Question

7. After mass extinction events, evidence from the fossil record shows: O diversity, in terms of genera, increased to levels above what was present just before the previous extinction. O descendants of lineages surviving the extinction event gave rise to entirely new lineages of animals. O groups of organisms replace each extinct group with a new, more derived, descendant group. O new animal phyla evolved after each extinction event.

Answer 1

• Determining the ages of fossils provides a record of the organisms that lived during different periods of Earth's history. The evidence from fossil record shows evolutionary relationship between species.
• Extinctions on a larger scale reduce diversity by killing off specific lineages, and with them, any descendent species they might have given rise to.
• There is abrupt disappearance of species,which creates new opportunities for the surviving species to grow - a process called rediversification .
• These surviving species may evolve specialization and may take over various ecological roles.This happens through natural selection.
• In this way, extinction can level the evolutionary playing field for a brief time, allowing lineages that were formerly minor players to diversify and become more prevalent.
• And it is this way that mass extinctions lead to macroevolution- it is the evolution of the species that had existed before the mass extinction,into something larger and more complex.In other words,it is a process which explains how the currently existing species came to be.