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Results for “Mate Selection”

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At least 397 records · Page 22Linked to original sources
PubMed2005

Direct mating between diploid sake strains of Saccharomyces cerevisiae.

Various auxotrophic mutants of diploid heterothallic Japanese sake strains of Saccharomyces cerevisiae were utilized for selecting mating-competent diploid isolates. The auxotrophic mutants were exposed to ultraviolet (UV) irradiation and crossed with laboratory haploid tester strains carrying complementary auxotrophic markers. Zygotes were then selected on minimal medium. Sake strains exhibiting a MATa or MATalpha mating type were easily obtained at high frequency without prior sporulation, suggesting that the UV irradiation induced homozygosity at the MAT locus. Flow cytometric analysis of a hybrid showed a twofold higher DNA content than the sake diploid parent, consistent with tetraploidy. By crossing strains of opposite mating type in all possible combinations, a number of hybrids were constructed. Hybrids formed in crosses between traditional sake strains and between a natural nonhaploid isolate and traditional sake strains displayed equivalent fermentation ability without any apparent defects and produced comparable or improved sake. Isolation of mating-competent auxotrophic mutants directly from industrial yeast strains allows crossbreeding to construct polyploids suitable for industrial use without dependence on sporulation.

Alcoholic Beverages↗
PubMed2003

Cognitive processes underlying human mate choice: The relationship between self-perception and mate preference in Western society.

This study tested two hypotheses concerning the cognitive processes underlying human mate choice in Western society: (i) mate preference is conditional in that the selectivity of individuals' mate preference is based on their perception of themselves as long-term partners, and (ii) the decision rule governing such conditional mate preference is based on translating perception of oneself on a given attribute into a comparable selectivity of preference for the same attribute in a mate. Both hypotheses were supported. A two-part questionnaire was completed by 978 heterosexual residents of Ithaca, New York, aged 18-24; they first rated the importance they placed on 10 attributes in a long-term partner and then rated their perception of themselves on those same attributes. Both women and men who rated themselves highly were significantly more selective in their mate preference. When the 10 attributes were grouped into four evolutionarily relevant categories (indicative of wealth and status, family commitment, physical appearance, and sexual fidelity), the greatest amount of variation in the selectivity of mate preference in each category was explained by self-perception in the same category of attributes. We conclude that, in Western society, humans use neither an "opposites-attract" nor a "reproductive-potentials-attract" decision rule in their choice of long-term partners but rather a "likes-attract" rule based on a preference for partners who are similar to themselves across a number of characteristics.

Adolescent↗
PubMed1998

Non-genetic benefits of mate choice: fecundity enhancement and sexy sons.

I compared reproductive success (lifetime number of fertilized eggs) as a function of mate choice among females of the stink bug, Nezara viridula L. (Hemiptera: Pentatomidae). 'Choosing' (C) females were placed with one of two males on alternate days. CI females chose between inexperienced males while CR females chose between males previously rejected by CI females. 'Non-choosing' (N) females were placed with the same male every day. Non-choosing NI, NR and NA females encountered, respectively, inexperienced males, previously rejected males, or previously accepted and mated males. Reproductive success was highest for CI females, showing direct selection on mate preferences. Reproductive success did not differ between CR and NR females, indicating that male quality, not the act of choosing a mate, affects fitness. CI females preferred males with longer antennae and their fecundity (lifetime number of eggs) was correlated with male antenna length, consistent with antenna length as an indicator of male ability to transfer nutritive sperm produced in paired harlequin lobes of the testes. Harlequin lobes were smaller in rejected than chosen males. In second-generation mate choice trials, sons of NR females competed well against sons of NA females but not against sons of CI females. This suggests that non-genetic paternal contributions that decline with prior mating account for the attractiveness of sons because sons of CI and NA females shared the same fathers. Sons experiencing mating success came from larger eggs and egg size was greatest for CI females, perhaps as a consequence of paternal nutritional contributions. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2002

Sexual selection and speciation in mammals, butterflies and spiders.

