Download Bot3404_11_week6.1 - Ecological Evolution – E

Announcements
Urban Forestry project starts this week. Go through
protocol.
We'll be sending you off on your own. Please act
responsibly.
Peer review of work. You will trade your results with
a different lab group at the end and they will attempt
to identify and use the data that you gave them.
They will provide a score, calculated based on their
ranking of various parts of the assignment.
BIOGEOGRAPHY
‘the geographic distribution of species'
Research focuses on geological and genetic
evidence and develops theories to explain
them.
Climate changed dramatically during the
recent ice ages and the end of the last ice age
was roughly 12,000 years ago.
BIOGEOGRAPHY
Humans have imposed an incredible
transformation on the natural world.
This process is very recent.
Science magazine had a special section on
Population.
PHYLOGENETICS
reconstruction of the historical
relationships among organisms.
What is a phylogenetic tree?
Cladogram vs. phylogram
PHYLOGENETICS
Parsimony - the simplest explanation is the
best.
many different algorithms to test for ‘optimality’
Maximum Likelihood (ML) based primarily on
molecular models
Bayesian analysis – prior probabilities are used to
generate null models
Coalescent theory – probabilistic approach based on
time to coalescence.
PHYLOGENETIC DATA
Homology – characters are identical by
descent.
Binary traits – morphology and DNA
How is 'parsimony' measured?
PHYLOGENETIC UNCERTAINTY
All trees are just hypotheses.
Species trees vs. Gene trees.
Ancestral polymorphism.
Interspecific introgression.
MORPHOLOGICAL DATA
Phenotype can be strongly affected by
environment and disease.
Good taxonomic characters should be linked to
genetic traits that drive species diversification.
Convergent evolution.
INDEPENDENT CONTRASTS
Each evolutionary event should be independent.
Good for testing character associations to see if
they are significant from an evolutionary
standpoint.
MOLECULAR DATA
Phytochemistry - liquid chromatography
Allozymes – electromorphs of various proteins
DNA – DNA sequence