2- Ch 20: Phylogeny Flashcards
Tree of life meaning
suggest that eukaryotes & archaea are more close to eo than bacteria
• Based on rRNA genes (ribosomes)
The transfer of genes from one genome to another thru plasmid exchange, viral activity, fusions of different organisms
Horizontal gene transfer
What is the neutral theory
evolutionary change in genes & proteins has not effect on fitness & not influenced by natural selection
Mutations happen randomly
Genetic changes happen by chance
how fast certain genes change over time and use that speed to estimate how long ago two species had a common ancestor.
Molecular clock
allow to predict features of ancestor from features of its descendants
• Test hypothesis about extinct species
Phylogenetic bracketing
When considering multiple explanations for observation, one should first investigate simplest explanation consistent with the facts
Maximum parsimony
allow to focus only on characters derived at various branch points for clade of interest
species or group that is not closely related to the main group being studied but is included for comparison.
- It helps scientists figure out which traits are ancient and which traits evolved later in the main group.
Outgroup
main group of organisms being studied. It includes species that share a common ancestor and are closely related
Ingroup
Shared ancestral character meaning
is a trait that an ancestor had and passed down to multiple descendant species.
- trait is NOT UNIQUE, shared by many groups
Shared derived character meaning
Trait newly evolved in group that is not found in distant ancestors
- shared by members of that group but not by earlier ancestors
Ex: fur is shared in mammals but distant ancestors (reptiles) did not
Polyphyletic meaning
• various species that lack common ancestor
- not closely related and dont share recent common ancestor
- grouped due to similar traits that evolved independently rather ancestor
• ancestor + some descendants
Atleast one group that evolved from common ancestor is left out
Paraphyletic group
• common ancestor’s + all descendants
- every species in group comes from same ancestor
Monophyletic
A group of organisms that includes common ancestor and all descendants
Clade or monophyletic group
hypothesis depicting patterns of shared characters among taxa
- shows evolutionary relationship bw diff species or groups where each branch point (node) represent common ancestor
Cladogram
Cladistic meaning
Method of classifying organisms based on evolutionary relationship, focusing on shared derived characteristics (traits evolved in common ancestor and passed down)
How does analogy and homology differ
Homology: shared ancestry
Analogy: traits evolving independently due to similar environment or needs
Refers to the appearance of similar traits in different species that did not come from common ancestor, due to convergent evolution (diff species independently evolve similar traits)
Homoplasy
When diff species independently evolve similar trait bc they live in similar environments
Convergent evolution
Basal taxon meaning
Group/species that is early in evolutionary tree & diverged before other groups (oldest branch)
Diagram that Shows evolutionary relationships b/w species with single common ancestor at the root
Rooted tree
In rooted tree, what does root and branch represent
Root - most ancient ancestor
Branches; how species have evolved over time
Refers to the line of species that trace ancestry back to a common ancestor to show how they have evolved over time
Evolutionary lineage
2 group or species that are more closely related to eo than to any other group
- share common ancestor that is not shared by other groups
Sister taxa
