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Molecules vs Morphology

• There is conflict

• Why is there conflict?

• A Quest

• Who’s right?

•• There is conflictThere is conflict

• Why is there conflict?

• A Quest

• Who’s right?

Examples

– Molluscs

– Birds

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AculiferaAculifera

ConchiferaConchifera

Morphological Topology

Molecular Topology (Giribet et al 2006)

Morphological Topology – generalised alternatives

Morphological conflict

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• New hypothesis

• Entirely dependent on

a monoplacophoran

specimen

in 100% EtOH

Example:

‘Pelicaniformes’

Morphological Molecular

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Molecular Molecular

• There is conflict

•• Why is there conflict?Why is there conflict?

• A Quest

• Who’s right?

Conventional reasons

• Convergence (non-homology)

• Rates of character evolution

• Long-branch attraction (non-homology)

• Contamination

• Taxon sampling

Many of the same reasons for conflict between genes,

or between morphological character-sets

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Taxon units are working

hypotheses

• Systematics depends on

species

• Species may be flawed

Species A

“Taxon Sampling”

• Dependent on preservation and

specimen availability

• Dependent on access to specimen material

– Museum specimens

– Fieldwork

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Molluscs

• 60,000+ species known

• 108 species sequenced

• There is conflict

• Why is there conflict?

•• A QuestA Quest

• Who’s right?

Is there a holy grail

of systematics?

DNA Bar-coding

• New plans to develop “zapper” technology

• Proposals to change species names to

“bar-codes” to facilitate higher rate of

species descriptions

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So why aren’t we happy?

• Not dependable

– Need working primers

– not known for most of the

1,400,000 species of animals,

and for plants…

• Not useful

Not useful?

• Species identification in the field requires

morphological evidence

– Biodiversity conservation

requires field identification

• Usefulness for new species unclear

• Impossible on preserved material

– Many taxa known from few

specimens

• There is conflict

• Why is there conflict?

• A Quest

•• WhoWho’’s right?s right?

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• The power of one character is never

absolute

• Use ALL available material

– Fieldwork

– Historical material

• Use ALL available data

– Find new characters

The most important bit

Specimen preservation influences

BOTH

morphological and molecular

data availability