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)
diversification rates across the Tree of Life
Varies
five clades account for__% of all known vertebrate diversity
85%
_____ is a strong predictor of species richness at any taxonomic level across the Tree of life
DIVERSIFICATION RATE
is diversification rates vary? what is the cause
-environmental factors + special traits (i.e. mutation rate, SS & conflict )
dispersal ability and its affect on diversification rates
- LOW dispersal correlated with FAST speciation rates
- HIGH dispersal may reduce the likelihood of population isolation
sexual selection and its affect on diversification rates
SS can drive divergence in mating traits between lineages but doesnt facilitate geographic range overlap (sympatry) amount sister species
diversification may be ___ when multiple factors coincide
FASTEST
__ &___ can be used to estimate speciation and extinction rates
dated phylogenic and LTT plots
