CH 226 Flashcards
Phylogeny
Evo history of organisms
Systematics
-science of classification
- uses fossil, molecular, genetic data
Taxonomy
-naming and classification
-hierarchy of life
-binomial nomenclature
What is another word for phylogenetic trees?
Cladograms
Phylogenetic trees: branch points
Where lineages diverge
Phylogenetic trees: sister taxa
Two most closely related on a particular tree
Basal taxon
Last on tree
Polytomy
Unresolved pattern of divergence w/o sister taxa
What are phylogenies useful for?
providing info about closely related species
Homology
Similarity in structure due to shared ancestry
Analogy
Similarity in function due to convergent evolution
How to determine if a similarity is a homology or analogy?
Use:
-fossil evidence
-underlying similarities
-degree of complexity
-molecular data
Cladistics
Organisms grouped by common ancestry
Clade
-includes ancestral spp. and all descendants
-not all groups are clades
Paraphyletic group
Ancestral spp. and all descendants
Polyphyletic group
Various spp. w/ different descendants
What do clades generally also have in common w/ancestor?
-shared ancestral characteristics
What are derived characteristics?
Ones not present in ancestral spp.
Outgroup
Spp. that diverge after lineage of interest
Ingroup
Spp. that diverged before lineage of interest
Maximum parsimony
-trees with fewest evolutionary events is most probable
Maximum likelihood
Based on DNA changes over time
If different data suggests different trees…
Best trees generally fit the most data
Phylogenetic bracketing
Predict ancestor’s characteristics from descendants
