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PubMed1997

Factors associated with appropriate physician management of sexually transmitted diseases in an urban Canadian center.

BACKGROUND AND OBJECTIVES: To explore physicians' management of selected sexually transmitted diseases (STDs), because previous studies suggest that physicians' management practices could be improved. GOALS: To determine the estimated annual incidence of STD seen by family/general practitioners (FPs), gynecologists (GYNs) and urologists (UROLs), adequacy of STD management practices, and any associations with demographic and other characteristics. STUDY DESIGN: A self-administered questionnaire was mailed to GYNs, UROLs, and a random sample of FPs in Hamilton, Ontario. RESULTS: Eighty-one of 102 (79.4%) FPs, 27 of 32 (84.4%) GYNs, and 7 of 8 (87.5%) UROLs responded. Vaginitis, male urethritis, and genital warts in women were the most frequently observed STDs. The treatment of bacterial vaginosis and pelvic inflammatory disease were most frequently at variance with published guidelines. CONCLUSIONS: Deficiencies exist in physicians' management of both common and potentially serious STD problems.

Attitude↗
PubMed1985

Quantitative genetic models of female choice based on "arbitrary" male characters.

Multivariate, quantitative genetic models are developed for the evolution of female mating preferences in situations where males contribute only their gametes to their progeny. Although female mating preferences may not be directly subject to selection, they can evolve via genetic correlations with other characters that are undergoing evolutionary change. The first set of models examines the evolutionary origin of mating preferences directed at one or more traits that may or may not be expressed only in males. When several selected characters possess additive genetic variance, an indirect selective force exists for the evolution of multivariate mating preferences. The magnitude of this force is proportional to the covariance between a female's relative preference for a given male's phenotype and the expected viability of his progeny. The contribution of any single character to this covariance determines its potential value as a mate choice criterion. The pattern of genetic and phenotypic covariation may cause selectively unimportant traits to be useful in mate choice. In the extreme, selectively neutral characters may become the objects of mating preferences, if they are relatively immune to random environmental variation and genetically correlated with selectively important characters. The second set of models examines the dynamic evolution of such a selectively neutral ("arbitrary") character that is both the object of a mating preference and genetically correlated with a third trait that affects viability. The outcome of evolution in this three character system is highly indeterminate. As in other sexual selection models, there exists a line of neutral equilibria wherein the mean of the criterion character matches the mean level of mating preference within the population, while the viability trait equilibrates at the phenotypic value conferring maximum viability. This line of equilibria, however, is not likely to be stable unless females choose mates according to absolute mating preferences. Thus, mating preferences that initially may arise as a mean of increasing offspring viability may nevertheless lead to indeterminate and potentially maladaptive evolutionary outcomes.

Animals↗
PubMed2003

The evolution of plumage polymorphism in birds of prey and owls: the apostatic selection hypothesis revisited.

Co-evolution between phenotypic variation and other traits is of paramount importance for our understanding of the origin and maintenance of polymorphism in natural populations. We tested whether the evolution of plumage polymorphism in birds of prey and owls was supported by the apostatic selection hypothesis using ecological and life-history variables in birds of prey and owls and performing both cross taxa and independent contrast analyses. For both bird groups, we did not find any support for the apostatic selection hypothesis being the maintaining factor for the polymorphism: plumage polymorphism was not more common in taxa hunting avian or mammalian prey, nor in migratory species. In contrast, we found that polymorphism was related to variables such as sexual plumage dimorphism, population size and range size, as well as breeding altitude and breeding latitude. These results imply that the most likely evolutionary correlate of polymorphism in both bird groups is population size, different plumage morphs might simply arise in larger populations most likely because of a higher probability of mutations and then be maintained by sexual selection.

Animals↗
PubMed1977

The role of attractiveness and mate selection in phylogenetic adaptation with particular reference to early man.

The author hypothesizes on the roles of sexual selection and assortative mating in human evolution. Basing his argument on a theory, which views neurosis as a maladaptive vicious cycle, he argues that there is dovetailing of the actions of neurosis and mate selection in promoting the phylogenetic adaptation of early man. He sees both neurosis and assortative mating as magnifying existing differences in viability. This process would, by favoring the most viable, have accelerated human evolution. The relationship between movement patterns and neurosis is also discussed.

Adaptation, Psychological↗
PubMedDate not supplied

Temporal and social aspects of gonorrhea transmission: the force of infectivity.

