Phylogenetics and Systematics
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What is systematic?
The branch of biology that investigates relationships among species to understand the history of life.
Where phylogeny refers to the history of that species, systematics refers to the _________ .
Methods used to discover that history.
What are the three types of phylogenic groups and what are the differences between these types?
- Monophyletic (share last common ancestor + ALL decedent species)
- Paraphyletic (share last common ancestor + SOME of the decedent species)
- Polyphyletic (a group of species that do not have the same last common acestor)
What is a synapomorphy?
In cladistics, a synapomorphy or synapomorphic character is a trait that is shared ("symmorphy") by two or more taxa and their most recent common ancestor, whose ancestor in turn does not possess the trait
Monophyletic groups are defined by ___________.
Homologous traits may be:
- Plesiomorphic: present in a common ancestor but secondarily lost in
- some of its descendants
- Synapomorphic: present in an ancestor and all of its descendants.
What is the difference between homology and homoplasy?
- Homology: Similarity due to common ancestry
- Homoplasy: Similarity of traits in different species arising from convergent evolution or reversal
What can phylogenies be used for?
- Molecular clocks
How old is the oldest common ancestor of all humans alive today?
Study of mtDNA in different human groups suggested that molecular ancestor of all human mtDNA lived 200 000 years ago.
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