Evolution by Natural Selection Flashcards

A set of key vocabulary flashcards covering the historical development of evolutionary theory, mechanisms of natural selection, and supporting biological concepts from BIOL 108 Topic 4.

Evolution

Defined by Charles Darwin as "descent with modification," explaining the gradual change, diversification, and appearance of new species over time.

Scala Naturae

The "scale of nature" on which the Greek philosopher Aristotle arranged species, viewing them as fixed and unchanging.

Carolus Linnaeus

A scientist who interpreted organismal adaptations as evidence that the Creator designed each species for a specific purpose, and who developed a hierarchical classification system.

Fossils

Remains or traces of organisms from the past, usually preserved in sedimentary rock layers called strata.

Strata

Layers of sedimentary rock formed underwater from deposited sediment; older strata lie deeper and contain older fossils, while younger strata lie closer to the top.

Georges Cuvier

A French scientist who largely developed paleontology, noted that fossils in older strata differed from living organisms, and proposed that boundaries between strata resulted from sudden catastrophic events.

Lamarckism

An unsupported 1809 evolutionary hypothesis by Jean-Baptiste Lamarck proposing that species evolve through the use and disuse of body parts and the inheritance of acquired characteristics.

HMS Beagle Voyage

A 5-year around-the-world voyage (1831–1836) commanded by Captain Robert FitzRoy, on which Charles Darwin served as an unpaid naturalist and collected South American plants, animals, and fossils.

Alfred Russel Wallace

A naturalist working in the Malay Archipelago who independently formulated a hypothesis of natural selection in 1858, prompting Darwin to publish "The Origin of Species".

Descent with Modification

Darwin's core evolutionary concept describing both the unity of life (all organisms share common ancestry) and the diversity of life (accumulation of heritable adaptations following lineage divergence).

Adaptation

An inherited characteristic of an organism that enhances its survival and reproductive success in a specific environment.

Artificial Selection

The process by which humans modify other species over generations by selectively breeding individuals with desired traits.

Genetic Variation

Heritable genotypic differences among individuals in a population that provide the raw material required for natural selection to operate.

Phenotypic Variation

The observed variability in external physical or physiological characteristics among individuals within a population.

Environmental Effect on Phenotype

Non-heritable phenotypic variation caused directly by environmental factors, such as hydrangea flowers turning blue in acidic soil with free aluminum versus pink in basic soil.

Selective Agent

An environmental factor (such as predation or food availability) that affects the survival or reproduction of individuals in a population.

Selection Pressure

An environmental condition produced when a selective agent consistently causes differences in survival or reproduction among different phenotypes in a population.

Context-Dependent Selection

The characteristic of natural selection where the direction of evolutionary change depends on environmental conditions and selective pressures; if environmental conditions change, selection may favor different traits.

Natural Selection in Galápagos Finches

A documented example of natural selection where a 1977 drought selected for larger beak depth in medium ground finches, whereas a 2004 drought combined with competition from large ground finches selected for smaller beak depth.