Chapt. 14a Macroevolution – The Long Run

Flashcards covering the vocabulary of macroevolution, biogeography, drivers of species diversity, models of evolutionary change, and historical mass extinction events based on the Chapter 14 lecture notes.

Microevolution

Change in allele frequencies in populations, often occurring quickly and observable from one generation to the next.

Macroevolution

Evolution occurring at the species level (speciation) and above, which often takes millions of years and relies on evidence like fossils.

Evo-devo

The study of the evolution of developmental processes, which includes comparing the timing and pattern of gene activity between different organisms.

Biogeography

The study of geographic patterns of taxa, including the processes that resulted in observed patterns.

Dispersal

The movement of individuals to colonize new areas, sometimes across a physical barrier such as an ocean, river, or mountain range.

Disjunctions

The physical or geographical separation of two closely-related species.

Vicariance

The formation of geographic barriers to dispersal and gene flow, most commonly caused by plate tectonics.

Area Phylogeny

A species phylogeny that reflects the geographic history of landmass separations.

Origination Rate ($\alpha$)

The rate at which new species evolve or originate over a unit of time.

Extinction Rate ($\Omega$)

The rate at which species go extinct over a unit of time.

Standing Diversity

The total number of species (diversity) in a particular clade present at any given time.

Turnover

The total number of originations and extinctions in a given time period.

Artiodactyls

Mammals that walk on their 3rd and 4th toes, such as sheep, goats, camels, pigs, cows, deer, and giraffes.

Intrinsic Factors

Factors involved with macroevolutionary change that are internal to the organism, such as its basic physiology.

Extrinsic Factors

Physical or environmental factors, such as climate or sea-level changes, that drive long-term changes in biodiversity.

Milankovitch Cycles

Three cycles ($96,000$, $41,000$, and $22,000$ years) relating to Earth's eccentricity, obliquity, and precession that influence incoming solar radiation.

Punctuated Equilibrium

A model of evolution where most species undergo relatively little change (stasis) for most of their history, interrupted by brief periods of rapid morphological change.

Gradualism

A model where a species gradually transforms into another species over time.

Anagenesis

The gradual transformation of a species lineage from one form to another.

Adaptive Radiation

The rapid diversification of a clade into many species that adapt to a wide range of resources and ecological niches ($\alpha \gg \Omega$).

Key Innovations

Newly evolved traits that allow a group or clade to access resources or environments that were previously inaccessible.

Cambrian Explosion

A major macroevolutionary event starting ~$541\,mya$ characterized by the near-simultaneous appearance of great animal diversity and diverse body plans.

Burgess Shale

A famous fossil deposit in British Columbia, Canada, that contains many soft-bodied specimens from the Cambrian period.

Background Extinction

The typical, continuous rate of extinctions seen in the fossil record due to factors like climate change, habitat loss, or competition.

Mass Extinction

A statistically significant increase in extinction rates above background levels, resulting in a permanent depression of taxonomic diversity.

Large Igneous Province

An extreme form of volcanism where massive amounts of molten rock are pushed to the surface over thousands or millions of years, often releasing high levels of $CO_2$ and greenhouse gases.

Permian-Triassic Extinction

Also known as "The Great Dying," it occurred ~$252\,mya$ and is the largest mass extinction in history, wiping out about $96\%$ of extant species.

Cretaceous-Tertiary (K-T) Extinction

A mass extinction event occurring $66\,mya$ associated with a giant asteroid impact and Large Igneous Province activity.