Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Reproductive Isolation”

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 415 records · Page 23Linked to original sources
PubMed1988

[Analysis of the effects of oxytocin, vasopressin, angiotensin, serotonin and histamine on the blood flow in the reproductive organs of swine the during estrous cycle].

We have measured the magnitude of flow in the uterine artery (ua) and in ovarian artery (oa) in the isolated reproductive organs of pig (100-130 kg/per head) perfused with their own blood or Krebs-Henseleit's solution. The pressure was kept on the constant level 100 mm Hg. Were administered intraarterially Oxytocin (O), vasopressin (W), histamine (H), serotonin (5-HT) and hypertensin (A). Their possible influence on the processes of regulation of blood flow in the porcine reproductive organs during oestrus cycle was analysed. It was stated that O produced a decrease of blood flow (bf) in the periovulatory period (1-2 and 16-18 day of cycle). On the other hand doses many times bigger did not cause significant changes in ua in the luteal phase and in oa in all phases of the cycle. Action of O is connected with its pressing action on the uterine vessels, contracted by the smooth muscular coat of this organ. Limiting bf action of W and A is mainly connected with their direct vasoconstructive effect. Our results indicated that in physiological conditions during oestrous cycle O, W and A did not evoke significant changes in the regulation of blood flow in the porcine reproductive organs. High sensitivity of the investigated vessels on 5-HT in the luteal phase and lower sensitivity in the periovulatory phase could indicate serotonin's influence on the regulating changes of blood flow during oestrous cycle. Vessels of both investigated areas were very sensitive to H. Especially high sensitivity of oa vessels on H is correlated with an increase of sensitivity of the vessels on 5-HT and catecholamines in the luteal phase. It seem that H has significant importance as a factor antagonising influence of 5-HT and catecholamines in the luteal phase of cycle in the pig. Sensitivity of oa vessels on the investigated drugs was lower in all phases of the cycle studied than sensitivity of ua vessels, the only exception was when H was used. We observed similar reaction on used drugs, both in experiments with perfusion with the blood and with the Krebs-Henseleit's solution. It may suggest that vessels reaction depends upon the functional state of the organ and it is not directly connected with the hormones present in the blood.

Angiotensin II↗
PubMed2004

Vocal communication in frogs.

The robust nature of vocal communication in frogs has long attracted the attention of natural philosophers and their biologically inclined successors. Each frog species produces distinctive calls that facilitate pre-mating reproductive isolation and thus speciation. In many terrestrial species, a chorus of simultaneously calling males attracts females to breeding sites; reproductive females then choose and locate one male, using distinctive acoustic cues. Males compete with each other vocally and sometimes physically as well. Anuran acoustic signaling systems are thus subject to the strong pressures of sexual selection. We are beginning to understand the ways in which vocal signals are produced and decoded by the nervous system and the roles of neurally active hormones in both processes.

Animal Communication↗
PubMed1999

Developmental isolation and subsequent adult behavior of Drosophila paulistorum. V. Survey of six sibling species.

In an investigation into the effects of developmental isolation from all conspecifics, the Drosophila willistoni group of six sibling species responded to differing degrees: all six are reproductively isolated from D. paulistorum, the tester species. Drosophila pavlovskiana, a narrow endemic, proved the most vulnerable, responding by reducing its adult sexual isolation, if eggs, any instar, and sometimes even pupae were socially isolated. To lesser degrees, D. tropicalis and D. willistoni both produced similar results only when their eggs were isolated, i.e., when from the moment of egg deposition on, there was absolutely no contact with other flies until testing for mating behavior. The remaining siblings, D. equinoxialis and D. insularis, were immovable.

Animals↗
PubMed2006

Interspecific hybridization in ants: at the intersection of ecology, evolution, and behavior.

Ants are social and are haplodiploid. This combination may allow the evolution of a variety of unusual genetic pathways to achieve reproductive success. These include hybridizing across species, differential use of sperm to create a hybrid worker population, and reproductively isolated gene pools that depend on each other for their survival. Although there are demonstrable costs for colony development and reproduction, these phenomena may nevertheless be relatively common in nature. The specific ecological advantages that favor the evolution of these reproductive modes remain to be discovered.

