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PubMed2000

Behavior of free-ranging and captive American kestrels under electromagnetic fields.

Wild birds, particularly raptors, commonly use electrical transmission structures for nesting, perching, hunting, and roosting. Consequently, birds are exposed to electromagnetic fields (EMFs). The amount of time that wild reproducing American kestrels (Falco sparverius) were exposed to EMFs was determined, and the effects of EMFs on the behavior of captive reproducing kestrels were examined. Wild kestrels were exposed to EMFs for 25% to 75% of the observed time. On a 24-h basis, estimated EMF exposure of wild kestrels ranged from 71% during courtship, to 90% during incubation, similar to that experienced by captive kestrels (88% of a 24-h period). Additionally, captive kestrels were exposed to EMF levels experienced by wild kestrels nesting under 735-kV power lines. Captive EMF females were more active, more alert, and perched on the pen roof more frequently than control females during courtship. EMF females preened and rested less often during brood rearing. EMF male kestrels were more active than control males during courtship, and more alert during incubation. Increased activity of kestrels during courtship may be linked to changes in corticosterone, but likely not melatonin. Observed behavioral changes were unlikely to directly result in the better growth of nestlings and fledging success, or poorer hatching success, of the EMF group, as previously reported. Behavioral changes of captive EMF kestrels may be observed in wild kestrels.

Animals↗

PubMed2000

Divergence and reticulation among montane populations of a jumping spider (Habronattus pugillis Griswold).

Populations of the jumping spider Habronattus pugillis Griswold isolated on nearby mountain ranges in southern Arizona are differentiated in many features of the males (color, shape, and orientation of setae on face; shape of carapace; markings of palpi and legs; motions during courtship behavior). These features are (mostly) consistent within a range and different between ranges. The concentration of differences in male courtship behavior and body parts exposed to the female during courtship and correlations between form and courtship behavior suggest sexual selection was involved in the differentiation. A phylogenetic analysis of the populations yields a tree that for the most part groups geographic neighbors, but the history of H. pugillis populations may not be adequately described by a tree. Geographic proximity of apparent convergences suggests that populations from at least some of the mountain ranges acquired characteristics through introgression. Lowering of the woodland habitat during the last glacial period probably brought some populations into contact, but it is not clear whether the interrange woodlands would have provided corridors for extensive mixing.

Altitude↗

PubMed2005

Male dwarf chameleons assess risk of courting large, aggressive females.

Conflict between the sexes has traditionally been studied in terms of costs of mating to females and female resistance. However, courting can also be costly to males, especially when females are larger and aggressively resist copulation attempts. We examined male display intensity towards females in the Cape dwarf chameleon, Bradypodion pumilum, in which females are larger than males and very aggressive. We assessed whether aggressive female rejection imposes potential costs on males and whether males vary their display behaviour with intensity of female rejection, female size or relative size differences. Males persisted in courtship after initial female rejection in 84% of trials, and were bitten in 28% of trials. Attempted mounts were positively associated with males being bitten. Males reduced courtship with increased intensity of female rejection. Male courtship behaviour also varied with female size: males were more likely to court and approach smaller females, consistent with the hypothesis that larger females can inflict more damage. These results suggest that, in addition to assessing female willingness to mate, male dwarf chameleons may use courtship displays to assess potential costs of persistence, including costs associated with aggressive female rejection, weighed against potential reproductive pay-offs associated with forced copulation.

Aggression↗

PubMed2003

The turn of the sword: length increases male swimming costs in swordtails.

Sexual selection via female mate choice can result in the evolution of elaborate male traits that incur substantial costs for males. Despite increased interest in how female mating preferences contribute to the evolution of male traits, few studies have directly quantified the locomotor costs of such traits. A sexually selected trait that could affect movement costs is the sword exhibited by male swordtail fishes: while longer swords may increase male mating success, they could negatively affect the hydrodynamic aspects of swimming activities. Here, we examine the energetic costs of the sword in Xiphophorus montezumae by experimentally manipulating sword length and measuring male aerobic metabolism during two types of activity, routine swimming and courtship swimming. Direct measurements of oxygen consumption indicate that males with longer swords expend more energy than males with shortened swords during both types of swimming. In addition, the sword increases the cost of male courtship. Thus, while sexual selection via female choice favours long swords, males with longer swords experience higher metabolic costs during swimming, suggesting that sexual and natural selection have opposing effects on sword evolution. This study demonstrates a hydrodynamic cost of a sexually selected trait. In addition, this study discriminates between the cost of a sexually selected trait used in courtship and other courtship costs.