Recently refined evolutionary theories propose that sexual selection and reproductive conflict could be drivers of speciation. Male and female reproductive optima invariably differ because the potential reproductive rate of males almost always exceeds that of females: females are selected to maximize mate 'quality', while males can increase fitness through mate 'quantity'. A dynamic, sexually selected conflict therefore exists in which 'competitive' males are selected to override the preference tactics evolved by 'choosy' females. The wide variation across taxa in mating systems therefore generates variance in the outcome of intrasexual conflict and the strength of sexual selection: monandry constrains reproductive heterozygosity and allows female choice to select and maintain particular (preferred) genes; polyandry promotes reproductive heterozygosity and will more likely override female choice. Two different theories predict how sexual selection might influence speciation. Traditional ideas indicate that increased sexual selection (and hence conflict) generates a greater diversity of male reproductive strategies to be counteracted by female mate preferences, thus providing elevated potentials for speciation as more evolutionary avenues of male-female interaction are created. A less intuitively obvious theory proposes that increased sexual selection and conflict constrains speciation by reducing the opportunities for female mate choice under polyandry. We use a comparative approach to test these theories by investigating whether two general measures of sexual selection and the potential for sexual conflict have influenced speciation. Sexual size dimorphism (across 480 mammalian genera, 105 butterfly genera and 148 spider genera) and degree of polyandry (measured as relative testes size in mammals (72 genera) and mating frequency in female butterflies (54 genera)) showed no associations with the variance in speciosity. Our results therefore show that speciation occurs independently of sexual selection.

Animals↗
PubMed1997

Female house crickets, Acheta domesticus, prefer the chirps of large males.

This study demonstrates that invertebrate acoustic signals can provide information about male phenotypic attributes, and that females can use this acoustic information in mate choice to select a phenotypically superior mate. I investigated the relationships between a male acoustic sexual signal, the phenotype of the signaller, and the female response to signal variation. I recorded and analysed the calling songs of male house crickets, Acheta domesticus. The analyses showed that chirps convey information about male size. With the exception of amplitude, the mean number of pulses per chirp was the best predictor of male size. I performed a laboratory tape-playback experiment to determine female preference during phonotaxis. Females preferred tapes playing the chirps of large males, specifically chirps with a greater number of pulses per chirp. Selection on the female preference is discussed.Copyright 1997 The Association for the Study of Animal Behaviour

Journal Article↗
PubMed2006

Cytonuclear disequilibria in a spatially structured hybrid zone.

A hybrid zone model was developed that uses a stepping-stone model of population structure along with both nuclear and cytoplasmic genotypes to evaluate the effect that migration has on random mating organisms when no selection is present. Numerical simulations indicate that a number of different allele frequency and cytonuclear disequilibrium patterns can be found across the hybrid zone when it has reached equilibrium, and these results are discussed in the context of relative migration rates of the two sexes and the two source populations. The importance of numbers of subpopulations sampled, census time, and the persistence of pure species individuals into the hybrid zone are also discussed. Although this model does not consider selection or assortative mating in the hybrid zone, it should provide a useful baseline for evaluating joint cytonuclear genetic data from a structurally complex hybrid zone.

Animals↗
PubMed2000

Emergence and maintenance of sex among diploid organisms aided by assortative mating.

Using computer simulations I studied the simultaneous effect of variable environments, mutation rates, ploidy, number of loci subject to evolution and random and assortative mating on various reproductive systems. The simulations showed that mutants for sex and recombination are evolutionarily stable, displacing alleles for monosexuality in diploid populations mating assortatively under variable selection pressure. Assortative mating reduced excessive allelic variance induced by recombination and sex, especially among diploids. Results suggest a novel adaptive value for sex and recombination. They show that the adaptive value of diploidy and that of the segregation of sexes is different to that of sex and recombination. The results suggest that the emergence of sex had to be preceded by the emergence of diploid monosexual organisms and provide an explanation for the emergence and maintenance of sex among diploids and for the scarcity of sex among haploid organisms.

Animals↗
PubMed1976

Boar management.

Many boar problems result from an insufficient number of boars in relation to the number of sows in the herd, sexually immature boars, inadequately preconditioned or improperly managed boars. The following factors which determine optimum boar efficiency are discussed: (a) sexual development and mating behaviour, (b) selection, (c) preconditioning, (d) mating systems, (e) examination and culling.

Animals↗
PubMed2003

The evolution of wing color: male mate choice opposes adaptive wing color divergence in Colias butterflies.

Correlated evolution of mate signals and mate preference may be constrained if selection pressures acting on mate preference differ from those acting on mate signals. In particular, opposing selection pressures may act on mate preference and signals when traits have sexual as well as nonsexual functions. In the butterfly Colias philodice eriphyle, divergent selection on wing color across an elevational gradient in response to the thermal environment has led to increasing wing melanization at higher elevations. Wing color is also a long-range signal used by males in mate searching. We conducted experiments to test whether sexual selection on wing melanization via male mate choice acts in the same direction as natural selection on mate signals due to the thermal environment. We performed controlled mate choice experiments in the field over an elevational range of 1500 meters using decoy butterflies with different melanization levels. Also, we obtained a more direct estimate of the relation between wing color and sexual selection by measuring mating success in wild-caught females. Both our experiments showed that wing melanization is an important determinant of female mating success in C. p. eriphyle. However, a lack of elevational variation in male mate preference prevents coevolution of mate signals and mate preference, as males at all elevations prefer less-melanized females. We suggest that this apparently maladaptive mate choice may be maintained by differences in detectability between the morphs or by preservation of species recognition.

