Evolution Lecture Notes - BIOL2040

These flashcards cover key vocabulary terms and definitions from the Evolution lecture notes for BIOL2040.

Evolution

Change in heritable characteristics of biological populations over successive generations.

Descent with modification

Change in characteristics over generations.

Natural selection

Process that explains how organisms’ traits change over time based on variation.

Mutation

Alteration in the DNA sequence of an organism.

Migration (gene flow)

Movement of genes between populations, leading to gene exchange.

Genetic drift

Random fluctuations in allele frequencies due to chance events.

Allele frequencies

Proportion of different alleles in a population.

Microevolution

Change in species over time at the level of populations.

Macroevolution

Evolutionary changes that result in the formation of new species.

Species

Group of organisms capable of interbreeding.

Common ancestor

Ancester from which different species have evolved.

Branching tree of life

Representation of the evolutionary relationships of species.

Variational process

Evolution occurs due to sorting among variants, influenced by natural selection.

Phenotype

The observable characteristics of an organism.

Genotype

The genetic constitution of an organism.

Heterozygote

Individual with two different alleles at a locus.

Homozygote

Individual with two identical alleles at a locus.

Epigenetics

Study of changes in gene expression without alteration of the DNA sequence.

Gene duplication

Process where a gene is copied, potentially leading to functional divergence.

Fixed allele

An allele that is the only variant present at a genetic locus in a population.

Effective population size

The number of individuals in a population who contribute offspring to the next generation.

Hardy-Weinberg equilibrium

Condition in which allele frequencies remain constant over generations.

Inbreeding depression

Reduced biological fitness due to mating of genetically similar individuals.

Selection coefficient (s)

Measure of the relative fitness reduction of a specific genotype.

Fitness

The reproductive success of an individual relative to others.

Assortative mating

Non-random mating where individuals with similar genotypes or phenotypes mate more frequently.

Disassortative mating

Non-random mating where individuals with different genotypes or phenotypes mate.

DNA methylation

A biochemical process that influences gene expression by adding a methyl group to DNA.

Phenotypic variation

Differences in appearance or function among individuals in a population.

Genetic drift

Random changes in allele frequencies in a population.

Population genetics

Study of how allele frequencies and genotype frequencies change in populations.

Nucleotide mutation

Change to the base pair sequence of a DNA molecule.

Selection pressure

Environmental factors that influence reproductive success in organisms.

Polygenic traits

Traits that are influenced by multiple genes.

Phenotypic plasticity

The ability of one genotype to produce different phenotypes in response to environmental changes.

Adaptation

Inheritable trait that improves an organism's fitness within its environment.

Exaptation

Trait that evolves for one function and is co-opted for another function later.

Gene flow

Transfer of alleles from one population to another.

Species diversity

Variety of different types of organisms within a community.

Genetic polymorphism

The occurrence of two or more variants of a particular gene in a population.

Founder effect

Loss of genetic variation that occurs when a new population is established by a small number of individuals.

Gene frequency

Rate at which a specific allele appears within a population.

Directional selection

Type of natural selection that favors one extreme phenotype.

Stabilizing selection

Type of natural selection that favors intermediate phenotypes.

Disruptive selection

Type of natural selection that favors extreme phenotypes over intermediate ones.

Neutral theory

Theory that most genetic variation is not affected by natural selection.

Founder effect

Small sample of a population becomes isolated, leading to reduced genetic diversity.

Adaptive radiation

Evolution of diversely adapted species from a common ancestor.

Bottleneck effect

Drastic reduction in population size due to environmental events leading to reduced genetic diversity.

Cline

Gradual change in a trait or allele frequency across geographical areas.

Mating system

The ways in which a species mates and raises its offspring.

Microevolution

Change in allele frequencies in a population over time.

Genetic variance

Variation in genotypes within a population.

Environmental variance

Variation in phenotypes attributable to environmental factors.

Quantitative traits

Traits that vary continuously and are typically influenced by multiple genes.

Heritability

Proportion of observed variation in a phenotype that can be attributed to genetic factors.

Broad-sense heritability (H2)

Total genetic variance in a trait; includes all genetic contributions.

Narrow-sense heritability (h2)

Proportion of phenotypic variance due to additive genetic variance.

GxE interaction

Interaction between an individual's genotype and their environment affecting phenotype.

Transcription

Process by which the DNA sequence of a gene is copied into RNA.

Translation

Process by which RNA is used to synthesize proteins.

Cytoskeleton

Network of fibers in a cell that helps maintain its shape and organization.