After evolu-tion, the Y chromosome becomes the smallest in size with the least number of genes but with the most number of copies of genes that are mostly spermatogenesis-related.

• 由于这样的特点，其内部基因不断发生重组，因此造成进化过程中Y染色体的体积及其基因数目不断减少，雄性特异性基因不断积累，并产生高度多态性。