Microevolution Basics
This is a change in allele frequencies within a population over time.
What is microevolution?
Individuals with favorable traits are more likely to do this.
What is survive and reproduce?
Genetic drift affects populations most strongly when they are this size.
What is small?
Evolutionary change above the species level.
What is macroevolution?
Structures with similar anatomy because of common ancestry.
What are homologous structures?
Natural selection, gene flow, genetic drift, and mutation are examples of these.
What are mechanisms of evolution?
Selection that favors one extreme phenotype.
What is directional selection?
A natural disaster suddenly reduces population size, causing random allele changes.
What is the bottleneck effect?
The formation of new species.
What is speciation?
Structures with similar functions but different evolutionary origins.
What are analogous structures?
When individuals move into or out of a population and bring alleles with them.
What is gene flow?
Selection that favors the average phenotype and removes extremes.
What is stabilizing selection?
A few individuals start a new population isolated from the original group.
What is the founder effect?
When populations become geographically separated.
What is allopatric speciation?
Reduced structures that have little or no current function.
What are vestigial structures?
A random change in allele frequencies caused by chance events.
What is genetic drift?
Selection that favors both extremes but not the middle.
What is disruptive selection?
Genetic drift is driven by this rather than fitness.
What is chance (random events)?
When new species form without geographic separation.
What is sympatric speciation?
Comparing DNA sequences provides this type of evidence for evolution.
What is molecular evidence?
This is the ultimate source of new genetic variation.
What is mutation?
Darwin called this process "descent with modification."
What is natural selection?
Genetic drift often causes populations to lose this.
What is genetic diversity?
When two species can no longer produce fertile offspring.
What is speciation?
The gradual change of one species into another over long periods demonstrates the connection between microevolution and this larger process.
What is macroevolution?