Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Copulation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,675 records · Page 93Linked to original sources
PubMed2001

Hybridization and adaptive mate choice in flycatchers.

Hybridization in natural populations is strongly selected against when hybrid offspring have reduced fitness. Here we show that, paradoxically, pairing with another species may offer the best fitness return for an individual, despite reduced fitness of hybrid offspring. Two mechanisms reduce the costs to female collared flycatchers of pairing with male pied flycatchers. A large proportion of young are sired by conspecific male collared flycatchers through extra-pair copulations, and there is a bias in favour of male offspring (which, unlike females, are fertile) within hybrid pairs. In combination with temporal variation in breeding success, these cost-reducing mechanisms yield quantitative predictions about when female collared flycatchers should accept a male pied flycatcher as a mate; empirical data agree with these predictions. Apparent hybridization may thus represent adaptive mate choice under some circumstances.

Adaptation, Physiological↗
PubMed2001

Sexual selection. Are ducks impressed by drakes' display?

Surprisingly few birds have penises, but among those that do, the Argentine lake duck (Oxyura vittata) tops the bill - the penis of this small stifftail duck from South America is shaped like a corkscrew and, at almost half a metre long, is the largest of any bird measured so far. Factors responsible for the evolution of this remarkable organ could include runaway selection, whereby drakes with longer penises gain dominance and copulate with more females, or preference by females for drakes with longer and more decorated penises.

Animals↗
PubMed2000

Reduced vas deferens contraction and male infertility in mice lacking P2X1 receptors.

P2X1 receptors for ATP are ligand-gated cation channels, present on many excitable cells including vas deferens smooth muscle cells. A substantial component of the contractile response of the vas deferens to sympathetic nerve stimulation, which propels sperm into the ejaculate, is mediated through P2X receptors. Here we show that male fertility is reduced by approximately 90% in mice with a targeted deletion of the P2X1 receptor gene. Male mice copulate normally--reduced fertility results from a reduction of sperm in the ejaculate and not from sperm dysfunction. Female mice and heterozygote mice are unaffected. In P2X1-receptor-deficient mice, contraction of the vas deferens to sympathetic nerve stimulation is reduced by up to 60% and responses to P2X receptor agonists are abolished. These results show that P2X1 receptors are essential for normal male reproductive function and suggest that the development of selective P2X1 receptor antagonists may provide an effective non-hormonal male contraceptive pill. Also, agents that potentiate the actions of ATP at P2X1 receptors may be useful in the treatment of male infertility.

Animals↗
PubMed1992

Genetic basis for female receptivity in Drosophila melanogaster: a diallel study.

Receptivity of sexually mature, virgin females, measured as the time to copulation, has been investigated. Two independent 5 x 5 diallel crosses were carried out, each one with a different male tester genotype. Interactions between male and female genotypes were detected because some lines appeared as dominant in one diallel and recessive in the other. The overall picture emerging from the analyses shows a genetic system for female receptivity characterized by additive genes, with dominance for high receptivity in one of the diallel crosses. This remarkable additive component does not support the action of natural selection favouring females with extreme values of receptivity, rather, the lack of intrasexual female competition for mates is suggested.

Alleles↗
PubMed1992

The evolutionary history of Drosophila buzzatii. XXV. Random mating in nature.

Using allozymes as the genetic probe, data are presented which show that wild Drosophila buzzatii females and males engaged in copulation mate at random. Hence, putative inbreeding due to local mating of genetically related flies emerging from the patchy distributed substrates, was not detected. We conclude that individuals raised from a niche disperse and mate at random with other members of the population, so only one round of drift due to the colonization of suitable and ephemeral breeding sites is taking place.

Alleles↗
PubMed1994

Postcopulatory, prezygotic isolation: intraspecific and interspecific sperm precedence in Tribolium spp., flour beetles.

