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PubMed2007

Changed environmental conditions weaken sexual selection in sticklebacks.

Environmental heterogeneity can cause the intensity and direction of selection to vary in time and space. Yet, the effects of human-induced environmental changes on sexual selection and the expression of mating traits of native species are poorly known. Currently, the breeding habitats of the three-spined stickleback Gasterosteus aculeatus are changing in the Baltic Sea because of eutrophication and increased growth of algae. Here we show that enhanced growth of filamentous algae increases the costs of mating by inducing an increase in the time and energy spent on courtship and mate choice. This is not followed by a concomitant increase in mate attraction, but instead the strength of selection on male red nuptial coloration and courtship activity is relaxed. Thus, the high investment into the costly sexually selected traits is maladaptive under the new conditions, and the mating system mediates a negative effect of the environmental change on the population. We attribute these environmentally induced changes in the benefit of the mating traits and in the strength of sexual selection to reduced visibility in dense vegetation. Anthropogenic disturbances hence affect the selection pressures that mould the species, which could have long-term effects on the viability and evolution of the populations.

Animals↗
PubMed1979

Aspects of species recognition by sound in four species of damselfishes, genus Eupomacentrus (Pisces: Pomacentridae).

Members of four sympatric species of Eupomacentrus carry out reproductive activities at the same time of the year and produce similar pulsed courtship sounds. Such sounds are known to facilitate courtship among conspecifics. Consequently, members of the four species in the field and in the laboratory were tested with the various sounds to determine if they could distinguish their own species sounds from those produced by congeners. The differential responses clearly demonstrate species specific recognition by sound and indicate that the pulse interval and the number of pulses per sound are the important parameters for this recognition.

Animals↗
PubMed2006

Modulation of singing-related activity in the songbird ventral tegmental area by social context.

Successful reproduction depends critically on social interactions. To understand the neural mechanisms underlying such interactions, the study of courtship singing of songbirds has many advantages. Male zebra finches produce a similar song during courtship of a female and while alone. However, singing-related neural activity in the anterior forebrain pathway (AFP), a basal ganglia-forebrain circuit, is markedly dependent on the social context in which singing occurs. Thus, the AFP should receive a signal of social context from outside the song system. Here, we have begun to investigate the neural source of such a signal by recording from neurons in the ventral tegmental area (VTA), which provides dopaminergic input to Area X, a striatal nucleus of the AFP. The level of activity of most VTA neurons we recorded (32/35) was clearly modulated during singing, especially when males sang to a female bird. Modulation of the level of activity could occur in the presence of a female without singing, but typically was further increased when males sang to the female. In addition, activity of some neurons was patterned in relation to song elements, and appeared related to motor output. These results suggest that VTA activity could carry signals related to motivational aspects of singing, as well as more primary sensory and motor signals.

Action Potentials↗
PubMed1988

Traditional Arabian marriages and mental health in a group of outpatient Saudis.

This is a prospective study of 150 consecutive outpatients who were either married or divorced. Marriage custom in Saudi Arabia is unique to the culture of that country and several different kinds of marriage are identified: arranged marriage of cousins; marriage of a couple who have not met before consummation; marriage of a couple who have met once before consummation; forced marriage; and, rarely, marriage preceded by a period of courtship. Marital discord defined by the patients as fully or partially responsible for their presenting symptoms, was correlated with the different kinds of marriage. Discord was found to be more likely when the couple had never met or when there had been a period of courtship; more likely associated with anxiety and dysthymic disorders; and to affect females more than males. Polygamy was a definite stress. The consanguinous marriage had a higher rate of marital discord than the non-consanguinous, but this was found to be not statistically significant. In 40% of discordant, consanguinous marriages the discord was directly related to the degree of consanguinity.

Anxiety Disorders↗
PubMed2005

Courting bird sings with stridulating wing feathers.