Theoretical consideration of the epidemiology of sexually transmitted diseases (STD) suggests that the key determinants of transmission dynamics are the duration of infectiousness and the extent to which subgroups in the population interact sexually. We used two empirical correlates to represent these concepts: (1) the force of infectivity, calculated by summing all the days of potential infectivity (the time between last sexual exposure and treatment of the contact) generated by a given case, and then summing the days for all cases within a given subgroup; (2) self-selection, representing the observed probability that members of a given subgroup select sexual partners from within their own group. Using data gathered in Colorado Springs, Colorado, we estimated that a single group i.e., black, male, heterosexual, military personnel residing in the core areas, generated 27% of the force of infectivity. Subgroups that select greater than 50% of their sexual partners from outside their sociodemographic boundaries generated a rate for the force of infectivity that was 4.5 times higher than the rate for self-selectors. These findings confirm the core group theory and suggest strategies for control of STD.

Adult↗
PubMed2005

Carotenoid availability affects the development of a colour-based mate preference and the sensory bias to which it is genetically linked.

Regardless of their origins, mate preferences should, in theory, be shaped by their benefits in a mating context. Here we show that the female preference for carotenoid colouration in guppies (Poecilia reticulata) exhibits a phenotypically plastic response to carotenoid availability, confirming a key prediction of sexual selection theory. Earlier work indicated that this mate preference is genetically linked to, and may be derived from, a sensory bias that occurs in both sexes: attraction to orange objects. The original function of this sensory bias is unknown, but it may help guppies find orange-coloured fruits in the rainforest streams of Trinidad. We show that the sensory bias also exhibits a phenotypically plastic response to carotenoid availability, but only in females. The sex-specificity of this reaction norm argues against the hypothesis that it evolved in a foraging context. We infer instead that the sensory bias has been modified as a correlated effect of selection on the mate preference. These results provide a new type of support for the hypothesis that mate preferences for sexual characters evolve in response to the benefits of mate choice--the alternatives being that such preferences evolve entirely in a non-mating context or in response to the costs of mating.

Analysis of Variance↗
PubMed2001

The evolution of female mate choice by sexual conflict.

Although empirical evidence has shown that many male traits have evolved via sexual selection by female mate choice, our understanding of the adaptive value of female mating preferences is still very incomplete. It has recently been suggested that female mate choice may result from females evolving resistance rather than attraction to males, but this has been disputed. Here, we develop a quantitative genetic model showing that sexual conflict over mating indeed results in the joint evolution of costly female mate choice and exaggerated male traits under a wide range of circumstances. In contrast to tradition explanations of costly female mate choice, which rely on indirect genetic benefits, our model shows that mate choice can be generated as a side-effect of females evolving to reduce the direct costs of mating.

Animals↗
PubMed2002

Paternal inheritance of a female moth's mating preference.

Females of the arctiid moth Utetheisa ornatrix mate preferentially with larger males, receiving both direct phenotypic and indirect genetic benefits. Here we demonstrate that the female's mating preference is inherited through the father rather than the mother, indicating that the preference gene or genes lie mostly or exclusively on the Z sex chromosome, which is strictly paternally inherited by daughters. Furthermore, we show that the preferred male trait and the female preference for that trait are correlated, as females with larger fathers have a stronger preference for larger males. These findings are predicted by the protected invasion theory, which asserts that male homogametic sex chromosome systems (ZZ/ZW) found in lepidopterans and birds promote the evolution of exaggerated male traits through sexual selection. Specifically, the theory predicts that, because female preference alleles arising on the Z chromosome are transmitted to all sons that have the father's attractive trait rather than to only a fraction of the sons, such alleles will experience stronger positive selection and be less vulnerable to chance loss than would autosomal alleles.

Alleles↗
PubMed2004

High-quality male field crickets invest heavily in sexual display but die young.

Only high-quality males can bear the costs of an extreme sexual display. As a consequence, such males are not only more attractive, but they often live longer than average. Recent theory predicts, however, that high-quality males should sometimes invest so heavily in sexual displays that they die sooner than lower quality males. We manipulated the phenotypic quality of field crickets, Teleogryllus commodus, by altering the protein content of their diet. Here we show that nymphs and adult females reared on a high-protein diet lived longer than those on a low-protein diet. In contrast, adult males reared on a high-protein diet died sooner than those on low-protein diets because they invested more energy in calling during early adulthood. Our findings uphold the theoretical prediction that the relationship between longevity and sexual advertisement may be dynamic (that is, either positive or negative), depending on local conditions such as resource availability. Moreover, they caution the use of longevity as a proxy for fitness in sexual selection studies, and suggest avenues for future research on the relationship between sexual attractiveness and ageing.

