1. CONSERVATION AND BIODIVERSITY 4.1 Biodiversity in ecosystems

2. Assessment Statements  4.1.1 Define the terms biodiversity, genetic diversity, species diversity, and habitat diversity  4.1.2 Outline the mechanism of natural selection as a possible driving force for speciation.  4.1.3 State that isolation can lead to different species being produced that are unable to interbreed to yield fertile offspring.  4.1.4 Explain how plate activity has influenced evolution and biodiversity.  4.1.5 Explain the relationships among ecosystem stability, diversity, succession and habitat.

3. 4.1.1 Define the terms biodiversity, genetic diversity, species diversity, and habitat diversity  Biodiversity – amount of biological or living diversity per unit area. Consists of species, habitat, and genetic diversity  Species diversity – the variety of species per unit area; includes the number of species present and their relative abundance.

4. 4.1.1 Define the terms biodiversity, genetic diversity, species diversity, and habitat diversity  Habitat Diversity – the range of different habitats in an ecosystem  Genetic Diversity – Range of genetic material present in a gene pool or population of a species.

5. 4.1.2 Outline the mechanism of natural selection as a possible driving force for speciation.  Evolution is the cumulative, gradual change in the genetic characteristics of successive generations of a species or race of an organism, ultimately giving rise to species or races different from the common ancestor.  Evolution reflects changes in the genetic composition of a population over time.

6. 4.1.2 Outline the mechanism of natural selection as a possible driving force for speciation.  Natural Selection (Evolution) comes down to a species adapting to their surroundings over time. A species with only plants to eat, will adapt to eating plants. A species with only animals to eat, will adapt to eating animals.

7. 4.1.2 Outline the mechanism of natural selection as a possible driving force for speciation.  Darwin’s theory of evolution by natural selection comes down to the following points:  Species show variation.  All species over-produce.  Despite over-production, population levels remain the same.  Over-production leads to competition for resources.  The fittest, or best adapted organisms, survive.  The survivors reproduce and pass on their adaptive genes to the next generation.  Over time, the population’s gene pool changes and new species emerge.

8. 4.1.3 State that isolation can lead to different species being produced that are unable to interbreed to yield fertile offspring.  Isolation is the process by which two populations become separated by geographical, behavioral, genetic, or reproductive factors. If gene flow between the two sub- populations is prevented, new species may evolve.  Geographical isolation is prominent by the fact that the species being physically divided stops the gene flow and therefore makes speciation more likely.

9. 4.1.3 State that isolation can lead to different species being produced that are unable to interbreed to yield fertile offspring.  Behavioral isolation is where changes to the appearance or behavior of the populations may result in there no longer being attraction among the two types, and therefore no longer breed.  Reproductive isolation is where two populations can no longer physically breed due to changes to reproductive organs.  Finally genetic isolation is where there are too many genetic differences for the two populations to produce fertile young.

10. 4.1.4 Explain how plate activity has influenced evolution and biodiversity.  The Earth’s crust (lithosphere) is divided into many different plates. These plates are carried on the mantle (asthenosphere), which can flow like a liquid on a geological time scale. Edges of adjacent plates can either move parallel to one another, push one under the other, or collide.  During the Paleozoic and Mesozoic eras all land mass was combined as the supercontinent Pangaea. However over time the land mass split apart into Laurasia and Gondwana.

11. 4.1.4 Explain how plate activity has influenced evolution and biodiversity.  The movement of the major and minor plates in relation to one another is called plate tectonics.  Movement of tectonic plates can produce barriers such as mountain ranges, oceans and rift valleys that can lead to isolation of gene pools and then speciation.

12. 4.1.4 Explain how plate activity has influenced evolution and biodiversity.  Land bridges can form from previously unconnected plates allowing species to spread.  The movement of plates through different climatic zones allows new habitats to present themselves, and allow for different adaptations.

13. 4.1.5 Explain the relationships among ecosystem stability, diversity, succession and habitat.  Organisms can colonize isolated land using several methods:  Air – By flying or passive transport  Sea – By swimming or floating on a log  Animal – By traveling inside or attached to animals that swim or fly  Colonization can be thought of as a type of dispersal as the organisms are dispersed to a new area

14. 4.1.5 Explain the relationships among ecosystem stability, diversity, succession and habitat.  Jump dispersal – Long-distance dispersal to remote areas by one or a few organisms. Explains wide distributions.  Diffusion – Slower than jump dispersal and involves populations, rather than individuals. Explain spread of species along edge of territory to new areas  Secular Migration – Dispersal over geological timescales. Takes place so slowly that the diffusing species undergoes evolutionary changes during the process.

15. 4.1.5 Explain the relationships among ecosystem stability, diversity, succession and habitat.  Remember that succession is when an ecosystem is formed from bare rock. As plants and animals arrive in a new area, they can get succession started. The succession will continue from there through a number of seres, which are sets of communities that succeed one another over the course of succession. If left uninterrupted, it will eventually lead to a climax community in this new locale. Species and genetic diversity increase through a succession.

16. 4.1.5 Explain the relationships among ecosystem stability, diversity, succession and habitat.  If there is a disturbance, the ability for the ecosystem to recover is based on three factors:  Inertia(persistence) – resistance to being altered  Resilience – ability of a system to recover after a disturbance  Diversity – the number and proportions of species present  The higher these are, the more likely they are to recover