Animals↗

PubMed1999

Inheritance of species differences in female receptivity and song requirement between Drosophila virilis and D. montana.

Females of two Drosophila virilis group species, D. virilis and D. montana, have different requirements for the courting males. In the present study we have examined species differences in female receptivity and male courtship song requirement using females' acceptance signal instead of copulation for measuring female readiness to mate. Behavior of D. virilis and D. montana females and F1 and backcross hybrid females was observed in a single-pair courtships with D. virilis and D. montana males and normal and wingless (mute) F1 hybrid males. D. virilis females were very receptive and they commonly accepted the courtship of males unable to produce courtship song. D. montana females, on the contrary, had a low receptivity and these females accepted the courting male only after hearing his song. Interspecific F1 and backcross (BCm) females resembled D. virilis more than D. montana in their receptivity. These females, however, resembled D. montana in their song requirement. These findings suggest that female song requirement and female receptivity are determined by different genetic factors.

Animals↗

PubMed1992

Evolutionary precedents for behavioral actions of oxytocin and vasopressin.

It is clear that the behavioral actions of oxytocin and vasopressin in mammals are not newly acquired, but have evolutionary antecedents. Injection studies with fish, amphibians, reptiles, and birds indicate that AVT can activate certain reproductive behaviors. The strongest evidence that AVT acts centrally to control reproductive behaviors comes from research on T. granulosa. In this amphibian, injections of AVT agonists activate courtship behaviors (amplectic clasping) in males and egg-laying behaviors in females, whereas injections of AVT antagonists inhibit the behaviors. Also, in Taricha males, AVT concentrations in specific brain areas are associated with the expression of courtship behaviors. Several conclusions about steroid-peptide interactions can be drawn, based on research with this amphibian. First, gonadal steroid hormones act to maintain the behavioral actions of AVT in both males and females. In Taricha, gonadectomy abolishes and steroid implants restore AVT-induced courtship in males and egg-laying in females. Second, gonadal steroids maintain the behavioral actions of AVT, in part, by modulating AVT receptor numbers on target neurons. In Taricha males and females, gonadectomy reduces AVT receptor concentrations (but not binding affinity) in certain brain areas (amygdala pars lateralis) and not others. Third, the type of gonadal steroid determines whether AVT elicits male-like or female-like reproductive behaviors. Ovariectomized Taricha females respond to AVT injections with egg-laying behaviors when implanted with estradiol and with male-like amplectic clasping when implanted with dihydrotestosterone. Fourth, the masculinization of AVT-induced behaviors in females most likely reflects site-specific actions of androgens on AVT-synthesizing neurons. In Taricha, AVTir concentrations in the optic tectum are sexually dimorphic (higher in males than females) and reach peak levels in males during the breeding season. Fifth, AVT content in specific brain areas increase as a function of performing the behaviors. In Taricha, AVTir concentrations in DPOA, CSF, and ventral infundibulum are higher in males that exhibit courtship behaviors than in males that do not. These conclusions illustrate how steroid-peptide interactions in the control of behaviors entail multiple neuroanatomical sites and neurochemical actions.

Animals↗

PubMed1994

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.

Animals↗

PubMed2001

11-Ketotestosterone inhibits the alternative mating tactic in sneaker males of the peacock blenny, Salaria pavo.

In the peacock blenny, Salaria pavo, a species with courtship sex-role reversal, smaller, younger males mimic the courtship behavior and the nuptial coloration of females in order to get access to nests during spawning and to parasitize egg fertilization from nest-holder males. Later in their life, sneakers transform both morphologically and behaviorally into nest-holder males. In the present paper we investigate the activational role of 11-ketotestosterone (KT), the most potent androgen in most teleost species, to promote the switch between tactics in sneaker males of S. pavo. Sneakers were implanted either with KT or with control (i.e. castor oil) silastic implants. A week after implantation they were subjected to a set of behavioral tests and morphometric measurements. KT treatment promoted the differentiation of secondary sex characters, such as the anal glands, and inhibited the expression of female courtship behavior. KT-treated sneakers also showed a trend toward less frequent display of female nuptial coloration. There was no effect of KT treatment on the expression of typical nest-holder male behavior. Finally, there was no effect of KT treatment on the number or soma size of arginine vasotocin neurons in the preoptic area, which are often associated with the expression of vertebrate sexual behavior. Thus, KT seems to play a key role in mating tactic switching by inhibiting the expression of female courtship behavior and by promoting the development of male displaying traits (e.g. anal glands). The lack of a KT effect on behavior typical of nest-holding males and vasotocinergic preoptic neurons suggests that a longer time frame or other endocrine/social signals are needed for the initiation of these traits in males that are switching tactics.

