microhabitat specialization in parasitic lice:

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microhabitat specialization in parasitic lice
The evolution of

• lineage assortment or character displacement?

Vincent S. Smith Kevin P. Johnson
Illinois Natural History Survey University of
Illinois Campus Champaign, Illinois USA
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Niche Specialization
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Niche Specialization is Common
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Patterns of Niche Evolution
CI 1.00
CI 0.33
Niche conserved
Niche convergent
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Process of Niche Evolution - consider hosts
Niche evolves early
Niche evolves late
(niche assorts with host lineages)
(niche displaces within host lineages)
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Louse Phylogeny
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Louse Phylogeny
Molecules
Morphology
Bootstrap gt 0.85
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Niche Evolution
Morphology
Molecules
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Randomization Tests - character fit
Molecules
Morphology
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Randomization Tests
(sister taxa occupying a different niche)
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Niche Evolution - Recap
Morphology
Molecules
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Lineage assortment or character displacement?
Morphology supports lineage assortment
Molecules supports character displacement
Niche evolves early
Niche evolves late
(niche assorts with host lineages)
(niche displaces within host lineages)
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Which hypothesis is best supported?

• Mol. phylogeny well supported

• Mol. data blind to niche

• Especially terminal clades

• There are only a few host niches

• Mit. nuclear genes agree

• We would expect to see strong selection
  morphological character convergence

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What use is morphology?
- phylogenetically speaking
Can we identify morphological characters that
co-vary with niche?
If so, what are they, and can we extract them to
build the correct louse phylogeny
i.e. one that is topologically more similar to
the molecular tree
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Identifying co-varying characters?
Morphology
Niche Constraint
Repeat until no more characters improve their fit

• 9 cycles, 61 characters excluded

• We need a better method - any suggestions?

• Almost half the dataset removed!

• Remaining characters very noisy

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Is character displacement common?

• Common mammal lice

• Traditionally considered unrelated

• Placed in different families

• Morphologically very different

• Occupy different host niches

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Is character displacement common?
Generic phylogeny of sucking lice
Human head louse
Human pubic louse
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Character displacement - a general mechanism
producing phenotypic diversity
Radiation of Anolis lizards on the Greater
Antilles
UPGMA Morphology (clusters phenotype)
Molecular Phylogeny (phenotype transitions common)
Losos et al. Science 279. 2115-2118
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Character displacement - a general mechanism
producing phenotypic diversity
Fig wasps
Weiblen Bush Mol. Ecol. 11. 1573-1578
Shared host use by wasp sister taxa promotes
character displacement
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Acknowledgements