Crossword puzzle clue "statistic relating to the study of human populations"

relating to demography, also DEMOGRAPHICAL

the study of population statistics and trends, such as births, deaths, and disease

to pack tightly

NERD, a person obsessed with computers at the expense of human interaction, also NURD

BIOTA, (Greek) the flora and fauna of a region

ECOTYPE, a group of organisms which have adapted to a particular environment and so have become different from other groups within the species