1. Chapter 12- Biodiversity
Biodiversity- the diversity to genes, species and ecosystems in a region
-the more different species in an area, the more biodiversity
Extinction- death of a species, elimination of all of a particular species
As species become extinct, they decrease the biodiversity of an area

2. Major factors of extinction:
1. low population density
(successful reproduction of a small number is less likely as compared to a larger number ex. cheetah)
2. found in only a small area
(if something happens in that area such as a natural disaster, then the species will die)
3. specialized niche
(ex. If eat only a certain type of food, then if that food is gone they will die)

3. Extinction due to human activity:
Exploit minerals and resources
(ex. Space)
Damage the environment
(ex. As humans used fire, they burned many ecosystems)
(ex. cutting down of timber damaged habitats)
(ex. Farming, eat many animals and plants)

4. Types of diversity: Genetic diversity Species diversity
Ecosystem diversity

5. Genetic diversity
Term used to describe the number of different kinds of genes present in a population or species
High genetic diversity means there are many genes present and the individuals have different structures and abilities

6. Factors that affect genetic diversity:
1. Mutations- changes in the genetic information of an organism
They introduce new genetic information into a population by modifying genes (DNA)
It changes characteristics of offspring

7. Factors that affect genetic diversity continued:
2. migration- movement of individuals from one population to another
ex. An animal takes characteristics from the old environment to the new one/he may not have characteristics that allow him to thrive in the new environment

8. Genetic diversity factors continued:
3. Sexual reproduction- contributing of different traits causes new genetic combinations resulting in new characteristics
4. Population size- the smaller the population the few variations of genes
5. Selective breeding- certain desired characteristics are passed on (lowers genetic diversity)

9. Species diversity:
Measure of the number of different species in the same area
Example: tropical rainforest has high species diversity

10. Measure of species diversity:
Species richness- count the number of the different kinds of species
Taxonomic richness- the number of different taxonomic groups in an area
ex. Number of frogs (all types)

11. Factors that affect species diversity:
Drastic change in the ecosystem such as disaster or human activity
Introduction of new species/migration
Size of the area

12. Ecosystem diversity Measure of the number of kinds of ecosystems
in an area
Topography has a lot to
do with the type of
ecosystem

13. 4 Major Human Threats to Biodiversity:
Habitat loss
Overexploitation
Introduction to exotic species
Persecution of pest organisms

14. Habitat loss: -80-90% of species lost are due to this
-Conversion of natural ecosystems to
human dominated ecosystems
-main human activities are farming,
grazing of livestock, modification of
aquatic habitats, conversion of
landscapes
-These activities reduce the number of existing species because it damages their habitat
-80-90% of species lost are due to this

15. Means of habitat removal (clearing of land):
Agriculture- about 40% of the world’s land has been converted to cropland and pasture
Desertification- over use of land for things such as grazing of pastures
Deforestation- removal of forests for building materials, clear land for fields
Clear-cutting- removal of all trees in a large area (it causes a lot of erosion)
Selective harvesting- choosing the trees that they want to harvest (ex. Mahogany)

16. Urban habitat loss:
About 4.3 percent of US land is used for urban centers, industrial sites, transportation infrastructures
These areas are mostly covered with impermeable surfaces (no plant growth)
It diverts rain to local stream and rivers

17. Overexploitation -Occurs when humans harvest organisms faster than
they reproduce
-causes 30% of endangered
animals (ex. Overfishing)
-illegal trade of wild animals produces $2 to 30.5 billion per year (meat from wild animals is called “bush meat”

18. Introduction of exotic species:
-Exotic species- species
brought from areas outside
of the ecosystem (not native)
-Competes with native
species for resources
such as food and space

19. Control of pest organisms (affect on biodiversity)
When you kill one species, it will affect other species
Example: killing large predators such as the grizzly bear and mountain lion because they kill livestock has reduced their population drastically.
This leads to more prey in an area (overpopulation of animals like rodents)

20. species in danger of extinction:
Endangered species- species that has such a small number that they are in immediate jeopardy of extinction
Their survival is unlikely of the conditions threatening them continue
Threatened species- could become extinct if a critical factor in their environment changes
The method to stop extinction is to preserve the habitat
This is why we try to preserve the wilderness- a place that is unaltered by man
ex. yellowstone

21. How to insure survival of animals?
Provide a suitable habitat and protect the animals and habitat (wildlife management)

22. Preserving biodiversity:
Understand the life history of the organism and its significance so that effective measures can be taken
Protect species that are endangered or threatened legally
(Convention of Biological
Diversity treaty)
Reduce the impact
of human activity