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

LateCretaceous

EarlyCretaceousLateJurassic

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

KT65 ma

Modern Birds

Fossil EvidenceBird

KT65 ma

What about their parasites?

Youngerthan their

hosts?

Parasitic lice

Molecular dataLouse

Modern Birds

Fossil EvidenceBird

KT65 ma

What about their parasites?

As old astheir hosts?

Parasitic lice

Molecular dataLouse

Modern Birds

Fossil EvidenceBird

KT65 ma

What about their parasites?

Older thantheir 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

Ordinalrelationshipsof birds unknown!

Quartets

F Corvidae

F Turdidae

F AnatidaeF Meleagrididae

Earliest fossils

Geneticdivergence

Geneticdivergence

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

• Collected Eckfeld maar nearEifel, Germany

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

• First fossil louse

• Completes ordinal representationof fossil insects

• Excellent preservation

• Phylogenetic affinities withmodern feather lice

Fossil Lice

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

Fossil Lice

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

Fossil Lice

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

Fossil Lice

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

Fossil Lice

Psocoptera

Menacanthus /Menopon - complex

Ricinidae

Laemobothriidae

Boopiidae

Austromenopon- complex

Dennyus- complex

Colpocephalum- complex

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

Fossil Lice

• Parasite of Anseriformes orCharadriiformes

• Crown group position• Suggests lice are very old• Points to a long coevolutionary

history with birds• Useful molecular calibration point

Psocoptera

Menacanthus /Menopon - complex

Ricinidae

Laemobothriidae

Boopiidae

Austromenopon- complex

Dennyus- complex

Colpocephalum- complex

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

Cospeciation Events

Constraints

Combined ML

0.1

(18s, COI, EF1-α)

Amblycera

IschnoceraAnoplura

Rhyn.

Louse Phylogeny (unsmoothed)

Cospeciation Events

Constraints

Min. Age 44 ma

Louse Fossil

Combined ML

0.1

(18s, COI, EF1-α)

Amblycera

IschnoceraAnoplura

Rhyn.

Louse Phylogeny (unsmoothed)

Cospeciation Events

Constraints

Combined ML

0.1

(18s, COI, EF1-α)

Amblycera

IschnoceraAnoplura

Rhyn.

Louse Phylogeny (unsmoothed)

Dove-LouseCospeciation

Age Fixed 19.8 ma

Cospeciation Events

Constraints

Combined ML

0.1

(18s, COI, EF1-α)

Rhea/Ostrich-Louse Cospeciation

Age Fixed 60 ma

Amblycera

IschnoceraAnoplura

Rhyn.

Louse Phylogeny (unsmoothed)

Cospeciation Events

Constraints

Combined ML

0.1

(18s, COI, EF1-α)

Amblycera

IschnoceraAnoplura

Rhyn.

Louse Phylogeny (unsmoothed)

Primate-LouseCospeciation

Age Fixed 4.5 ma

Host Implications

2-300ma ?