Lecture 1 & 2 Flashcards
Define phylogeny
The history of decent with modification and accumulation of change over time.
What are homologous traits?
Traits that have evolved in different species from a common ancestor.
What are analogous traits?
Traits that have evolved in different species independent of each other.
What is a synapomorphy?
A shared derived characteristic.
Define monophyletic
A group that includes one common ancestor and all of its descendants.
Define paraphyletic
A group that includes a common ancestor but not all of its descendants.
Define polyphyletic
A group of organism that do not include a common ancestor.
What is the timeline of Earth’s major evolutionary events?
- The Earth is 4.5 BYA
- Prokaryotes evolved 3.5 BYA
- Eukaryotes are 1.5 BYA
- Large multicellular organisms evolved half a billion years ago
What were the two largest extinction events?
- Permian/Triassic extinction - 96% of species extinct
- Cretaceous/Paleogene extinction - dinosaurs extinct
Where did life likely begin?
Deep sea volcanoes.
Describe the RNA world hypothesis
- Over long periods of time. RNA began to self-replicate and synthesize proteins
- Proteins took over catalytic functions and RNA was just a coding molecule
- DNA eventually replaces RNA as a coding molecule
Describe the great oxygenation event
- For the first 2 BY, Earth contained little to no Oxygen
- 2.4 BYA years ago the oxygen rose to 1-10% of modern levels
- 580 MYA oxygen increased to levels that humans could breathe
Describe the 3 kinds of atmospheres.
Primary atmosphere - H2 and He
Secondary atmosphere - reducing atmosphere developed from volcanic gases - contained H2S, CO, CH4
Oxidizing atmosphere - came form photosynthetic oxygenic bacteria
What organisms dominated when there was a reducing atmosphere?
Anaerobes and chemotrophs
What caused the oxidizing atmosphere?
The evolution of cyanobacteria which are photosynthetic and release oxygen.
