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PubMed1981

A multilocus estimator of mating system parameters in plant populations.

A multilocus method of estimating mating system parameters in populations is presented that recovers information from classification over multiple loci that single-locus estimators do not detect. It is shown that the multilocus estimator provides a standard of reference (null hypothesis) that can be useful in analyzing the effects of factors such as population heterogeneity and post-mating zygotic selection on the transmission of genetic information at the population level.

Journal Article↗
PubMed2006

Dystocia in beef heifers: a review of genetic and nutritional influences.

Breeding beef heifers for the first time at 15 months of age has potential to increase the efficiency of the beef breeding-cow herd. An increased incidence of dystocia in heifers calving at 2 years of age, compared to mature cows, is a major reason many farmers in New Zealand have not adopted the practice. The predominant type of dystocia affecting 2-year-old heifers is feto-maternal disproportion, a condition in which the fetus is too large relative to the size of the heifer's pelvis. Reducing birthweight of the calf is a means of reducing the incidence of dystocia. Birthweight and length of gestation are determined by genotype of the calf, maternal genetic effects and environmental effects. Bulls with low estimated breeding values for birthweight have been selected for mating heifers; however, the positive genetic correlation between birthweight and mature weight meant that the progeny of these bulls tended to be lighter at finishing, making them less desirable in the beef industry. The genotype of the dam also plays a role in determining the risk of dystocia; the maternal ability of the dam to nurture the fetus influences birthweight, and the dam's genetic potential for growth influences the size of her pelvic area. Heavy heifers tend to produce high birthweight calves, counteracting the reduction in the incidence of dystocia resulting from the larger pelvis in larger heifers. Manipulating feeding level during pregnancy offers an alternative method for manipulating the birthweight of calves. Little is known about the effects of nutrition in early gestation on placental development or birthweight of calves. No differences in the birthweight of calves have been observed in response to variation in feeding in mid-pregnancy, and variable responses in birthweight and the incidence of dystocia to feeding in the third trimester of pregnancy have been reported. Differences in birthweight have not always resulted in differences in the incidence of dystocia, primarily due to differences in liveweight of the heifer also induced by feeding regimens. Variability in the incidence of dystocia in response to feeding level in the third trimester of pregnancy makes it difficult to make recommendations for the feeding of heifers at this stage of gestation. More research is needed into the effects of nutrition in early gestation on fetal and placental development in cattle.

Animal Nutritional Physiological Phenomena↗
PubMedDate not supplied

Temporal variation in the mating structure of Sanday, Orkney Islands.

Pedigree and vital statistics data from the population of Sanday, Orkney Islands, Scotland, were used to assess temporal changes in population structure. Secular trends in patterns of mate choice were analysed for three separate birth cohorts of spouses: 1855-1884, 1885-1924 and 1925-1964. The degree to which mating was random or assortative with respect to both genealogical and geographic distance was determined by comparing average characteristics of all potential mates of married males with those of actual wives. We integrated this procedure, originally developed by Dyke (1971), into a three-fold investigation of population structure: (1) comparison of random and non-random components of relatedness as measured from pedigree data; (2) an analysis of marital distance distributions for actual and potential mates of married males; and (3) the relationship between genealogical relatedness and geographic distance. As population size decreased from 1881 to the present, total kinship and spatial distances between spouses increased. Whereas the random component of relatedness increased over time, consanguinity avoidance was sufficient to decrease the total coefficient of kinship over time. Part of the increase in consanguinity avoidance was associated with isolate breakdown, as distances between island-born spouses, as well as the total amount of off-island migration, increased from the mid-nineteenth century to the present. Mate choice was influenced by geographic distance for all time periods, although this effect diminished over time. Since decreases in population size, concomitant with increases in consanguinity avoidance and community exogamy, have probably occurred quite frequently in small human populations, as well as in rural Western communities in the past century, observed secular trends illustrate the potential for change in population structure characteristic of isolate breakdown.

Consanguinity↗
PubMedDate not supplied

Assortative mating, differential fertility and abnormal pregnancy outcome.