Animals↗

PubMed1991

Elements of the fruitless locus regulate development of the muscle of Lawrence, a male-specific structure in the abdomen of Drosophila melanogaster adults.

A genetically defined element of the fruitless (fru) locus in Drosophila melanogaster regulates the development of a male-specific muscle spanning the fifth abdominal segment in adult males, the 'muscle of Lawrence' (MOL). The region is defined by two cytological deletions, each with a breakpoint that co-maps with previously described mutant courtship phenotypes at cytogenetic interval 91B on the third chromosome. Flies that carry both of these deletions are viable, and males express abnormalities of courtship similar to those caused by the fru inversion breakpoint at 91B. In addition, these double-deletion males show the complete absence of the MOL, suggesting that they have little or no gene expression of a postulated MOL determinant; the musculature in the fifth abdominal segment of these mutants to indistinguishable from that of a normal female. Other mutant combinations that produce fruitless courtship phenotypes--including deletion and inversion breakpoints, and a marked transposon inserted at 91B--produce intermediate forms of the MOL. A new genetic variant, induced by imprecise excision of the marked transposon, is homozygous lethal and disrupts fru functions related to courtship and the MOL. The MOL is shown to be dispensable for fertility and is therefore not the causative factor of fru-induced behavioral sterility. These genetic variants and their phenotypic results are discussed with regard to a model for the organization of the fru locus.

Animals↗

PubMed1997

The role of antennal sensory cues in female responses to courting males in the cricket Teleogryllus oceanicus

Courtship communication in the field cricket Teleogryllus oceanicus is multimodal, involving a minimum of both acoustic and chemical cues. The acoustic signal, or courtship song, is necessary to elicit normal levels of female mounting of the male during courtship. Antennal input is also crucial since antennectomized females show highly reduced levels of mounting. Immobilization of the scapepedicel and pedicelflagellum joints of female antennae had no effect on mounting probability, suggesting that mechanosensory input from chordotonal organs at the base of the antenna is not necessary. The antennal flagellum is a multimodal sensory organ, which contains both mechanoreceptors and chemoreceptors. In order to dissect the roles of different flagellar modalities, we treated antennae with zinc sulphate. This suppressed a well-characterized contact-chemosensory behaviour, initiation of courtship by males, and eliminated responsiveness of most chemosensory hairs as assayed electrophysiologically. Zinc sulphate treatment had no effect on a tactile antennal reflex, indicating that it selectively silenced chemoreceptors. Treatment of antennae with zinc sulphate reduced mounting levels nearly as much as antennectomy, suggesting that the main antennal cue required for the mounting responses is chemosensory, rather than mechanosensory, in nature.

Journal Article↗

PubMed2004

Female mate preference in goby Eviota prasina: do secondary sexual traits influence female choice?

Males of the small gobiid fish Eviota prasina have longer dorsal fins than females and use their dorsal fins for courtship displays and male-male competition. We examined the influence of male dorsal fin length as well as the frequency of courtship displays on female mate preference using sequential choice experiments. Females responded more frequently to courting males with longer dorsal fins than males with shorter dorsal fins. This indicates female mate preference on the basis of male dorsal fin length in this goby. In addition, the logistic regression analysis showed that male courtship frequency positively influenced female mate preference. Since males incur costs to produce and maintain longer dorsal fins and to perform frequent courtship displays, these secondary sexual traits may indicate the quality of physical characteristics. In E. prasina, only males conducted parental care for eggs in their nests. Therefore, females may be able to ensure greater survival rates as well as higher genetic quality of their offspring by choosing males with better qualities based on these male traits.

Analysis of Variance↗

PubMed2004

The male red-sided garter snake (Thamnophis sirtalis parietalis): reproductive pattern and behavior.

