Cahter 23 Broad Patterns of Evolution

What is macroevolution?

Large

What is the fossil record?

The preserved remains or traces of organisms from the past.

What are strata?

Layers of sedimentary rock that contain fossils.

What is relative dating?

Determining whether a fossil is older or younger than another fossil.

What is radiometric dating?

Using radioactive decay to determine the age of rocks and fossils.

What is a half life?

The time required for half of a radioactive isotope to decay.

What are the major divisions of geologic time?

Eons, eras, periods, and epochs.

What are stromatolites?

Structures formed by ancient photosynthetic microorganisms.

Why was oxygen important in Earth's history?

Photosynthetic organisms increased atmospheric oxygen, changing Earth's environment and allowing more complex life to evolve.

What is continental drift?

The movement of Earth's continents over time.

How can continental drift affect evolution?

It can separate populations, causing geographic isolation and potentially leading to speciation.

What is allopatric speciation?

Speciation that occurs when populations become geographically separated.

What is a mass extinction?

A period when unusually large numbers of species become extinct.

How many major mass extinctions occurred during the past 500 million years?

Five

What are the Big 5 mass extinctions in order?

Ordovician → Devonian → Permian → Triassic → Cretaceous.

What happened during the Permian mass extinction?

About 96% of marine animal species were lost.

What likely contributed to the Permian extinction?

Extreme volcanism, rapid warming, ocean acidification, and oxygen depletion.

When was the Permian mass extinction?

About 252 million years ago.

What happened during the Cretaceous mass extinction?

More than half of marine species disappeared, and all dinosaurs except birds became extinct.

What evidence supports an asteroid impact at the end of the Cretaceous?

Iridium deposits and the Chicxulub crater.

When was the Cretaceous mass extinction?

About 66 million years ago.

What is the order mnemonic for the Big 5?

O → D → P → T → C (“Old Dinosaurs Prefer Tasty Cookies”).

What is adaptive Radiation?

The rapid diversification of a lineage into many different species.Why can mass extinctions lead to adaptive radiation?

Why can mass extinctions lead to adaptive radiation?

Extinctions leave ecological opportunities that surviving organisms can occupy.

What is heterochrony?

An evolutionary change in the timing or rate of developmental events.

What is paedomorphosis?

When an organism retains juvenile features into adulthood.

What are Hox genes?

Genes involved in controlling the development and organization of body structures.

Can evolution create completely new genes from nothing?

Evolution can modify existing genes and their regulation to produce new traits and structures.

Is evolution goal-oriented?

No. Evolution does not work toward a predetermined goal.

What is exaptation?

A structure that evolved for one function and was later co-opted for another function.