estimating divergence dates some practical problems: - can be a steep learning curve - new methods...

Estimating Divergence Dates

Some practical problems:

- Can be a steep learning curve

- New methods outstrip supply of software

- Suitable datasets hard to come by

Some rewards:

- Gain a better understanding for phylogenetic methodology

- Add a new dimension to your analyses

- Address some really cool questions!

Paleocene

Cretaceous

Late Cretaceous

Early Cretaceous

Late Jurassic

157ma ±

146ma ±

97ma ±

65ma ±

Modern Birds

‘Ratites’ and

tinamousNeognathae

Neornithes

Archaeopteryx

Paleognathae

The Radiation of Modern Birds

Feduccia, 1995Tertiary ‘big bang’

Did modern birds survive the K-T boundary?

Modern Birds

Fossil EvidenceBird

Modern birds much older - Gondwanic origin?

Molecular data

Modern Birds

Bird

KT

65 ma

Modern Birds

Fossil EvidenceBird

KT

65 ma

What about their parasites?

Younger than their

hosts?

Parasitic lice

Molecular dataLouse

Modern Birds

Fossil EvidenceBird

KT

65 ma

What about their parasites?

As old as their hosts?

Parasitic lice

Molecular dataLouse

Modern Birds

Fossil EvidenceBird

KT

65 ma

What about their parasites?

Older than their hosts?

Parasitic lice

Molecular dataLouse

Did modern birds & their lice survive the K-T boundary?Did modern birds & their lice survive the K-T boundary?Did dinosaurs have lice?

Part 1 Part 2

http://darwin.zoology.gla.ac.uk/~vsmith/temp/rates/

Or get the files from my USB flash drive

Part 1: (Qdate) Mac OS Classic or MS Windows

Part 2: (r8s) Mac OSX only

Files available at:

Quartets

All dating methods require:

- Calibration points

- Estimates of genetic divergence

- “Some” estimate of phylogeney

Ordinalrelationships of birds unknown!

Quartets

F Corvidae

F Turdidae

F AnatidaeF Meleagrididae

Earliest fossils

Genetic

divergence

Genetic

divergence

Divergence time estimatedfrom calibrated evolutionaryrates of distantly related pairs of taxa.

Divergence date

- Tree topology not in question- No assumptions needed

(two orders are compared at a time)about rate constancy - maybe?

- Estimate across multiple quartets

Fossil Lice

Psocoptera

Menacanthus /Menopon - complex

Ricinidae

Laemobothriidae

Boopiidae

Austromenopon- complex

Dennyus- complex

Colpocephalum- complex

• Collected Eckfeld maar near Eifel, Germany

• Middle Eocene (Middle Lutetian, 44.3±0.4 Ma)

• First fossil louse

• Completes ordinal representation of fossil insects

• Excellent preservation

• Phylogenetic affinities with modern feather lice

• Parasite of Anseriformes or Charadriiformes

• Crown group position

• Suggests lice are very old

• Points to a long coevolutionary history with birds

• Useful molecular calibration point

Wappler, Smith & Dalgleish, Proc.R.Soc., 2004.

Cospeciation Events

Constraints

Min. Age 44 ma

Louse Fossil

Combined ML

0.1

(18s, COI, EF1-)

Dove-Louse Cospeciation

Age Fixed 19.8 ma

Rhea/Ostrich-Louse Cospeciation

Age Fixed 60 ma

Primate-Louse Cospeciation

Age Fixed 4.5 ma

Amblyce

raIsch

noce

raAnoplu

ra

Rhyn.

Louse Phylogeny (unsmoothed)

Host Implications

2-300ma ?