Lecture 8: Phylogeny and diversification Flashcards
open tree of life project aims
to build a tree of all 2.3million described spp on earth
species richness of the kingdoms of life
highest animal plant fungi lowest continued...
species richness of animal phyla
highest -arthropoda -chordata -mollusca continues.. lowest
unevenness in diversity is _ throughout the tree of life
ubiquitous (found everywhere)
how much does species richness vary across clades in the Tree of Life?
A GREAT DEAL
what is phylogenetic tree imbalance?
relative numbers of descendent tips (usually species) on the branches that originate at the focal node
what is phylogenetic tree imbalance? perfectly balanced:
equal numbers of descendants on each side of the focal node (ratio 1:1)
what is phylogenetic tree imbalance? Maximum imbalance
unequal numbers of descendants on each side of the focal node (E.g. ratio 7:1)
Equal rates Markov model:
- species diverge from other species
- probability of speciation per unit is constant across all lineages
- Constant-rates birth-death Markov process or equal-rates Markov model
species richness can be imbalanced due to:
variation in diversification rate
imbalanced trees are more common than expected in what model?
ERM model (equal rates markov model)
there is __ relationship between clade age and diversity
NO
what is diversification rate? Net diversification (R) is the rate of lineage spitting:
Speciation rate (S) - Extinction rate (E) (lineage birth rate - lineage death rate)
how do u measure diversification rate
Lineage Through Time (LTT) plot:
Lineage Through Time (LTT) plot: :if speciation rat his constant AND extinction is zero
then clade growth is exponential (straight line if logged)
