8.7 Disruptions in Ecosystems

Explain the interaction between the environment and random or preexisting variations in populations.

• An adaptation is a genetic variation that is favored by selection and manifests as a trait that provides an advantage to an organism in a particular environment.
• Heterozygote advantage is when the heterozygous genotype has a higher relative fitness than either the homozygous dominant or homozygous recessive genotype.
• Mutations are not directed by specific environmental pressures.

Explain how invasive species affect ecosystem dynamics.

• The intentional or unintentional introduction of an invasive species can allow the species to exploit a new niche free of predators or competitors or to outcompete native species for resources.

Describe human activities that lead to changes in ecosystem structure and dynamics.

• Human impact accelerates changes at local and global levels. These activities can drive changes in ecosystems, such as the following, that cause extinctions to occur:
  • i. Biomagnification
  • ii. Eutrophication

Explain how geological and meteorological activity leads to changes in ecosystem structure and dynamics.

• Geological and meteorological events affect habitat change and ecosystem distribution. Biogeographical studies illustrate these changes.