Name the four conditions Darwin described for a population to evolve.
Describe natural selection and cite an example
Describe artificial selection and cite an example.
Sexual selection
Sexual dimorphism
Evidence supporting Darwin’s “descent with modification”
Conditions are needed for a gene frequency to remain constant?
Genetic drift
Gene flow
Founder effect
Hardy Weinberg
Cline
Morphology
Stabilizing selection
Disruptive selection
Neutral variations
Directional selection
Variation
Conditions that maintain variation
Bottleneck effect
Polymorphism
Conditions that promote variation
Frequency Dependent Selection
Heterozygote Advantage
Gene pool
Population
Balancing selection
Sexual Reproduction
Mutation
Gene variation
A change in the nucleotide sequence creating genetic variation. [must be a gamete in multi-cellular
organisms to cause change]
Variation in non-coding regions of DNA.
Large population
Allele frequencies change by chance.
fossils, embryology, biogeography, comparative anatomy, molecular biology,
Individuals with certain traits are more likely to obtain mates.
Favors intermediate phenotypes, in stable environments. Eliminates extreme phenotypes. Human birth
weights are usually 6.5 to 9 pounds, extremes have higher infant mortality.
No mutation of genes.
When selection maintains two or more phenotypes and/or several different environments where a species
lives.
Joining of unique gametes that creates genetic variation.
A static environment.
excess offspring,
Developed a method to analyze gene frequency in a population.
A few individuals colonize a new or isolated environment. New gene frequencies for the new pop.
unequal reproductive success, coloration in desert lizard.
variations exist
A changing environment.
No selection
A balancing selection that maintains two different phenotypic forms. Selection occurs against any
phenotype if it becomes too common. “Left handed” and “right handed” predators. Prey learns how to
avoid the most common attack “left” or “right” so the trait is selected against.
antlers on male elk
competition
Selecting for organisms at both extremes of a phenotypic range. Produces two or more contrasting
phenotypes.
A balancing selection where heterozygous individuals have greater reproductive success.
wild mustard giving rise to cabbage and broccoli and brussels sprouts, varieties of cattle and dogs.
No immigration/emigration
All organisms are equal in their ability to reproduce. Large pop. No selection for traits, random mating, no
immigration/emigration.
Random mating.
Drastic reduction in a population with new gene frequency in the survivors.
Selects for individuals at one of the phenotype extremes. Environmental change or migrating to new
habitat.
Gaining or losing fertile individuals from the population; immigration/emigration or gametes are
transferred between populations.
Unique set of genes in each individual*
Developed a method to analyze the gene frequencies in populations.
The physical structure of an organism.
A graded change in a species related to geographic location. Bird body size increases with latitude, larger
organisms in colder climates.
Total collection of genes in a population at any onetime.
limited resources,
A group of organisms of the same species living at the same place and the same time.
Darwins 4 conditions
variations exist, excess offspring, limited resources, competition
Natural Selection
unequal reproductive success, coloration in desert lizard.
Artificial selection
wild mustard, varieies of cattle and dogs.
Sexual selection
Individuals with certain traits are more likely to obtain mates.
Sexual dimorphism
antlers on male elk
Evidence for Darwin
fossils, embryology, biogeography, comparative anatomy, molecular biology,
What conditions are needed for a population gene frequency to remain unchanged.
All organisms are equal in their ability to reproduce. Large pop. No selection for traits, random mating, no
immigration/emigration
Genetic drift
Allele frequencies change by chance.
Bottleneck effect.
Drastic reduction in a population with new gene frequency in the survivors.
Founder Effect
A few individuals colonize a new or isolated environment. New gene frequencies for the new pop.
Gene Flow
Gaining or losing fertile individuals from the population; immigration/emigration or gametes are transferred between
populations.
Hardy-Weinberg
Developed a method to analyze gene frequency in a population.
Cline
A graded change in a species related to geographic location. Bird body size increases with latitude, larger organisms in
colder climates.
Population
A group of organisms of the same species living at the same place and the same time.
Gene Pool
Total collection of genes in a population at any onetime.
Gene variation
Unique set of genes in each individual*
Mutation
A change in the nucleotide sequence creating genetic variation. [must be a gamete in multi-cellular organisms to cause
change]
Sexual reproduction
Joining of unique gametes that creates genetic variation.
Morphology
The physical structure of an organism
Stabilizing Selection
Favors intermediate phenotypes, in stable environments. Eliminates extreme phenotypes. Human birth weights are
usually 6.5 to 9 pounds, extremes have higher infant mortality.
Directional Stabilization
Selects for individuals at one of the phenotype extremes. Environmental change or migrating to new habitat.
Disruptive selection
Selecting for organisms at both extremes of a phenotypic range. Produces two or more contrasting phenotypes.
Balancing selection
When selection maintains two or more phenotypes. Several different environments where a species lives.
Heterozygote advantage
A balancing selection where heterozygous individuals have greater reproductive success
Frequency dependent selection
A balancing selection that maintains two different phenotypic forms. Selection occurs against any phenotype if it
becomes too common. “Left handed” and “right handed” predators. Prey learns how to avoid the most common attack
“left” or “right” so the trait is selected against.
Neutral variation
Variation in non-coding regions of DNA