (dsx). Because both genes are involved in creating a sexually dimorphic CNS [8, 9] and are necessary for song production [10–13], we investigated the individual contributions of fru and dsx to the specification of a male CNS and song production. We show a novel requirement for dsx in specifying a sexually dimorphic population of fru-expressing neurons in the Msg. Moreover, by using females constitutively expressing the male-specific isoforms of fru (FruM), we show a critical requirement for the male isoform of dsx (DsxM), alongside FruM, in the specification of courtship song. Therefore, although FruM expression is sufficient for the performance of many male-specific behaviors [14], we have shown that without DsxM, the determination of a male-specific CNS and thus a full complement of male behaviors are not realized.

N‐methyl‐1‐(1,3‐benzodioxol‐5‐yl)‐2‐butanamine (MBDB): its properties and possible risks

Abstract MBDB (N -methyl-1-(1,3-benzodioxol-5-yl)-2-aminobutane) is the alpha-ethyl homologue of MDMA (3,4-methylenedioxy-N-methylamphetamine). MBDB is metabolized and excreted similarly to MDMA: presumably, the majority of oral MBDB is excreted in urine unmetabolized.The main metabolic routes in man are thought to be O-dealkylation and subsequent methylation, sulphation and glucuronidation of the newly formed hydroxy groups. The major acute neuropharmacological effects of MBDB in the rat are an increase in serotonin release in the brain and an inhibition of serotonin and noradrenaline re-uptake. These effects compare well with those of MDMA, although the latter is more potent. MBDB may also slightly increase dopamine release and inhibit dopamine re-uptake, but to a lesser extent than MDMA. This is important, as dopamine release has been implicated in the reinforcing qualities of substances such as cocaine and amphetamine. The neuroendocrine effects of MBDB resemble those of MDMA. Both substances increase plasma ACTH, corticosterone, prolactin and renin. The neurophysiological effects of MBDB are characterized by a decrease in electrical activity throughout the brain, most notably in the alpha 2 and delta frequency bands. In contrast, hallucinogens increase the activity in the alpha 1 band, especially in the corpus striatum. In drug discrimination tests in the rat, MBDB, like MDMA, can be distinguished clearly from both stimulants and hallucinogens.The class of substances to which MBDB belongs may be named entactogens. MBDB dose-dependently increases locomotor activity and decreases exploratory behaviour in the rat and causes distress vocalization and wing extension in the newly hatched chicken. The rewarding properties of MBDB appear to be smaller than those of MDMA, as suggested by a 2.5 times weaker potency in the conditioned place preference test in rats. The main subjective effects of MBDB in man are a pleasant state of introspection, with greatly facilitated interpersonal communication and a pronounced sense of empathy and compassion between subjects. In this respect, MBDB again resembles MDMA. However, there are also differences. MBDB has a slower and more gentle onset of action than MDMA, produces less euphoria and has less stimulant properties. The few toxicological data available suggest that MBDB may cause serotonergic deficits in the brain, although the potency of MBDB to cause this neurotoxic effect is smaller than that of MDMA. Severe acute reactions in man as have been reported for MDMA have not been published for MBDB. The dependence potential of MBDB appears to be small, probably even smaller than that of MDMA. MBDB has been available at least since 1994 but its position on the synthetic drugs market is marginal. Subjective reports indicate that MBDB is less popular among users than MDMA. The reason may be that MBDB produces less euphoria than MDMA. Another possible explanation is that MBDB largely lacks the stimulant properties of MDMA.We calculated a margin of safety with a method similar to one used in the risk assessment of pharmaceuticals. The results suggest that MBDB is three times less likely to cause serotonergic brain deficits than MDMA. However, it should be noted that for both substances the margin of safety is less than one, indicating that the risk of neurotoxicity is not negligible. In animals, serotonergic brain deficits after exposure to MDMA have been linked to the degeneration of serotonergic nerve terminals.

