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PubMed2005

Female soldier beetles display a flexible preference for selectively favored male phenotypes.

In Georgia (USA) the soldier beetle, Chauliognathus pennsylvanicus (Coleoptera; Cantharidae), exhibits clinal variation in the length of the spot on its elytron. This suggests that the viability of phenotypes varies by habitat. Evidence of viability selection comes from within-site changes in the spot length distribution across a breeding season. When males with spots of intermediate length became less frequent, they became disproportionately less likely to mate, consistent with either a loss of vigor among remaining males or female rejection of disfavored phenotypes. Persistent, daily courtship by males provides females with the opportunity to track changes in male phenotype frequency and to exercise choice for phenotypes favored under natural selection. A laboratory experiment in which the frequency of one spot morph (long) or the other (short) was increased from 25% to 75% over a period of 30 days revealed that females possess a flexible preference that leads them to prefer whichever spot type has become more common over time. A haploid genetic model demonstrates that a flexible female preference for the locally favored male phenotype can be selected for when different viability alleles, genetically correlated with the male trait, are favored in different habitats that are linked by gene flow. Thus, migration between different kinds of habitat patches of a metapopulation could maintain the variation in male quality. This variation favors female choice for any trait that is directly or indirectly favored by natural selection. Such choice imparts positive frequency-dependent selection that could rapidly fix traits pleiotropically linked to viability. Rapid fixation would cause differentiation between populations of colonizing species as females exercise choice for mates favored under new ecological conditions.

Animals↗
PubMed2006

Population genetic models of male and mutual mate choice.

Examples of male mate choice are becoming increasingly common, even in polygynous species. We create a series of population genetic models to examine the evolutionary equilibria and dynamics resulting from male mate choice during polygyny, alone and in the context of mutual mate choice by both sexes. We find that unless males with a preference are able to increase their overall courtship output, male preference will be lost. This loss can be counteracted if males choose females not based on arbitrary traits, but based on a trait that indicates high fertility or viability. We also conclude that if male and female preferences and traits are all controlled by different loci, the male and female mate choice systems are decoupled; the presence of a male preference then has no influence on the equilibria or dynamics of female mate choice. If male and female traits are coupled by pleiotropy, it becomes possible for a male preference to be maintained, regardless of whether preferences between the sexes are pleiotropic or controlled by separate loci.

Animals↗
PubMed2006

Effects of natural and sexual selection on adaptive population divergence and premating isolation in a damselfly.

The relative strength of different types of directional selection has seldom been compared directly in natural populations. A recent meta-analysis of phenotypic selection studies in natural populations suggested that directional sexual selection may be stronger in magnitude than directional natural selection, although this pattern may have partly been confounded by the different time scales over which selection was estimated. Knowledge about the strength of different types of selection is of general interest for understanding how selective forces affect adaptive population divergence and how they may influence speciation. We studied divergent selection on morphology in parapatric, natural damselfly (Calopteryx splendens) populations. Sexual selection was stronger than natural selection measured on the same traits, irrespective of the time scale over which sexual selection was measured. Visualization of the fitness surfaces indicated that population divergence in overall morphology is more strongly influenced by divergent sexual selection rather than natural selection. Courtship success of experimental immigrant males was lower than that of resident males, indicating incipient sexual isolation between these populations. We conclude that current and strong sexual selection promotes adaptive population divergence in this species and that premating sexual isolation may have arisen as a correlated response to divergent sexual selection. Our results highlight the importance of sexual selection, rather than natural selection in the adaptive radiation of odonates, and supports previous suggestions that divergent sexual selection promotes speciation in this group.

Adaptation, Physiological↗
PubMed2006

Unidirectional introgression of a sexually selected trait across an avian hybrid zone: a role for female choice?