Aging↗
PubMed2006

The evolutionary ecology of the major histocompatibility complex.

The major histocompatibility complex (MHC) has become a paradigm for how selection can act to maintain adaptively important genetic diversity in natural populations. Here, we review the contribution of studies on the MHC in non-model species to our understanding of how selection affects MHC diversity, emphasising how ecological and ethological processes influence the tempo and mode of evolution at the MHC, and conversely, how variability at the MHC affects individual fitness, population dynamics and viability. We focus on three main areas: the types of information that have been used to detect the action of selection on MHC genes; the relative contributions of parasite-mediated and sexual selection on the maintenance of MHC diversity; and possible future lines of research that may help resolve some of the unanswered issues associated with MHC evolution.

Biological Evolution↗
PubMed2003

Migratory costs and contemporary evolution of reproductive allocation in male chinook salmon.

Energetically demanding migrations may impact the resources available for reproductive trait development and activity, and hence favour evolution of new investment strategies for remaining resources. We conducted a large-scale experiment to evaluate the proximate cost of migration on male reproductive investment in chinook salmon (Oncorhynchus tshawytscha) and contemporary evolution of reproductive allocation. Experimentally induced differences in migratory costs (17 km inland and 17 m elevation vs. 100 km and 430 m) influenced dorsal hump size and upper jaw length, two traits influencing male mating success that are developed during migration. Longer migration also reduced tissue energy reserves available for competition and length of breeding life. Corresponding shifts in the balance between natural and sexual selection appear to have been responsible for heritable population divergence in secondary sexual trait investment, in approximately 26 generations, following colonization of spawning sites with different migratory demands.

Adaptation, Physiological↗
PubMed2004

Ecological context and the importance of body and gnathopod size for pairing success in two amphipod ecomorphs.

Ecological context generates interspecific variation in mating behavior by imposing differential constraints on the action of sexual selection, but operation of these constraints in nature is not well understood. We used field and laboratory studies to examine the importance of body size and size of sexually dimorphic appendages, the gnathopods, for pairing success in two freshwater amphipod species within the Hyalella azteca species complex. We focused on a large-bodied species found in habitats where ecological factors tend to favor large body size, and a small-bodied species in habitats where small body size is favored by size-selective predation. A field study indicated that although male pairing success was greater for larger males in both species, pairing success increased throughout the range of variation in male size in the large species, whereas, in the small species, pairing success was low for smaller individuals, but roughly constant across intermediate to larger sizes. A laboratory mate choice experiment was consistent with the field study, finding that females of the large species exhibited a preference for larger males that was independent of absolute male size, but females of the small species were indifferent when choosing between males of intermediate to larger size. Species also differed in the direction of sexual size dimorphism in the field, with males being the larger sex in the large species but the smaller sex in the small species, a pattern consistent with the species differences in mate preference. Large gnathopod size relative to body size was associated with enhanced pairing success across all body sizes for the large species, but, in the small species, large gnathopod size enhanced pairing success only in smaller males. Species differences in mating behavior appear consistent with change driven by differing forms of the interaction between sexual and natural selection.

Amphipoda↗
PubMed2004

Sexual behavior, reproductive physiology and sperm competition in male mammals.

Sperm competition involves competition between the gametes of two or more males of a species for fertilization of a given set of ova. Sperm competition is widespread among mammals, as in many other groups of vertebrates. Effects of sexual selection, via sperm competition, upon the evolution of reproductive physiology and behavior are much better understood in invertebrates (and especially in insects) than is the case for mammals. However, if the reproductive organs of male mammals are viewed as an integrated system for production and delivery of spermatozoa (and accessory glandular secretions) to females, then it is logical to assume that sperm competition might influence the evolution of all parts of the system, as well as associated physiological mechanisms (e.g., testicular endocrinology) and behavior (e.g., copulatory patterns). Here we analyze and review relationships between mating systems, relative testes sizes and sperm morphology, phallic morphology, circulating testosterone levels and sexual behavior in male mammals.

Animals↗
PubMedDate not supplied

Sexually transmitted diseases among young heterosexual urban adults.

