Ecology is the study of the relationships of living organisms with the abiotic and biotic components of their environment. It is concerned with four levels of biological organization- organisms, populations, communities and biomes.
Important physical factors which affect how organisms adapt:
Evolutionary changes through natural selection occur at population level. A population is a group of individuals of a given species sharing or competing for similar resources in a defined geographical area.
Ecological effect of any factors on a population is generally reflected in its size.
Population grows through births and immigration and decline through deaths and emigration.
Depending on the outcome, interactions between two species are classified as:
Competition: Both species suffer
Predation and parasitism: One benefits and the other suffers
Commensalism: One benefits and the other is unaffected
Amensalism: One is harmed, other unaffected
Mutualism: Both species benefit
Predation is a very important process through which the trophic energy transfer is facilitated and some predators help in controlling their prey populations.