7 - Evolution & Biogeography

What does the theory of evolution say?

Explains the biodiversity of life

Says nothing about the origin of life (abiogenesis)

What is the story is the history of life?

Diversification and extinction

What percentage of all species that ever lived are now extinct?

99%

Where is the evidence for life in the past found?

Embedded in the rock record as fossils and trace fossils

How old is the Earth?

About 4.6 billion years old

What are the 4 eons that the history of Earth is broken up into (in order)?

Hadean (4.6-4.0 BYA)

Archaean (4.0-2.5 BYA)

Proterozoic (2.5 BYA-542 MYA)

Phanerozoic (542 MYA-Present)

What is the first stage of oxygen build-up in the Earth’s atmosphere?

3.85-2.45 Ga

Practically no oxygen in the atmosphere

What is the second stage of oxygen build-up in the Earth’s atmosphere?

2.45-1.85 Ga

Oxygen produced but absorbed in oceans and seabed rock

What is the third stage of oxygen build-up in the Earth’s atmosphere?

1.85-0.85 Ga

Oxygen starts to gas out of the oceans but is absorbed by land surfaces and formation of ozone layer

What is the fourth and fifth stage of oxygen build-up in the Earth’s atmosphere?

0.85 Ga-Present

Oxygen sinks filled, the gas accumulates

What are the characteristics & evidence of LUCA?

Hypothesized common ancestral cell of the three domains of life

Had a lipid bilayer

Possessed the genetic code and ribosomes

Anerobic chemotroph

What are the properties of the fossil record?

Incomplete

Not necessarily ancestral characters

The oldest known fossil of a taxon is not definitively the earliest taxon nor the date of origin of that taxon

Chronologically consistent

Describe the evolution of wings

They evolved without the loss of other appendages

Embryological evidence

Initial wings were not for flight

If the initial wings were not for flight, what could they have been for?

Display

Thermoregulation

Spiracle/Leg protection

What can influence organism distributions?

Gradients of latitude, elevation, isolation, and habitat area

What is the relationship between area and isolation diversity gradients?

The more isolated a location, the lower the species diversity