Question

explain how this relationship between niche overlap, phylogenetic relationship , and competition would lead to the prediction that competitive exclusion of one species by another is more likely when two species are close relatives.

Answer 1

An ecological niche is the role and position a species has in its environment; how it meets its needs for food and shelter, how it survives, and how it reproduces.Niche overlap occurs when two species try to occupy the same niche.Two species would try to occupy same niche and use identical resources if they have similar phylogenetic relationship.In other words, phylogenetically related species are also ecologically similar.When such phylogenetically related species try to occupy the same niche, they will have to fight for the limited amount of resources available in the particular environment which leads to competition.One of the two competitors having even the slightest advantage over the other will lead to extinction of the second competitor in the long to an evolutionary shift of the inferior competitor towards a different ecological niche, thus excluding the second competitor from the niche termed as competitive exclusion.These three related concepts lead to development of Competitive exclusive principle which states that competitive exclusion of one species by another is more likely when two species are close relatives try to occupy the same niche.