ULTRASOUND THERAPY FOR THE PREVENTION AND CORRECTION OF CONTRACTURES AND BONE MINERAL LOSS ASSOCIATED WITH WING BANDAGING IN THE DOMESTIC PIGEON (COLUMBA LIVIA)

Figure-of-eight wing bandaging is widely used to treat wing injuries, to immobilize wings before and after fracture repair, and during transient wing paralysis. However, prolonged bandaging can lead to bone loss and to contractures and reduced range of joint motion. Studies evaluating the efficacy of therapeutic ultrasound to reverse and prevent bandaging-associated contractures in pigeons (Columba livia) showed a significant increase in elbow and carpal extension after 10 twice weekly ultrasound treatments when started either 4 or 11 days after bandage placement. In addition, after 42 days of wing bandaging, three ultrasound treatments stimulated a faster reversal of carpal wing rotation loss than removal of the bandage over the 10-day treatment period. Finally, bone loss in response to 28 days of bandaging was significant, progressed at 2.8% per week, and was not affected by ultrasound treatment twice weekly during this period. Therefore, therapeutic ultrasound prevented and reversed loss of wing extension associated with figure-of-eight bandaging but did not lessen the disuse osteoporosis created by bandaging in these birds.

Review of N-Body Models of Tidal Interactions

Considerable progress has been made in the current decade with the help of N-body simulations towards a deeper understanding of the nature of the dynamical relationship between the Large and Small Magellanic Clouds and the Galaxy. The origin of such features as the Magellanic Stream, the inter-Cloud Bridge, the Wing and large extension in depth of the SMC has come to be interpreted in the context of the tidal interactions among the members of the LMC-SMC-Galaxy triple system. The inclusion of gas-dynamical effects and star formation in the latest models has added further refinements to this picture and confirmed the enhancement of the star formation rate in the SMC as a result of the recent LMC-SMC encounter.

Inheritance of behavioural differences between two interfertile, sympatric species, Drosophila silvestris and D. heteroneura.

The Hawaiian fly species, Drosophila silvestris and D. heteroneura, are sympatric and interfertile but show strong behavioural isolation and major differences in male aggressive behaviour and the associated morphology. As a first step in elucidating the genetic control of the differences between these species, we examined the mating and aggressive behaviour of their reciprocal F1 hybrids. The latency to the first wing vibration and the latency to copulate did not differ significantly between the parental species. However, D. heteroneura females had a very low tendency to copulate with D. silvestris males, rarely mating during the observation period. The duration of copulation also differed significantly; same-species pairs of D. silvestris had copulations that lasted about 50% longer than those of same-species pairs of D. heteroneura. The hybrids were intermediate between the parental species for both the tendency to copulate with D. silvestris males and the duration of copulation, suggesting codominance or polygenic inheritance for those traits. The aggression traits that we scored were the leg posture and wing extension during early aggression, and the leg posture and head position during escalated aggression. The parental species showed clear differences for each of these traits. The F1 hybrids resembled one parent or the other, without showing intermediate values, suggesting single-gene dominance or threshold expression of many genes for those traits. None of the courtship or aggressive traits showed X-chromosomal effects, although the head shape of hybrids is influenced by genes on the X chromosome. It is difficult to reconcile the patterns of inheritance of aggressive behaviour and the lack of an X-chromosomal effect with the hypothesis that these traits are influenced by a coadapted gene complex.

Inheritance of behavioural differences between two interfertile, sympatric species, Drosophila silvestris and D. heteroneura

