Module 4 Intro
1. Module 4 Intro
1.26. Page 6
Module 4—Mechanisms of Population Change
Lesson Summary
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 genesis of a new species. Speciation has occurred if the two populations can no longer mate successfully.
Now that you have completed the last lesson of Unit B: Module 4, there are three things you need to do.
First, hand in your Lesson 4 Assignment.
Second, you have been working on a module project. It is now time to finish your play, game, or podcast. This has been discussed in Reflect on the Big Picture.
Finally, you need to head to the Unit Summary and Assessment. There you will find a Unit Assessment that you should start working on.
Once all of these tasks have been completed, you will be ready to move from “Ecosystems and Population Change” to “Photosynthesis and Cellular Respiration.”
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
gradualism: the theory that evolution occurs slowly and steadily in a linear fashion
punctuated equilibrium: the theory that suggests that evolutionary history consists of long periods of stasis (stable equilibrium), punctuated by periods of divergence
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