Macroevolution Lecture Flashcards

Vocabulary practice flashcards covering early Earth, origin of life experiments, key geologic time events, mechanisms of macroevolution, and phylogenetic systematics.

Macroevolution

The broad pattern of changes in life on Earth over long periods of geologic time.

Stromatolites

Fossils dating back $3.5\text{ billion years}$ that were built by ancient photosynthetic prokaryotes and represent the earliest direct evidence for life on Earth.

Abiotic Synthesis

The nonliving formation of small organic molecules, such as amino acids and nitrogenous bases, from inorganic precursors.

Protocells

Abiotically created, membrane-bounded droplets or vesicles that maintain an internal chemistry distinct from their surroundings and are capable of growth and division.

Oparin-Haldane Hypothesis

A proposal made independently in the 1920s by Russian scientist A. I. Oparin and British scientist J. B. S. Haldane stating that organic molecules could have formed on early Earth in a reducing atmosphere.

Miller-Urey Experiment

A 1953 experiment conducted by Stanley Miller under Harold Urey that demonstrated the abiotic synthesis of organic molecules is possible using an airtight apparatus with circulating gases and electrical discharges.

Archaean Eon

One of Earth's early geologic eons that, together with the Proterozoic eon, lasted about $4\text{ billion years}$ and included the origin of prokaryotes.

Proterozoic Eon

A geologic eon during which atmospheric oxygen accumulated and the first single-celled and multicellular eukaryotes appeared.

Phanerozoic Eon

The most recent eon of geologic time, covering the last $542\text{ million years}$, which is divided into the Paleozoic, Mesozoic, and Cenozoic eras.

Radiometric Dating

A method used to determine the actual ages of rocks and fossils based on measuring the decay of radioactive isotopes.

Half-Life

The amount of time required for $50\%$ of a radioactive isotope sample to decay.

Geologic Record

A time scale established by geologists that documents the sequence and age of fossils found in rock strata.

Plate Tectonics

The theory that Earth's crust is divided into giant, irregularly shaped plates that float on the underlying mantle.

Continental Drift

The movement of Earth's tectonic plates caused by thermal movements within the underlying mantle.

Pangaea

A supercontinent formed roughly $250\text{ million years ago}$ when Earth's landmasses fused, altering habitats and triggering the Permian mass extinction.

Permian Mass Extinction

A mass extinction event occurring about $251\text{ million years ago}$ at the boundary between the Paleozoic and Mesozoic eras that claimed $96\%$ of marine animal species.

Cretaceous Mass Extinction

A mass extinction event occurring about $65.5\text{ million years ago}$ that eliminated all non-avian dinosaurs, likely triggered by a large asteroid impact.

Adaptive Radiation

A period of evolutionary change in which many new species evolve from a common ancestor upon colonizing new, unexploited areas or following mass extinction events.

Gradual Refinement

The evolutionary process by which complex structures evolve by incremental modifications from simpler versions, where each step provides a selective advantage.

Exaptation

A structure that originally evolved in one context for a specific function and later became co-opted for a new function.

Phylogeny

The evolutionary history of a species or group of related species.

Homology

A similarity between organisms that exists because of shared ancestry.

Convergent Evolution

The process by which distinct evolutionary lineages independently evolve similar adaptations due to similar environmental pressures.

Analogy

A similarity between species that is due to convergent evolution rather than shared ancestry.

Systematics

A discipline of biology focused on classifying organisms and determining their evolutionary relationships.

Taxonomy

The formal system of naming and classifying species, introduced by Carolus Linnaeus.

Binomial

The two-part scientific name of a species, consisting of its genus name and a unique specific epithet.

Taxon

A named taxonomic unit at any level of the biological hierarchy.

Phylogenetic Tree

A branching diagram depicting hypotheses about the evolutionary history and relationships of species or groups.

Molecular Systematics

A field of study that uses DNA, RNA, or other molecular sequences to infer evolutionary relationships.

Three-Domain System

A system of biological classification that categorizes all cellular life into three domains: Bacteria, Archaea, and Eukarya.

Horizontal Gene Transfer

A process in which genes are transferred from one genome to another across species or domain boundaries through mechanisms such as plasmid exchange or viral infection.