Animals↗
PubMed1999

Evaluation of protective immunity in gilts inoculated with the NADC-8 isolate of porcine reproductive and respiratory syndrome virus (PRRSV) and challenge-exposed with an antigenically distinct PRRSV isolate.

OBJECTIVES: To determine whether intrauterine inoculation of porcine reproductive and respiratory syndrome virus (PRRSV) interferes with conception and whether exposure to one strain of PRRSV provides protection against challenge-exposure (CE) with homologous or heterologous strains of PRRSV. ANIMALS: 40 gilts. PROCEDURE: Gilts were inoculated by intrauterine administration of a PRRSV isolate (NADC-8) at breeding. Inoculated and noninoculated gilts were exposed oronasally to homologous (NADC-8) or heterologous (European isolate) PRRSV during late gestation. Specimens from gilts and fetuses were tested against CE virus. Lack of virus in gilts indicated protective immunity for the dam, in fetuses indicated protection of gilt from reproductive losses, and in both groups indicated complete protection. RESULTS: In the homologous CE group, interval from inoculation to CE ranged from 90 to 205 days, and protection was complete. In the heterologous CE group, interval from inoculation to CE ranged from 90 to 170 days, and protection was incomplete. The CE virus was detected in gilts necropsied 134 to 170 days after CE and in a litter necropsied 170 days after CE. CONCLUSIONS: Homologous protection can be induced in gilts by exposure to live PRRSV. Heterologous protection from reproductive losses can be induced in gilts by exposure to live PRRSV; however, this protection is incomplete and may have a shorter duration than homologous protection. CLINICAL RELEVANCE: Exposure of swine to enzootic PRRSV will provide protection against homologous PRRSV-induced reproductive losses. Extent and duration of protection against heterologous PRRSV may be variable and dependent on antigenic relatedness of the virus strains used for inoculation and CE.

Animals↗
PubMed1985

Symmetrical and asymmetrical sexual isolation among laboratory strains of Drosophila ananassae.

Male-choice experiments using five isofemale lines of Drosophila ananassae originating from different localities were performed to study sexual isolation within the species. In most of the crosses homogamic matings outnumber heterogamic ones, and deviation from randomness is statistically significant in 11 of 20 crosses. This provides evidence for positive assortative mating within D. ananassae. Isolation indices range from -0.057 to 0.555. Eleven positive isolation indices are significantly greater than zero. Both types of sexual isolation, symmetrical and asymmetrical, have been observed among different strains. Thus the present results clearly indicate that the laboratory strains of D. ananassae have developed behavioural reproductive isolation as a result of genetic divergence.

Animals↗
PubMed1999

Male-female interactions and socio-sexual isolation of Mus spicilegus toward two other species of east-European mice, M. macedonicus and M. m. musculus.

Social and sexual interactions were analysed as potential behavioural processes assessing reproductive isolation between the mound-building mouse, Mus spicilegus, and two other wild species, M. macedonicus and M. musculus. Dyadic encounters among strange M. spicilegus individuals and between M. spicilegus and the two other species members were conducted with females in an oestrus state. In intraspecific M. spicilegus encounters, there was a high incidence of close contact behaviours initiated by the females. In interspecific encounters M. musculus males and females and M. macedonicus females showed social interest toward their M. spicilegus protagonists, whereas the later behaved in an unfriendly or aggressive manner. Thus socio-sexual interactions shown by the different species seem to be sufficient to prevent any attempt to mate interspecifically. Arguments in favour of recognition against reinforcement hypothesis are discussed.

Analysis of Variance↗
PubMed1994

Host fidelity is an effective premating barrier between sympatric races of the apple maggot fly.

