Theme 5AB Flashcards
What is a phylogeny
History of descent with branching
Shown as phylogenetic trees/phylogenies
What does a branching diagram tell us
Shows relationships between species often according to time since a common ancestor
What do the tips, branches, node and root tell us on a phylogenetic tree
Tips: terminal node
Branches: new species
Node: point where a branch splits, represents a common ancestor from which the descendant species emerge
Root: common ancestor population
What are sister groups
Two species that share a common ancestor not shared with any other species or groups
What hypothesis do phylogenies provide
Hypothesis of evolutionary relationships
What is a phylogram
Tree where the branch lengths represent evolutionary change/time
What is a cladogram
Tree where the branch lengths are all the same (no time)
How can you use morphological data to infer phylogenies
Use “characters” shared among organisms (vary among, but not within species)and have a genetic basis
What is considered to be the “best” phylogenetic tree
The one with the fewest number of changes required
How can DNA data be used to infer phylogenies
Each nucleotide in a sequence can act as a trait underlying logic of phylogenetic inference is identical for morphological and molecular characters
DNA sequence differences represent time since common ancestor
What is a monophyletic group
Includes a common ancestor and all of its descendants
What is a paraphyletic group
Included a common ancestor and some but not all of its descendants
What is a polyphyletic group
Does not include common ancestor
What is adaptive radiation
The rapid evolution of new species occupying new niches
What is anagenesis
Speciation where the ancestor species is wholly replaced by a new species (evolution within lineage)