numbers of organisms within an ecosystem. Climate is always changing, which changes the ecosystem over time. Despite the dynamic nature of ecosystems, they are always in equilibrium, in which there is a balance of organisms in the ecosystem with relatively steady levels of the different organisms in the system. The problem happens when there is a disturbance to an ecosystem, which disrupts the balance of organisms. A disruption can be a major fire, acid rain, algal blooms, deforestation, and the introduction of a new species into the system. Some ecosystems will recover, while others will fall apart. Ecosystems can be resistant to a disturbance and will be able to recover despite the change. The system can also be resilient so that it stays steady over a long period of time. A key factor in the ecosystem is the biodiversity in the ecosystem. It means that, while some organisms do not recover after a disturbance, others will survive and will continue the ecosystem, even though it may take a while to recover.
POPULATION ECOLOGY There are many factors in the study of ecology, including the effects of the environment and the changes in the genetics of the ecosystems. Population ecology is a branch of the study of ecology and involves the different biological populations within an ecosystem, such as their structure and dynamics. This study is similar to community ecology, which studies the structure and dynamics of the different communities in an ecosystem as well as the study of population genetics, which is the study of gene frequencies within the ecosystem. Populations will differ in their level of stability. Some will be stable for many thousands of years, while others will die off and become extinct. Other populations will be transient, such as larval forms of insects that survive only until they get past that stage of their life cycle and leave the ecosystem to go to another ecosystem. Populations are groups of different individual organisms that share the same characteristics. Even though the organisms are unique within the population, they are considered ecologically “equivalent”. This means basically that they have the same life cycle, live in the same ecological environment, and react the same to the environment. 233