Hybridization can be an evolutionary creative force by forming new polyploid species, creating novel genetic variation or acting as conduits of potentially advantageous traits between hybridizing forms. Evidence for the latter is often difficult to find because alleles under positive selection can spread rapidly across a hybrid zone and sweep to fixation. In Western Panama, an avian hybrid zone between two species of manakins in the genus Manacus exists where the unidirectional introgression of bright, yellow plumage into a white population provides evidence for the importance of hybrid zones as conduits of advantageous traits. Several lines of indirect evidence suggest that sexual selection favoring yellow plumage drives this asymmetrical spread, but more direct evidence is lacking. Along the edge of the hybrid zone, both yellow- and white-collared manakins are found in the same mating arenas or leks and compete for the same females ("mixed leks"), providing us with a unique opportunity to understand the dynamics of yellow plumage introgression. We studied these mixed leks to determine whether yellow males have a mating advantage over white males and, if so, whether the mating advantage is driven by male-male interactions, female choice, or both. We found that yellow males mated more than white males, suggesting that sexual selection favoring yellow males can, indeed, explain the spread of yellow plumage. However, we found that this advantage occurred only in mixed leks where the frequency of yellow males is greater than white males. This suggests that the advantage of yellow males may depend on the presence of other yellow males, which may slow the rate of introgression in leks where yellow frequency is low such as in areas where yellow males are beginning to colonize the white population. This, along with the geographic barrier posed by major rivers in the hybrid zone, may initially limit or slow the spread of yellow plumage. Finally, we found that yellow and white males were similar in aggression and body size, and held comparable positions within leks. Because these traits or factors are often important in or dictated by aggressive male-male interactions, these comparisons indicate that male-male interaction is not the primary mechanism for the spread of yellow plumage. However, white and yellow males received similar numbers of courtship visits from females but differed in the number of matings, suggesting that females actively rejected white in favor of yellow males. Our results indicate that sexual selection by female choice has driven the unidirectional introgression of yellow plumage into the white population, providing a mechanism for how hybrid zones act as conduits of novel and advantageous traits.

Animals↗
PubMed2006

Lift outs: how to acquire a high-functioning team.

More and more, expanding companies are hiring high-functioning groups of people who have been working together effectively within one company and can rapidly come up to speed in a new environment. These lifted-out teams don't need to get acquainted with one another or to establish shared values, mutual accountability, or group norms; their long-standing relationships and trust help them make an impact very quickly. Of course, the process is not without risks: A failed lift out can lead to loss of money, opportunity, credibility, and even native talent. Boris Groysberg and Robin Abrahams studied more than 40 high-profile moves and interviewed team leaders in multiple industries and countries to examine the risks and opportunities that lift outs present. They concluded that, regardless of industry, nationality, or size of the team, a successful lift out unfolds over four consecutive, interdependent stages that must be meticulously managed. In the courtship stage, the hiring company and the leader of the targeted team determine whether the proposed move is, in fact, a good idea, and then define their business goals and discuss strategies. At the same time, the team leader discusses the potential move with the other members of his or her group to assess their level of interest and prepare them for the change. The second stage involves the integration of the team leader with the new company's top leadership. This part of the process ensures the team's access to senior executives-the most important factor in a lift out's success. Operational integration is the focus of the third stage. Ideally, teams will start out working with the same or similar clients, vendors, and industry standards. The fourth stage entails full cultural integration. To succeed, the lifted-out team members must be willing to re-earn credibility by proving their value and winning their new colleagues' trust.

Commerce↗
PubMed1991

Revelations of adolescent mothers: an intensive case-study approach.

An intensive case-study approach was utilized with a sample of low-income females (19 black, 1 white) enrolled in a program for adolescent mothers. Audiotaped interviews examined self-image, gender role beliefs, relationships, ways of knowing, and future plans. Participants revealed a positive self-image, an association of womanhood with motherhood, an ability to picture themselves in a variety of future roles and relationships, negative attitudes toward men, matriarchal family structures, and subjective ways of knowing. The results were interpreted in the context of identity formation. Limitations included the presence of white interviewers and confounding effects of program participation. The findings have implications for future research in relationship and courtship patterns of the black subculture and the role of motherhood in identity development.

Adolescent↗
PubMed1990

Tests of Sabethes cyaneus leg paddle function in mating and flight.

Both sexes of the mosquito Sabethes cyaneus have conspicuous midleg paddles of unknown function. These paddles are displayed prominently by males during courtship. However, we found that paddle removal reduced successful mating of females, not males. Males without paddles approached and courted females normally, but females without paddles were rarely approached by males. Paddle removal appeared not to alter flight, and paddleless females oviposited in the manner characteristic of Sabethes, suggesting that the paddles do not aid in hovering or rapid reverse flight. We conclude that paddles of females are used in attracting males but that their function in males remains undetermined.

Animals↗
PubMed1990

Differentiation of sexual behaviour in pigs.

