Natural selection is the process in nature by which only the organisms best adapted to their environment tend to survive and transmit their genetic characteristics in increasing numbers to succeeding generations while those less adapted tend to be eliminated.
Genetic drift refers to random fluctuations in the frequency of the appearance of a gene in a small isolated population, presumably owing to chance rather than natural selection. Genetic drift can result in genetic traits being lost from a population or becoming widespread in a population without respect to the survival or reproductive value of the gene pairs involved. A random statistical effect, genetic drift can occur only in small, isolated populations in which the gene pool is small enough that chance events can change its makeup substantially.
Chromosomes are ?t?h?r?e?a?d?l?i?k?e? linear strand of DNA and associated proteins ?that carries th??e genes and functions in the transmission of hereditary information??.? ??T?h?e?y? ?a?r?e? ?l?o?c?a?t?e?d? ????in the nucleus of eukaryotic cells ???.???