Unit 2: Evolution Flashcards
Catastrophism
The idea that catastophies periodically destroy species living in a region, allowing species from neighboring regions to repopulate the area.
- Georges Cuvier
Uniformitarianism
The theory that geological processes operated at the same rate in the past as they do today and that changes result from the action of continuous and uniform processes. Slow and unperceivable change. (gradualism)
- Charles Lyell
Mass Extinction
Over 50% of all species become extinct in a short time (usually about 2 years)
Fossil Record
Traces and remains of past life found in sedimantary rock.
- Shows species alive and history
- helful for finding ancestors of species
Mutable
Changing
Transitional Fossils and Trace Fossils
A fossil that shows links between groups of organisms and shares characteristics common to two now seperate species (links from past to present). Trace fossils are fossils of a trace of an animals but not the animal itself.
Vestigial Structure
A structure that is a reduced version of one functional in the organisms ancestors.
Biogeography
The study of past and present geographical distribution of species populations.
homologous Structures
- different funtion
- same structure
- common ancestor
(evidence of divergent evolution)
Divergent Evolution
Species with a common ancestor change to become more different over time.
Convergent Evolution
Species with no ancestral similarities changing to develope similar characteristics.
Analagous Structures
- same function
- different structure
- no common ancestor
(evidence of convergent evolution)
Microevolution
Changes in characteristics within a species (smaller changes). Changes in allele frequency.
Macroevolution
Evolution that creates a new species (large changes).
Adaptation
A change where a species becomes better suited to its environment.
Species and “the species problem”
A group of similar individuals capable of exchanging genes. The species problem in the debate over how to define the word species and how to identify species.
Mutation
A random alteration in the nucleic acis (structure of genes) causing a variant form which may be passed to future generations.
Variations
Every individual is not the same as every other individual.
Background Extinction
Species going extinct based on non human factors at a normal rate.