This study examines the relationship between spousal likeness in stature and two measures of reproductive success: the number of live-born children and the frequency of abnormal pregnancies, in a large British national sample. The analyses showed that as the husband-wife height difference increases so does the probability of having an abnormal pregnancy outcome. Increasing spousal similarity for height associates with increasing numbers of live-born children even after correcting for parental age, social and regional differences.

Adult↗
PubMedDate not supplied

Population structure of two black Venezuelan populations studied through their mating structure and other related variables.

In order to obtain information about the population structure of two black Venezuelan populations with historical differences both in their origins and development, a variety of variables were utilized, especially on marital structure, including: frequency of surnames, isonymy, population genealogical consanguinity, multiple unions, and marital distances, all of which provided information and isolation, migration, endogamy, consanguinity, and patri-matrifocality. Results showed differences in the extent of isolation and endogamy, as well as differences in population structure, which can be directly related with historical conditions of each population. Results agree with those previously obtained with traditional genetic polymorphisms and with the historical information available. Thus, the usefulness of surnames for inferring about population structure is supported, as well as the usefulness of historical information for explaining genetic diversity.

Anthropology, Cultural↗
PubMed1993

Sensitivity analysis in a multidimensional demographic projection model with a two-sex algorithm.

"Formulas are derived for the effect that a slight change in the occurrence/exposure rate of the multidimensional projection model has on the elements of the population vector. The projection model classifies the population by sex, age, and marital status. The model includes a two-sex algorithm in order to ensure consistency between numbers of male and female marriages, number of divorces for the two sexes, and new widows (widowers) and deceased spouses. The sensitivity functions and elasticities are applied to data from the Netherlands for the period 1980-1984. The results indicate that marriage market mechanisms, in particular competition and substitution effects, are reasonably well modelled."

Age Distribution↗
PubMedDate not supplied

Parallel cousin marriages in Madras, Tamil Nadu: new trends in Dravidian kinship.

The frequency distribution of various consanguineous marriages was studied in the city of Madras, Tamil Nadu, South India. Parallel first cousin marriages (PFC) were found to occur in appreciable frequencies in all caste groups of Hindus. While it has been generally believed that PFC marriages among Hindus are mere exceptions and are usually not tolerated, our data show that they can no longer be treated as exceptions. The high frequency (27 per cent) of PFC marriages in some Hindu communities necessitates in-depth studies to elucidate the forces at work which go against the very fundamentals of Dravidian kinship.

Consanguinity↗
PubMedDate not supplied

The norm for perceived husband superiority: a cause of human assortative marriage.

I have suggested that human assortative marriage for a number of variables is partially caused by behavior in accordance with two norms. Epstein and Guttman (1987) have suggested that there is no empirical evidence for these norms. In this note evidence is reviewed for the norm of perceived husband-superiority. Others have shown that the evidence for this norm is strong in regard to height, and it is shown here that the evidence is strong also in regard to age. Evidence for the norm seems suggestive in regard to IQ, education, and social class, and nonexistent in regard to physical attractiveness. With respect to height, it seems that the magnitude of the correlation between spouses is associated with the size of the breeding population to which they belong. Thus, it seems likely that the hypothesized norms are learned rather than genetically coded.

Adolescent↗
PubMedDate not supplied

Effects of pregnancy and progesterone on the consumption of ethanol by the high ethanol preferring (HEP) rat.

A significant fraction of women continue to drink heavily during pregnancy, which is associated with the fetal alcohol syndrome, alcohol-related birth defects, alcohol-related neurodevelopmental disorder, and spontaneous abortion. The objective of this study was to determine whether the selectively bred genetic drinking Myers High Ethanol Preferring (HEP) rat would continue to drink through pregnancy. Rats from the F7 generation were screened by a 10-day 3-30% (v/v) ethanol concentration 'step up' procedure in order to determine the concentration which resulted in maximal drinking with an ethanol solution to total fluid ratio closest to 0.5. After baseline drinking of the preferred concentrations was established, female HEP rats were randomly selected for mating and their ethanol bottles were removed. Upon finding a 'sperm plug', male rats were removed and the ethanol was returned. A second group received injections of progesterone in sesame oil beginning with a 1.0 mg/kg/day dose which was increased to 3.0 mg/kg/day on gravid days (GD) 5-20. Vaginal smears confirmed that progesterone rendered the rats anoestrous. Neither pregnancy nor progesterone changed either the amount or proportion of ethanol consumed compared to the baseline period. The rats drank an average of 8.4 g/kg daily throughout pregnancy. A sharp drop in food intake was noted the day after mating. Beginning on GD 13, it was observed that pregnant rats showed a marked increase in the variance for proportion of ethanol consumed and body weight. Subsequently, only one of the eight impregnated rats successfully delivered a litter. The ethanol solution was removed and these rats mated again: seven of the eight rats delivered litters. These two findings suggest that the pregnant females must have begun to lose their litters on or after GD 13. Further, pregnancy does not affect the consumption of ethanol in the HEP rat. In addition, due to the fact that drinking by HEP rats during pregnancy leads to such a high rate of resorption of the fetus, this hybrid strain may also constitute a useful model for the study of alcohol-induced spontaneous abortion.

