Central auditory processing development in adolescents with and without learning disabilities.

Auditory processing deficit (APD) is estimated to affect 5% of school-age children and adolescents, and 30-50% of those diagnosed with learning problems. The diagnosis and indeed the existence of APD, however, remain controversial. One reason for this controversy is that the factors contributing to normal variations in auditory processing and its development are poorly understood.

Genetic differences between the Chinese and European races of the common carp : 6. Growth of fish in cages.

Relative growth rates of six genetic groups of common carp were compared in small netting cages and in earthen ponds. These groups of carp included an isolate of the Chinese 'Big Belly Carp', its crossbred with a European isolate, and four European progenies, purebreds or crossbreds. Five different environments were produced in the ponds, mainly by varying the stocking rates of carp.

Genetic differences between the Chinese and European races of common carp : 5. Differential adaptation to manure and artificial feeds.

Common carp of the Chinese and European races and their cross were tested in different environments. The test groups were either stocked together into the same pond, or each group was stocked separately. Mean growth, taken as a measure of the quality of the environment, varied widely between treatments.

Genetic improvement of wild fish populations.

A plan for the genetic improvement of commercially exploited wild animals is presented. It consists of crossing wild with domesticated breeds to produce heterotic hybrids and to upgrade the wild stocks. Empirical evidence is presented from experiments with the carp.

The genetic basis of egg lay response to conditioned medium in the flour beetle, Tribolium castaneum : I. Two-way selection.

The rate of egg laying in Tribolium castaneum is affected by the quality of the environment and can thus serve not only as a component of fitness of the individual, but also as an adaptation to the long-term survival of the population. In an attempt to determine whether it is an independent genetic character, selection for high and low rates of response was carried jut in beetles from three wild populations. When tests were done on virgin females, and responsiveness, corrected for scale effects, was used as the criterion for selection, separation between the lines was achieved in one generation.

Genetic aspects of the transition from traditional to modern fish farming.

A theoretical model describing the genetic aspect of the transition from traditional to modern animal husbandry is presented. Traditional races are characterized by high tolerance to harsh environments but a low rate of response to increased management inputs. Modern, artificially-selected breeds are efficient convertors of management inputs to higher production but have a low resistance to harsh environments.

Two-way selection for growth rate in the common carp (Cyprinus carpio L.).

The domesticated European carp was subjected to a two-way selection for growth rate. Five generations of mall selection for faster growth rate did not yield any response, but subsequent selection between groups (families) resulted in considerable progress while maintaining a large genetic variance. Selection for slow growth rate yielded relatively strong response for the first three generations.

Genetic differences between the Chinese and European races of the common carp. II. Multi-character variation-a response to the diverse methods of fish cultivation in Europe and China.

The European and Chinese races of the common carp and their F1 crossbreds were tested in five experimental environments. The two races differ widely and conspicuously in many characters. The Chinese carp has poorer growth rate but higher viability and fertility, earlier sexual maturity, higher resistance to crowding, better adaptation to unfavourable pond conditions, higher seine escapability, longer body and larger weight differences between females and males.

Genetic differences between the Chinese and European races of the common carp.I. Analysis of genotype-environment interactions for growth rate.

Growth rate of 12 groups of common carp was measured at five experimental environments. Three of the 12 tested groups were strains of the domesticated European race of the common carp, one group was a representative of the Big-Belly Chinese race, and the remaining eight groups were F1 crossbreds among the European strains and between the European and the Chinese races. The average growth rate over the five environments of the Chinese Big-Belly was considerably poorer than that of the European carp.

Variability of intermuscular bones, vertebrae, ribs, dorsal fin rays and skeletal disorders in the common carp.

The number of intermuscular bones, vertebrae, ribs, dorsal fin rays and an index of bone disorders were determined from x-ray photographs of over 1000 common carp. These carp represented a broad genetic range, including five distinct lines of the domesticated European carp, one group of the Chinese race Big-Belly and 12 crossbreds. The genetic, and even the phenotypic, variation in intermuscular bones were much smaller than those found in earlier experiments.