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Gene-sequence analysis reveals at least three species hidden in Zausodes arenicolus

This study analyzes the gene sequences of Zausodes arenicolus and provides evidence for the existence of at least three hidden species within this complex. The reliability of previous species boundaries is tested using morphological and DNA sequence data, and the presence of unrecognized species is explored. The results highlight the importance of combining morphological and DNA sequence methods for taxonomic discrimination and species identification.

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Gene-sequence analysis reveals at least three species hidden in Zausodes arenicolus

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  1. Gene-sequence analysis reveals at least three species hidden in Zausodes arenicolus Erin Easton November 13, 2008

  2. Zausodes-complex species • Bouck et al., (1999) split genus and described new species • Five species occur locally • Species co-occur

  3. Z. arenicolus and Z. septimus • Occur in an implausible number of habitats • Have been used in ecological studies (including local studies)

  4. Verification important If Bouck et al. are correct, then (1) ecological studies should be redone, (2) Zausodes species are less attractive for ecological studies, and (3) the new morphological characters provide additional tools for taxonomic discrimination

  5. Verify with DNA-sequence data • Presence of phenotypic plasticity • Absence of morphological differentiation • Identification of taxonomic groups that need additional taxonomic revision • Increase in confidence of species’ boundaries with a combined morphological and DNA-sequencing approach

  6. Purpose • To use DNA-sequence methods to test the reliability of the species’ boundaries proposed by Bouck et al. (1999) for specimens collected in the northeastern Gulf of Mexico. • To test whether evidence of unrecognized species exists using DNA-sequence data.

  7. Samples • Five sites • Five species • Specimens identified by morphological characters

  8. Obtaining sequences • DNA was extracted • Target genes were amplified and sequenced

  9. Analyze sequences • Align sequences • Develop neighbor-joining and maximum likelihood trees

  10. Compare and re-evaluate • Compare morphological and DNA-sequence data with respect to species’ boundaries • Identify whether additional morphological characters were overlooked

  11. Cytochrome b ML tree

  12. Morphological re-evaluation • Three morphotypes observed in Zausodes arenicolus • Differences in P5 endopod setae

  13. Conclusions • Combined DNA-sequence and morphological data suggest at least three species hidden in Zausodes arenicolus. • Bouck et al.’s characters supported but species were still overlooked. • Sequence data reveal specimens that require additional taxonomic focus.

  14. Thank you

  15. Cytochrome b divergences

  16. 18S ML tree • Z. arenicolus are divided into four clades • Least divergent cytb clades form one 18S clade

  17. 18S divergences

  18. Future plans • Apply combined DNA-sequence and morphological analysis to deep-sea harpacticoids to better understand their ranges and genetic diversity.

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