Animals↗
PubMed2004

Toward a theory of marker-assisted gene pyramiding.

We investigate the best way to combine into a single genotype a series of target genes identified in different parents (gene pyramiding). Assuming that individuals can be selected and mated according to their genotype, the best method corresponds to an optimal succession of crosses over several generations (pedigree). For each pedigree, we compute the probability of success from the known recombination fractions between the target loci, as well as the number of individuals (population sizes) that should be genotyped over successive generations until the desired genotype is obtained. We provide an algorithm that generates and compares pedigrees on the basis of the population sizes they require and on their total duration (in number of generations) and finds the best gene-pyramiding scheme. Examples are given for eight target genes and are compared to a reference genotype selection method with random mating. The best gene-pyramiding method combines the eight targets in three generations less than the reference method while requiring fewer genotypings.

Algorithms↗
PubMed1992

Ampicillin tolerance of Legionella pneumophila for counter-selection of transconjugants in heterospecific matings with Escherichia coli donors.

Legionella pneumophila, the causative agent of Legionnaires' disease is sensitive to ampicillin. However, the slowly growing bacteria are not killed even by high doses of this antibiotic. This natural tolerance was used for counter-selection of trans-conjugants in heterospecific matings with Escherichia coli as donor. This approach is useful for gentic manipulations in Legionella, as it avoids the use of antibiotic-resistant variants, which have to be tested for full virulence before use.

Ampicillin↗
PubMed1980

Multiple matings, effective population size and sexual selection in Drosophila melanogaster.

The distribution of sexually efficient males has been analysed in two populations made up of 5 times more females than males. When observation stops as soon as the number of inseminated females equals the number of males, 25 per cent of males in both strains had not mated, 50 per cent of the matings were performed by 50 per cent of the males who mated only once and the other 50 per cent of matings were performed by 25 per cent of the males who mated 2 or 3 times. Productivity of the successive matings falls drastically after the third mating. The relative role of sexual selection and multiple matings as components of fitness are discussed, as well as their implications for the effective population size.

Animals↗
PubMed1977

Social organization and mating success in local song populations of village indigobirds, Vidua chalybeata.

Behavioral interactions among color-marked individual Vidua chalybeata that shared common song dialects were observed for 5 years in two populations at Lochinvar National Park, Zambia. Social interactions involved males visiting and competing for mating sites and female visiting male in an apparent sampling of potential copulating partners. Differences in mating success among the polygynous males were compared with male behavior and territory resources, and criteria were developed to test the importance of intrasexual male competition and female mate choice in explaining the mating system of the populations. Song behavior best explained differences in mating success of males, with lesser effects of neighboring males and the defensible resources around the call-sites. The social organization of song populations resembles that of a dispersed lek with females visiting many males but mating with few males. We discuss the observations on indigobirds in relation to behavioral selection, sexual selection, and mating systems. Mating systems of certain populations and species are compared using statistics of individual mating success.

Aggression↗
PubMed2005

Character displacement as the "best of a bad situation": fitness trade-offs resulting from selection to minimize resource and mate competition.

Character displacement has long been considered a major cause of adaptive diversification. When species compete for resources or mates, character displacement minimizes competition by promoting divergence in phenotypes associated with resource use (ecological character displacement) or mate attraction (reproductive character displacement). In this study, we investigated whether character displacement can also have pleiotropic effects that lead to fitness trade-offs between the benefits of avoiding competition and costs accrued in other fitness components. We show that both reproductive and ecological character displacement have caused spadefoot toads to evolve smaller body size in the presence of a heterospecific competitor. Although this shift in size likely arose as a by-product of character displacement acting to promote divergence between species in mating behavior and larval development, it concomitantly reduces offspring survival, female fecundity, and sexual selection on males. Thus, character displacement may represent the "best of a bad situation" in that it lessens competition, but at a cost. Individuals in sympatry with the displaced phenotype will have higher fitness than those without the displaced trait because they experience reduced competition, but they may have reduced fitness relative to individuals in allopatry. Such a fitness trade-off can limit the conditions under which character displacement evolves and may even increase the risk of "Darwinian extinction" in sympatric populations. Consequently, character displacement may not always promote diversification in the manner that is often expected.

Animals↗
PubMed1989

Quantitative genetic analysis of longitudinal trends in adoption designs with application to IQ in the Colorado Adoption Project.

