title: Assessing divergence time of Spirulida and Sepiida (Cephalopoda) based on hemocyanin sequences.
abstract: The phylogenetic position of the mesopelagic decabrachian cephalopod Spirula is still a matter of debate. Since hemocyanin has successfully been used to calibrate a molecular clock for many molluscan species, a molecular clock was calculated based on this gene with special attention to the cephalopod genera Spirula and Sepia. The obtained partial sequence comprising ca., one third (3567 bp) of the complete gene is similar to that of Sepia officinalis. The molecular clock was calibrated using the splits of Gastropoda-Cephalopoda (ca. 550 ± 50 mya) and Heterobranchia-Vetigastropoda (ca. 380 ± 10 mya). The resulting hemocyanin-based molecular clock is stable, and the estimated divergence time of Spirulida and Sepiida, some 150 ± 30 million years ago, can be deemed reliable.
authors.affiliation: FR Paläontologie, Freie Universität Berlin, Berlin, Germany. warnke@zedat.fu-berlin.de
authors.forename: Kerstin Martina
authors.initials: KM
authors.lastname: Warnke
authors.forename: Achim
authors.initials: A
authors.lastname: Meyer
authors.forename: Bettina
authors.initials: B
authors.lastname: Ebner
authors.forename: Bernhard
authors.initials: B
authors.lastname: Lieb
mesh_terms: D000818:Animals; D049830:Cephalopoda / Q000145:classification / Q000235:genetics*; D019143:Evolution, Molecular; D006433:Hemocyanins / Q000235:genetics*; D010802:Phylogeny; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D006433:Hemocyanins