The Hawaiian fly species, Drosophila silvestris and D. heteroneura, are sympatric and interfertile but show strong behavioural isolation and major differences in male aggressive behaviour and the associated morphology. As a first step in elucidating the genetic control of the differences between these species, we examined the mating and aggressive behaviour of their reciprocal F1 hybrids. The latency to the first wing vibration and the latency to copulate did not differ significantly between the parental species. However, D. heteroneura females had a very low tendency to copulate with D. silvestris males, rarely mating during the observation period. The duration of copulation also differed significantly: same-species pairs of D. silvestris had copulations that lasted about 50% longer than those of same-species pairs of D. heteroneura. The hybrids were intermediate between the parental species for both the tendency to copulate with D. silvestris males and the duration of copulation, suggesting codominance or polygenic inheritance for those traits. The aggression traits that we scored were the leg posture and wing extension during early aggression, and the leg posture and head position during escalated aggression. The parental species showed clear differences for each of these traits. The F1 hybrids resembled one parent or the other, without showing intermediate values, suggesting single-gene dominance or threshold expression of many genes for those traits. None of the courtship or aggressive traits showed X-chromosomal effects, although the head shape of hybrids is influenced by genes on the X chromosome. It is difficult to reconcile the patterns of inheritance of aggressive behaviour and the lack of an X-chromosomal effect with the hypothesis that these traits are influenced by a coadapted gene complex.

A test of how well the repeatability of courtship predicts its heritability

We compared repeatability and heritability estimates for courtship traits in the houseflyMusca domesticaL., to test the expectation that the repeatability of a behaviour is an upper-bound estimate of its heritability. The repeatabilities across and within mating partners for two courtship traits, male wing buzzing (Buzz) and female wing extension (Wing-out), were compared to heritabilities calculated from the divergence among subpopulations due to founder-flush events or artificial selection. The male's Buzz showed highly significant repeatabilities within and across female partners, but the values ranged widely (0.3–0.5). The intensity of Buzz decreased significantly with successive courtship attempts to the same female, apparently as a male strategy to optimize his efforts to gain copulation by modulating behaviour for specific females. Repeatabilities for female Wing-out within and across male partners were not significant, but this trait yielded significant heritabilities in two assessments (based on successful courtships). We attribute this contradiction to biased sampling because only the subset of reluctant females met the necessary restriction to refuse copulation throughout four successive courtships. These results demonstrate that repeatabilities are labile within individuals and may actually underestimate heritabilities when there is a genetic predisposition not to repeat performance. We concur with related studies that repeatabilities can identify evolutionary potential, but we advise caution in interpreting low values or comparing their absolute values.

Load Measurements on the Leading-Edge Extension, Wing, and Body of an F/A-18

The pressure difference across the wing and leading-edge extension (LEX) of a rigid 6% scale model of an F/A-18 was measured, and the integrated static and rms loads were computed. The total loads on the aircraft were obtained using a sting-mounted balance from which the body loads can be deduced by subtracting the LEX and wing loads. The effects of Mach number and angle of attack were analyzed and results for M = 0.25, 0.6, and 0.8 at a = 20‐35 deg are presented. The effectiveness of the LEX as a highlift device is demonstrated by comparing the individual lift contributions from the wing and LEX at different angles of attack and Mach numbers. It is shown that the LEX vortex can generate large nonlinear static lift while inducing high unsteady lift on the aircraft.

Anatomy and histochemistry of spread-wing posture in birds. 2. Gliding flight in the California gull, Larus californicus: a paradox of fast fibers and posture.

Gliding flight is a postural activity which requires the wings to be held in a horizontal position to support the weight of the body. Postural behaviors typically utilize isometric contractions in which no change in length takes place. Due to longer actin-myosin interactions, slow contracting muscle fibers represent an economical means for this type of contraction. In specialized soaring birds, such as vultures and pelicans, a deep layer of the pectoralis muscle, composed entirely of slow fibers, is believed to perform this function. Muscles involved in gliding posture were examined in California gulls (Larus californicus) and tested for the presence of slow fibers using myosin ATPase histochemistry and antibodies. Surprisingly small numbers of slow fibers were found in the M. extensor metacarpi radialis, M. coracobrachialis cranialis, and M. coracobrachialis caudalis, which function in wrist extension, wing protraction, and body support, respectively. The low number of slow fibers in these muscles and the absence of slow fibers in muscles associated with wing extension and primary body support suggest that gulls do not require slow fibers for their postural behaviors. Gulls also lack the deep belly to the pectoralis found in other gliding birds. Since bird muscle is highly oxidative, we hypothesize that fast muscle fibers may function to maintain wing position during gliding flight in California gulls.

