Darwin's Theory of Evolution

35 vocabulary flashcards covering key terms from the lecture notes on Darwin and evolution.

Origin of Species

Darwin's 1859 book proposing evolution by natural selection, supported by evidence from biology, geology, and paleontology.

Natural Selection

Process by which heritable traits that improve survival and reproduction become more common in a population over generations.

Descent with Modification

Darwin's idea that lineages descend from ancestors with changes accumulated over time.

Homology

Similarity due to shared ancestry; homologous structures can have different functions.

Vestigial Structures

Remnants of features that served functions in ancestors but are reduced or unused in descendants.

Fossil

Imprints or remains of organisms from the past, showing differences and extinct forms.

Fossil Record

Chronicle of life in rock strata, showing the order of appearance of living forms.

Transitional Fossil

Fossil showing intermediate features linking major groups (e.g., jaw evolution).

Geologic Time Scale

Timeline of Earth's history spanning millions of years, used to date fossils.

Charles Lyell

Scottish geologist whose work argued that Earth is ancient and shaped by gradual processes.

Alfred Wallace

Naturalist who independently conceived a theory of natural selection similar to Darwin's.

HMS Beagle

Darwin's survey ship on which he collected observations that influenced his theory.

Galápagos Islands

Islands noted for diverse organisms that influenced Darwin's ideas on evolution.

Biogeography

Study of the geographic distribution of organisms.

Artificial Selection

Selective breeding by humans to modify species.

Thomas Malthus

Economist whose ideas on population growth and resources inspired Darwin's struggle for existence.

Struggle for Existence

Competition for limited resources that affects survival and reproduction.

Relative Fitness

An individual's contribution to the next generation's gene pool relative to others.

Adaptation

Heritable trait that improves survival or reproduction in a given environment.

Mutation

Change in a DNA nucleotide sequence; source of new alleles.

Allele

One of several alternative forms of a gene at a locus.

Gene Pool

All copies of every allele present in members of a population.

Hardy-Weinberg Equilibrium

Condition where allele and genotype frequencies remain constant in the absence of evolutionary forces.

Allele Frequency

Proportion of a given allele among all alleles at a locus in a population.

Genotype Frequency

Proportion of different genotypes (e.g., AA, Aa, aa) in a population.

Five Hardy-Weinberg Conditions

A very large population; no gene flow; no mutations; random mating; no natural selection.

Nonrandom Mating

Mating that is not random; can change genotype frequencies but often has little effect on allele frequencies.

Genetic Drift

Random fluctuations in allele frequencies due to chance, more impactful in small populations.

Bottleneck Effect

Sharp population size reduction causing loss of genetic diversity.

Founder Effect

When a small group colonizes a new area, creating a new population with limited genetic variation.

Gene Flow

Movement of alleles between populations; tends to reduce differences.

Pesticide Resistance

Allele frequency shift under pesticide exposure; example of directional selection.

Stabilizing Selection

Selection that favors intermediate phenotypes, reducing variation.

Directional Selection

Selection that favors one extreme phenotype, shifting the population's trait distribution.

Disruptive Selection

Selection that favors extreme phenotypes over intermediates, potentially creating a bimodal distribution.