Systematics is the study of organismic diversity as that diversity is relevant to some specific kind of relationship thought to exist among populations, species or higher taxa (Wiley, 1989).
See also: taxonomy, phylogeny
... householder with no husband present, and 32.8% are non-families. 29.3% of all households are made up of individuals and 22.4% have someone living alone who is 65 years ...
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