IB ESS

  • Biodiversity is a broad concept encompassing the total diversity of living

systems, which includes the diversity of species, habitat diversity and

genetic diversity.

  • Species diversity in communities is a product of two variables: the number of

species (richness) and their relative proportions (evenness).

  • Communities can be described and compared through the use of diversity

indices. When comparing communities that are similar, low diversity could

be indicative of pollution, eutrophication or recent colonization of a site. The

number of species present in an area is often indicative of general patterns of

biodiversity.

  • Habitat diversity refers to the range of different habitats in an ecosystem

or biome.

  • Genetic diversity refers to the range of genetic material present in a

population of a species.

  • Quantification of biodiversity is important to conservation efforts so that

areas of high biodiversity may be identified, explored, and appropriate

conservation put in place where possible.

  • The ability to assess changes to biodiversity in a given community over time is

important in assessing the impact of human activity in the community

  • Evolution is a gradual change in the genetic character of populations over many generations, achieved largely through the mechanism of natural selection

  • Environmental change gives new challenges to species, which drives the evolution of diversity.

  • There have been major mass extinction events in the geological past.

  • Biodiversity arises from evolutionary processes.

  • Biological variation arises randomly and can either be beneficial to, damaging

    to, or have no impact on, the survival of the individual.

  • Natural selection occurs through the following mechanism.

    • Within a population of one species, there is genetic diversity, which is

      called variation.

  • Due to natural variation, some individuals will be fitter than others. 3. Fitter individuals have an advantage and will reproduce more successfully than individuals who are less fit. 4. The offspring of fitter individuals may inherit the genes that give that advantage.

  • This natural selection will contribute to the evolution of biodiversity

    over time.

  • Environmental change gives new challenges to species: those that are suited

    will survive, and those that are not suited will not survive.

  • Speciation is the formation of new species when populations of a species

    become isolated and evolve differently from other populations.

  • Isolation of populations can be caused by environmental changes forming

    barriers such as mountain formation, changes in rivers, sea level change,

    climatic change or plate movements. The surface of the Earth is divided

    into crustal, tectonic plates that have moved throughout geological time.

    This has led to the creation of both land bridges and physical barriers with

    evolutionary consequences.

  • The distribution of continents has also caused climatic variations and

    variation in food supply, both contributing to evolution.

  • Mass extinctions of the past have been caused by various factors, such

    as tectonic plate movements, super-volcanic eruption, climatic changes

    (including drought and ice ages), and meteorite impact—all of which resulted

    in new directions in evolution and therefore increased biodiversity