#14 Evolution Flashcards
(21 cards)
Evolution
- a change in genetic allele frequencies in a population (not individuals) over time
- only detectable in a population
- formation of new species is a special case of evolution
the theory is falsifiable
Darwin
Origin of Species (1859)
-Natural selection: unequal reproduction between types
Modern Synthesis
Joins genetics and evolution into a single body of knowledge
Microevolution
Short time spans
Change in allele frequencies within a population
Macroevolution
Long time span
Cumulative effects of microevolutionary processes
Support for the evolutionary theory
Fossil records Biogeography Comparative anatomy Comparative embryology Molecular biology Observed natural and artificial selection
Strata
Rock layers
- organisms preserved here as “sample”
- see change in historical sequence
Biogeography
Geographic distribution of species
-areas separated longer, more unique collection of species
Homology
Similarity that results from common ancestry
E.g. same structures change for different functions
Vestigial organs
Organs with no use to organism, had use in ancestor
Comparative embryology
Compare early stages of development
-early structures become vestigial or highly modified in evolutionarily “newer” organisms
ALL organisms use
DNA and RNA to code for protein
Natural selection based on
- Variation among indiv. (diff phenotypes)
- Variation is heritable (genetic)
- Diff reproduction among phenotypes (beneficial to have variet)
Artificial selection
Differential reproduction generated by human breeding
Natural selection
Editing mechanism
Four mechanisms that contribute to evolutionary change
- Selection
- Natural
- Sexual
- Mutation
- Genetic drift
- Gene flow
Sexual selection
Caused by mating differences - preference for showy traits - weapons for fighting off mates Often leads to sexual dimorphism Traits that may help repro. may hurt survival
Mutation
Spontaneous (must be in gametes)
Largely cause by chemical or ionizing radiation
Most have no effect (eye color) or are deleterious and recessive
Genetic drift
Change in gene frequencies due to chance (no adv. or disadv.)
Small pop
Founder effect
Bottleneck effect
Gene flow
Change in frequency due to dispersal
Introduces new alleles to pop.
Evolution fashions imperfect organisms
Organisms limited by historical constraints
Selection can only EDIT existing variation
Adaptations are often compromises
Selection and chance interact