We have been considering populations as defined by species. We can also think of the population of species that inhabits some area or ecosystem (e.g. the islands of Hawaii). Biodiversity attempts to describe the variation within such a population.

How to measure biodiversity? A simple measure of biodiversity would be the number of species in that area. Of course, if you are including microbes, this could be very difficult to ascertain. So you can restrict your measure of biodiversity to larger organisms. Yet, a simple number count of species doesn't take into account other factors. Consider the case where you have a forest composed of pine trees with one lone oak versus another forest that was 50% pine trees and 50% oaks. Is their biodiversity the same? In addition, an area could be dominated by many types of beetles and little else. Therefore some would include a component of genetic diversity of the organisms in the ecosystem population of species. Finally, there is an area effect - the larger the area, the more species you are likely to include. The result is that there are multiple measures of biodiversity.

Why is biodiversity important to humans?

What controls biodiversity?

Some biodiversity links to follow:

Genetic diversity within species.

What is the genetic diversity, and hence the population size necessary to have a sustainable population. The idea is that below a certain level there just isn't enough genetic variability for the species to develop or offspring to be healthy (think of the effects of inbreeding). This question is crucial for attempts to protect endangered species. It is a difficult question to answer.

An example of the importance of genetic diversity - sickle cell anemia. Great video clip associated with this.

A more thorough explanation of genetic diversity from the U. S. National Biological Information Infrastructure.

Journal writing exercise: We have made some arguments for the utility of biodiversity. Explore and comment on how, in your opinion, these arguments do or don't translate to the utility of cultural diversity.

Why did human population growth rate dramatically increase in the 1800s?

Why has the human population growth rate decreased in the past few decades? Read this carefully - the human population is still growing. However, the rate at which it is growing has decreased. Of course there are multiple reasons for this trend.

What should be done with the above information and thinking on population dynamics?

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Defines geodiversity: