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At least 289 records · Page 16Linked to original sources
PubMed2002

Sandpipers (Scolopacidae) switch from monoester to diester preen waxes during courtship and incubation, but why?

Recently, a shift in preen wax composition, from lower molecular weight monoesters to higher molecular weight diesters, was described for individuals of a sandpiper species (red knot, Calidris canutus) that were about to leave for the tundra breeding grounds. The timing of the shift indicated that diester waxes served as a quality signal during mate choice. Here, this hypothesis is evaluated on the basis of a survey of preen wax composition in 19 sandpiper species. All of these species showed the same shift observed in the high-Arctic breeding red knots. As the shift also occurred in temperate breeding species, it is not specific to tundra-breeding sandpipers. Both sexes produced the diester waxes during the incubation period until hatching, in addition to the short period of courtship, indicating that diesters' functions extend beyond that of a sexually selected 'make-up'. The few non-incubating birds examined (males of curlew sandpipers (C. ferruginea) and ruffs (Philomachus pugnax)) had the lowest likelihood of secreting diesters, indicating a functional role for diester preen waxes during incubation. We propose that diester preen waxes enhance olfactory crypticism at the nest.

Animals↗
PubMed2002

A model of the interaction between 'good genes' and direct benefits in courtship-feeding animals: when do males of high genetic quality invest less?

Conflict between mates over the amount of parental investment by each partner is probably the rule except in rare cases of genetic monogamy. In systems with parental care, males may frequently benefit by providing smaller investments than are optimal for individual female partners. Females are therefore expected to choose males that will provide the largest amounts of parental investment. In some species, however, the preferred males provide less care than their rivals. Focusing on species in which males invest by feeding their mates, I use a simple model to demonstrate the conditions under which males preferred by females may have optimal donations that are smaller than those of less-preferred rivals. Pre-mating female choice may sufficiently bias the perception of mate availability of preferred males relative to their rivals such that preferred males gain by conserving resources for future matings. Similarly, 'cryptic' biases in favour of high-quality ejaculates by females can compensate for smaller than average donations received from preferred males. However, post-fertilization cryptic choice should not change the optimal donations of preferred males relative to their rivals. I discuss the implications of this work for understanding sexual selection in courtship-feeding animals, and the relevance of these systems to understanding patterns of investment for animals in general.

Animals↗
PubMed2001

Species-specific genitalic copulatory courtship in sepsid flies (Diptera, Sepsidae, Microsepsis) and theories of genitalic evolution.

Males of Microsepsis eberhardi and M. armillata use their genitalic surstyli to rhythmically squeeze the female's abdomen with stereotyped movements during copulation. Squeezing movements did not begin until intromission had occurred and, contrary to predictions of the conflict-of-interest hypothesis for genitalic evolution, did not overcome morphological or behavioral female resistance. Contrary to predictions of the lock-and-key hypothesis, female morphology was uniform in the two species and could not mechanically exclude the genitalia of either species of male. The complex pattern of squeezing movements differed between the two species as predicted by the sexual selection hypothesis for genitalic evolution. Also, evolutionarily derived muscles and pseudoarticulations in the male's genitalic surstyli facilitated one type of movement, whose patterns were especially distinct. The data support the hypothesis that the male surstyli evolved to function as courtship devices.

Adaptation, Physiological↗
PubMed2000

Courtship in Drosophila.

Courtship is a complex behavior in Drosophila that recruits a wide range of genes for its realization, including those concerning sex determination, ion channels, and circadian rhythms. Results from different experimental approaches-behavioral and genetic comparisons between species, analysis of mutants and mosaics, and identification of specific sensory stimuli-sketch the outlines of a set of pleiotropic genes acting on a distributed system in the brain to produce the species-specific sequence of responses and actions.

Animals↗
PubMed1999

Sexual dimorphisms in avian and reptilian courtship: two systems that do not play by mammalian rules.