Alcohol Drinking↗
PubMedDate not supplied

Blastoderm degeneration, an early embryonic failure in dwarf Single Comb White Leghorn chickens.

Blastoderm degeneration is an early embryonic lethal condition observed in selected paired matings within a line of dwarf Single Comb White Leghorn chickens that results in a 25% reduction of the hatch of fertilized eggs. The disorder is macroscopically evident at 32 h of incubation by the presence of a small localized indentation on the outer periphery of the expanding blastoderm. The affected blastoderms undergo a series of rapid macroscopic degenerative changes that conclude at about 120 h characterized by the presence of dispersed blastoderm fragments on the surface of the egg's yolk. Microscopically, this embryonic failure appears to manifest itself between Hamburger-Hamilton stages 8 and 9 of development and is characterized by a series of retarded developmental processes: closure of the anterior neuropore, brain vesicle differentiation, somite formation, and cardiac development. The disorder is inherited as an autosomal recessive trait. Attempts to identify factors that influence the disorder have thus far been unsuccessful. The symbol bld is proposed for this recessive gene.

Animals↗
PubMed2000

Effect of ultraviolet radiation on the performance of intact male turkeys.

Ultraviolet (UV) sensitivity in birds has been shown to be intrinsically involved in the selection of mates; UV may, therefore, also play a role in the establishment and maintenance of social hierarchies in intensively housed turkeys. Cereal seeds and straw are known to reflect UV, and turkeys may use these cues for foraging and exploratory behaviors. A series of trials was conducted to see if supplementation of the photoperiod (12 h at various white light intensities) with UV radiation (0.06 to 0.16 W/m2 at floor level) and regular supplies of straw to the litter allow a better recognition of individuals within a flock, enrich the environment by the provision of new pecking material and of radiation across the whole range of avian sensitivity, and, as a consequence, reduce the incidence of injurious pecking in male turkeys that have not been beak-trimmed, detoed, or desnooded. Body weight gain, feed intake, feed conversion efficiency, and leg integrity were generally not significantly affected by UV supplementation and environmental enrichment. In contrast, the provision of UV radiation, simultaneous with a 12-h photoperiod of white light at intensities of <70 lx to 5 wk and of 10 lx to 20 wk, and the regular addition of straw to the litter, significantly reduced the incidence of culling because of injurious pecking. However, complex interactions among UV supplementation, white light intensity, and material environmental enrichment precluded a simple recommendation to solve the problem of injurious pecking.

Animal Nutritional Physiological Phenomena↗
PubMed2002

Genome-wide analysis of the odorant-binding protein gene family in Drosophila melanogaster.

Olfaction is of considerable importance to many insects in behaviors critical for survival and reproduction, including location of food sources, selection of mates, recognition of colony con-specifics, and determination of oviposition sites. An ubiquitous, but poorly understood, component of the insect's olfactory system is a group of odorant-binding proteins (OBPs) that are present at high concentrations in the aqueous lymph surrounding the dendrites of olfactory receptor neurons. OBPs are believed to shuttle odorants from the environment to the underlying odorant receptors, for which they could potentially serve as odorant presenters. Here we show that the Drosophila genome carries 51 potential OBP genes, a number comparable to that of its odorant-receptor genes. We find that the majority (73%) of these OBP-like genes occur in clusters of as many as nine genes, in contrast to what has been observed for the Drosophila odorant-receptor genes. Two of the presumptive OBP gene clusters each carries an odorant-receptor gene. We also report an intriguing subfamily of 12 putative OBPs that share a unique C-terminal structure with three conserved cysteines and a conserved proline. Members of this subfamily have not previously been described for any insect. We have performed phylogenetic analyses of the OBP-related proteins in Drosophila as well as other insects, and we discuss the duplication and divergence of the genes for this large family. [The sequence data from this study have been submitted to FlyBase. Annotations for these sequences are available as supplementary material at http://www.genome.org.]

