Revision of the phycoerythrin 545-containing cryptophytes

点击翻译按钮获取中文摘要

The Cryptophyceae consist predominantly of photosynthetic flagellates that successfully conquered marine as well as freshwater habitats. They are ecologically important as prey for several planktic predators (e.g. clliate, copepod or dinoflagellate species). Although cryptophytes as such can be easily identified due to a unique combination of characters, dimorphisms and a lack of species-specific morphological characters cause problems in identification at lower classification levels. This resulted in an inconsistent systematic seriously compromising biodiversity surveys of cryptophyte taxa. This project aims at establishing a sound systematics of the predominantly marine phycoerythrin 545-containing cryptophyte genera. All examinations are based on clonal strains. To examine relationships among the cryptophyte lineages, phylogenetic trees are inferred from combined data sets of ribosomal DNA sequences of two genomes, nucleus and nucleomorph. By mapping morphological characters onto phylogenetic trees, genus- or species-specific characters can be identified. Since sexual reproduction cannot be induced in cryptophyte cultures, compensating base pair changes in the internal transcribed spacer 2 of the nuclear ribosomal operon will be used as indirect markers to predict putative biological species. The taxonomic revisions include molecular signatures as diagnostic characters to allow for an identification of genetically distinct but morphologically ambiguous taxa.