Evolutionary importance Extinction event

mass extinctions have accelerated evolution of life on earth. when dominance of particular ecological niches passes 1 group of organisms another, because new dominant group superior old , because extinction event eliminates old dominant group , makes way new one.

for example, mammaliformes ( mammals ) , mammals existed throughout reign of dinosaurs, not compete large terrestrial vertebrate niches dinosaurs monopolized. end-cretaceous mass extinction removed non-avian dinosaurs , made possible mammals expand large terrestrial vertebrate niches. ironically, dinosaurs had been beneficiaries of previous mass extinction, end-triassic, eliminated of chief rivals, crurotarsans.

another point of view put forward in escalation hypothesis predicts species in ecological niches more organism-to-organism conflict less survive extinctions. because traits keep species numerous , viable under static conditions become burden once population levels fall among competing organisms during dynamics of extinction event.

furthermore, many groups survive mass extinctions not recover in numbers or diversity, , many of these go long-term decline, , these referred dead clades walking .

darwin firmly of opinion biotic interactions, such competition food , space—the ‘struggle existence’—were of considerably greater importance in promoting evolution , extinction changes in physical environment. expressed in origin of species: species produced , exterminated acting causes…and import of causes of organic change 1 independent of altered…physical conditions, namely mutual relation of organism organism-the improvement of 1 organism entailing improvement or extermination of others .