Evolution Flashcards
What is the biological definition of evolution?
A change in the gene pool of a population from generation to generation by such processes as mutation, natural selection, and genetic drift
What are three important, non-biology definitions of evolution?
- A process of formation or growth
- A process of gradual, peaceful, and progressive change or development, as in social or economic structure of institutions
- A pattern formed by, or as if by, a series of movements: the evolution of a figure skater
Definition of evolution in terms of alleles
A change in allele frequencies in a population from generation to generation
What is a gene?
A unit of DNA that codes for a protein
A unit of heredity
What are alleles?
Alternate forms of the same gene; different alleles may code for different phenotypes
What is a phenotype?
The set of observable physical characteristics of an organism, a product of genes and the environment
What is a genotype?
An individual’s set of genes
The pair of alleles an organism has for a gene
What does it mean to be inherited?
Passed from parent to offspring via genes
What is a mutation?
A permanent change in an organism’s DNA sequence that may or may not result in phenotypic change
How can mutations occur?
Randomly or due to physical, chemical, or biological agents
Mutations are the source of what?
All genetic variation
What is frequency in a biological sense?
How common an allele is in a population relative to the alleles for that gene
What is population in a biological sense?
The set of individuals of a species that live in the same area and can interbreed
What is an inference?
A conclusion reached on the basis of evidence and reasoning
What are the three inferences made about evolution by natural selection?
- Survival and reproduction differ among varied phenotypes in response to an environmental pressure
- Individuals with phenotypes better suited to the environment pass their alleles to offspring at a greater rate than individuals with phenotypes poorly suited to their environment
- Alleles for an adaptive phenotype well suited to the environment are more common in the population in the next generation
What is natural selection?
When individuals with certain heritable characteristics are more likely to survive/reproduce in their environment because of those characteristics.
Alleles for these characteristics thus become more common in the next generation
Populations can only evolve regarding traits that are _________
Heritable/Inherited
What are 2 observations of evolution in terms of random events?
- Random occurrences can result in evolution of a population
- These populations are not always better suited to their environment
What are 3 inferences of evolution in terms of random events?
- Evolution is not always predictable
- Evolution does not always result in better adapted populations
- Evolution can happen via multiple mechanisms
What is genetic drift?
When there are random, non-adaptive changes in allele frequency between generations
What is an observation of evolution in terms of allele frequency?
Allele frequencies can’t change if 100% of the population has the same allele
What is an inference of evolution in terms of allele frequency?
Evolution works on preexisting variation in a population
What are 3 inferences of evolution in terms of mutations and adaptations?
- Evolution is not goal-oriented
- Organisms don’t mutate or adapt because they “need to”
- Individuals/populations poorly suited to the environment may die out
What is an inference of evolution based on migration/gene flow?
Evolution can occur via migration, or gene flow, as new alleles are introduced to a population
Mutations are…
The ultimate source of all genetic variation
By default, introducing a new allele to a population does what to it?
Changes the allele frequency of that population
What are the 4 mechanisms from which evolution can occur?
Natural selection, mutations, genetic drift, and gene flow
Which mechanism(s) of evolution result(s) in adaptive/non-random evolution?
Natural selection
Which mechanism(s) of evolution result(s) in non-adaptive/random evolution?
Mutations, genetic drift, and gene flow
What is gene flow?
Movement of alleles from one population to another
Phenotype is the product of both ______ and _______.
Genes, the environment