Among the small group of species (e.g., some temperate zone turtles, snakes, and bats) that exhibit a dissociated reproductive pattern, the red-sided garter snake (Thamnophis sirtalis parietalis) is probably the most well studied. For these species, courtship and mating occur immediately upon emergence from winter dormancy; the gonads remain essentially inactive. Male red-sided garter snakes are a particularly informative animal model for examining the role of neuroendocrine factors associated with reproductive physiology and behavior because unlike species that exhibit an associated reproductive pattern, in which sex steroids initiate and control sexual behavior, reproductive behavior in the male garter snake appears to be independent of circulating sex hormone control. In fact, the only factor associated with the initiation of courtship behavior and mating in the male garter snake is an extended period of low temperature dormancy followed by exposure to warm temperatures. Yet the presence of sex steroid-concentrating neurons within the pathways regulating courtship and mating suggests that sex hormones may be involved in the activation of sexual behavior. Although circulating androgens are elevated upon emergence from hibernation, the initiation of courtship behavior and mating appears to be independent of direct androgen control. Thus steroid hormones may have indirect effects on mating behavior in animals that display "dissociated" reproductive behaviors.

Animal Husbandry↗

PubMed2003

Acoustic communication in two freshwater gobies: the relationship between ambient noise, hearing thresholds and sound spectrum.

Two freshwater gobies Padogobius martensii and Gobius nigricans live in shallow (5-70 cm) stony streams, and males of both species produce courtship sounds. A previous study demonstrated high noise levels near waterfalls, a quiet window in the noise around 100 Hz at noisy locations, and extremely short-range propagation of noise and goby signals. To investigate the relationship of this acoustic environment to communication, we determined audiograms for both species and measured parameters of courtship sounds produced in the streams. We also deflated the swimbladder in P. martensii to determine its effect on frequency utilization in sound production and hearing. Both species are maximally sensitive at 100 Hz and produce low-frequency sounds with main energy from 70 to 100-150 Hz. Swimbladder deflation does not affect auditory threshold or dominant frequency of courtship sounds and has no or minor effects on sound amplitude. Therefore, both species utilize frequencies for hearing and sound production that fall within the low-frequency quiet region, and the equivalent relationship between auditory sensitivity and maximum ambient noise levels in both species further suggests that ambient noise shapes hearing sensitivity.

Acoustic Stimulation↗

PubMed2001

Song production in auditory mutants of Drosophila: the role of sensory feedback.

To test the role of sensory feedback in song production. we analyzed the courtship songs of Drosophila males expressing auditory mutations. We compared the courtship songs of atonal (ato), beethoven (btv) and touch-insensitive-larva-B (tilB) to wild-type songs. These mutations have in common the fact that the chordotonal organs are disrupted. Since chordotonal organs subserve both hearing (in the antenna) and proprioception (from the wing), these two potential routes for sensory feedback are defective in the mutant flies. We measured six song characters: pulse number within a train, inter-pulse interval, pulse duration, sine burst duration, the carrier frequency of the sine song and the relative amplitude of the sine song. Using multivariate analysis, we found significant differences between mutant and normal songs. In addition many mutant flies exhibit an unusual wing position during singing. The results indicate that sensory feedback plays an important role in shaping the courtship song of Drosophila.

Animal Communication↗

PubMed1987

The effect of light on the sexual behavior of Drosophila affinis.

Drosophila affinis is a species whose mating is facilitated by light. Although sexually mature D. affinis males court D. affinis males and females vigorously in the light, they do not perform any of the courtship behaviors in the dark. This lack of courtship is not caused by the males and females being unattractive in the dark, since D. affinis males and females elicit high levels of courtship from Drosophila melanogaster males in light and in darkness. Fertility tests confirmed previous observations that mating occasionally occurs in the dark, suggesting that some D. affinis males are capable of courting in the dark.

Aging↗

PubMed2001

Ethological concepts revisited: immediate early gene induction in response to sexual stimuli in birds.