LATERAL OSCILLATIONS OF AN AIRCRAFT MODEL AT HIGH ANGLES OF ATTACK

Lateral oscillations occurring on the aircraft model of NASA TP 1803 at angles of attack ranging from 25° to 60° have been investigated in a low-speed wind tunnel for configurations including fuselage with wing or with a combination of wing and leading-edge extension (LEX). The wind tunnel experiment was conducted in the range of Mach number from 0·1 to 0·2, and the range of the Reynolds number based on the body diameter from 2·8×10 5to 5·6×10 5. The time-varying side force coefficients, which may represent the displacements of oscillation in the lateral direction, were measured to obtain the root-mean-square values and the power spectra. Flow visualization of the vortices generated from the forebody, wing and LEX of the model has also been performed in a water tunnel. It was found that the entire system of the flow and the sting-supported model locks-in at the resonant oscillation frequency as the lateral oscillation occurs. The presence of LEX significantly enhances the oscillation amplitude especially at high enough angles of attack, i.e., α>40 °.The enhancement of the lateral oscillation, as suggested by the water tunnel visualization, seems closely related to the breakdown of the LEX vortices in general and the location of breakdown in particular. The power spectra of the test model with wind and LEX exhibit a transition from weakly nonlinear to broad band oscillations as αis increased from 45° to 60°. The appearance of a broad range of frequencies around or below the dominant frequency, that can be indicative of possible chaotic oscillation, corresponds to a sharp drop of the lateral oscillation amplitude. The effect of Reynolds number is notable only at α>50°.Variation of the sideslip angle between 0 and 10° appears to have no discernible effects on the amplitude of lateral oscillation for the test model with wing and LEX.

Mechanics of the avian propatagium: Flexion-extension mechanism of the avian wing.

The supporting elements of the avian propatagium were examined in intact birds and as isolated components, using static force-length measurements, calculated models, and airflow observations. The propatagial surface supported between Lig. propatagiale (LP) and brachium-antebrachium is equally resistant to distortion over the range of wing extension used in flight. The lengths LP assumes in flight occur across a nearly linear, low-stiffness portion of the force-length curve of its extensible pars elastica. In an artificial airflow, intact wings automatically extend; their degree of extension is roughly correlated with the airflow velocity. Comparisons between geometric models of the wing and the passive force-length properties of LPs suggest that the stress along LP blances the drag forces acting to extend the elbow. The mechanical properties (stiffness) of the LP vary and appear to be tuned for flight-type characteristics, e.g., changes in wing extension during flight and drag. Lig. limitants cubiti and LP combine to limit elbow extension at its maximum, a safety device in flight preventing hyperextension of the elbow and reduction of the propatagium's cambered flight surface. Calculations using muscle and ligament lengths suggest that M. deltoideus, pars propatagialis, via its insertions onto both the propatagial ligaments, controls and coordinates propatagial deployment, leading edge tenseness, and elbow/wing extension across the range of wing extensions used in flight. The propatagial ligaments and M. deltoideus, pars propatagialis, along with skeleto-ligamentous elbow/carpus apparatus, are integral components of the wing's extension control mechanism. © 1995 Wiley-Liss, Inc.

A behavioral comparison of Nexus, cathinone, BDB, and MDA

The effects of 4-bromo-2,5-dimethoxy-phenethylamine (Nexus), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxyphenyl-2-butanamine (BDB), and cathinone were studied in the newly hatched chicken and compared to the effects of d-amphetamine and three hallucinogens in the same species. Cathinone, a psychomotor stimulant in man (6), produced effects that were qualitatively similar to effects seen after administration of d-amphetamine (i.e., distress vocalization, wing extension, inability to stand, and loss of righting reflex). BDB, a compound with unknown activity in man, and two known hallucinogens, Nexus (5) and MDA (1), produced effects in the chicken that are common to both stimulants and hallucinogens in this species. For example, both MDA and BDB produced abnormal body posture that was identical to that reported after administration of hallucinogens such as lysergic acid diethylamide (LSD) and harmine (11). Nexus, on the other hand, produced rigid penguin-like posture, an effect seen in the chicken after administration of another hallucinogen, mescaline (12). BDB also produced bursting forward movements, an effect commonly observed after LSD and harmine. Our findings suggest that the young chicken can be used as an alternative, nonmammalian, model for predicting classification of new compounds.

