the current study investigated the effect of short-term selection for four week body weight (bw) on performance of divergent lines of japanese quail and their crosses. the mean of bw at hatching time, one, two, three and four week oldand bw at sexual maturity time, age at sexual maturity, number of eggs (from 50 to 100 days old), mean of egg weight, percentage of fertility and hatchability in e...

This study was conducted to evaluate maternal breed effects, direct breed effects, and individual heterosis on subsequent steer performance, carcass, and feed efficiency traits. This was a consecutive 2-yr trial using 158 steers. The same dam breeds, Angus (AN) and purebred Simmental (SM), were used both years. Also, the same AN and SM sires (n=11) were used both years. Steers were AN, SM, or A...

The genetic basis of heterosis of an elite rice hybrid was investigated by using an "immortalized F(2)" population produced by randomly permutated intermating of 240 recombinant inbred lines from a cross between the parents of Shanyou 63, the most widely cultivated hybrid in China. Measurements of heterosis for crosses in the immortalized F(2) population were obtained from replicated field tria...

Heterosis describes a phenotypic phenomenon of hybrid superiority over its homozygous parents. It is a genetically intriguing phenomenon with great importance for food production. Also called hybrid-vigor, heterosis is created by non-additive effects of genes in a heterozygous hybrid made by crossing two distinct homozygous parents. Few models have been proposed to explain how the combination o...

OR the reasons that heterosis has immense value in practical utilization in F agriculture and the evolutionary significance of heterosis in natural populations is important, a number of investigators have worked on this problem and proposed numerous hypotheses for the explanation of this phenomenon. The hypotheses which have been proposed can be classified into two categories: (a) dominance the...

Today the concept of heterotic groups and patterns is fundamental to hybrid breeding theory and practice. Our objectives were to (i) review various hypotheses on the causes of heterosis in maize and on the experimental evidence supporting or refuting them, (ii) examine advantages and disadvantages of the concept of heterotic groups and patterns, (iii) describe the status of heterotic patterns i...

Compared with understanding of biological shape and form, knowledge is sparse regarding what regulates growth and body size of a species. For example, the genetic and physiological causes of heterosis (hybrid vigor) have remained elusive for nearly a century. Here, we investigate gene-expression patterns underlying growth heterosis in the Pacific oyster (Crassostrea gigas) in two partially inbr...

HE heterozygous carriers of some genetic variants are superior in fitness to Tthe corresponding homozygotes. The causation of this hybrid vigor or heterosis (euheterosis according to DOBZHANSKY 1952) constitutes an important but as yet little understood problem. One possibility is that some gene alleles are “overdominant” with respect to fitness, and thus give heterosis in heterozygous conditio...

A line (E) of turkeys selected long-term (37 generations) for increased egg production was reciprocally crossed with its randombred control population (RBC1) that served as the base population of the E line to study the influence of long-term selection on the development of nonadditive genetic variation for egg production and body weight traits. Heterosis was significant for BW at 8, 16, and 20...