Geographic Barriers

Geographic Isolation

Involves physical barriers like rivers or mountains that divide a population into separate groups, leading to genetic differences over time.

Temporal Isolation

Occurs when timing prevents reproduction between populations, leading to speciation due to differences in reproductive periods.

Convergent Evolution

Different species adapt to similar environments, evolving similar characteristics despite being unrelated.

Divergent Evolution

Closely related species evolve in different directions, becoming increasingly different due to adapting to different environments.

Background Extinctions

Continuous extinctions at a low rate, affecting a few species in a small area due to local environmental changes.

Mass Extinctions

Rare but intense events that occur globally, leading to the loss of many species, often caused by catastrophic events like asteroid impacts or ice ages.

Trilobite Eye Evolution

New form of eye in trilobites linked to improved defense mechanism of rolling into a protective ball.

Punctuated Equilibrium

Theory proposing species show little change for long periods followed by rapid speciation events.

Evolutionary Gradualism

Concept suggesting species evolve slowly over long periods of time.

Adaptive Radiation

Rapid evolution of diverse species from a common ancestor, adapting to various environments.

K-T Boundary

Layer marking the collision of an asteroid with Earth, leading to the extinction of dinosaurs and rapid evolution of mammals.

Radiometric Dating

Technique using decay rate of unstable isotopes to determine the absolute age of materials, like fossils.

Radiometric Dating

A method of dating objects based on the decay of radioactive isotopes, such as carbon-14, to estimate the age of fossils or artifacts.

Carbon-14

A radioactive isotope used in radiometric dating, with a half-life of approximately 5700 years, commonly used for dating objects up to about 45,000 years old.

Index Fossils

Fossils of organisms that existed only during specific time spans over large geographic areas, used as markers to determine the age of rock layers.

Adaptive Radiation

The process where a single species evolves into multiple forms adapted to different environmental niches, often occurring after mass extinctions, leading to diversification and speciation.