Structure-activity relationships of BDB and its monomethyl and dimethyl derivatives

The purpose of the present study was to evaluate the behavioral effects of 3,4-methylenedioxyphenyl-2-butanamine (BDB), N-methyl BDB (MBDB), and N, N-dimethyl BDB (MMBDB) in the newly hatched chicken. The primary amine, BDB, produced effects that are commonly seen in the chicken after administration of both hallucinogens and psychomotor stimulants (i.e., distress vocalization, tremor, and wing extension). It also produced abnormal body posture and bursting forward locomotion, effects elicited only by hallucinogens. Loss of righting reflex also occurred at the highest (16 mg/kg) dose of BDB, and this effect is typical of d-amphetamine but has not been reported for hallucinogens. The monomethylated derivative of BDB, MBDB, was less potent than BDB, and the N, N-dimethyl analogue of BDB, MMBDB, had no effect on behavior at the doses tested.

Effects of short-term whole body vibration on animals with particular reference to poultry

Animals are exposed to various vibration and movement stimuli during transport. The vibrations are a potential source of stress in birds because the resonances they set up in the internal organs are likely to be major aversive stimuli. This paper considers the possible effects of vibration on broilers in transport by reference to the known effects of vibration on other species. The fundamental frequency of poultry transporters is between 1 and 2 Hz, with a secondary peak of 10 Hz and a chassis vibration in the lateral axis of 12–18 Hz. Suggested resonance frequencies for the viscera of broiler chickens exposed to vertical vibration are around 10 Hz, and so coincide with the secondary peak. Skeletal muscle responds to movement and vibration in order to maintain postural stability and reduce the effects of resonance. Standing birds maintain stability by wing extension and by flapping or squatting. Involuntary muscle and cardiac muscle are also affected by vibration with blood circulation, heart beat and possibly gut control changing as a result. Vibration-induced vasodilatation may occur, as may blood pooling in the organs, pulmonary damage and impaired thermoregulation. Biochemical changes resulting from vibration could have adverse effects on meat quality in birds unable to recover before slaughter.

Effects of designer drugs on the chicken embryo and 1-day-old chicken

The present study was conducted to examine the effects of d-amphetamine and the designer drags 3,4-methylenedioxymethamphetamine (MDMA), N-methyl-3,4-methylenedioxyphenyl-3-butanamine (HMDMA), 3,4-methylenedioxyphenyl-2-butanamine (BDB), 3,4-methylenedioxyphenyl-1-ethanamine (MDM1EA) in the chick embryo and the young chicken. HMDMA and MDM1EA had no effect on motility on day 14 of embryogenesis, while MDMA, BDB, and d-amphetamine decreased embryonic motility at one or more doses. On day 1 posthatch, chickens were challenged with cumulative injections of water or the same drag that they had received in ova. With the exception of MDM1EA, all of the drags produced effects such as distress vocalization, wing extension, tremor, flat body posture, bursting forward movements, loss of righting reflex, and convulsant-like kicking. Pretreatment with drag in ova resulted in tolerance to certain drug effects and supersensitivity to other drag effects. Furthermore, BDB significantly decreased hatchability, MDM1EA decreased body weight, and HMDMA decreased liver weight. Further studies are neeeded to determine the mechanism(s) of toxicity in this species.

Gliding flight in the American Kestrel (Falco sparverius): An electromyographic study.