Sexual dimorphisms in the central nervous system exist in numerous vertebrate species, and in many cases these structural differences between males and females parallel differences in the display of reproductive behaviors. Often both the behavioral and anatomical differences are controlled by exposure to gonadal steroid hormones, either during ontogeny or in adulthood. This article reviews some of the evidence supporting the hypothesis that in mammals, testosterone or its metabolites regulate the structure and function of neural and muscle systems involved in the control of masculine sexual behaviors. It then describes data suggesting that the mechanisms regulating sexually dimorphic courtship systems in zebra finches and green anole lizards are not completely parallel to the mammalian systems. Finally, some directions for future study are suggested, with the hope that they will stimulate thought about the nature of comparisons made across vertebrate models when investigators are attempting to determine both which morphological sex differences are important to the control of the reproductive behaviors, and which mechanisms regulating both structure and function are widely employed or are unique.

Animals↗
PubMed1995

Neurophysiological effects of vasotocin and corticosterone on medullary neurons: implications for hormonal control of amphibian courtship behavior.

Research on a wide variety of vertebrates, from fish to mammals, reveals that corticosteroid hormones and vasotocin-like neuropeptides can potently modulate reproductive behaviors. But, it is not clear how the behavioral effects of these chemical messengers relate to functional properties of behavior-controlling neurons. This problem was investigated in the roughskin newt, Taricha granulosa, an amphibian in which the administration of arginine vasotocin (AVT) facilitates and corticosterone (CORT) inhibits courtship clasping of females by males. In waking, immobilized male newts, neurophysiological effects of AVT and CORT were studied in neurons in the rostral medulla due to the probable role of these neurons in the control of clasping. Topical medullary application of a clasp-facilitating dose of AVT produced a rapid increase in neuronal responsiveness to pressure on the cloaca, a trigger stimulus for clasping responses. Neuronal responses to noncloacal somatic stimuli and to moving visual stimuli were also enhanced. Systemic CORT administration, which has previously been shown to depress newt medullary neuronal sensory responsiveness, reversed the action of AVT such that the peptide depressed sensory responsiveness when applied 30 min after CORT. When AVT application preceded CORT injection by 10-17 min, however, the usual suppressive CORT effect was reversed and this treatment resulted in a rapidly appearing potentiation of neuronal activity and enhanced somatic sensory responsiveness. If the interval between AVT and CORT was increased to 30 min, the steroid caused a rapid depression of firing and a diminished somatic sensory responsiveness in most neurons, similar to what occurs in newts treated with CORT alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2004

Expression level of sarah, a homolog of DSCR1, is critical for ovulation and female courtship behavior in Drosophila melanogaster.

To better understand the genetic bases of postmating responses in Drosophila melanogaster females, we screened a collection of P{GS} insertion lines and identified two insertions in sarah (sra), whose misexpression in the nervous system induced high levels of ovulation in virgins. The gene sra encodes a protein similar to human Down syndrome critical region 1 (DSCR1). The ovulation phenotype was reproduced in transgenic virgins expressing UAS-sra in the nervous system. The flies also extruded the ovipositor toward courting males as seen in wild-type mated females, supporting the notion that ovulation and behavioral patterns are physiologically coupled. The sra insertions were found to be hypomorphic alleles with reduced expression levels. Females homozygous for these alleles show: (1) spontaneous ovulation in virgins, (2) sterility with impaired meiotic progression, and (3) compromised postmating responses with lower ovulation level, higher remating rate, and shorter period for restoration of receptivity. No obvious defects were observed in the homozygous males. The gene sra is predominantly expressed in oocytes, nurse cells, and the nervous system. Taken together, these results indicate that the expression level of sra is critical for ovulation and female courtship behavior, including their postmating changes.

Amino Acid Sequence↗
PubMedDate not supplied

Behavior of triatomines (Hemiptera: Reduviidae) vectors of Chagas' disease. I. Courtship and copulation of Panstrongylus megistus (Burm., 1835) in the laboratory.

A study of the courtship and copulation behavior of Panstrongylus megistus was carried out in the laboratory. Fifty-five newly-fed virgin couples were used. Experiments were performed during the day (9:00 to 12:00 a.m.) and at night (7:00 to 10:00 p.m.). Behavior was recorded by direct observation and was found to consist of the following sequence of behavioral patterns: the male approached the female and jumped on her or mounted her; he took on a dorsolateral position and immobilized the female dorsally and ventrally with his three pairs of legs; the male genital was placed below those of the female; the paramers of the male immobilized the female's genitals; copulation started. The couple joined by the iniciative of the male. The female could be receptive and accept copulation, or nonreceptive and reject the male. Copulation occurred more often on the occasion of the first attempt by the male. Duration of copulation was X = 29.3 +/- 9.3 min (CV = 83%). No behavioral differences were observed between couples tested during the day or at night.