Amino Acid Sequence↗
PubMed1997

A second-generation linkage map of the bovine genome.

We report a bovine linkage map constructed with 1236 polymorphic DNA markers and 14 erythrocyte antigens and serum proteins. The 2990-cM map consists of a sex-specific, X chromosome linkage group and 29 sex-averaged, autosomal linkage groups with an average interval size of 2.5 cM. The map contains 627 new markers and 623 previously linked markers, providing a basis for integrating the four published bovine maps. Orientation and chromosomal assignment of all the linkage groups, except BTA20 and BTA22, was provided by 88 markers that were assigned previously to chromosomes. This map provides sufficient marker density for genomic scans of populations segregating quantitative trait loci (QTL) and subsequent implementation of marker-assisted selection (MAS) mating schemes.

Animals↗
PubMed1995

cycMs3, a novel B-type alfalfa cyclin gene, is induced in the G0-to-G1 transition of the cell cycle.

Cyclins are key regulators of the cell cycle in all eukaryotes. We have previously isolated two B-type cyclin genes, cycMs1 and cycMs2, from alfalfa that are primarily expressed during the G2-to-M phase transition and are most likely mitotic cyclin genes. Here, we report the isolation of a novel alfalfa cyclin gene, termed cycMs3 (for cyclin Medicago sativa), by selecting for mating type alpha-pheromone-induced cell cycle arrest suppression in yeast. The central region of the predicted amino acid sequence of the cycMs3 gene is most similar to the cyclin box of yeast B-type and mammalian A- and B-type cyclins. In situ hybridization showed that cycMs3 mRNA can be detected only in proliferating cells and not in differentiated alfalfa cells. When differentiated G0-arrested cells were induced to reenter the cell cycle in the G1 phase and resume cell division by treatment with plant hormones, cycMs3 transcript levels increased long before the onset of DNA synthesis. In contrast, histone H3-1 mRNA and cycMs2 transcripts were not observed before DNA replication and mitosis, respectively. In addition, cycMs3 mRNA was found in all stages of the cell cycle in synchronously dividing cells, whereas the cycMs2 and histone H3-1 genes showed a G2-to-M phase- or S phase-specific transcription pattern, respectively. These data suggest that the role of cyclin CycMs3 differs from that of CycMs1 and CycMs2. We propose that CycMs3 helps control reentry of quiescent G0-arrested cells into the G1 phase of the cell cycle.

Amino Acid Sequence↗
PubMed2002

Nuptial gifts and the evolution of male body size.

In many insect systems, males donate nuptial gifts to insure an effective copulation or as a form of paternal investment. However, if gift magnitude is both body size-limited and positively related to fitness, then the opportunity exists for the gift to promote the evolution of large male size. In the striped ground cricket, Allonemobius socius, males transfer a body size-limited, somatic nuptial gift that is comprised primarily of hemolymph. To address the implications of this gift on male size evolution, we quantified the intensity and direction of natural (fecundity) and sexual (mating success) selection over multiple generations. We found that male size was under strong positive sexual selection throughout the breeding season. This pattern of selection was similar in successive generations spanning multiple years. Male size was also under strong natural selection, with the largest males siring the most offspring. However, multivariate selection gradients indicated that gift size, and not male size, was the best predictor of female fecundity. In other words, direct fecundity selection for larger gifts placed indirect positive selection on male body size, supporting the hypothesis that nuptial gifts can influence the evolution of male body size in this system. Although female size was also under strong selection due to a size related fecundity advantage, it did not exceed selection on male size. The implications of these results with regard to the maintenance of the female-biased size dimorphic system are discussed.

Analysis of Variance↗