In birds and other vertebrates, most acoustic signals are produced pneumatically by moving air through a vocal apparatus. Here we describe a unique mechanism used to produce a tonal acoustic signal in vertebrates. Video recordings of the courtship displays of male Club-winged Manakins, Machaeropterus deliciosus, reveal that males produce sustained harmonic tones through interactions among oscillating secondary wing feathers. This mechanism of sound production shows morphological and mechanistic convergence with arthropod stridulation. Intersexual selection for production of a nonvocal courtship song has led to major morphological, functional, and likely physiological modifications in the wing of this flying bird.

Animal Communication↗
PubMed2001

Identification of X chromosomal restriction fragment length polymorphism markers and their use in a gene localization study in Drosophila virilis and D. littoralis.

We have identified six restriction fragment length polymorphism (RFLP) markers based on unique gene sequences on the X chromosome of Drosophila virilis and D. littoralis. The markers were localized by in situ hybridization on larval polytene chromosomes, and the conjugation of the X chromosomes of the two species was studied in salivary glands of interspecific hybrid female larvae. The gene arrangement of D. virilis and D. littoralis appeared to be very different at the proximal end of the X chromosome preventing recombination between RFLP markers located in this area. Simple quantitative trait loci (QTL) analysis showed that five of our marker genes (including nonA and Dmca1A, previously found to affect male courtship song in D. melanogaster) are linked with a gene(s) having a major effect on species differences in the male courtship song between D. virilis and D. littoralis. This shows that the song gene(s) may be located inside a large X-chromosomal inversion in D. littoralis (as previously suggested), but that it may also be located on an area between this inversion and the centromere, close to nonA and Dmca1A. Localization of this gene or gene complex will be continued with the aid of our newly identified RFLP markers by making interspecific crosses between D. virilis group species with more similar X chromosomes.

Animals↗
PubMed2002

Enhancer of garnet/deltaAP-3 is a cryptic allele of the white gene and identifies the intracellular transport system for the white protein.

The white gene encodes an ABC-type transmembrane transporter that has a role in normal eye pigment deposition. In addition, overexpression in Drosophila leads to homosexual male courtship. Its human homologue has been implicated in cholesterol transport in macrophages and in mood disorders in human males. The garnet gene is a member of a group of other Drosophila eye colour genes that have been shown, or proposed, to function in intracellular protein transport. Recent molecular analysis indicates that it encodes the delta subunit of the AP-3 adaptin complex involved in vesicle transport from the trans-Golgi network to lysosomes and related organelles, such as pigment granules. This identification revealed a novel role for intracellular vesicular transport in Drosophila pigmentation. To further analyze this intracellular transport system, we examined the genetic interactions between garnet and a second site enhancer mutation, enhancer of garnet (e(g)). We show here that e(g) is a cryptic allele of the white gene. The white-garnet interaction is highly sensitive to the levels of both gene products but also shows some allele specificity for the white gene. The additive effect on pigmentation and the predicted protein products of these genes suggest that the garnet/AP-3 transport system ensures the correct intracellular localization of the white gene product. This model is further supported by the observation of homosexual male courtship behavior in garnet mutants, similar to that seen in flies overexpressing, and presumably mis-sorting, the white gene product. The w(e(g)) allele also enhances mutations in the subset of other eye-color genes with phenotypes similar to garnet. This observation supports a role for these genes in intracellular transport and leads to a model whereby incorrect sorting of the white gene product can explain the pigmentation phenotypes of an entire group of eye-color genes.

ATP-Binding Cassette Transporters↗
PubMed1999

Mate choice in tree crickets and their kin.

Mate choice theory has become a major field of research in behavioral ecology. Tree crickets provide excellent opportunities for studying the diversity and variability of mate choice. The evidence for female mate choice in tree crickets is reviewed, and broad comparisons with other orthopteran groups are made. The evidence shows that female choice may occur during several different stages of mating and may target several different criteria. Song preferences are perhaps dominated by stabilizing preferences for the cues of species recognition, but there is a growing body of evidence for directional preferences based on sensory biases or mate quality. Mate rejection during courtship and forms of postcopulatory choice may favor males, based both on phenotypic quality and on the amount of nutritious courtship gifts they provide, and may differ with the value of mating incentives. Understanding the balance and trade-offs between different forms of mate choice may help in understanding their evolutionary causes.