Electromyographic (EMG) activity was studied in American Kestrels (Falco sparverius) gliding in a windtunnel tilted to 8 degrees below the horizontal. Muscle activity was observed in Mm. biceps brachii, triceps humeralis, supracoracoideus, and pectoralis, and was absent in M. deltoideus major and M. thoracobrachialis (region of M. pectoralis). These active muscles are believed to function in holding the wing protracted and extended during gliding flight. Quantification of the EMG signals showed a lower level of activity during gliding than during flapping flight, supporting the idea that gliding is a metabolically less expensive form of locomotion than flapping flight. Comparison with the pectoralis musculature of specialized gliding and soaring birds suggests that the deep layer of the pectoralis is indeed used during gliding flight and that the slow tonic fibers found in soaring birds such as vultures represents a specialization for endurant gliding. It is hypothesized that these slow fibers should be present in the wing muscles that these birds use for wing protraction and extension, in addition to the deep layer of the pectoralis. © 1993 Wiley-Liss, Inc.

Passive stretch of adult chicken muscle produces a myopathy remarkably similar to hereditary muscular dystrophy

The wings of 10 chickens between 1 and 5 years of age were passively extended. An increase in plasma creatine phosphokinase activity was observed in 30 min, continued to rise for 24 h, and then declined, suggesting mechanically induced damage to muscle fibers. Wing muscles were removed and examined histologically at various times after stretch. Patagialis muscles, but not biceps brachii, showed the development of muscle fiber pathology. The patagialis muscle is less active than the biceps brachii and is stretched to a greater degree by wing extension. Susceptibility of muscles to development of pathology appeared to be correlated with the age of the chickens. Pathology was remarkably similar to that observed in young chickens with hereditary muscular dystrophy. Necrotic fibers exhibiting segmental necrosis, abnormal shapes, enlargement, splitting, vacuolation, and phagocytosis were evident. Of particular interest was the appearance of abnormal clusters of acetylcholinesterase activity along the sarcolemma. These sites were shown to appear on fibers of 2-week-old dystrophic chicks prior to necrosis and increase in plasma creatine phosphokinase activity. It is suggested that aging of inactive muscles may promote adhesions between muscle fibers rendering them susceptible to damage when stretched and that necrosis of dystrophic fibers may be initiated by a similar mechanism. Such could occur if the genetic defect resulted in interfiber adhesions. Support for this hypothesis by other reports in the literature is discussed.

The Structure of Courtship in the Drosophila Melanogaster Species Sub-Group

[A quantitative comparison and sequence analysis of courtship behaviour of four-day old virgin flies from seven species of the Drosophila melanogaster species subgroup is described. In three species (D. melanogaster, D. simulans and D. mauritiana) courtship was observed until copulation. In four species (D. yakuba, D. teissieri, D. erecta and D. orena) courtships were truncated after a standard period. Wing rowing by the male was seen in four species (simulans, mauritiana, yakuba and teissierz). In both mauritiana and simulans the proportion of time spent in rowing tended to increase as courtship proceeded. The four species showing the greatest proportion of wing vibration in courtship (melanogaster, yakuba, erecta and orena) also showed an increase in the proportion of time spent vibrating as courtship proceeded. The amount of wing vibration and wing extension in yakuba is greater than in any other species in the subgroup. The proportion of time spent in wing extension in yakuba declined whilst vibration increased during courtship. In six species the proportion of courtship time spent licking increased during courtship. The mean lick duration was longer in yakuba than in any other species of the subgroup. When males were following actively moving females the time they spent performing courtship behaviours and the mean bout lengths were shorter than in courtship as a whole. D. simulans males expressed scissoring at a low level when courting moving females. Females of all species preened more than the males, but preening during courtship appeared to have no excitatory or inhibitory effect on the male. The behavioural sequence characteristic of the species subgroup is orientation→wing display→licking→ copulation. In five species wing vibration was the only element of wing display immediately to precede licking, but in simulans licking could also be preceded by scissoring and in yakuba by wing extension. The transition vibration→licking appears to be a characteristic of the subgroup., A quantitative comparison and sequence analysis of courtship behaviour of four-day old virgin flies from seven species of the Drosophila melanogaster species subgroup is described. In three species (D. melanogaster, D. simulans and D. mauritiana) courtship was observed until copulation. In four species (D. yakuba, D. teissieri, D. erecta and D. orena) courtships were truncated after a standard period. Wing rowing by the male was seen in four species (simulans, mauritiana, yakuba and teissierz). In both mauritiana and simulans the proportion of time spent in rowing tended to increase as courtship proceeded. The four species showing the greatest proportion of wing vibration in courtship (melanogaster, yakuba, erecta and orena) also showed an increase in the proportion of time spent vibrating as courtship proceeded. The amount of wing vibration and wing extension in yakuba is greater than in any other species in the subgroup. The proportion of time spent in wing extension in yakuba declined whilst vibration increased during courtship. In six species the proportion of courtship time spent licking increased during courtship. The mean lick duration was longer in yakuba than in any other species of the subgroup. When males were following actively moving females the time they spent performing courtship behaviours and the mean bout lengths were shorter than in courtship as a whole. D. simulans males expressed scissoring at a low level when courting moving females. Females of all species preened more than the males, but preening during courtship appeared to have no excitatory or inhibitory effect on the male. The behavioural sequence characteristic of the species subgroup is orientation→wing display→licking→ copulation. In five species wing vibration was the only element of wing display immediately to precede licking, but in simulans licking could also be preceded by scissoring and in yakuba by wing extension. The transition vibration→licking appears to be a characteristic of the subgroup.]

