Answer to Question #113001 in Evolution for NIBEDITA RUDRA

Question

What is a karyotype ? Explain with any two
examples how it is useful in biosystematics.

Answer 1

Karyotape is a set of characters (number, size, shape, ) of a complete set of chromosomes inherent in cells of a given biological species (species karyotype), a given organism (individual karyotype), or cell line (clone).Karyotype can be used for many purposes,such as to study chromosomal abnormalities, taxonomic relationships, and to get information about past evolution  events.Some species are polymorphic for different chromosome structural forms.The structural variation may be associated with different numbers of chromosomes in different individuals .The karyotype study is important to help identify karyotypic polymorphism and evolution. It also helps us in understanding the relationship between chromosome number, amount of DNA, and complexity of the organisms.

The genomes of all species are remarkably conserved, not only in transcribed sequences, but also in some chromosome-specific non-coding sequences and in gene order. A close examination with chromosome painting shows that this conservation can be resolved into small numbers of large chromosomal segments. Rearrangement of these segments into different combinations explains much of the observed diversity in species karyotypes Their analysis can determine the evolutionary relationships of all organisms and their descent from a common ancestor.

Heterochromatin is an important feature of the genomes. It is composed of highly repeated DNA sequences and its location and amount may vary at the species, population, and/or individual level. However, it is clearly of biological and evolutionary importance, so it is used in biosystematic .