Journal Article↗
PubMed1988

Sexually dimorphic behaviors.

Sex differences in behavior are the result of natural and sexual selection. The dimorphic classes of behavior described here, courtship, copulatory, and parental behaviors, reflect both kinds of evolutionary selective pressures. We can further distinguish two kinds of mechanisms that produce differences in male and female behaviors. In one, both sexes can perform a behavior but one does not because of sex differences in the external stimuli or the endocrine milieu. Maternal behavior in rodents falls into this category, as do certain other reproductive behaviors. In the other, the sensory, CNS, or motor components that produce behaviors are different in males and females. Many courtship and copulatory behaviors are in this category. I have considered some cellular mechanisms that generate sex differences in behavioral effector neurons, including sensitivity to hormones, cell number, and synaptic connectivity. A common feature of many such systems is a degree of developmental arrest: sexually dimorphic, hormone-sensitive neurons or muscles are immature at stages when other cells have completed differentiation. The cellular and molecular processes whereby hormones harness the developmental programs of behavioral effector cells remain largely unknown and are the focus of active investigation.

Animals↗
PubMed2006

Lesions of an avian basal ganglia circuit prevent context-dependent changes to song variability.

Trial-by-trial variability is important in feedback-based motor learning. Variation in motor output enables evaluation mechanisms to differentially reinforce patterns of motor activity that produce desired behaviors. Here, we studied neural substrates of variability in the performance of adult birdsong, a complex, learned motor skill used for courtship. Song performance is more variable when male birds sing alone (undirected) than when they sing to females (directed). We test the role of the anterior forebrain pathway (AFP), an avian basal ganglia-forebrain circuit, in this socially driven modulation of song variability. We show that lesions of the lateral magnocellular nucleus of the anterior nidopallium (LMAN), the output nucleus of the AFP, cause a reduction in the moment-by-moment variability in syllable structure during undirected song to the level present during directed song. This elimination of song modulation is immediate and long-lasting. We further show that the degree of syllable variability and its modulation are both attenuated in older birds, in concert with decreased variability of LMAN activity in these birds. In contrast to the requirement of LMAN for social modulation of syllable structure, we find that LMAN is not required for modulation of other features of song, such as the number of introductory elements and motif repetitions and the ordering of syllables or for other motor and motivational aspects of courtship. Our findings suggest that a key function of avian basal ganglia circuitry is to regulate vocal performance and plasticity by specifically modulating moment-by-moment variability in the structure of individual song elements.

Acoustic Stimulation↗
PubMed2002

Multisensory cues and multimodal communication in spiders: insights from video/audio playback studies.

Spiders perceive the world using multiple sensory modes, including vibration, vision, and chemical senses, for prey detection and communication. These sensory modes are used in many communication contexts, either individually or in multimodal signaling. Selection for effective signaler-receiver communication and species discrimination is especially strong for these predatory and potentially cannibalistic arthropods, resulting in the evolution of considerable diversity in signaling behaviors. In this paper, we review sensory mechanisms involved in spider signaling and present an overview of recent work done on wolf spiders (Lycosidae) that use multimodal communication (simultaneous visual and vibratory signals) in sexual signals during courtship. The relative importance of visual and vibratory signaling modes, and the use of multiple modes varies among closely related species in the genus Schizocosa, providing a model system for investigating multisensory guidance of complex behavior. Here we examine previous and current research on responses of female spiders to components of male courtship behavior, using several experimental techniques including cue isolation (single sensory modes), video/audio digitization and playback, and cue-conflict (mixed conspecific/heterospecific components) to tease apart elements of multimodal signaling.

Animal Communication↗
PubMed1991

Sex recognition by electric cues in a sound-producing mormyrid fish, Pollimyrus isidori.

