Chapter 8
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Genetic diversity
Total number of genetic characteristics of a specific species, subspecies, or group of species
What is biological diversity
Refers to the variety of life in an area Expressed in 2 ways Number of species in an area Number of genetic types in an area
Habitat diversity
The different kinds of habitats in a given unit area
Species richness
Total number of species
Species evenness
Relative abundance of species
Species dominance
The most abundant species
Number of species on Earth
1.5 million species have been identified Estimated at almost 3 million different species currently exist
Categorized into taxa
Kingdom Phylum Class Order Family Genus Species
Mutation
Changes in DNA
Natural selection
Survival of the fittest
Migration
Introducing I removing isolation
Genetic drift
Chance changes in the frequency of a gene
Four primary characteristics of natural selection
Genetic variability Environmental variability Differential reproduction that varied with the environment Influence off the environment on survival and reproduction
When two populations become geographically isolated for a long time
Differences accumulate so that they no longer reproduce Two new species have formed
Genetic drift
Changes in frequency of a gene in a population simply by chance
Founder defect
Small number of individuals are isolated from larger population Less genetic variation than original population Characteristics present are affected by chance Individuals may not be better adapted
Competition
The outcome is negative for both groups
Symbiosis
Benefits both participants
Predation and parasitism
The outcome benefits one and is detrimental to the other
Competitive exclusion principle
Two species that have exactly the same requirements cannot coexist in exactly the same habitat
Biomes
Similar environments provide similar opportunities and similar constraints Leads to evolution of organisms similar in form and function Rule of climatic similarity
Divergent evolution
Population is divided and each evolves separately
In save species
Introduction is a prices not native to an ecosystem May have few, if any, predators May compete with, and reduce numbers of, native species