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

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)

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)

Types of diversity: Genetic diversity Species diversity Ecosystem diversity

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

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

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

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)

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

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)

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

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

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

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

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)

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

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”

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

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)

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

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

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