Activity 1.Reporting on an ecosystem

Ecosystems are comprised of abiotic (non-living, environmental) and biotic (living) components. The interaction of abiotic and biotic factors can influence the energy and population dynamics of an ecosystem. Measuring these factors enables scientists to classify an ecosystem. This is important, as it enables scientists to begin to work towards effective ecosystem management.

 60 - 90 minutes

Biodiversity, or biological diversity, refers to the variety of organisms living within a particular area. Biodiversity can be measured by the number and diversity of species, the extent to which a particular habitat or ecosystem varies, or the amount of genetic diversity within a species. The more diverse an area is, the more likely it is to withstand environmental pressures or disasters. Biodiversity is often used as an indication of the health of a habitat.

 60 minutes

A population is defined as members of the same species living in the same geographical area at the same point in time. In other words, they have the ability to interbreed to produce viable o spring. It is necessary to survey populations for many reasons. For example, a population may be endangered or increasing in numbers and impacting negatively on another species. Information about population sizes can assist in forming decisions in regards to land management and conservation efforts.

In the early 1900s, mathematicians G. Hardy and W. Weinberg used their knowledge of binomial expansion and applied it to population genetics (microevolution). Microevolution involves the change in allele frequency over time. A population that is in Hardy-Weinberg equilibrium shows no change in allele frequency over time; it is a non-evolving population. In order for a population to comply with Hardy-Weinberg equilibrium, five conditions must be met:

• The population is infinitely large. This reduces the probability that genetic drift (random change in allele frequency) will occur.

• Mating is random. No sexual selection.

• No natural selection. All genotypes have the same chance of survival.

• No mutation of alleles. No new alleles enter the population.

• No gene flow. No emigration or immigration.

A Hardy-Weinberg population cannot exist in the real world, as it is impossible to meet all five of the conditions simultaneously. The Hardy-Weinberg principle simply provides a baseline to determine whether or not allele frequencies have changed in a population and, thus, whether evolution has occurred.