Unit 1 Study Guide — Evolution Flashcards

A complete set of vocabulary flashcards covering evolutionary principles, genetics review, heritability, selection forms, genetic drift, constraints, and biological mechanisms from the lecture transcript.

Evolution

A change in allele frequencies in a population over generations.

DNA

The molecule that contains genetic information.

Chromosome

A long, packaged piece of DNA containing many genes.

Gene

A section of DNA associated with a particular function or trait.

Allele

A different version of a gene.

Genotype

The specific alleles an individual has.

Phenotype

The observable characteristics of an individual.

Mutation

A change in DNA that occurs randomly with respect to what an organism needs.

Heritability

The proportion of phenotypic variation within a population that is explained by genetic variation, calculated as $\text{Heritability} = \frac{\text{genetic variation}}{\text{total phenotypic variation}}$ with values ranging from $0$ to $1$.

Fitness

Reproductive success, defined as contributing more offspring or genes to the next generation.

Artificial Selection

Humans choose.

Natural Selection

Enviormental conditions cause some phenotypes to reproduce more.

Sexual selection

mate choice/ competition cause some individuals to produce more offspring than others.

Darwin's Four Postulates

1. Individuals within populations vary. 2. Some variation is heritable. 3. More offspring are produced than can survive or reproduce. 4. Survival and reproduction are non-random.

Adaptation

A heritable trait that evolved through natural selection because it increased fitness.

Sexual Dimorphism

Differences in traits between males and females of the same species produced by different reproductive pressures.

Mutation-Selection Balance

mutation keeps adding harmful alleles to a population while natural selection keeps removing them.

Pleiotropy

A genetic phenomenon where one single gene affects multiple traits.

Neoteny

When an organism brings young traits into adulthood.

Human Self-Domestication

The hypothesis that humans experienced long-term selection favoring traits like cooperation, social tolerance, and reduced aggression.

Sampling Error

when random sample does not perfectly represent the original population just because of chance.

Genetic Drift

Random change in allele frequencies caused by chance

Founder Effect

A type of genetic drift that occurs when a small group leaves a larger population and establishes a new population with random sampling and different allele frequencies.

Bottleneck Effect

A type of genetic drift that occurs when an existing population suddenly shrinks due to events like disasters, disease, or hunting.

Neutral Mutation

A mutation that does not significantly affect an organism's fitness.

Neutral Theory

the idea that many genetic changes involved in evolution do not affect an organism’s fitness.

Exaptation

A trait that originally evolved for one function and was later used for a different function.

Spandrel (Byproduct)

A characteristic that exists as a side effect of selection acting on another trait rather than being directly favored by natural selection.

Migration (Gene Flow)

The movement of individuals and their alleles between populations.

Four Major Mechanisms of Evolution

The four forces driving evolution are mutation, natural selection, genetic drift, migration.

Proximate Explanation

explains HOW something happens — the immediate biological or environmental mechanism behind a trait or behavior.

Ultimate Explanation

An ultimate explanation explains why a trait or behavior evolved.

Natural selection misconceptions from reading

Selection and genetic drift are both mechanisms of evolution, natural selection is non-random and can produce adaptations, genetic drift is random.

How does the fox experiment support domestication as retention of juvenile traits?

the domesticated foxes retained young traits, behaviors and physical characteristics into adulthood. an example of neoteny.

Heritability scale of closest to 0

none is explained by genetic differences.

Heritability scale closest to 1

all explained by genetic differences.

does genetic drift negate natural selection

no, both are mechanisms of evolution, genetic drift is random while natural selection is non random differences in reproductive success. Evolution can contain both non-random and random processes.