BIOL 1105 Lesson 21: Mechanisms of Evolutionary Change

_____________ is the change in populations of organisms over time through shifts in allele frequencies.

Evolution

True or False: evolution can occur at an individual level

False

___________________is the presence of different alleles of genes in a population

Genetic Variation

What variation do the flowers lupin display?

polymorphic variation

Phenotype is the result of the ____________ and ________________.

Genotype and environment

_____________ is defined as a change in the base sequence of DNA.   

Mutation

The movement of alleles from one population to another

Gene flow

When an organisms moves to a new population.

Gene flow

_____________________is defined as a change in allele frequencies due to sampling error (random chance)

Genetic drift

________________ has the largest effect in small populations.

Genetic drift

When a new population is established by a small number of individuals and is likely to carry all alleles found in parent population.

Founder effect

When a small number of individuals are contributing gametes to the next generation due to a drastic reduction in population.

Bottleneck effect

________________ is when organisms produce differential numbers of offspring based on phenotype and behavior.

Selection

What are the four mechanisms of evolutionary change?

1) Mutation

2) Gene flow

3) Genetic drift

4) Selection

In _________________, individuals in a population must exhibit variability in traits.

variation

Natural selection is a process that occurs when _______________________ affect which individuals produce the most offspring.

environmental conditions

Outcome of natural selection depends on both _____________________________.

fitness and allele frequency

Mutations and genic drift can counter ______________.

Selection

_______________________occurs when humans select certain characteristics.

Artificial selection

True or False: Evolution and natural selection are essential the same concept.

False; natural selection is the process that leads to evolution

True or False: Survival and reproduction are not random.

True

Fitness refers to ________________________, not just survival. 

reproductive success

Natural selection favors phenotypes with the greatest ___________.

fitness

____________________is the influence of predators on the survival and reproduction of prey species. 

Predation Pressure

Evolutionary phenomenon where darker individuals are favored due to environmental changes (e.g., peppered moths). 

Industrial Melanism

What are three components of fitness?

Survival, mating success, number of offspring per mating

The ___________________ is a concept that predicts genotype frequencies in a population will remain constant from generation to generation under certain conditions, indicating no evolutionary forces are acting on the population.

Hardy-Weinburg principle

What are the conditions for Hardy-Weinberg equilibrium?

• No mutations.

• No gene flow (no migration into or out of the population).

• Random mating (mates are not chosen based on genotype or phenotype).

• Large population size.

• No natural selection occurring.

When the proportion of genotypes in a population does not change, the population is said to be in ____________________.

Hardy-Weinberg equilibrium

If allele or genotype frequencies change over time, ______________________ (e.g., selection, gene flow) are at work.

Evolutionary forces

Evolution can help us understand ___________________ and infectious diseases.

antibiotic resistance

____________________ are mechanisms that alter allele frequencies in a population, such as mutation, gene flow, genetic drift, natural selection, and nonrandom mating.

Evolutionary forces