This paper evaluates the role of electric cues in the sex recognition behavior of an African electric fish, Polimyrus isidori, during courtship behavior observed in the laboratory. I examined the importance of the electric organ discharge (EOD: waveform of the stereotyped electric organ discharge) and the sequence of pulse intervals (SPI: temporal pattern formed by sequences inter-EOD intervals) experimentally by presenting caged fishes, and electric playbacks (models) to male residents. In this species males court females with sounds, and I used this sonic behavior to measure sex recognition. Resident males produced many more grunt sounds when females were introduced onto their territories, compared with caged males, revealing that residents discriminated the sex of the caged fish. Response rates were correlated with characteristic patterns in the SPI of the introduced fish, suggesting that discrimination was based on electric cues. Moreover, I noted several significant sex differences in the SPIs of caged fishes. Residents also discriminated between electric signals from female and male fishes, played to them through electrodes, indicating that electric cues alone were sufficient for sex recognition. An ANOVA was used to ascertain the role of the SPI and the EOD, by analyzing responses to natural female and male models, as well as responses to male EODs combined with female SPIs, and to female EODs combined with male SPIs (hybrid models). I found that discriminating residents used SPI cues alone, with no dependence on the EOD. Taken together with new data showing that females generate a highly regular SPI during natural courtship encounters with singing males, these result show that SPIs are important in sex recognition in P. isidori.

Agonistic Behavior↗
PubMed1990

Significance of kin relations and individual preferences in the social behaviour of Cebus apella.

Captive tufted capuchins (Cebus apella) formed a group characterized by greater affiliative behaviour within matrilines. Affiliation within the matriline is dependent upon social intimacy during infancy with matriline members. Courtship and mating are not identically distributed: subordinate and subadult males participate in a larger proportion of matings than of courtships. In all these aspects of social behaviour, variability across individuals contributes to the complex dynamics of the social group.

Animals↗
PubMed2006

Male pheromone protein components activate female vomeronasal neurons in the salamander Plethodon shermani.

BACKGROUND: The mental gland pheromone of male Plethodon salamanders contains two main protein components: a 22 kDa protein named Plethodon Receptivity Factor (PRF) and a 7 kDa protein named Plethodon Modulating Factor (PMF), respectively. Each protein component individually has opposing effects on female courtship behavior, with PRF shortening and PMF lengthening courtship. In this study, we test the hypothesis that PRF or PMF individually activate vomeronasal neurons. The agmatine-uptake technique was used to visualize chemosensory neurons that were activated by each protein component individually. RESULTS: Vomeronasal neurons exposed to agmatine in saline did not demonstrate significant labeling. However, a population of vomeronasal neurons was labeled following exposure to either PRF or PMF. When expressed as a percent of control level labeled cells, PRF labeled more neurons than did PMF. These percentages for PRF and PMF, added together, parallel the percentage of labeled vomeronasal neurons when females are exposed to the whole pheromone. CONCLUSION: This study suggests that two specific populations of female vomeronasal neurons are responsible for responding to each of the two components of the male pheromone mixture. These two neural populations, therefore, could express different receptors which, in turn, transmit different information to the brain, thus accounting for the different female behavior elicited by each pheromone component.

Animals↗
PubMed1978

Hormonal control of male reproductive behavior in the lizard, Anolis carolinensis: role of testosterone, dihydrotestosterone, and estradiol.

The androgen aromatization hypothesis was examined in the male lizard, Anolis carolinensis. After castration, sc silastic implants of testosterone (T) restored both challenge and courtship behavior, while dihydrotestosterone (DHT) or 17beta-estradiol (E) had no effect on male behaviors. Both T and DHT, but not E, stimulated hypertrophy and colloid production by the renal sex segment, a secondary sexual characteristic of male lizards. In two separate studies, castrates received DHT in combination with E. In each replicate, half of the castrates responded with increases in courtship behavior after hormone treatment. Epithelial cell height of the sex segment of all DHT and E-treated castrates was comparable to T- or DHT-treated castrates, but colloid production was not stimulated. These experiments indicate that in this species, treatment with T stimulates both sexual behavior and secondary sex character development, whereas treatment with E alone is without effect centrally or peripherally.

Animals↗
PubMed1999

Embryonic temperature and gonadal sex organize male-typical sexual and aggressive behavior in a lizard with temperature-dependent sex determination.

