Module 13 – Evolution

Module Introduction

Introduction

What is evolution ? What does this term really mean? Evolution is something that is frequently referenced incorrectly. In this module, you will begin to better understand this term in general, how it applies to the development of new organisms, and agents that promote evolution.

One thing to consider as you begin your work in this module, is that evolution, as scientists speak of it, is the gradual (slow) change in species that can lead to the development of new organisms/ species over time. There are many factors that can contribute to the “change in species” that allow for development of new species and much of your work in this module will be in reviewing these factors.

Another important consideration is that some organisms may be able to “evolve” quicker than others. Consider bacteria, for example. These organisms have a faster life cycle than we do, they can exchange genetic information in many ways, and have a higher rate of mutation than us. All of these factors allow for more diversity and that diversity can set the stage for the production of a new species.

A mutation is a change in the DNA or the genetic material of the organism. There are different ways that mutations can result and when a mutation occurs, that change in the DNA might

• have no effect on the organism and proteins produced from this gene,
• produce a new protein that increases the “fitness” of the organism,
• produce a new protein that does not increase the “fitness” of the organism, etc.

It is important to consider that a bacteria cannot just decide that it would like to be resistant to a given antibiotic. Rather, a mutation may occur that allows for resistance to a give antibiotic and this resistance would provide the bacteria with a selective advantage and increased “fitness” when compared to other bacteria. By exposing resistant and susceptible bacteria to the antibiotic in question, the resistant bacteria would obviously have an advantage – they will not die ¹ .