Evolution, Speciation, and Extinction – Vocabulary Flashcards

These flashcards cover key vocabulary from the lecture on evolution, speciation, and extinction, including foundational theories, mechanisms of natural selection, evidence supporting evolution, pathways and barriers to speciation, and factors influencing extinction and conservation.

Evolution

Genetic change in a population over successive generations.

Natural Selection

Process in which individuals with favorable traits survive and reproduce more successfully, passing those traits to future generations.

Neo-Darwinian Evolution

Darwin’s theory of natural selection expressed in modern genetic terms such as allele-frequency change.

Microevolution

Evolutionary change within a single population that does not create a new species (e.g., antibiotic-resistant bacteria).

Macroevolution

Large-scale evolutionary change leading to new species that may not interbreed with ancestral forms, often seen in the fossil record.

Binomial Nomenclature

Linnaeus’s two-part naming system for species (e.g., Homo sapiens).

Fixity of Species

Pre-Darwinian belief that species are unchanging since creation.

Buffon’s Law

Idea that geographic isolation and struggle for existence shape how species appear in different regions.

Catastrophism

Cuvier’s hypothesis that Earth’s features and extinctions result from past violent events.

Lamarckianism

Disproved theory that organisms acquire traits during life and pass them to offspring.

Gradualism (Hutton)

Concept that geological features form through slow, continuous processes over long time spans.

Uniformitarianism

Lyell’s view that geological processes act at constant rates, implying an old Earth.

Malthusian Principle

Observation that populations overproduce offspring while resources are limited, influencing Darwin’s thinking.

HMS Beagle

Ship on which Darwin spent five years collecting observations that led to his evolutionary theory.

Galápagos Islands

Archipelago where distinct tortoise and finch forms helped inspire Darwin’s ideas on natural selection.

Heritable Traits

Characteristics passed genetically from parents to offspring.

Overproduction

Production of more offspring than the environment can support, creating competition.

Variation

Differences among individuals in a population; raw material for natural selection.

Phenotype

Observable traits of an organism on which natural selection directly acts.

Fossil Record

Preserved remains or traces of past life that document evolutionary history.

Law of Superposition

Geological rule stating that in undisturbed strata, older layers lie below younger layers.

Transitional Fossil

Fossil showing intermediate features linking ancestral and descendant groups (e.g., horse toe-to-hoof series).

Biogeography

Study of geographic distribution of organisms that reveals evolutionary relationships.

Homologous Structures

Anatomically similar features with different functions, indicating common ancestry (e.g., human arm and whale fin).

Analogous Structures

Features with similar function but different origin, showing convergent evolution (e.g., insect wing vs. bat wing).

Vestigial Structures

Reduced or non-functional remnants of structures that were functional in ancestors (e.g., pelvic bones in whales).

Embryological Evidence

Similar early developmental stages (tail, pharyngeal pouches) across vertebrates supporting common ancestry.

Biochemical Evidence

Universality of DNA, 20 amino acids, and shared molecules like cytochrome C among all life forms.

Cytochrome C

Respiratory protein often compared between species to measure evolutionary relatedness.

Species (Biological Definition)

Group of interbreeding populations that produce fertile, viable offspring.

Morphological Species Concept

Defines species by measurable physical traits and structural features.

Biological Species Concept

Defines species by ability to interbreed and produce fertile offspring in nature.

Phylogenetic Species Concept

Identifies species as the smallest group sharing a unique evolutionary lineage and genetic similarities.

Gene Flow

Movement of genes between populations; restriction of gene flow initiates speciation.

Gradual Change (Anagenesis)

Slow transformation of a single lineage into a new form over time.

Population Splitting (Cladogenesis)

One lineage divides, and descendants evolve independently, producing new species.

Allopatric Speciation

Formation of new species after geographic separation divides a population.

Sympatric Speciation

Speciation within the same geographic area, often via ecological or genetic barriers.

Polyploidy

Speciation mechanism in which chromosome duplications create reproductive isolation, common in plants and some animals.

Reproductive Isolating Mechanism

Biological feature that prevents species from interbreeding or producing viable offspring.

Habitat Isolation

Prezygotic barrier where species live in different environments and rarely meet.

Temporal Isolation

Prezygotic barrier where species reproduce at different times or seasons.

Behavioral Isolation

Prezygotic barrier due to different courtship rituals or mating calls.

Mechanical Isolation

Prezygotic barrier where reproductive structures are incompatible.

Gametic Isolation

Prezygotic barrier where sperm and egg cannot fuse even if mating occurs.

Hybrid Inviability

Postzygotic barrier where hybrid embryos fail to develop to maturity.

Hybrid Sterility

Postzygotic barrier where hybrids mature but cannot reproduce (e.g., mule).

Adaptive Radiation

Rapid divergence of a single ancestor into many species adapted to different niches (e.g., Darwin’s finches).

Convergent Evolution

Independent evolution of similar traits in unrelated lineages facing similar environmental pressures.

Extinction

Complete disappearance of a species with no surviving individuals.

Abrupt Environmental Change

Sudden climate or habitat shift that can drive species to extinction.

Natural Catastrophe

Events like volcanic eruptions or floods that can wipe out populations.

Small Population Effects

Higher extinction risk due to inbreeding, low genetic diversity, and demographic instability.

Overharvesting

Human-driven removal of organisms faster than they can reproduce, leading to decline or extinction.

Habitat Destruction

Loss or fragmentation of living space critical for species survival.

Invasive Species

Non-native organisms that outcompete or prey on native species, contributing to extinctions.

Climate Change (Extinction Driver)

Human-accelerated warming and weather shifts that alter habitats and threaten species.

Devil’s Hole Pupfish

Critically endangered fish living in a single Nevada cavern pool, illustrating vulnerability of restricted species.

Passenger Pigeon

Once-abundant North American bird hunted to extinction; last individual died in 1914.

Dodo Bird

Flightless island bird driven extinct in the 1690s by introduced predators and human hunting.

Steller’s Sea Cow

Large marine mammal hunted to extinction within 27 years of discovery.

Wildlife Refuge

Protected area established to conserve threatened species and their ecosystems.

Conservation

Efforts to protect biodiversity, habitats, and small populations from further decline.

Rediscovery Phenomenon

Occasional finding of species once thought extinct, highlighting survey limitations.

Biodiversity

Total variety of life on Earth, reflecting millions of years of evolutionary history.

Geographic Isolation

Physical separation of populations by barriers such as mountains or rivers, leading to divergence.

Selective Pressure

Environmental factor that favors certain heritable traits over others.

Darwin’s Finches

Galápagos bird group whose varied beaks exemplify adaptive radiation and natural selection.