Biology Chapter 19 Process of Evolution

What is soft inheritance?

Environmental forces can cause organisms to develop traits within their lifetime that are passed to offspring

What is evolution

Change in genetic composition of a population over time

What is natural selection?

The evolutionary process by which individuals best adapt to their environment, survive, and reproduce

What is artificial selection?

Selective breeding of organisms by humans

What is homology?

Similar features from shared ancestry

What is vestigial structures?

Structures that have lost original function

What is biological fitness?

The relative survival and reproduction success of an individual compared to others in the population.

What is an adaptation?

A heritable trait that evolved in a population through natural selection, it refers to both the trait and to this process

What is gene flow?

The transfer of alleles between populations, typically through migration of individuals or movement of gametes, can change allele frequencies in a population

What is genetic drift?

Random change in allele frequencies over time, especially potent when a population is reduced dramatically in size.

What is the bottleneck effect?

A large decrease in population size, where only a few individuals survive, will result in a random loss of genetic diversity

What is the founder effect?

Occurs when a small group of individuals establishes a new population, resulting in a random sample of the original population’s alleles

What is non-random mating?

Occurs when individuals choose mates with particular phenotypes, which can lead to changes in allele frequencies

What is sexual selection?

Occurs when individuals of one sex mate preferentially with particular individuals of another sex rather than at random

What does the Hardy-Weinberg equation demonstrate?

Shows that the allele frequencies in a population do not change when no evolution is occurring

What is the Hardy-Weinberg equation?

p² + 2pq + q² = 1

What are the H-W assumptions:

1. No mutation

2. No selection

3. No gene flow

4. Mating is random

5. Population size is infinite (no drift)

What is stabilizing selection?

Occurs when the mean phenotype has higher fitness than the extreme phenotypes

What is directional selection?

Occurs when an extreme phenotype has a higher fitness than the average phenotype

What is disruptive selection?

Occurs when both extreme phenotypes have higher fitness than the mean phenotype

What is the Heterozygote advantage?

Occurs when heterozygotes have higher fitness than homozygotes, maintaining alleles in a population

What is temporally variable selection?

Occurs when changing environments favor different phenotypes at different times, preventing allelic fixation

What is spatially variable selection?

Occurs when different local environments favor different phenotypes

What are evolutionary trade-offs?

Occur when a trait that improves fitness in one context reduces fitness in another.