Integrative taxonomy
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Transcript of Integrative taxonomy
Integrative taxonomy
Gustav Paulay
Florida Museum of Natural History
University of Florida
Integrative taxonomy
• Use of multiple lines of evidence
• Field - museum - lab
• Ecology - behavior - morphology - genetics - geography
• Distinguishing between morphs and species
• Two or more independent characters showing distinction between species
Integrative taxonomy:
Actinopyga mauritiana - guamensis
Integrative taxonomy:
Actinopyga mauritiana - guamensis
Not seeing species where there are
• cukes vs. primates – different foci for sensory perception
• unequal rates of evolution– phenotype: morphology, behavior, color pattern...– genotype: sequence divergence– reproductive isolation
Supposed distribution of Scutellastra flexuosa and exusta
Powell, 1968
but what is really going on...
NJ K2P COI
Seeing species where there aren’t
• ecophenotypic variation
• ontogenetic variation
• geographic variation
• ecological variation - depth, habitat, etc
• polymorphism
• paralogous loci
• former divergence now united
Paralogous loci:mitochondrial
genes gone nuclear in Alpheus
Williams & Knowlton 2001 Mol Biol Evol
Cypraea tigris a species differentiated, then
united
ESU - reciprocal monophyly
• DNA - gene flow - BSC
• reciprocal monophyly implies lack of recent genetic connections
• need several samples of each form to test
• reliability of conclusion depends on depth of intra- vs. inter-specific variation
• in sympatry - separate biological species
• in allopatry - separate ESUs, species status subjective
Basinal/subbasinal speciation common
• perceived as other dominant mode of speciation by past studies
• predominant mode in Cypraeidae, Aspidochirotida, Diogenidae, Parribacus
Cypraea punctata complex
Where are the species limits?
Lack of reciprocal monophyly
• morphs rather than species
• distinct species, but:– introgression– insufficient time for sorting
• deep coalescent
• rapid speciation
Introgression in Astralium
Introgression in Bohadschia argus?• Unusual form only in W Pacific; never seen in Polynesia, etc.
• Need compare independent markers to test
Insufficient time for sorting
Gene trees vs. species trees:
coalescence theory
Avise 1999 Phylogeography
Evolution of reproductive isolation
• Slow– most gastropod– deep divergence among allopatric ESUs– clear reciprocal monophyly– slow to secondary sympatry / biological species
• Rapid– echinoids, holothuroids– shallow divergence among sympatric species– potential paraphyletic species– rapid to secondary sympatry / biological species
1. Two deeply divergent clades: A & B
sympatric on 8 island groups
2. 30 ESUs so far
3. Pigmentation separates major and minor
clades.
Astralium rhodostomum complex
Geographic signal
no signal0
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0 4 8 12
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Ma
# E
SE
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structure no structure
94% divergences < 10 Maretain signal (115 of 122)
Persistence of allopatry - Cypraeidae
94% divergences < 10 Maretain allopatry (115 of 122)
Echinometra mathaei complex Rapid secondary sympatry
Facilitated by rapid evolution of fertilization proteins?
~1 MaCOIBindin
Landry et al. 2003 Proc Roy SocCOI
Bindin
Cukes like urchins:Actinopyga obesa complex
Stichopus variegatus complex
Advantages of sequence data
• Directly test genetic connections
• Very large number of characters
• Independent markers - independent sources
• “Independent” of morphology - so can trace evolution of form, etc on gene tree without circularity
Potential problems with sequence data
• depth of coalescent vs. interspecific divergence
• paralogous sequences
• introgression– selective sweeps– homogenization through drift