1. Mutation- addtion of new alleles to a population through changes in DNA
2. Immigration- introduction of new allele or additional copies of existing alleles via members of different populations
3. Genetic Drift- changes in frequency of alleles in a population due to random effects
4. Selection- changed in frequency of alleles in a population due to differential survival and reproductive sucess of individuals carrying specific alleles
Euridian
Element that has a great inifinity to to bind to iron, usually comes from surface of extraterrestial sources- indicating major impact event
Mass Extinction
(Principle of Hierarchial View)
5 major mass extinctions have played a significatn role in shaping modern diversity
ex. KT extinction
Bolide impact events
Flood Basal Eruptions- Volcanism
Eustatic sea-level changes- changing sea level due to Plate tectonics and climate change <-- buggest mechanism for evolution
Faunal Turnover
(Principle of Hierarchial View)
Comparision of clade diversification can reveal major events in the history of life
representatives from 3 statistically distinct "Faunal Cohorts" showing patterns of diversification:
1. Vendian-Cambrian Fauna
2. Cambrian-Palaeozoic Fauna
3. Mesozoic-Cenozoic Fauna
Gambler's Ruin Model
(Principle of Hierarchial View)
Orgin and extinction of clades can be modeled as a random process
repeates many times before the "gambler losses"--> total extinction
Hierachical model of Macroevolution
Patterns of orgin, diversification & extinction of clades can reveal major events in the history of life
arises through unique, large-scale phenomena
contingent historical events are important-especially random
e.g. KT extinction
Extrapolationist model of Macroevolution
Accummulated effects of microevolution over very long periods of time
no unique phenomena
extinction
evolution is continous adaptations
e.g. horse
Macroevolution
Broad scale patterns of change above species level over geological time. Historical contingency determines which lineages persist.
Cladogenesis(speciation) is the main creative process
Extinction (lineage sorting) is the main destructive process
Microevolution
Genetic changed within a population level over ecological time scales; selection determines which traits persist.