Patterns of Evolution

Natural selection is a key mechanism in the development of diversity among organisms.  A flock of migratory birds gets divided in a storm while headed for warmer climates. Half of the flock reached the warmer climate and half of the flock lands on a new island and stays.  Over time, members of the flock that settled on the island develop characteristics that increase their rate of survival on the island.  The population on the island eventually evolves into a different species than their ancestors.  

Which of the following patterns of evolution does this represent?

Natural selection is a key mechanism in the development of diversity among organisms.  Scientist Charles Darwin studied finches (birds) on the Galapagos Islands off of the coast of South America.  He discovered that more than a dozen species evolved from a single species of finch that first populated the Galapagos Islands.

Which of the following patterns of evolution does this represent?

Species in the fossil record can be documented to be in a period of stasis, or equilibrium. During stasis, the characteristic of the species may remain unchanged for thousands of years.

Which of the following best explains why stasis occurs?

The Cambrian Explosion was an event that scientists theorized occurred approximately 541 million years ago in the Cambrian period when most major animal phyla appeared in the fossil record.  It lasted for about 20 million years and resulted in the emergence of most known phyla today.  Before the Cambrian explosion, most organisms were simple and composed of individual cells.  Almost all present animal phyla known today appeared during this period and have had few structural changes.

Which of the following statements supports this theory?