A self-administered, confidential survey of respondents' history of selected sexually transmitted disease (STD) was conducted in 1987-88 among adults enrolled in a multicenter study of cardiovascular disease. Respondents (and response rates) included 535 white men (78 percent), 694 white women (89 percent), 262 black men (48 percent), and 472 black women (64 percent), ages 21 to 40 years at the time of the survey. Among those who were heterosexually active, 43 percent of black women, 37 percent of black men, 33 percent of white women, and 21 percent of white men reported ever having had at least one STD in the survey. A history of syphilis or gonorrhea was more commonly reported by blacks than whites; a history of genital herpes, chlamydia, or genital warts was more commonly reported by women than men. Independent risk factors for having had at least one STD in the survey included female sex; use of cocaine, amphetamines, or opiates; and lifetime number of sex partners. The number of sex partners was the most predictive risk factor. Black race was a significant marker for other, unidentified STD risk factors. The data show a high prevalence of a lifetime history of STD among young heterosexual urban U.S. adults with possible implications for the future spread of human immunodeficiency virus infection.

Adult↗
PubMed2003

Divergent selection during speciation of Lake Malawi cichlid fishes inferred from parallel radiations in nuptial coloration.

Repeated evolution of the same phenotypic difference during independent episodes of speciation is strong evidence for selection during speciation. More than 1,000 species of cichlids, >10% of the world's freshwater fish species, have arisen within the past million years in Lakes Malawi and Victoria in eastern Africa. Many pairs of closely related sympatric species differ in their nuptial coloration in very similar ways. Nuptial coloration is important in their mate choice, and speciation by sexual selection on genetically or ecologically constrained variation in nuptial coloration had been proposed, which would repeatedly produce similar nuptial types in different populations, a prediction that was difficult to test in the absence of population-level phylogenies. We measured genetic similarity between individuals within and between populations, species, and lake regions by typing 59 individuals at >2,000 polymorphic genetic loci. From these data, we reconstructed, to our knowledge, the first larger species level phylogeny for the most diverse group of Lake Malawi cichlids. We used the genetic and phylogenetic data to test the divergent selection scenario against colonization, character displacement, and hybridization scenarios that could also explain diverse communities. Diversity has arisen by replicated radiations into the same color types, resulting in phenotypically very different, yet closely related, species within and phenotypically highly similar yet unrelated sets of species between regions, which is consistent with divergent selection during speciation and is inconsistent with colonization and character displacement models.

Africa, Eastern↗
PubMed1999

Central males instead of multiple pairs in redfronted lemurs, Eulemur fulvus rufus (Primates, Lemuridae)?

In group-living Malagasy primates (Lemuriformes), certain demographic and morphological traits deviate both from theoretical expectations derived from sexual selection theory and from patterns in better-known anthropoid primates. Lemurs lack sexual dimorphism in body and canine size and live in relatively small multimale-multifemale groups with, on average, even adult sex ratios, despite a polygynous mating system. In addition, the majority of gregarious lemurs are cathemeral, that is, they are regularly active both day and night. The social system of cathemeral lemurs has been considered an adaptation to their activity pattern. If so, groups should consist of multiple pairs that aggregate during diurnal activity and range separately at night in response to predation and infanticide risk, respectively. Moreover, mating privileges should exist between pair partners. We tested this hypothesis with data collected on two groups of wild redfronted lemurs in western Madagascar during 1023 focal animal hours spanning 4 months including the mating season. In addition, data on spatial relations were collected on 12 nights. We found no differences in group cohesion between day and night and no behavioural evidence for multiple male-female pairs. Instead, one male in each group monopolized social interactions with all females. However, females copulated with all resident males, although most often with the central male. Thus, basic predictions of the cathemerality hypothesis are unsupported. Multiple matings and indications of oestrous synchrony can be viewed as female counterstrategies against infanticide, whereas reproductive strategies of redfronted lemur males remain obscure. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2005

Differences in color vision make passerines less conspicuous in the eyes of their predators.

Sexual selection often favors brighter and exaggerated traits, which also increase the risk of detection by predators. Signals that are preferentially conspicuous to conspecifics would reduce the predation cost of signaling and, therefore, might facilitate the evolution of stronger sexual and social signals. This selective signaling is possible if predators and prey have differently tuned sensory systems. By using a retinal model to compare reflectance from the plumages of Swedish songbirds to the reflectance of their natural backgrounds, we found their color badges to be significantly more conspicuous to other songbirds (which have a UV-tuned visual system) than to raptors and corvids (which have a violet-tuned system) in both coniferous and deciduous forests, consistent with an adaptive private communication system.

Adaptation, Physiological↗