title: Evolutionary relationships among squids of the family Gonatidae (Mollusca: Cephalopoda) inferred from three mitochondrial loci.
abstract: The oceanic squid family Gonatidae (Mollusca: Cephalopoda) is widely distributed in subpolar and temperate waters, exhibiting behavioral and physiological specializations associated with reproduction. Females of several species undergo muscular degeneration upon maturation; origins of this complex morphogenic change are unknown, hindering our understanding of ecological and morpho-physiological adaptations within the family. To provide further information regarding the evolutionary relationships within Gonatidae, three mitochondrial loci (12S rRNA, 16S rRNA, and cytochrome c oxidase subunit I) were analyzed for 39 individuals representing fourteen gonatid and six outgroup cephalopod species. In addition to elucidating relationships among gonatids, molecular data provided more information than morphological data for problematic specimens. Although some data sets are incongruent or have low nodal support values, combined molecular analysis confirms the presence of gonatid groups previously established by morphological characteristics (i.e., possessing radular teeth in seven longitudinal rows and muscular mantle tissue). These characteristics are basal to taxa possessing radular teeth in five longitudinal rows and less muscular mantle tissue, indicating that the derived forms are those species exhibiting physiological adaptation such as tissue degeneration upon maturation and egg brooding.
authors.affiliation: Department of Biology, New Mexico State University, Box 30001, MSC 3AF, Las Cruces, NM 88003-8001, USA.
authors.forename: A R
authors.initials: AR
authors.lastname: Lindgren
authors.forename: O N
authors.initials: ON
authors.lastname: Katugin
authors.forename: E
authors.initials: E
authors.lastname: Amezquita
authors.forename: M K
authors.initials: MK
authors.lastname: Nishiguchi
mesh_terms: D000818:Animals; D004272:DNA, Mitochondrial / Q000235:genetics; D049832:Decapodiformes / Q000145:classification* / Q000235:genetics*; D003576:Electron Transport Complex IV / Q000235:genetics; D019143:Evolution, Molecular; D010802:Phylogeny; D012335:RNA, Ribosomal / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013045:Species Specificity
chemical_list: D004272:DNA, Mitochondrial; D012335:RNA, Ribosomal; D012336:RNA, Ribosomal, 16S; C075526:RNA, ribosomal, 12S; D003576:Electron Transport Complex IV