Traditional Pedigree Research Articles

Yield performance at three nitrogen rates of a set of honeycomb vs traditional pedigree selected bread wheat varieties

The honeycomb nil interplant competition selection procedure has been proposed as effective breeding methodology in developing high yielding and broadly adapted wheat varieties. The objective of this research were to (i) evaluate the performance under low and high nitrogen (N) fertility of a set of honeycomb vs traditional pedigree selected bread wheat varieties and (ii) to compare the effectiveness of honeycomb vs traditional pedigree selection in developing high yielding and broadly adapted wheat varieties. Seven F 2 populations, which underwent honeycomb selection in the F 2 for grain yield (GY), were the basic material for the derived F 9 varieties used in this study. Three population were selected as promising (HC-PR) and four were discarded (HC-D). From each HC-PR the selected material entered honeycomb selection through the F 6 and the high and corresponding low yielding genotypes (HY and LY) were advanced to the F 9. The honeycomb F 2 discarded material from each HC-PR entered traditional pedigree selection and resulted in developing the corresponding F 9 varieties (TPS). Then for each HC-PR a set of three varieties, including the HY its LY counterpart and their corresponding TPS, was formed. A 4th set including four F 9 varieties, one from each HC-D, developed through traditional pedigree (TPS) was also formed. These 13 varieties along with four commercial check varieties were grown with 0, 90 and 180 KgN ha −1 in a 2 year field study. Grain (GY) and biomass (BY) yield, harvest index (HI) and 1000 kernel weight (Kwg) were recorded. Both, the TPS and LY varieties yielded equal to or significantly outyielded their HY counterparts at all N treatments. This yielding superiority was associated with higher HI and heavier kernels. In the same manner the TPS varieties of the 4th set were equal to or superior than the HY for GY, HI and Kwg. Data indicated that honeycomb method selected mainly for environmental effects and/or high biomass yielding ability combined with poor N using efficiency genotypes. Data indicated that the honeycomb breeding methodology was nearly equal to or less effective than the traditional pedigree.

A scan for linkage disequilibrium across the human genome.

Linkage disequilibrium (LD), the tendency for alleles of linked loci to co-occur nonrandomly on chromosomal haplotypes, is an increasingly useful phenomenon for (1) revealing historic perturbation of populations including founder effects, admixture, or incomplete selective sweeps; (2) estimating elapsed time since such events based on time-dependent decay of LD; and (3) disease and phenotype mapping, particularly for traits not amenable to traditional pedigree analysis. Because few descriptions of LD for most regions of the human genome exist, we searched the human genome for the amount and extent of LD among 5048 autosomal short tandem repeat polymorphism (STRP) loci ascertained as specific haplotypes in the European CEPH mapping families. Evidence is presented indicating that approximately 4% of STRP loci separated by <4.0 cM are in LD. The fraction of locus pairs within these intervals that display small Fisher's exact test (FET) probabilities is directly proportional to the inverse of recombination distance between them (1/cM). The distribution of LD is nonuniform on a chromosomal scale and in a marker density-independent fashion, with chromosomes 2, 15, and 18 being significantly different from the genome average. Furthermore, a stepwise (locus-by-locus) 5-cM sliding-window analysis across 22 autosomes revealed nine genomic regions (2.2-6.4 cM), where the frequency of small FET probabilities among loci was greater than or equal to that presented by the HLA on chromosome 6, a region known to have extensive LD. Although the spatial heterogeneity of LD we detect in Europeans is consistent with the operation of natural selection, absence of a formal test for such genomic scale data prevents eliminating neutral processes as the evolutionary origin of the LD.

Detecting inbreeding depression is difficult in captive endangered species

AbstractDuring the past two decades, pedigree analysis has documented inbreeding depression in many captive populations. This and subsequent research has led to a recognition that inbreeding depression is a potentially important determinate of small population fitness, in both captivity and the wild. Modern captive‐breeding programmes now universally avoid inbreeding. We use simulation to investigate how much traditional pedigree analysis will reveal about the effect of inbreeding in such populations. We find that pedigrees typical of breeding programmes designed to avoid inbreeding have low statistical power to detect inbreeding depression.

Linkage disequilibrium in two‐stage marker‐assisted selection

Linkage disequilibrium in two‐stage marker‐assisted selection

Comparative efficacy of pedigree selection and selective intermating in greengram (Vigna radiata (L.) Wilczek)

Selective intermating and pedigree selection methods were applied simultaneously to highly heterogeneous and heterozygous base populations of greengram in order to compare their relative efficacy in terms of evolving the number of productive lines as well as their production potential. Selection after two cycles of selective intermating was found to be a better method than traditional pedigree selection. The demerits of pedigree selection and merits of selective intermating are discussed. It is suggested that selective intermating replace the widely adopted but less effective pedigree selection for generating promising new material in such autogamous crops as greengram.

A contribution to the validity of Leonhard's classification of endogenous psychoses.

The author made a clinical-genetical study of the schizophrenias and cycloid (schizoaffective) psychoses following the Leonhardian classification, using the traditional pedigree analysis and multiple threshold method. According to the latter method--on the basis of phenotypical correlations--the systematic schizophrenias could be clearly distinguished from the cycloid psychoses, while the non-systematic category presumably occupies a genetical position between the two former categories.