Competition is most severe between two _________________________ .
Closely related species growing in the same habitat
When the species are closely related they tend to require the same resources, the same habitat and food, this leads to high competition between them, whereas two distantly related species in the same habitat, will have different food requirements and different shelter requirements and therefore do not compete for the same resources or atleast will have different modes to acquire these resources, thereby decreasing competition between them. Species occupy different ecological niches to apportion resources between them and to decrease the competition between them. Ecological niche can be defined as the role of an organism in its environment. Therefore closely related species that occupy different niches, do not compete heavily.