Unit B

Module 4 ~ Lesson 4


In this lesson you explored the following essential question:

  • What conditions are necessary for speciation?

Divergence and transformation are the two pathways in which new species can evolve. All of the estimated two to 100 million species in the world have evolved from these two pathways. But in order for a species to diverge or transform, certain conditions must be present.

Essential to evolution is genetic diversity. A population must have genetic variation in order for any kind of change to be possible. Mutations, sexual reproduction, and recombinations provide this genetic diversity.

An environment must change in some way in order for certain characteristics to become dominant in a population. The change in environment (either geographical or biological) must create reproductive isolation. This isolation prevents the two populations from exchanging genetic information. Adaptations in each population can eventually lead to the creation of a new species. Speciation has occurred if the two populations can no longer mate successfully.

 Lesson Glossary

allopatric: speciation that occurs from a geographical barrier

barrier: anything that prevents organisms from reproducing

biological barrier: a factor such as behaviour that keeps species reproductively isolated even when they exist in the same region

divergence: the development of one or more new species from a parent species as a result of mutation and adaptation to changing environmental conditions; the parent species continues to exist

geographical barrier: geological formations that keep organisms separated

speciation: the formation of new species

transformation: the evolution of one species into another as a result of mutation and adaptation to changing environmental conditions, resulting in the replacement of the old species

viable offspring: offspring that are healthy and able to reproduce and create new offspring


Complete Unit B: Section 4 Assignment now.