Courtship behaviors were interpreted by ethologists as being examples of 'sign stimuli' that would act as 'releasers' of stereotypic species-typical behaviors in conspecifics. A key component of the sign stimulus concept is that some form of stimulus filtering occurs that is responsible for the marked selective behavioral responsiveness. Studies of immediate early gene induction in the avian brain in response to conspecific stimuli associated with courtship and mating reveal that such gene induction is highly selective. In male Japanese quail (Coturnix japonica), studies of the immediate early gene c-fos or zenk have been conducted in birds engaging in both appetitive and consummatory aspects of male sexual behavior. High induction of immediate early genes occurs in hypothalamic and limbic areas such as the medial preoptic nucleus, bed nucleus striae terminalis and parts of the archistriatum in birds who had copulated and/or who had expressed a learned social proximity response, reflecting appetitive sexual behavior. Immediate early gene expression was also increased in telencephalic areas such as the hyperstriatum ventrale that presumably plays a role in the integration of sensory cues related to female recognition. In European starlings, studies of zenk induction have been conducted in females who hear male-typical courtship song. Clayton and Mello had shown that zenk is induced in the auditory telencephalon of canaries and zebra finches at high levels specifically in response to conspecific song. Immediate early genes such as fos and zenk are also expressed in song control nuclei specifically in association with song production. In starlings it was found that song was effective in rapidly inducing zenk expression in the auditory telencephalon in males and in females in the breeding as well as in the non-breeding season. Thus, the expression is not greater in females who use song to choose mates or during the breeding season when females are choosing mates. However, there is evidence that high levels of induction in certain areas of the auditory telencephalon in females are greater in response to songs organized in longer bouts that females prefer. Though immediate early gene induction in the brain does not exactly mimic selective behavioral responses to sign stimuli it may represent one important way in which stimulus selectivity of the sort hypothesized previously by Tinbergen and Lorenz is coded. Engaging in species-typical behaviors is also associated with motor-driven immediate early gene expression.

Animals↗

PubMed2005

A cis-regulatory sequence within the yellow locus of Drosophila melanogaster required for normal male mating success.

Drosophila melanogaster males perform a courtship ritual consisting of a series of dependent fixed-action patterns. The yellow (y) gene is required for normal male courtship behavior and subsequent mating success. To better characterize the requirement for y in the manifestation of innate male sexual behavior, we measured the male mating success (MMS) of 12 hypomorphic y mutants and matched-outbred-background controls using a y+ rescue element on a freely segregating minichromosome. We found that 4 hypomorphs significantly reduced MMS to varying degrees. Reduced MMS was largely independent of adult pigmentation patterns. These mutations defined a 300-bp regulatory region upstream of the transcription start, the mating-success regulatory sequence (MRS), whose function is required for normal MMS. Visualization of gene action via GFP and a Yellow antibody suggests that the MRS directs y transcription in a small number of cells in the third instar CNS, the developmental stage previously implicated in the role of y with regard to male courtship behavior. The presence of Yellow protein in these cells positively correlates with MMS in a subset of mutants. The MRS contains a regulatory sequence controlling larval pigmentation and a 35-bp sequence that is highly conserved within the genus Drosophila and is predicted to bind known transcription factors.

Animals↗

PubMed2001

Abnormalities of male-specific FRU protein and serotonin expression in the CNS of fruitless mutants in Drosophila.

The fruitless gene in Drosophila produces male-specific protein (FRU(M)) involved in the control of courtship. FRU(M) spatial and temporal patterns were examined in fru mutants that exhibit aberrant male courtship. Chromosome breakpoints at the locus eliminated FRU(M). Homozygous viable mutants exhibited an intriguing array of defects. In fru(1) males, there were absences of FRU(M)-expressing neuronal clusters or stained cells within certain clusters, reductions of signal intensities in others, and ectopic FRU(M) expression in novel cells. fru(2) males exhibited an overall decrement of FRU(M) expression in all neurons normally expressing the gene. fru(4) and fru(sat) mutants only produced FRU(M) in small numbers of neurons at extremely low levels, and no FRU(M) signals were detected in fru(3) males. This array of abnormalities was inferred to correlate with the varying behavioral defects exhibited by these mutants. Such abnormalities include courtship among males, which has been hypothesized to involve anomalies of serotonin (5-HT) function in the brain. However, double-labeling uncovered no coexpression of FRU(M) and 5-HT in brain neurons. Yet, a newly identified set of sexually dimorphic FRU(M)/5-HT-positive neurons was identified in the abdominal ganglion of adult males. These sexually dimorphic neurons (s-Abg) project toward regions of the abdomen involved in male reproduction. The s-Abg neurons and the proximal extents of their axons were unstained or absent in wild-type females and exhibited subnormal or no 5-HT immunoreactivity in certain fru-mutant males, indicating that fruitless controls the formation of these cells or 5-HT production in them.

Animals↗