Animals↗
PubMed2004

Analysis of the copulatory courtship songs of Lutzomyia longipalpis in six populations from Brazil.

The sand fly Lutzomyia longipalpis Lutz & Neiva (Diptera: Psychodidae: Phlebotominae), the main vector of Leishmania infantum in the Americas, is believed to be a species complex, although the status of different Brazilian populations is still somewhat unclear. Preliminary analysis of the acoustic signals that are produced during copulation by L. longipalpis males has suggested the existence of three sibling species in Brazil. In the current report, we analyze in more detail a number of parameters of the copulatory courtship songs of L. longipalpis males from four allopatric populations from different parts of the country (Marajó Island, Natal, Jacobina, and Lapinha Cave) and from two sympatric populations from the locality of Sobral, where two types of males can be differentiated by the number of pale spots (one or two pairs) found on the abdomen. We show that males from the localities of Natal, Marajó, and Sobral (two-spot morph) have very similar songs composed of successive bursts, which are modulated in frequency and amplitude. No significant differences were found in the song parameters of these three populations. In contrast, one-spot males from Sobral and males from Jacobina and Lapinha produce songs that are made of pulses but with distinct patterns for each population and significant differences in all song parameters studied. The results suggest that the L. longipalpis complex in Brazil is composed of four sibling species and that the differences in song patterns between the populations are consistent with the level of divergence found in the period gene.

Animals↗
PubMed2000

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[UAS(G)] 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[UAS(G)] 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.

ATP-Binding Cassette Transporters↗
PubMed1996

Mosaic analysis in the Drosophila CNS of circadian and courtship-song rhythms affected by a period clock mutation.

The period gene in Drosophila melanogaster controls not only daily rhythms associated with adult emergence and behavior, but also a much higher frequency rhythm that accompanies the male's courtship song. This oscillation in the rate of sound production (normal period, ca. one minute) is either sped up (by perS), slowed down, or eliminated in the three classic per mutants. We have conducted a mosaic analysis in which both lovesong and circadian locomotor cycles were examined in a series of flies that were each part perS and part per+. Consistent with previous studies, the focus for per control of the adult's circadian rhythm of locomotion was found to be in the brain. However, several mosaic individuals were found to exhibit a mutant locomotor rhythm but a wild-type song cycle, or vice-versa, enabling us provisionally to map the song-rhythm focus to the thoracic ganglia. That per is expressed only in glial cells in the thoracic nervous system and, in general, mediates slow (hour-by-hour) fluctuations in the levels of its own products are discussed from the standpoint of the current mosaic mapping results and the renewed focus they bring to the gene's influence on an ultradian rhythm.

Animals↗
PubMed1991

Hospital-physician relations. Beyond courtship to the ties that bind.

Years ago, perhaps when relationships were simpler and possibly more enduring, physicians had one request of hospitals, namely, "Give us a good workshop in which to practice." With increased diversification and competition in the health care environment, their demands have become more complex, even as hospitals have become more eager to please. Hospitals and physicians know they need each other, but the hospital usually plays the role of the suitor. It is a role that can involve wasteful investments in time, energy and money if the courtship isn't inspired by real knowledge of what physicians actually want from the relationship.

Data Collection↗
PubMed2000

Green stink bug Nezara viridula detects differences in amplitude between courtship song vibrations at stem and petiolus.

Green stink bug Nezara viridula courtship songs are transmitted through plants as substrate vibrations. The amplitude of the vibrations is different at different distances from the source of vibration and at different locations on the plant. Amplitudes of the local vibration were measured on stem and petioli of the bean plant (Phaseolus vulgaris) with a Laser-Doppler vibrometer. Differences of the amplitudes of vibration between adjacent points around the nodes were large enough to release differential nerve activities of vibration receptor cells of different legs. There was no correlation between the signal amplitude and the distance from the singing bug, however; the differences in amplitudes of vibrations between the stem and the adjacent petioli of leaves potentially permitted direction finding in the green stink bug males.

Animal Communication↗