We investigated intraspecific and interspecific patterns of paternity in Tribolium castaneum, the flour beetle, by mating females either to pairs of conspecific males or to one conspecific and one heterospecific male of the closely related species, T. freemani. Females of both species store sperm in the spermatheca after copulation and postcopulatory, prezygotic reproductive isolation has been reported between this pair of species. When conspecific males of contrasting genotype are mated simultaneously to T. castaneum females, we observed extremely high levels of variation among females in the pattern of sperm precedence as shown by the offspring genotypes. In contrast, T. castaneum females mated simultaneously to a conspecific and a heterospecific male produced over 99 per cent conspecific progeny. When conspecific males were mated sequentially to T. castaneum females, within 3-7 days, all offspring were sired by the second male. In contrast, when a conspecific male was replaced with a T. freemani male, most females continued to produce only first-male, conspecific offspring for the next 10 days. When a heterospecific male was replaced with a conspecific male, T. castaneum females changed from producing hybrid to conspecific offspring within 3 days. We discuss the evolutionary implications of these findings.

Animals↗
PubMed2002

Genetic similarity between mates and extra-pair parentage in three species of shorebirds.

Matings between close relatives often reduce the fitness of offspring, probably because homozygosity leads to the expression of recessive deleterious alleles. Studies of several animals have shown that reproductive success is lower when genetic similarity between parents is high, and that survival and other measures of fitness increase with individual levels of genetic diversity. These studies indicate that natural selection may favour the avoidance of matings with genetically similar individuals. But constraints on social mate choice, such as a lack of alternatives, can lead to pairing with genetically similar mates. In such cases, it has been suggested that females may seek extra-pair copulations with less related males, but the evidence is weak or lacking. Here we report a strong positive relationship between the genetic similarity of social pair members and the occurrence of extra-pair paternity and maternity ('quasi-parasitism') in three species of shorebirds. We propose that extra-pair parentage may represent adaptive behavioural strategies to avoid the negative effects of pairing with a genetically similar mate.

Adaptation, Biological↗
PubMed2003

Captivity masks inbreeding effects on male mating success in butterflies.

Small isolated populations are frequently genetically less diverse than core populations, resulting in higher homozygosity that can hamper their long-term survival. The decrease in fitness of organisms owing to matings between relatives is well known from captive and laboratory animals. Such inbreeding can have strongly deleterious effects on life-history traits and survival, and can be critical to the success of population conservation. Because pedigrees are hard to follow in the wild, most field studies have used marker loci to establish that fitness declines with increasing homozygosity. Very few have experimentally explored the effects of inbreeding in the wild, or compared observations in the laboratory with field conditions. Here, using a technique involving the transfer of marker dusts during copulation, we show that a small decrease in mating success of captive inbred male butterflies in cages is greatly accentuated in conditions with unconstrained flight. Our results have important implications for conservation and for studies of sexual selection because they show that the behaviours underlying patterns of mating can be profoundly influenced by a history of inbreeding or by any restraining experimental conditions.

Animals↗
PubMed2004

Expression and function of orphan nuclear receptor TLX in adult neural stem cells.

The finding of neurogenesis in the adult brain led to the discovery of adult neural stem cells. TLX was initially identified as an orphan nuclear receptor expressed in vertebrate forebrains and is highly expressed in the adult brain. The brains of TLX-null mice have been reported to have no obvious defects during embryogenesis; however, mature mice suffer from retinopathies, severe limbic defects, aggressiveness, reduced copulation and progressively violent behaviour. Here we show that TLX maintains adult neural stem cells in an undifferentiated, proliferative state. We show that TLX-expressing cells isolated by fluorescence-activated cell sorting (FACS) from adult brains can proliferate, self-renew and differentiate into all neural cell types in vitro. By contrast, TLX-null cells isolated from adult mutant brains fail to proliferate. Reintroducing TLX into FACS-sorted TLX-null cells rescues their ability to proliferate and to self-renew. In vivo, TLX mutant mice show a loss of cell proliferation and reduced labelling of nestin in neurogenic areas in the adult brain. TLX can silence glia-specific expression of the astrocyte marker GFAP in neural stem cells, suggesting that transcriptional repression may be crucial in maintaining the undifferentiated state of these cells.

Aging↗
PubMed2004

Population density drives the local evolution of a threshold dimorphism.