Models of sympatric speciation for phytophagous insects posit a central role for host plant-associated mating as a premating isolating mechanism in lieu of geographic barriers to gene flow. Here, by means of three mark-and-recapture studies, we confirm that host fidelity (i.e., the tendency of an insect to reproduce on the same host species that it used in earlier life-history stages) restricts gene flow between sympatric apple- and hawthorn-infesting races of Rhagoletis pomonella (Diptera: Tephritidae) to approximately 6% per generation. Genetically based differences in host preference, adult eclosion under the "correct" host species, and allochronic isolation contribute to host fidelity in various degrees in the races. The results verify that host-associated adaptation can produce reproductive isolation as a correlated character (a key premise of sympatric speciation). The study also represents one of the few or perhaps only example in animals where the intra-specific isolating effects of specific phenotypes have been quantified in nature.

Journal Article↗
PubMed2005

Sexual isolation and cuticular hydrocarbon differences between Drosophila santomea and Drosophila yakuba.

Drosophila santomea and Drosophila yakuba are two sister species inhabiting Saõ Tomé island. Previous studies showed that both species display strong reproductive isolation, although they can produce a few viable hybrids. Our study tried to understand the mechanism of this ethological isolation between two allopatric strains. A strong sexual isolation was confirmed, with a marked asymmetry. Comparisons of latency times to either courtship or copulation suggest that males do not discriminate females, whereas D. yakuba females, but not D. santomea females, accept their homospecifics more quickly. Cuticular hydrocarbon compositions of both species and sexes were also established with gas chromatography (GC) and GC/mass spectrometry analysis. All have (Z)-7-tricosene as their major compound. There are several quantitative differences between species for few minor compounds. The largest difference concerns n-heneicosane, which is more abundant in D. santomea than in D. yakuba flies (up to seven times more between males). A similar quantitative difference was also found in a pair of sympatric strains. Furthermore, D. yakuba males artificially perfumed with n-heneicosane were discriminated negatively by D. yakuba females, suggesting a role for this compound in the sexual isolation between these two species.

Alkenes↗
PubMed2004

Biogeographic patterns and current distribution of molecular-genetic variation among populations of speckled dace, Rhinichthys osculus (Girard).

We examined genetic diversity within- and among-populations of speckled dace (Rhinichthys osculus) in five major drainage systems in the state of Oregon in western North America. Analysis of sequence variation in a 670-bp segment of the mitochondrial cytochrome b gene revealed deep divergence among basins and high genetic diversity within basins. Application of a molecular clock indicated that the divergence time among basins reflects vicariant events during the late Miocene to early Pliocene. The high levels of genetic diversity observed within basins is likely due to large historic population sizes, in particular, within the Klamath Basin. Two highly divergent mtDNA lineages were found to co-occur in populations in the Klamath Basin. This result may be indicative of a complex history of isolation and reconnection in this basin and/or multiple colonization events. Based on the observed level of mtDNA divergence these lineages may represent two reproductively isolated sympatric taxa. We recommend that major basins be regarded as distinct ESUs based on high levels of subdivision, deep divergences, and reciprocal monophyly among basins.

Animals↗
PubMed2005

Transgene escape: what potential for crop-wild hybridization?

To date, regional surveys assessing the risk of transgene escape from GM crops have focused on records of spontaneous hybridization to infer the likelihood of crop transgene escape. However, reliable observations of spontaneous hybridization are lacking for most floras, particularly outside Europe. Here, we argue that evidence of interspecific reproductive compatibility derived from experimental crosses is an important component of risk assessment, and a useful first step especially where data from field observations are unavailable. We used this approach to assess the potential for transgene escape via hybridization for 123 widely grown temperate crops and their indigenous and naturalized relatives present in the New Zealand flora. We found that 66 crops (54%) are reproductively compatible with at least one other indigenous or naturalized species in the flora. Limited reproductive compatibility with wild relatives was evident for a further 12 crops (10%). Twenty-five crops (20%) were found to be reproductively isolated from all their wild relatives in New Zealand. For the remaining 20 crops (16%), insufficient information was available to determine levels of reproductive compatibility with wild relatives. Our approach may be useful in other regions where spontaneous crop-wild hybridization has yet to be well documented.

