Week 1 Flashcards
Monophyletic groups
Single origin and include all species descended form original ancestor
Paraphyletic groups
Comprise some but not all descendants of a stem species
Polyphyletic groups
Composite groups consisting of lineages evolved independently
5 conditions of natural selection
- Variation within population
- Variation is heritable
- Overproduction of offspring
- Differential survival and reproduction, determined by
- Result is a change in gene frequencies that correlates with a change in morphology, physiology, etc.
Systematics
a branch of biological science that studies the distinctive characteristics of species and how they are related to other species through time
Apomorphy
Where character state appears for first time
Plesiomorphy
Ancestral character state for a particular clade
Homologous features
Character states occur in all descendants and ancestor
How old is the earth?
4.6 billion years old
When did the 1st prokaryotes arise?
3 BYA
When did the 1st eukaryotes arise?
1.5 BYA
When did the 1st metazoans arise?
0.7 BYA
Evidence for Endosymbiotic Theory
- Mitochondria chloroplasts have their own DNA and divide
- Different genetic code in mitochondria
- Double membranes
- rRNA similarities (btw bacteria, mitos, chloros)
- Recent endosymbiotic events in protists (more later)
- Facultative endosymbiosis (prokaryote + eukaryote)
- Secondary endosymbiosis (eukaryote + eukaryote)
- Cytoskeleton?
What did animals arise from?
Choanoflagellate (single-celled eukaryotic ancestor)
When did animals first appear?
~600 MYA
Ediacaran fauna
Cambrian “explosion”
