Theories of Evolution
Agents of Change/ Sources of Variation
Natural Selection
Speciation
Reproductive Isolation
100
Define evolution.
a change in allelic frequencies over time
100
What is the only way new alleles in a population can be created?
mutations
100
What is natural selection?
ability of an organism to survive to reproduce in their environment based on their genetic fitness
100
Define species.
a group of animals capable of interbreeding and producing fertile offspring
100
What is prezygotic barrier?
a barrier that prevents mating or fertilization
200
Name two tenants of Darwin's theory of evolution.
1. there are variations with populations 2. some variations are more favorable than others 3. competition results as more offpsring are produced than can be supported 4. survival of the fittest 5. over time, the more favorable traits become more common than the unfavorable traits
200
How does diploidy facilitate diversity in a population?
Each organism has two copies of an allele. A phenotype may be selected for or against, but the recessive allele "hiding" in a heterozygote can allow that allele to persist.
200
What is stabilizing selection? Give an example.
Extremes are selected against i.e. birth weights
200
What is allopatric speciation? Give an example.
When speciation occurs with/because of a geographical barrier i.e. squirrels on different sides of Grand Canyon
200
What is a postzygotic barrier?
prevents the zygote from devloping into a fertile adult with fertile offspring
300
Describe a theory (other than creation theory) of how life formed on Earth.
Inorganic molecules-organic molecules such as amino acids, proteins, etc. with addition of lightning, volcano eruption, etc., then proteinoid structures- single-celled prokaryotes, eukaryotes from endosymbiont theory, etc.
300
What is balanced polymorphism?
when existence of more than one gene is encouraged because it is beneficial i.e. heterozygote advantage or hybrid vigor
300
What is directional selection? Give an example.
Natural selection favors one option over another, i.e. drought produces harder seeds so birds with larger beaks are favoured over ones with smaller beaks
300
What is sympatric speciation?
When a new species is formed without geographic isolation
300
What are two types of prezygotic reproductive barriers?
habitat, behavioral, mechanical isolation
400
Name two fields of study or pieces of scientific evidence that support the theory of evolution.
the fossil record, biogeography, comparative anatomy, comparative embryology, molecular biology
400
What is gene flow?
The reduction or addition of alleles as organisms leave or enter the population
400
What is diversifying selection? Give an example.
where two extremes are favored i.e. black and white vs. brown rabbits in a snowy, rocky environment
400
What is the difference between convergent evolution and coevolution?
convergent evolution-when two species that are not closely related develop similar adaptations to their environments coevolution-when one species evolves in response to another species evolving, usually predator/prey
400
What are two types of postzygotic reproductive barriers?
reduced hybrid viability, reduced hybrid fertility, hybrid breakdown
500
Compare and contrast the two main theories for the tempo (timing) of evolution.
Both gradualism and punctuated equilibrium happen over long periods of time (at least hundreds of years). In gradualism, species from a common ancestor diverge more and more as they acquire unique adaptations (lots of intermediate forms). In punctuated equilibrium, species change most when they split off from a parent species, but change little after that.
500
What is genetic drift? What are the two main types that we talked about?
the random increase or decrease of an allele's frequency in a small population-founder effect or bottleneck effect
500
What is sexual selection? Give an example.
selection of a mate based on a specific trait i.e. birds with colorful plumage, bigger males, etc.
500
What is adaptive radiation? Where is this type of speciation very common?
when several organisms evolve from a single ancestor, island chains
500
Name two hybrid species that suffer from reduced hybrid fertility.
mules and ligers
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