HSC Biology Textbook-Evolution

Chapter 13 - future management of ecosystems

13.1 - human-induced changes in ecosystems

  • one of the main factors affecting natural ecosystems is human population growth.

Increasing population

  • Human activities act as a selection pressure on ecosystems

  • Increasing populations of humans lead to increased demands on the resources provided by ecosystems

Agriculture

Chapter 7 - Effects of the environment on organisms

7.1 - Ecosystems

  • an ecosystem is the combination of all the organisms (biotic factors) living in a community (a group of different populations in an area or habitat) and the non-living features (abiotic factors) with which they interact.

  • In short, an ecosystem is a combination of abiotic and biotic factors that interact with one another in a community

  • Within an ecosystem, an environment is made up of the non living (abiotic) factors.

  • The variety and distribution of ecosystems in Australia is due to the range of abiotic and biotic factors within each area.

Types of ecosystems

  • In both aquatic and terrestial ecosystems, biotic and abiotic components significantly influence species diversity.

  • Terrestial environments are affected by abiotic factors on land whereas aquatic environments are affected by abiotic factors like salt concentration, light availability, pressure etc.

  • The three types of aquatic environments are saltwater/marine environments, freshwater environments, and a combination of the two, estuarine environments.

  • The types of organisms in aquatic environments are influenced by salinity levels

  • Examples of aquatic ecosystems are wetlands and mangrove systems; estuaries, rivers and lakes and oceans and coral reefs.

  • Examples of terrestrial environments include deserts, tropical rainforests, grassland, shrubland, woodlands and temperate forests

  • Biotic and abiotic factors differ significantly between ecosystems,

Chapter 9 - The Theory of Evolution by Natural Selection

  • 250 years ago, scientists proposed the theory of evolution—that living things change over time to try to xplain how living organisms have become so diverse

9.1–Biological diversity and the theory of evolution by natural selection

  • biological diversity or biodiversity refers to the variety of all forms of life on earth, and the variety of ecosystems which they are components of.

Biodiversity exists on three different levels:

  • genetic diversity—refers to the total number of genetic characteristics in the genetic make-up of a species

  • Species diversity—a measure of the diversity of different species in an ecological community

  • Ecosystem diversity—the variety of ecosystems found in a region