SEMINAR: Thursday, July 23, 1998, 12:00 am
Lister Hill Center (NIH BLdg 38A), 8th floor conference room

David B. Carlini
----------------
The Phylogeny of Coleoid Cephalopods Inferred through Molecular
Evolutionary Analyses of the Cytochrome c Oxidase I, Muscle Actin,
and Cytoplasmic Actin Genes

David B. Carlini is at the College of William and Mary,
Virginia Institute of Marine Science, VA. He has applied for the
taxonomist position. The title and abstract of his seminar are
appended below.

  Detlef

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David B. Carlini,
Virginia Institute of Marine Science, College of William and Mary

	The Phylogeny of Coleoid Cephalopods Inferred through Molecular
	Evolutionary Analyses of the Cytochrome c Oxidase I, Muscle Actin,
	and Cytoplasmic Actin Genes

     Although the fossil record of early cephalopods is rich and
demonstrates the dominance of the group in Paleozoic times, the mainly
soft-bodied coleoids (Cephalopoda:  Coleoidea) are poorly represented.
Therefore, little is known of the evolutionary history of coleoids through
paleontology and current classifications of the subclass are based
primarily on the morphology of extant representatives.  There is
substantial disagreement among the various higher-level classifications of
the Coleoidea.  This incongruence can be attributed to the difficulty in
obtaining comparative material for morphological studies, the paucity of
information regarding ancestral character states, and the lack of
objective criteria used in constructing phylogenetic relationships in many
of the previous studies.  A molecular phylogenetic analysis of the
Coloeidea is therefore clearly required.
     Phylogenetic relationships within the Coleoidea were constructed
using molecular sequence data from one mitochondrial and two nuclear
genes:  cytochrome c oxidase I (COI) and two unlinked actin genes (Actin I
and Actin II).  A 657 base-pair portion of the COI gene was examined for
55 coleoid taxa encompassing a broad spectrum of diversity in the
subclass.  The COI gene exhibited the most rapid evolutionary rate among
the three genes examined, yet the gene was informative for determining
deep as well as shallow-level relationships within the Coleoidea.
Eighty-two sequences from a 784 base-pair portion of three paralogous
actin genes were obtained from 43 terminal taxa.  The Actin I gene (38
taxa) was highly conserved and provided information for determining
deep-level relationships.  The Actin II gene (32 taxa) was intermediately
conserved, exhibited a broad range of sequence divergence, and was
informative for inferring deep and shallow-level relationships. The
evolution of the actin gene family in cephalopods was compared to that in
other molluscs, protostomes, and deuterostomes.  Analyses of actin gene
family evolution provided evidence that the Actin I gene encodes a
muscle-type of actin, and that the Actin II gene encodes a cytoplasmic
actin.  These analyses also supported at least two independent derivations
of muscle-type actins during the evolution of the protostome lineage.
Analyses of the COI, Actin I, and Actin II genes did not provide
phylogenetic stability in the inference of intermediate-level
relationships, particularly those among many families in the diverse
suborder Oegopsida.  The codon usage patterns of selected taxa were
determined and compared within and among each of the three genes.
     With regard to higher-level phylogenetic relationships, the following
conclusions were drawn from the results of phylogenetic analyses:  1)the
cephalopod subclass Coleoidea is monophyletic; 2)the order Octopoda is
monophyletic and is sister group to the monotypic order Vampyromorpha;
3)the Decapodiformes, consisting of the orders Teuthoidea and Sepioidea,
is monophyletic; 4)the orders Teuthoidea and Sepioidea are polyphyletic;
5)the teuthoid suborders Myopsida and Oegopsida are monophyletic and
polyphyletic, respectively; 6)the Myopsida and the oegopsid families
Chtenopterygidae and Bathyteuthidae are more closely related to the
sepioid families Spirulidae, Sepiidae, and Sepiolidae, than they are to
other teuthoid groups.