Adaptive radiation is the process of development of new forms of organisms from an ancestral species. <u>When an environment changes or some new niches open, speciation from the ancestral species occurs.</u> New species have morphological and physiological adaptations which allow them to exploit a whole range of divergent environment.
Although the DNA packaging with histones proteins is mean to form nucleosomes (groups of 8 histones proteins), the higher structures why the genetic material is packaged with those molecules is to form chromosomes, as you said.
