Exam 3: 8 Flashcards
Why do we construct phylogenies?
- Visual representation of relationships between different organisms
- They are a map of species in evolutionary space
- They tell us about how organisms change, and which changes came before or after other changes
- They provide a way to group/classify organisms
- They provide a way to infer past events
- They are evidence of evolution
Why do we study the evolutionary history of diseases?
- Understand how genetic differences relate to pathology
- Improved diagnostic assays, treatments, drugs and vaccines
- Identify origins of new diseases
- Describe rate of evolutionary change
- Make predictions about future outbreaks
What are phylogenies?
Diagrams with lines and nodes that is a simplified representation of the “reticulate” nature of evolution.
What is sister-group pairs in a phylogeny?
Individual species/ groups that share the same common ancestor
What does branch length in a phylogeny represent?
- Time
- Rate of genetic change
Why does lineages split?
- Speciation
- Cladogenesis event (branch splitting that can occur without speciation)
Monophyletic clade
A single common ancestor and ALL of its descendants
= legit clade
Paraphyletic clade
A single common ancestors and SOME (but NOT ALL) of its descendants
Polyphyletic clade
Multiple ancestors and all or some of their descendants
How come phylogenies are evidence to evolution?
A phylogeny of apes based on DNA matches the phylogeny of 2 types of body lice found on apes.
*When trees have more tips but still match each other, this is VERY strong evidence that evolution is true.
Autapomorphy
Apo = Derived (evolved new/recently)
Morphy = Character (trait)
Apomorphy = A Derived Character
Autapomorphy
Aut = Unshared
Autapomorphy = An unshared derived character (An unique trait that evolved recently)
Synapomorphy
Syn = Shared
Synapomorphy = A shared derived character
Plesiomorphy
Plesio = Ancestral (inherited from the past)
Plesiomorphy = An ancestral character (a trait inherited from the past)
