Evolution & Natural Selection Flashcards
The physical appearance and actual behavior of a particular individual; results from interaction of genotype and the environment
Phenotype
The genetic makeup of a particular individual
Genotype
A group of organisms that can reproduce and produce viable offspring.
Biological definition of Species
Group of organisms with similar unique sets of physical characteristics
Morphological definition of species
All of the members of a particular species in a particular area
Population
All of the varieties of all genes in a population
Gene Pool
The % of each gene variety (allele in a population
Gene Frequency
Change in gene frequency over time
Evolution
2 sources of new genetic variation
2 other ways gene frequencies change
Mutation
Recombination (sex repr)
Gene flow
Genetic drift
A small mistake in the DNA code
Mutation
Sperm + Egg puts existing gene varieties into new combinations
Recombination / sexual reproduction
When one individuals move from one population to the next, bringing new gene varieties with it
Gene Flow
The loss of gene varieties due to random chance
Genetic Drift
The mechanism by which evolution changes gene frequencies
determines the direction (+/-) of the gene frequency change
Natural Selection
A trait that gives an organism a survival & greater reproductive success in a particular environment
(Reproductive success & biological fitness)
Adaptions
3 kinds of Adaption
- Physical -part of body
- Behavioral -action
- Physiological -biochemical
Natural Selection acts on the ______ BUT evolution only occurs if there is some _____ basis for the _______.
- Phenotype (the adaption)
- Genetic
- Phenotype
Natural selection can be DIRECTIONAL, DIVERGENT, or STABILIZING. Explain the 3.
- Directional: favors individuals at one end of the phenotypic range
- Divergent: favors individuals at both extremes of the phenotypic range
- Stabilizing: favors intermediate variants & acts against extreme phenotypes
Applying microevolution to long time scales to explain how new species originate and evolve
Macroevolution
Process of two populations becoming two distinct species
Speciation
No reproduction or no viable offspring
Reproductive isolation
Happens before sperm and egg join
Pre-zygotic
Egg & sperm have met
inferior offspring, babies can not reproduce
Post-zygotic
Allopatric Speciation
1 population becomes geographically isolated
2 geographic isolation prevents gene flow
3. Natural selection acts on each population separately
4. Small changes accumulate until two populations are reproductively isolated