Behaviour in pigs is sexually dimorphic as early as 1 month of age; mounting of penmates is observed more frequently for males than for females. This mounting reaches its highest frequency during the 2nd month of life and then declines to a low frequency in prepubertal pigs. During the prepubertal period (3-5 months of age), bipotentiality of sexual behaviour is apparent in boars because they will not only mount oestrous females but they are also receptive to mounts by older, mature boars. If males are castrated during neonatal development (first 2 months of life) and treated acutely with oestrogen during adulthood, they display sexual behaviour that is characteristic of females; i.e. show a selective preference to remain near mature boars in a choice test, are receptive to mounts by mature boars, and have a short latency to receptivity after contact with a mature boar. Males that are castrated at 6 months of age or later, or males that are castrated neonatally and treated chronically with oestrogen or testosterone during the prepubertal period, display significantly less female behaviour after acute oestrogen treatment than do males castrated neonatally. Additionally, exposure of females to elevated testosterone during early fetal development results in no detectable changes in oestrous behaviour as adults. These observations support the hypothesis that defeminization of sexual behaviour in boars occurs as a result of elevated testicular steroids during pubertal development. The limited data available on masculine sexual behaviour in pigs indicate an activational role for gonadal steroids with little evidence for true masculinization per se. After prolonged testosterone treatment of mature females or males that are castrated before puberty, considerable courtship and mounting behaviours are exhibited by these individuals when placed with oestrous females. Studies have not evaluated differential sensitivity of such animals to dosage or duration of testosterone treatment. Differentiation of sexual behaviour in boars therefore involves primarily a loss of sensitivity to display female-typical behaviours. Presently, pigs differ from other mammals that have been investigated because sexual differentiation of reproductive behaviour occurs during pubertal development and not during gestation.

Animals↗
PubMed1990

Chronobiology and agroecosystems.

Influences of seasonal changes on the circadian system were observed in studies of feeding activity in four species of ducks and of feeding and locomotor activity in two species of mammals kept in captivity in the natural LD cycle. Feeding and locomotor oscillators had different sensitivities to exogenous synchronizers. Changes from a circadian to an ultradian feeding rhythm occurred as a result of courtship and breeding behavior in two duck species. Different phases of feeding rhythms in ducks were shown to have important ecological consequences for establishing the species in appropriate time niches in agricultural wetlands. Detailed study of annual, seasonal and daily rhythms of feeding and locomotion measured simultaneously in captivity and in free-ranging animals is necessary to elucidate the structure and function of food chains and webs. Activity rhythms of both producers and consumers (predators and prey) during daily and annual cycles is of special concern. This contribution of chronobiology will further our understanding of the niche of selected species in agricultural ecosystems.

Activity Cycles↗
PubMed1986

Reflections on the evolution of the regulation of spermatogenesis.

We have developed the concept that mechanisms evolved very early for the modulation of spermatogenesis in response to changes in the external environment, and that these ancient control mechanisms were retained during subsequent evolution. In nearly all animals, the regulation of germinal cell development is postulated to be mediated through the control of gonadal somatic cell functions, associated with the creation and maintenance of an optimal milieu within the spermary of seminiferous tubule in which gametogenesis takes place. In primitive organisms, a small number of stages intervenes between environmental stimuli and subsequent alteration of gonadal somatic cell functions. In contrast, in more complex organisms, the number of intervening stages is greatly amplified and modulated via neuroendocrine mechanisms involving receptors, transducers, and various sorts of relays and messengers. The evolution of these neural and endocrine controls appears to have occurred in lock-step with the evolution of increasing layers of complexity of regulators of spermatogenesis. This is not unduly surprising, since the requirement to have functionally fertile male and female partners of the same species together at the same time and place would require considerable integration of behavioral and recognition mechanisms during courtship and mating. The nature of these neural mechanisms is likely to prove no less complex than that of mechanisms in the gonad required for successful gamatogenesis. The neuroendocrine regulation of spermatogenesis in starfish and in chordates is postulated to act in a manner completely homologous to the ways in which external environmental stimuli influence spermatogenesis in more primitive organisms. In both sets of cases, the gonadal somatic cells (nurse cells) are the ultimate targets which mediate the effective turning on or turning off of spermatogenesis. The hormone-responsive nurse cells are postulated to achieve this simply by creating a microenvironment in the vicinity of germinal cells which permits the expression of program required for development, or by failing to do so. In mammals, Sertoli cells and peritubular cells, only when optimally stimulated by hormones and paracine factors, are thought to form a functional unit which provides this necessary microenvironment. In less complex organisms, other nurse cell arrangements exist to nourish the syncytia of developing germ cells with the mixture of nutrients, salts, etc. required for a gametogenesis to take place in a protected milieu.