Crops, Agricultural↗
PubMed1997

Mucosal immunity in the human female reproductive tract: cytotoxic T lymphocyte function in the cervix and vagina of premenopausal and postmenopausal women.

PROBLEM: To investigate the mucosal immune system in the cervix and vagina of premenopausal women in terms of immune cells present and cytolytic capacity of mucosal CD3+ T cells in the lower reproductive tract. METHODS: Fresh tissue fragments prepared by vibratome sectioning were analyzed for the presence of cells by confocal scanning laser microscopy (CSLM). Isolated reproductive tract cells prepared by enzymatic were analyzed for CD3+ T cell phenotype by FACS analysis and for cytolytic function by an anti-CD3 mAb mediated redirected lysis assay. RESULTS: As determined by CSLM, CD3+ cells as well as macrophages and dendritic cells are distributed throughout the lower female reproductive tract in both the epithelium and subepithelial mucosa. It was found that cervical and vaginal tissues from pre- and post-menopausal women contain CD3+ T cells (CTL) that have cytolytic activity, when measured in an antigen non-specific anti-CD3 mAb mediated redirected lysis assay. CONCLUSIONS: These results indicate that the lower reproductive tract of women is immuno-competent as judged by the presence of CD3, CD4, CD8, macrophage, and dendritic cells in the endocervix, ectocervix, and vagina of premenopausal and postmenopausal women. Further, these studies demonstrate that CD3+ T cells with cytolytic activity are present in the cervix and vagina during the proliferative and secretory phases of the menstrual cycle and following menopause.

CD3 Complex↗
PubMed2004

Testing alternative models for sexual isolation in natural populations of Littorina saxatilis: indirect support for by-product ecological speciation?

Two ecotypes of the rough periwinkle Littorina saxatilis occur at different shore levels, showing assortative mating for size and partial reproductive isolation when they meet at the mid-shore. This system represents a putative case of incomplete speciation in sympatry. Two processes contribute to the assortative mating: morph-specific microhabitat aggregation and mate choice. The estimation of mate choice coefficients in nature and a simulation of the aggregation effects on sexual isolation were used to disentangle these processes as well as to test alternative mechanisms of mate choice. Mate choice significantly increased the frequency of within-morph pairs and significantly decreased the frequency of between-morph pairs, whereas those pairs including at least one hybrid morph mated randomly. These results allow us to reject a discriminant mate choice and support a model of evolution of sexual isolation as a side-effect of size-assortative mating in a context of divergent natural selection for size in the population. This mechanism is more compatible with a model of incomplete by-product ecological speciation, as suggested by previous evidence.

Animals↗
PubMed2006

The evolution of host preference in allopatric vs. parapatric populations of Timema cristinae walking-sticks.

Divergent habitat preferences can contribute to speciation, as has been observed for host-plant preferences in phytophagous insects. Geographic variation in host preference can provide insight into the causes of preference evolution. For example, selection against maladaptive host-switching occurs only when multiple hosts are available in the local environment and can result in greater divergence in regions with multiple vs. a single host. Conversely, costs of finding a suitable host can select for preference even in populations using a single host. Some populations of Timema cristinae occur in regions with only one host-plant species present (in allopatry, surrounded by unsuitable hosts) whereas others occur in regions with two host-plant species adjacent to one another (in parapatry). Here, we use host choice and reciprocal-rearing experiments to document genetic divergence in host preference among 33 populations of T. cristinae. Populations feeding on Ceanothus exhibited a stronger preference for Ceanothus than did populations feeding on Adenostoma. Both allopatric and parapatric pairs of populations using the different hosts exhibited divergent host preferences, but the degree of divergence tended to be greater between allopatric pairs. Thus, gene flow between parapatric populations apparently constrains divergence. Host preferences led to levels of premating isolation between populations using alternate hosts that were comparable in magnitude to previously documented premating isolation caused by natural and sexual selection against migrants between hosts. Our findings demonstrate how gene flow and different forms of selection interact to determine the magnitude of reproductive isolation observed in nature.