Temperature during embryonic development determines gonadal sex in the leopard gecko, Eublepharis macularius. Moreover, both embryonic temperature and gonadal sex influence adult behavior. Yet it remains unclear whether the effects of embryonic temperature and gonadal sex on behavior are irreversibly organized during development. To address this question, we gonadectomized adult females and males generated from a temperature that produces mostly females (30 C) and a temperature that produces mostly males (32.5 C). Females and males from both temperatures were then treated with equivalent levels of various sex steroids. We found that both embryonic temperature and gonadal sex had persistent effects on the expression of male-typical sexual and aggressive behaviors. For example, adult females do not scent mark and display very little courtship and mounting behavior even when treated with levels of hormones (primarily androgens) that activate these behaviors in males. In contrast, species-typical aggressive displays were less sex specific and were activated by both dihydrotestosterone and testosterone (T) in males and by T in females. Nevertheless, the average duration of aggressive displays was significantly shorter in T-treated females than that in T-treated males. With regard to submissive behavior, androgens decreased flight behavior in males, but had no effect in females. Embryonic temperature had enduring effects on certain behaviors in males. For instance, males from a male-biased embryonic temperature scent-marked more than males from a female-biased embryonic temperature when treated with dihydrotestosterone or T. Conversely, and across hormone treatments, males from a female-biased embryonic temperature mounted more than males from a male-biased embryonic temperature. Finally, treatment with 17beta-estradiol decreased submissive behavior in males from a male-biased embryonic temperature compared with that in males from a female-biased embryonic temperature. Courtship and aggressive behavior were not influenced by temperature. These results strongly suggest that male-typical behaviors in the adult leopard gecko are permanently organized by both embryonic temperature and gonadal sex during development.

Aggression↗
PubMed2003

Seismic signals in a courting male jumping spider (Araneae: Salticidae).

Visual displays in jumping spiders have long been known to be among the most elaborate animal communication behaviours. We now show that one species, Habronattus dossenus, also exhibits an unprecedented complexity of signalling behaviour in the vibratory (seismic) modality. We videotaped courtship behaviour and used laser vibrometry to record seismic signals and observed that each prominent visual signal is accompanied by a subsequent seismic component. Three broad categories of seismic signals were observed ('thumps', 'scrapes' and 'buzzes'). To further characterize these signals we used synchronous high-speed video and laser vibrometry and observed that only one seismic signal component was produced concurrently with visual signals. We examined the mechanisms by which seismic signals are produced through a series of signal ablation experiments. Preventing abdominal movements effectively 'silenced' seismic signals but did not affect any visual component of courtship behaviour. Preventing direct abdominal contact with the cephalothorax, while still allowing abdominal movement, only silenced thump and scrape signals but not buzz signals. Therefore, although there is a precise temporal coordination of visual and seismic signals, this is not due to a common production mechanism. Seismic signals are produced independently of visual signals, and at least three independent mechanisms are used to produce individual seismic signal components.

Abdomen↗
PubMed2006

Seismic signal production in a wolf spider: parallel versus serial multi-component signals.

Animal signals can consist of multiple parts within or across sensory modalities (multi-component signals or multimodal signals). While recent work has focused on multimodal signals, the production, processing and evolution of multi-component signals has received considerably less attention. Here, using synchronous high-speed video and laser vibrometer recordings followed by experimental manipulations of putative sound-producing structures, we explored the mechanisms of seismic signal production in the courtship display of Schizocosa stridulans Stratton. Two types of seismic courtship signals were observed: 'rev' and 'idle' signals. Revs consist of a high-frequency component produced by flexions of the male pedipalp (stridulation) simultaneous with a low-frequency component produced by movements of the abdomen (tremulation). This multi-component signal is produced by independent structures and represents a parallel multi-component display. By contrast, idle displays consist of a high-intensity component produced by drumming of the forelegs on the substrate (percussion) followed by a high-frequency component produced by flexions of the male pedipalp (stridulation). While the components of the idle display are also produced by independent structures, the leg drumming and palp flexions occur serially and do not overlap in time. We discuss the selective pressures that may drive the evolution of multiple sound-producing structures as well as the selective pressures that drive the evolution of parallel versus serial multi-component signals.

Animals↗