Animals↗
PubMed1986

Ultrasonic vocalizations by male house mice (Mus musculus) to novel odors: roles of infant and adult experience.

Two experiments were conducted to examine 70-kHz ultrasonic courtship vocalizations by adult male mice (Mus musculus) to novel odors following exposure to these odors in infancy and/or adulthood. The research was performed in hopes of better understanding the experiences giving rise to vocalizations to naturally occurring chemosignals. Experiment 1 demonstrated that adult males normally do not vocalize to the urine of female rats but would come to do so if adult female mice odorized with female rat urine were repeatedly encountered postpubertally. On the other hand, encountering their own mother odorized with female rat urine from birth until weaning did not promote vocalizations to the urine of female rats. Experiment 2 was designed to examine vocalizations to the urine of female mice whose urinary odor was altered by the ingestion of fenugreek, a spice. Although the magnitude of the effect was smaller in this experiment, greater amounts of vocalization again were seen by males that as adults encountered females that had ingested fenugreek. Males with such experience also showed a small but significant elevation in vocalizations to the fenugreek odor itself. Again, experience with the novel odor during infancy was not associated with elevated vocalizations during adulthood either to fenugreek-altered urine or to the fenugreek odor itself. Thus vocalizations to two different novel odors occurred only after an adult male had encountered an adult female odorized with the novel odor. On the other hand, none of the novel odor experiences eliminated vocalizations to the naturally occurring chemosignal in female mouse urine.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1986

Estrogen establishes sex differences in androgen accumulation in zebra finch brain.

In zebra finches, androgens stimulate the production of a learned courtship song in males but not in females. Corresponding to this behavioral dimorphism, neural regions controlling the learning and production of song are much larger in males than in females. In two of these song-related brain regions, magnocellular nucleus of the anterior neostriatum (MAN) and hyperstriatum ventrale pars caudale (HVc), males have a larger percentage of androgen-accumulating cells than females. Since sex differences in the capacity for song and in the size of songrelated nuclei are established by gonadal hormones shortly after hatching, we determined whether the early hormonal environment also establishes sex differences in androgen accumulation within MAN and HVc. Newly hatched female zebra finches received either estradiol (E2) or cholesterol (Ch). Three to six months later, E2-females, Ch-females, and normal adult males were gonadectomized and injected 24 hr later with 3H-dihydrotestosterone. Autoradiograms were prepared, and the incidence of androgen-labeled cells was determined for MAN, HVc, and a control region, the lateral septal nucleus (SL). In females, early E2 exposure dramatically increases the percentage of androgen-accumulating cells in MAN and HVc, without influencing androgen accumulation in SL. In MAN and HVc, the percentage of androgen-concentrating cells in E2-females approximates that observed in normal adult males. Cells also tended to be more densely labeled in E2-females than in Ch-females. Since early E2 exposure renders the female song system neuroanatomically and functionally responsive to androgens, we suggest that E2 establishes this responsiveness by regulating the number of androgen target neurons within MAN and HVc.

Androgens↗
PubMed1983

Genetic architecture of olfactory discriminative avoidance conditioning in Drosophila melanogaster.

Recent claims to have demonstrated associative learning ability in Drosophila melanogaster raise questions about the adaptive significance of behavioral modifiability of this species. In a strain survey and a 9 X 9 half diallel cross study of olfactory discriminative avoidance conditioning, a low narrow heritability and strong directional dominance or heterosis controlling nonrandom phenotypic variation were found. Furthermore, the predicted inbreeding depression and asymmetrical response to bidirectional genetic selection were both observed. The genetic architecture revealed in these experiments is consistent with a close association between this conditioning phenotype and evolutionary fitness. Predictions from this interpretation to the nature of new mutations have been confirmed, and a possible role for conditioning in courtship behavior has been identified.

