Evolution & Natural Selection Flashcards
What is Evolution?
It is an on going process
Characteristics of the individuals that make up a population can change over time
We can observe such change in nature and can even cause such change to occur
What is Natural Selection?
It is a mechanism of evolution
Consequences of certain individuals organisms in a population being born with characteristics that enable them to survive better ( reproduce more ) than others
Who evolves populations or individuals?
Evolution occurs when the allele frequencies in a population change over time.
Populations evolve, not individuals
What are the mechanisms of evolution?
Mutation
Genetic drift
Migration
Natural selection
What is the Evolutionary change: Mutation?
Mutation cases evolution when an alternation of the base- pair sequence in the DNA of an individuals gamete producing cells changes an alleles frequency
Mutations direct changes in the DNA of an individual….
It is the ultimate source of all genetic variation
What is Mutation?
An alternative of the base pair sequence in the DNA of an individuals gamete producing cells that changes an allele’s frequency
What is genetic drift ?
A random change in allele frequencies, unrelated to any allele’s influence on reproduction success
What is Migration?
A change in allele frequencies caused by individuals moving into or out of a population
What is Natural Selection?
A change in allele frequencies that occurs when individuals with one version of a heritable trait have greater reproductive success than individuals with a different version of the trait
What is genetic drift: Founder Effect?
Genetic drift occurs via the founder effect when the founding members of a new population have different allele frequencies than the original source population
ALLELE FREQUENCIES ARE UNRELATED TO REPRODUCTIVE SUCCESS
What is genetic drift: Bottleneck effect?
Occasionally, famine or disease or rapid environmental change may cause the deaths of a large, random proportion of the individuals in a population.
Evolution by Natural Selection: A Summary
Natural selection causes evolution as individuals with one version of a heritable trait have greater reproductive success than individuals with a different version of the trait
What is the evolutionary change in natural selection ?
- Variation for a trait
- Heritability
- Differential Reproductive success
Natural selection a mechanisms for…
Evolution
What is a summary of variation for a trait?
Different versions of a trait are present within a population
What is a summary for Heritability?
The different versions of a trait may be passed from parents to offspring
What is a summary for Differential Reproductive Success?
Individuals with the version of a trait most suited to reproduction in their environment generally leave more offspring than individuals with other versions of the trait.
Organisms in a population can become better matched to their environment through
Natural selection
Natural selection can change the traits in a population in several ways.. Which are they?
Stabilizing selection
Directional Selection
Disruptive Selection
What is directional selection?
Individuals with one extreme from the range of variation in the population have higher fitness
Ex: turkey Breast and there reproduction
What is stabilizing Selection ?
The average value of a trait remains the same while extreme versions of the trait are selected against
Ex: average size baby’s
What is Disruptive Selection?
Individuals with extreme phenotypes have the highest fitness
Ex: small and large coho salmon
What is convergent Evolution?
Analogous structures that develop from different original structures
NOT ALL adaptations that appear similar actually share ancestors
