Big Picture

Cheetahs, the fastest of all land animals, have had a rapid loss of variation in their gene pools. Examination of 52 different gene loci has failed to show any polymorphisms (more than one allele). The lack of genetic variability is so profound that cheetahs will accept skin grafts from each other, just as identical twins do. Whether a population with this little genetic diversity can adapt in a changing environment remains to be seen.

 

This loss of diversity, an increasingly common scenario in this time of rapid environmental change, holds the potential for extinction. The ability to accurately measure the degree of genetic diversity is critical. In this module, we will look at the work of two geneticists who have given us the mathematical tools to easily, but accurately, measure the degree of genetic diversity in a population. The same tool allows us to predict whether a population is stable (in equilibrium), or evolving in response to a change in the environment. 

 

Over a period of time, individuals in a population contribute to the gene pool, resulting in changes to the composition of the populations of their communities.  The important thing to grasp is that gene pool change is normal for all populations on this planet as environments change. The concerning issue is whether the changes we are currently seeing are due to the natural mechanisms of evolution or due to environmental changes caused by our species. The other important point is the rate of change, in that adaptation (movement of allele frequencies towards more adapted forms) takes many generations. With the current rate of environmental change produced by human activity, there may not be adequate time for favorable alleles to replace those that are ill suited to new environments – the result can be (and has been for many species to date) extinction. Perhaps the most important question worth thinking about as a result of your studies in this module is whether having the skills and knowledge to calculate genetic change and predict the effect of our actions on gene pools obliges us to change our ways and prevent further disruption.   

 

Essential Questions

In this Module you will explore the following essential questions:

  1. What are the factors and conditions that exist when individuals in a population can change the gene pool?
  2. How can we analyze the effect of these factors?

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