An association of individuals of different species living in the same habitat and having functional interactions is
ecosystem
population
ecological niche
biotic community.
$A$ population is
The ecological niche of population is a
$A$ : Population ecology is a link of ecology to population genetics and evolution.
$R$ : Natural selection operates at population level to evolve the desired traits.
Define self sustainability.
Ecology is basically concerned with how many basic levels of organisation?