Courtship Behaviour in the Melanogaster Species Sub-Group of Drosophila

Abstract Descriptions of courtship behaviour are given for seven members of the melanogaster species sub-group: Drosophila melanogaster, simulans, mauritiana, yakuba, teissieri, erecta and orena. A male wing behaviour not previously reported, wing extension, was observed in either 1- or 2-wing variants in all species except melanogaster and simulans. Male wing rowing, previously reported in mauritiana and teissiri, was seen in 1- or 2-wing variants in all species except melanogaster and orena. D. teissieri showed the most extreme form of wing rowing, and yakuba the widest variety of angles of wing vibration. Tapping by the male was observed in all species except simulans and mauritiana, but not always at the onset of courtship and not in every courtship. Extrusion in virgin females was observed in melanogaster and erecta, and abdomen extension in female simulans, yakuba, teissieri and orena. Female wing behaviours were observed in all species except simulans. Wing extension and wing rowing are distinct from vibration and scissoring (behaviours they strongly resemble). There is strong a behavioural connection between these pairs of behaviours, in that wing extension often leads to vibration, wing rowing to scissoring, and vice versa. A mechanical function for licking is proposed, following observation of long duration licking in yakuba. The function of licking is thought to be elevation of the female's abdomen, preparatory to copulation. The relationship between the seven species based on their courtship behaviours was examined using principal coordinates analysis. This suggests that the two cosmopolitan species, simulans and melanogaster, differ most widely in their courtship behaviour, with mauritiana being the most similar to simulans. This finding is assessed in relation to the ecology of the seven species, the role of courtship behaviour in speciation, and the reliability of inferences from behaviour in phylogenetic analyses.

Control of male reproductive behavior by the central nervous system of Drosophila: dissection of a courtship pathway by genetic mosaics.

In gynandromorphs of Drosophila, a detailed examination was made of the association between male courtship behavior and the chromosomal genotype of various parts of the central nervous system. Mosaic flies that behave as males repeatedly show a shorter courtship than normal males. If there is to be male behavior, the posterior dorsal brain must be haplo-X on at least one side for occurrence of the early courtship events. Tapping, following of females and wing extension. Licking (proboscis extension) has nearly the same focus but is submissive; that is, male tissue must be present in both left and right dorsal brain. The next courtship step, attempted copulation, has a focus (especially for actual genital contact) located in the thoracic ganglia, though apparently not in a discrete region. Attempted copulation, which can occur even in mosaics with a gravid abdomen, may be correlated with the presence of sex combs. The role of courtship foci are interpreted in terms of known sensory inputs to and functions of the major insect ganglia.