A factor model is presented that provides for either multivariate or developmental specification of longitudinal genetic and environmental effects in the presence of assortative mating and cultural transmission. Delta path methods are employed for the treatment of assortative mating and selective placement effects. The proportions of genetic and environmental variance and covariance attributable to assortative mating and cultural transmission are modeled explicitly. The model was applied to cognitive ability data on 493 families in the Colorado Adoption Project by means of maximum-likelihood pedigree analysis. A test of the assumption of multivariate normality of error provided an additional model criterion beyond the log-likelihood ratio statistic. No significant effects were found for cultural transmission, genetic-environmental covariance, or selective placement. The results suggest that the phenotypic stability of IQ during early childhood is largely, if not entirely, genetic in origin and that these longitudinal genetic effects can be represented most parsimoniously in the form of developmental transmission.

Adoption↗
PubMed2001

Sexual dimorphism in primate evolution.

Sexual dimorphism is a pervasive phenomenon among anthropoid primates. Comparative analyses over the past 30 years have greatly expanded our understanding of both variation in the expression of dimorphism among primates, and the underlying causes of sexual dimorphism. Dimorphism in body mass and canine tooth size is familiar, as is pelage and "sex skin" dimorphism. More recent analyses are documenting subtle differences in the pattern of skeletal dimorphism among primates. Comparative analyses have corroborated the sexual selection hypotheses, and have provided a more detailed understanding of the relationship between sexual selection, natural selection, and mating systems in primates. A clearer picture is emerging of the relative contribution of various selective and nonselective mechanisms in the evolution and expression of dimorphism. Most importantly, recent studies have shown that dimorphism is the product of changes in both male and female traits. Developmental studies demonstrate the variety of ontogenetic pathways that can lead to dimorphism, and provide additional insight into the selective mechanisms that influence dimorphism throughout the lifetime of an animal. Evidence from the fossil record suggests that dimorphism probably evolved in parallel twice, and the dimorphism in some extinct hominoids probably exceeded that of any living primate. Our advances in understanding the behavioral/ecological correlates of dimorphism in living primates have not improved our ability to reconstruct social systems in extinct species on the basis of dimorphism alone, beyond the inference of polygyny or intense male-male competition. However, our understanding of the behavioral/ecological correlates of growth and development, and of the expression of dimorphism as a function of separate changes in male and female traits, offers great potential for inferring evolutionary changes in behavior over time.

Animals↗
PubMed2005

Male reproductive physiology as a sexually selected handicap? Erectile dysfunction is correlated with general health and health prognosis and may have evolved as a marker of poor phenotypic quality.

Many extravagant physical traits are selected because they are used as cues for mate choice (sexual selection). Why is mate choice driven by costly ornaments? A theory of sexual selection posits that extravagant traits are preferred because are reliable indicators of superior (heritable) phenotypic quality. In particular, the preferred traits can be expressed only in individuals with superior conditions because are handicaps which impose a high cost to the carrier. The human penis achieves its reproductive function by the complex neuro-vascular mechanisms that controls erection. Surprisingly, erectile dysfunction and infertility, two condition which nearly annihilate fitness, are widespread medical conditions which affect millions of people of any age worldwide. The very high incidence of erectile dysfunction appears as an evolutionary paradox. Impotence is associated with all major systemic diseases as well depression and stress. Stress is also one of the causes of infertility. Therefore, male reproduction appears to be extremely sensitive to internal and external stressors. Moreover, erectile dysfunction is a predictor of myocardial infarction and stroke, whereas men with regular sexual activity have lower risk of death due to coronary disease. This large body of medical literature makes erection the best case for a fitness indicator in the human male. We suggest that the fragility of male sexual physiology observed in modern society is the specific consequence of an evolutionary process driven by the handicap principle.

Animals↗
PubMed2000

Mental traits as fitness indicators. Expanding evolutionary psychology's adaptationism.

According to most evolutionary psychologists, human psychological adaptations can be recognized by criteria such as high efficiency, high complexity, high modularity, low phenotypic variance, low genotypic variance, low heritability, universality across cultures, and universality across individuals. These criteria are appropriate for adaptations that have been shaped through stabilizing selection for survival utility. However, they are often inappropriate for adaptations that have been shaped by sexual selection through mate choice as reliable signals of heritable fitness. If some psychological adaptations evolved as sexually selected fitness indicators of this type, we should expect them to violate many standard criteria used by evolutionary psychology to distinguish adaptations from non-adaptations. This paper addresses the problems raised by new developments in sexual selection theory and animal signaling theory for evolutionary psychology's adaptationism. It suggests that our adaptationist criteria must recognize two typical kinds of psychological adaptations: naturally selected survival mechanisms and sexually selected fitness indicators.

Adaptation, Psychological↗