Animals↗
PubMed1991

Identification of a serum protein polymorphism via two-dimensional electrophoresis. Family and population studies in two genetically isolated groups: North American Hutterites and Australian aborigines.

We report the identification and initial family and population studies of a previously undescribed serum protein polymorphism with two allelic forms. It was discovered in Hutterites, a reproductively isolated religious sect, and is also present in Australian aborigines and a sample of Chicago residents. A two-allele model is consistent with the segregation pattern observed in five kindreds within our initial study group. This polymorphism, provisionally designated SPPM-158, appears as a horizontal (charge-based) doublet in silver-stained ISO-DALT high-resolution two-dimensional electrophoresis gels. It is a low-concentration polypeptide (approximately 1 mg/dL) that has an apparent MWSDS of 43.6 kD and an isoelectric point of approximately 5.5. We infer that it circulates as a multimer or in a high-molecular-weight (greater than 200 kD) complex with other proteins because it is not observed in normal body fluids derived from physiologically ultrafiltered plasma such as amniotic fluid, urine, or cerebrospinal fluid; however, it is present in urine of patients with glomerular proteinuria. The high heterozygosity rates imply utility of this new serum protein marker for both forensic and population studies.

Australia↗
PubMed2006

Selection on gamete recognition proteins depends on sex, density, and genotype frequency.

Gamete recognition proteins can evolve at astonishing rates and lie at the heart of reproductive isolation and speciation in diverse taxa. However, the source of selection driving this evolution remains unknown. We report on how the sperm bindin genotype influences reproductive success under natural conditions. An interaction between genotype frequency and spawning density determines how sperm bindin genotype influences reproductive success. Common genotypes are selected under sperm-limited conditions, whereas rare genotypes are selected under conditions of intense sperm competition and sexual conflict. Variation in the evolutionary rates of bindin may reflect historic differences in sperm availability.

Alleles↗
PubMed2005

Reinforcement of pre-zygotic isolation and karyotype evolution in Agrodiaetus butterflies.

The reinforcement model of evolution argues that natural selection enhances pre-zygotic isolation between divergent populations or species by selecting against unfit hybrids or costly interspecific matings. Reinforcement is distinguished from other models that consider the formation of reproductive isolation to be a by-product of divergent evolution. Although theory has shown that reinforcement is a possible mechanism that can lead to speciation, empirical evidence has been sufficiently scarce to raise doubts about the importance of reinforcement in nature. Agrodiaetus butterflies (Lepidoptera: Lycaenidae) exhibit unusual variability in chromosome number. Whereas their genitalia and other morphological characteristics are largely uniform, different species vary considerably in male wing colour, and provide a model system to study the role of reinforcement in speciation. Using comparative phylogenetic methods, we show that the sympatric distribution of 15 relatively young sister taxa of Agrodiaetus strongly correlates with differences in male wing colour, and that this pattern is most likely the result of reinforcement. We find little evidence supporting sympatric speciation: rather, in Agrodiaetus, karyotypic changes accumulate gradually in allopatry, prompting reinforcement when karyotypically divergent races come into contact.

Animals↗
PubMed2001

Analyses of reproductive interactions that occur after heterospecific matings within the genus Caenorhabditis.

Formation of zygotes in internally fertilizing organisms requires a number of successful interactions between oocytes and sperm within a receptive female reproductive tract. These interactions are usually assumed to be species-specific. For most species, it is either not possible to inseminate females with sperm from a different species or not possible to observe the consequences of such an insemination because the female is opaque. Nematodes of the genus Caenorhabditis are optically transparent and prior work indicates copulation between individuals of two different species is possible. We have used a series of vital stains and other cytological methods to analyze sperm after cross-species mating. We present here a series of analyses of the postcopulatory, prefertilization interactions among three Caenorhabditis species and find that reproductive biology is conserved, to varying degrees, among all three species. This approach allows investigation into which in vivo interactions between sperm and both oocytes and the somatic gonad have been maintained during the reproductive isolation that accompanies speciation.

Animals↗