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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

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Integrative taxonomy

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  1. Integrative taxonomy Gustav Paulay Florida Museum of Natural History University of Florida

  2. 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

  3. Integrative taxonomy:Actinopyga mauritiana - guamensis

  4. Integrative taxonomy:Actinopyga mauritiana - guamensis

  5. 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

  6. Supposed distribution of Scutellastra flexuosa and exusta Powell, 1968

  7. but what is really going on... NJ K2P COI

  8. Seeing species where there aren’t • ecophenotypic variation • ontogenetic variation • geographic variation • ecological variation - depth, habitat, etc • polymorphism • paralogous loci • former divergence now united

  9. Paralogous loci:mitochondrial genes gone nuclear in Alpheus Williams & Knowlton 2001 Mol Biol Evol

  10. Cypraea tigris a species differentiated, then united

  11. 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

  12. Cypraea punctata complex Basinal/subbasinal speciation common • perceived as other dominant mode of speciation by past studies • predominant mode in Cypraeidae, Aspidochirotida, Diogenidae, Parribacus

  13. Where are the species limits?

  14. Lack of reciprocal monophyly • morphs rather than species • distinct species, but: • introgression • insufficient time for sorting • deep coalescent • rapid speciation

  15. Introgression in Astralium

  16. Introgression in Bohadschia argus? • Unusual form only in W Pacific; never seen in Polynesia, etc. • Need compare independent markers to test

  17. Insufficient time for sortingGene trees vs. species trees:coalescence theory Avise 1999 Phylogeography

  18. 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

  19. Astralium rhodostomum complex • Two deeply divergent clades: A & B sympatric on 8 island groups • 30 ESUs so far • Pigmentation separates major and minor clades.

  20. Persistence of allopatry - Cypraeidae 94% divergences < 10 Ma retain allopatry (115 of 122) 94% divergences < 10 Ma retain signal (115 of 122) Geographic signal no signal

  21. Echinometra mathaei complex Rapid secondary sympatryFacilitated by rapid evolution of fertilization proteins? ~1 Ma COI Bindin Bindin COI Landry et al. 2003 Proc Roy Soc

  22. Cukes like urchins: Actinopyga obesa complex

  23. Stichopus variegatus complex

  24. 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

  25. Potential problems with sequence data • depth of coalescent vs. interspecific divergence • paralogous sequences • introgression • selective sweeps • homogenization through drift

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