Evolution can favour more than one reproductive tactic among conspecifics of the same sex. Under the conditional evolutionarily stable strategy, individuals adopt the tactic that generates the highest fitness return for their status: large males guard females, whereas small males sneak copulations. Tactics change at the status at which fitness benefits switch from favouring one tactic to favouring the alternative. This 'switchpoint' is expressed in many species as a threshold between divergent morphologies. Environmental and demographic parameters that influence the relative fitness of male tactics are predicted to determine a population's switchpoint and consequently whether the population is monomorphic or dimorphic. Here we show threshold evolution in the forceps dimorphism of the European earwig Forficula auricularia and document the transition from completely monomorphic to classical male-dimorphic populations over a distance of only 40 km. Because the superior fighting ability of the dominant morph will be more frequently rewarded at high encounter rates, population density is likely to be a key determinant of the relative fitness of the alternative tactics, and consequently the threshold. We show that, as predicted, population density correlates strongly with the shift in threshold, and that this factor drives the local evolution of the male dimorphism in these island populations. Our data provide evidence for the origin of phenotypic diversity within populations, through the evolution of a switchpoint in a conditional strategy that has responded to local population density.

Animals↗
PubMed2005

Kin selection and cooperative courtship in wild turkeys.

In the few species of birds in which males form display partnerships to attract females, one male secures most or all of the copulations. This leads to the question of why subordinate males help in the absence of observable reproductive benefits. Hamilton's concept of kin selection, whereby individuals can benefit indirectly by helping a relative, was a crucial breakthrough for understanding apparently altruistic systems. However in the only direct test of kin selection in coordinated display partnerships, partners were unrelated, discounting kin selection as an explanation for the evolution of cooperation. Here I show, using genetic measures of relatedness and reproductive success, that kin selection can explain the evolution of cooperative courtship in wild turkeys. Subordinate (helper) males do not themselves reproduce, but their indirect fitness as calculated by Hamilton's rule more than offsets the cost of helping. This result confirms a textbook example of kin selection that until now has been controversial and also extends recent findings of male relatedness on avian leks by quantifying the kin-selected benefits gained by non-reproducing males.

Altruism↗
PubMed2004

Effect of nicotine exposure during gestation on neonatal rat crystalline lenses.

PURPOSE: To assess histologically the influence of maternal nicotine exposure during gestation in vivo on crystalline lenses in neonatal rats using different dosages of the test compound simulating the range of low, moderate, and heavy smokers in humans. METHODS: Experimentally naive, adult female Wistar-albino rats (200-250 g) were mated with adult male rats over 2 days for copulation in the proportion of two females for every male animal. After confirming pregnancy with vaginal smear method, 40 gravid rats (dams) were then randomly assigned into four equal groups (three experimental and one control; n=10 in each). Groups 1, 2, and 3 experimental dams were treated with intraperitoneal (i.p.) (-)-nicotine tartrate at doses of 0.5, 1, and 2 mg/kg body weight/day, respectively, during pregnancy from gestational days 9 through 21. Group 4 control dams were given i.p. saline solution daily for the same period. After normal delivery, the eyes were removed at postnatal day 1 or day 30 for macroscopic and histopathologic investigation of the lenses. RESULTS: Control and group 1 litters had normal anterior lens capsules with a single layer of anterior cuboidal epithelial cells, regularly orientated cortical and nuclear lens fibres, and a clear posterior lens capsule with no lining epithelial cells behind the equator. On the other hand, some lenses in groups 2 and 3 litters had mature or immature cataract macroscopically at postnatal 30th day. Histopathologic findings suggesting cataractogenesis included cortical lens fibre cell swelling and liquefaction, prominent epithelial cells lining the posterior lens capsule behind the equator, and the retention of lens nuclei into the deeper and central area. Moreover, some lenses were immature developmentally, indicating arrested lenticular embryogenesis at vesicle stage. CONCLUSIONS: Nicotine exposure during pregnancy has teratogenic and cataractogenic effects on developing crystalline lenses in neonatal rats both macroscopically and histopathologically. If appropriate dose of nicotine can be identified, nicotine-induced cataract formation may possibly be used as a new experimental cataract model in animal studies. Therefore, future studies are needed in this respect. Eye (2004) 18, 67-73. doi:10.1038/sj.eye.6700511

Abnormalities, Drug-Induced↗
PubMed2002

Combining DNA sequences and morphology in systematics: testing the validity of the dragonfly species Cordulegaster bilineata.

