chapter  4
23 Pages

Chromosomal Changes and Biodiversity

WithArchana Sharma, Sumithra Sen

Chromosomal analysis in the material is commonly carried out at the pachytene stage. Monosomies are produced due to chromosomal aberration and deficiency in one pole, arising out of nondisjunction. Intrachromosomal structural changes detected through genetic studies were originally interpreted in various ways. Variability of chromosome structure arising out of chromosomal aberrations may be interchromosomal or intrachromosomal. Of the interchromosomal aberrations, translocation, which mostly involves normal interchange of segments as in crossing-over, is quite common in plants. Homozygotes form bivalents during meiosis while heterozygotes, depending on the nature of the change, exhibit different types of chromosomal behavior. Heterozygotes, involving minor alterations or alterations of heterochromatic segments, have a greater chance of survival since there will, in general, be less gross alteration in the phenotype. Each individual has a unique DNA pattern and is a component of the broad spectrum of biodiversity.