Most recently the emphasis has been upon chromosomal aberrations in various animal species to include mammals, birds, and fish. In most organisms the number of chromosomes is constant and characteristic for each species. However, intraspecific karyotypic variation exist in some natural animal populations and we are interested in the extent of such variation and its impact upon the organism and the population. A second major area of interest involving chromosomal aberrations is the overall effect of polyploidy on animals. Triploidy has been shown to alter cell size, morphology, and various physiological parameters in fish.
Karyotypic analyses involve nondifferentially stained and banded metaphase chromosomes.
Genetic variation in populations is investigated by electrophoretic analyses of allozymes. Such analyses allow estimates of the extent of polymorphism and heterozygosity within and among animal populations. We are concerned with the effects that biological processes have upon genetic variation. Heterochromatin in mitotic chromosomes of the virilis species group of Drosophila. Kennedy, P.K., M. L. Kennedy, and M. L. Beck 1987.