bsci 160 9/12/25 Evolution: History, Evidence, and Mechanisms

Vocabulary flashcards covering key concepts from the evolution lecture, including historical ideas, evidence for evolution, and mechanisms of evolutionary change.

Evolution

Change in allele frequencies in a population over time; the process by which modern organisms have descended from ancient ones; not goal-directed.

Natural selection

Differential survival and reproduction of individuals due to heritable variation, leading to adaptation over generations.

Lamarck

Early evolutionary thinker who proposed inheritance of acquired characteristics and a drive toward perfection; later disproven as the sole mechanism of evolution.

Inheritance of acquired characteristics

Lamarck's idea that traits developed during an organism's life could be passed to offspring.

Uniformitarianism

Geological theory that present-day processes have operated similarly in the past; contributed to the view that Earth is very old and change is gradual.

Gradualism

Idea that evolution (and geological change) occurs through slow, continuous processes over long timescales.

James Hutton

Geologist who advocated gradualism and an ancient Earth; influenced the concept of deep time.

Charles Lyell

Geologist who formalized uniformitarianism and applied it to biology, reinforcing Darwin's thinking about deep time.

Punctuated equilibrium

Idea that evolution can occur in rapid bursts separated by long periods of little change; a contrasted mode of evolutionary tempo.

Darwin's finches

Finches on the Galápagos Islands studied by Darwin; variation in beak shape linked to different ecological niches and evidence for evolution.

Biogeography

Study of the geographic distribution of species and how historical processes shape present patterns.

Malthus

Economist whose ideas on population growth and competition influenced Darwin's concept of natural selection.

On the Origin of Species

Darwin's 1859 book proposing descent with modification and natural selection; did not explicitly use the term 'evolution'.

Unity and diversity of life

Concept that all life shares a single common origin (unity) yet shows vast diversity due to adaptation and divergence.

Descent with modification

Darwin's idea that species share a common ancestry and diverge over time through differential survival and reproduction.

Pakicetus

One of the early whale ancestors; fossil showing transitional features between land mammals and later fully aquatic whales.

Ambulocetus

Early semi-aquatic whale ancestor showing a transitional form between terrestrial and aquatic life.

Vestigial structures

Remnants of features that served a function in ancestors but have little or no current use (evidence of evolutionary history).

Appendix (human)

Historically thought vestigial; recent evidence suggests it may play a role in gut microbiome and immune function.

Homologous structures

Body parts in different species that share a common evolutionary origin; often diverge in form and function (divergent evolution).

Divergent evolution

Process by which related organisms evolve different traits due to different environments or selective pressures.

Analogous structures

Body parts that look similar and serve similar functions but do not derive from a common ancestor (convergent evolution).

Transitional fossil

Fossil that exhibits traits common to both an ancestral group and its derived descendants, illustrating evolutionary change.

Radiometric dating

Dating method that uses radioactive decay of isotopes to estimate the age of rocks and fossils.

Fossil record

Collection of fossils arranged in order of age, showing historical sequence of life and gradual changes over time.

Mutation

Random changes in DNA that create new alleles; source of genetic variation necessary for evolution; not inherently adaptive.

Gene flow

Movement of genes between populations due to migration and interbreeding; mixes genetic material, not inherently adaptive.

Genetic drift

Random changes in allele frequencies due to chance events; can lead to fixation or loss of alleles in small populations.

Bottleneck

Event that drastically reduces population size, causing a loss of genetic variation and random shifts in allele frequencies.

Founder effect

Genetic drift that occurs when a new population is established by a small number of individuals, leading to different allele frequencies from the original population.