Morphological and molecular techniques are rarely combined when answering questions of taxonomic validity. In this study, we combine morphological techniques with DNA sequences to determine the validity of the dragonfly species Cordulegaster bilineata. The two dragonfly species C. bilineata and C. diastatops are very similar in size, body color, and morphological characters, and due to these similarities, the status of C. bilineata as a valid species is in question. In this study we compare morphological measurements of males and internal transcribed spacer 1 (ITS-1) sequences of rDNA between the two taxa. The hamule measurements (where copulation occurs) of males show little difference between the taxa in question, but the anal appendage measurements (where the male first contacts the female) show marked divergence between the two taxa. Cluster analysis with these anal appendage measurements correctly assigns almost all individuals measured into their respective taxon. PCR amplification products of ITS-1 display a approximately 50 bp size difference between C. bilineata (n = 4) and C. diastatops (n = 5) regardless of collection site. Sequence data for these amplifications show 51 bp missing in one locus in the ITS-1 of C. bilineatarelative to C. diastatops. A lone population of C. diastatops from Wisconsin has three individuals with ITS-1 products that match the size of both C. bilineata and C. diastatops. One individual from this population appears to yield two ITS-1 amplification products that match both C. bilineata and C. diastatops. Although this population may be evidence for hybridization between the two taxa, such hybridization is not necessarily sufficient to disqualify the validity of a separate species designation for C. bilineata. Morphology and ITS-1 sequences depict a high degree of divergence that is consistent with species-level differences.

Animals↗
PubMed2006

The quantitative genetic basis of polyandry in the parasitoid wasp, Nasonia vitripennis.

Understanding the evolution of female multiple mating (polyandry) is crucial for understanding sexual selection and sexual conflict. Despite this interest, little is known about its genetic basis or whether genetics influences the evolutionary origin or maintenance of polyandry. Here, we explore the quantitative genetic basis of polyandry in the parasitoid wasp Nasonia vitripennis, a species in which female re-mating has been observed to evolve in the laboratory. We performed a quantitative genetic experiment on a recently collected population of wasps. We found low heritabilities of female polyandry (re-mating frequency after 18 h), low heritability of courtship duration and a slightly higher heritability of copulation duration. However, the coefficients of additive genetic variance for these traits were all reasonably large (CV(A)>7.0). We also found considerable dam effects for all traits after controlling for common environment, suggesting either dominance or maternal effects. Our work adds to the evidence that nonadditive genetic effects may influence the evolution of mating behaviour in Nasonia vitripennis, and the evolution of polyandry more generally.

Animals↗
PubMed2006

The Influence of prolonged beta-blockers treatment on male rabbit's sexual behavior and penile microcirculation.

The aim of the study was to assess the effect of the prolonged intake of three beta-blocking drugs (propranolol, metoprolol and nebivolol) on the sexual behavior and penile microcirculation of rabbits. Drugs were administered p.o. for 9 weeks and every three weeks in each group (n=13) one subgroup (n=7) performed behavioral tests, whereas in the second subgroup (n=6) penile microcirculation was measured with a laser Doppler flowmeter. The copulation studies revealed significant impairment of sexual function only in the propranolol treated group. The measured behavioral parameters suggest that at a given dose propranolol affects more performance rather than arousal aspects of rabbits' sexual behavior. In the course of the whole study no significant difference was observed among groups in penile blood flow. The data indicate that among the beta-blockers given only propranolol interferes with sexual behavior, and that beta-blockers do not appear to have a negative effect on penile microcirculation.

Adrenergic beta-Antagonists↗
PubMed2005

Chemosensory cues are essential for mating-induced dopamine release in MPOA of male Syrian hamsters.

