Geo2:Chapter 9

-genetically controlled changes in physiology, anatomy and behavior that occur over time

different species with the same ancestor

the development of two or more different species from a single common ancestor species

• -father of genetics
• -Pea experiments
• -Units of inheritance do not change or blend

• 1. Genes
• -chemical unit of heredity
• -formed of DNA
• 2. DNA
• -a molecule with a double helix structure

genetically controlled variation in appearance within a population

full range of genes present in a species

differences in physiology,anatomy, or behavior within a species

genetic differences within a species

random changes in the genes or chromosomes of a cell

a geographic gradient in a genetically controlled trait

sexual reproduction between two different species

the process by which the genes for genetically controlled traits become more common in a population over time because individuals with those traits are reproductively more successful than other individuals

The development of two or more different species from a single common ancestor species

there should be a barrier between a new species and an original species

• 1. Ranges of tolerance
• -determine where on Earth a species may be found
• 2. Ecological optimum
• -the environmental conditions under which a species will prosper

long period of time with no evolutionary changes

a slow steady process

speciation occurs within an originally small group, which later expands

There are patterns but no general direction

• 1. Founder principle
• -small isolated populations have less genetic variation than the main population.
• -favors allopatric speciation
• 2. Bottleneck
• -decrease in genetic diversity as a result of a significant decrease in population size

geological event of environmental changes that splits a range of species in tow isolated partys

formation of several species from a single ancestor

• 1. Convergent evolution
• -the development of similar traits in unrelated species living in similar environments
• Ex. Tenrec and Hedgehog
• 2. Divergent evolution 
• -separation of a species into new types
• Ex. Aardvark, numbat and anteater

• 1. Parallel evolution 
• -geographically isolated populations derived from the same ancestor evolve into morphologically and physiologically similar descendant species
• 2. Coevolution
• -two unrelated species evolve traits that are tied to their interaction

total loss of a species, genus, family, or order

• 1. Local extinction
• -a species disappears in one area but persists in others
• 2. Global extinction 
• -a species disappears completely
• 3. Phyletic extinction
• -when a species/genus evolves into a new species/genus

• the loss an important prey species causes further extinctions for higher predators 
• Ex. California condor

• persist without considerable evolutionary changes for a geologically long time
• -Ex. Atlantic horseshoe

• 5 largest mass extinction
• -Most recent is the Cretaceous Tertiary
• -dinosaurs died