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.
What is the hierarchical biological classification
Domain, phylum, subphylum, class, order, family, genus, species
What is the difference between plesiomorphy and synapomorphy?
A synapomorphy is a shared derived character. A plesiomorphy is a primitive or ancestral character.
What are trace fossils?
Soft-bodied organisms and microbes form poor fossils. But trace fossils show traces of their movement and structures are useful data.