Animals↗
PubMed1983

Habituation, sensitization, and redirection of aggression and feeding behavior in the three-spined stickleback (Gasterosteus aculeatus L.).

Three-spined stickleback males maintained in individual aquaria built nests and defended the entire aquarium as a territory. Adjacent compartments containing another male stickleback, a gravid female, or a nongravid female provided a social context within which to study the habituation and sensitization of aggression elicited by a conspecific male intruded into the subject's territory. Typical sensitization-habituation curves were found for all fish regardless of the kind of neighbor. However, behavior redirected as a result of the stimulation of the intruded male differed between conditions. The group with a male neighbor showed increased aggression toward the neighbor, the group with a gravid female neighbor showed courtship, and the group with nongravid female showed neither. A third behavior, nest building, showed no difference between conditions, a result providing little evidence for a simple explanation in terms of general arousal. A second experiment elicited the same motor response to the intruded stimulus, but the motivational category was changed by eliciting the behavior by presenting live brine shrimp. In this experiment, aggression did not change during habituation, but the waning predation was redirected to another food-securing behavior, picking at the substrate. The results provide evidence for the important role that social context plays in understanding the redirection of behaviors, a phenomenon predicted from an extension of the dual-process theory of habituation.

Aggression↗
PubMed1980

Hormonal control of head-wart development in the snail, Euhadra peliomphala.

The terrestrial snail, Euhadra peliomphala, has a peculiar organ between the optic tentacles named the head-wart, which releases a sex pheromone just before courtship. The development of the head-wart was closely correlated with the sexual maturity of the snail. Castration led to the atrophy of the head-wart. Subsequent injection of hermaphrodite gland homogenate into the body cavity of castrated individuals induced the development of the head-wart. The peripheral regions of the acini in the hermaphrodite gland showed a positive reaction for 3 beta-hydroxy steroid dehydrogenase. Furthermore, preliminary radioimmunoassay also showed that the hermaphrodite gland of the snail contained testosterone and estradiol. When the immature head-wart was cultured for 10 days in a medium containing testosterone and estradiol respectively, development of the head-wart was found only in medium containing testosterone. From these results, it is concluded that head-wart development in the snail, Euhadra peliomphala, is under direct control from the hermaphrodite gland, probably by means of testosterone.

Animals↗
PubMed1980

The wooing of primary prevention.

The metaphor of the paper's title offers a framework for a brief summary. Effective wooing of primary prevention requires that we take seriously and adhere to, its clear, sensible defining guidelines; systematize, and further develop, its generative base; use that base to guide the formulation of new primary prevention programs; further develop frameworks to promote informed choices of program directions from among many attractive possibilities; and be more hard-nosed as program evaluators. That type of courtship should improve our love life with--and perhaps even, science of--primary prevention in mental health.

Child↗
PubMed1995

Correlation between the level of infection with Bunodera inconstans and Neoechinorhynchus rutili and behavioral intensity in female brook sticklebacks.

We investigated the influence of 2 intestinal helminths, Bunodera inconstans and Neoechinorhynchus rutili, on the development of female behavioral and morphological characters in brook sticklebacks. The number of N. rutili per female is positively correlated with standard length. Both the number of B. inconstans per female and the number of N. rutili per female are negatively correlated with the intensity of a female's aggressive response to an intruding female and are positively correlated with the intensity and duration of female courtship. The results of this study indicate that infection with N. rutili and B. inconstans may influence a female brook stickleback's ability either to compete for a mate or to sample from a large subset of territorial males.

Acanthocephala↗
PubMed1995

Taiwanese love styles and their association with self-esteem and relationship quality.

This study is an examination of how Lee's (1973, 1977, 1988) love styles are related to Taiwanese attitudes toward romantic relationships. Traditional literature was explored to ascertain Chinese beliefs about love and customs surrounding courtships and marriage. Taiwanese students at the University of Texas completed the Love Attitudes Scale (C. Hendrick & S. Hendrick, 1990), a measure of Lee's love styles. Six factors were extracted, using a principle components analysis, that were similar in many ways to the love styles derived from American samples, but that reflected Chinese beliefs and attitudes. The relationships of Taiwanese love styles to self-esteem and relationship quality (i.e., satisfaction, the probability of breaking up, and the number of conflicts experienced in a month) suggested the significance of Chinese traditions as well as current social changes in Taiwan.

Adolescent↗