The medial preoptic area (MPOA) is crucial for male sex behavior. Dopamine (DA) is released in MPOA during copulation, and contributes to the reinforcing effects of mating. The aim of the present study was to identify sensory stimuli responsible for mating-induced DA release. Specifically, we determined if chemosensory cues are essential for mating-induced MPOA DA release using in vivo microdialysis in male Syrian hamsters. Hamsters were used because chemosensory cues from the olfactory mucosa and vomeronasal organ are essential for sexual behavior in this species. Sexually experienced adult male hamsters were implanted with a microdialysis guide cannula over MPOA. At the same time, males received sham olfactory bulbectomy (Sham Bx, n = 11), bilateral bulbectomy (Bibx, n = 6), or unilateral bulbectomy (Ubx) ipsilateral (Ipsi Ubx, n = 9) or contralateral (Contra Ubx, n = 8) to the microdialysis probe. This model takes advantage of the predominantly ipsilateral projections of the olfactory bulbs. Microdialysis samples were collected from the MPOA during baseline, exposure to a receptive female, and after removal of female. Extracellular DA was measured using high-performance liquid chromatography with electrochemical detection. During mating, DA increased in MPOA of Sham Bx males (to 146.7 +/- 17.5% of baseline). Bibx males did not mate, and MPOA DA did not increase (96.1 +/- 15.8% of baseline). Although both groups of Ubx males mated to ejaculation, MPOA DA increased significantly only in Contra Ubx males (to 161.8 +/- 35.3% of baseline), and not in males with Ipsi Ubx (107.6 +/- 11.5% of baseline). The results demonstrate that chemosensory cues are essential for MPOA DA release during mating in male Syrian hamsters.

Analysis of Variance↗
PubMed1967

The proteins and protein-bound carbohydrates of the serum of the developing pig.

1. The concentrations of total nitrogen, hexosamine and protein-bound hexose and the amounts of these constituents precipitated by trichloroacetic acid were determined in the serum of pigs at various ages from 57 days after copulation to 42 days after birth. The concentrations of the same constituents were also determined in the serum of mature pigs. 2. A rise in the concentrations of total nitrogen, hexosamine and protein-bound hexose between 90 days' gestation and term was entirely due to material soluble in trichloroacetic acid. This material disappeared from the serum by 7 days after birth. 3. Electrophoresis of the serum proteins showed that the concentration of alpha(1)-globulin fell steadily during gestation, being lower at term than at 57 days' gestation. No alpha(1)-globulin was detected at 7 days of age. 4. It was concluded that high values for non-protein nitrogen in the serum of newborn piglets, determined after precipitation of the proteins with trichloroacetic acid, is largely due to the presence of one or more mucoproteins and not to alpha(1)-globulin. 5. The protein migrating in the alpha(1)-globulin position is possibly a foetal protein of the fetuin type.

Alpha-Globulins↗
PubMed2002

Distribution of androgen receptor mRNA expression and immunoreactivity in the brain of the green anole lizard.

Male courtship and copulation are androgen dependent in the green anole lizard, and female receptivity can be facilitated by testosterone. However, only a few, and relatively large, regions in the brain have been implicated in the control of these behaviours. In situ hybridization and immunohistochemistry were therefore used to determine in detail where androgens are likely to act in the brains of breeding males and females. A 697-bp fragment of the anole androgen receptor (AR) was cloned from total RNA isolated from the kidney, which contains the highly androgen-sensitive renal sex segment. The cloned fragment spanned part of the C, the entire D, and part of the E domains, and shared a high degree of similarity with the AR of various species. 35S-labelled antisense and sense probes were generated from the 697-bp fragment for use in in situ hybridization, and the AR antibody PG-21 was used for immunohistochemistry. Both sexes consistently had AR mRNA expression and immunoreactivity in areas associated with vertebrate reproductive behaviours and in motor areas of the brainstem. Interestingly, the PG-21 antibody produced labelling in both the nucleus and cytoplasm, including neuronal processes. The distribution of mRNA and immunoreactivity were comparable in males and females, and the amount of labelling was generally similar, although slightly greater in females. The expression pattern of AR in this species supports the idea that distribution is highly conserved among vertebrates, but that it probably does not dictate behavioural differences between the sexes in anoles.

Amino Acid Sequence↗