Evolutionary Radiation of Present-DayNautilusandAllonautilus

Abstract

Background: Mitochondria contain small genomes that are physically separate from those of nuclei. Their comparison serves as a model system for understanding the processes of genome evolution. Although complete mitochondrial genome sequences have been reported for more than 600 animals, the taxonomic sampling is highly biased toward vertebrates and arthropods, leaving much of the diversity yet uncharacterized.

The contribution of molecular data to our understanding of cephalopod evolution and systematics: a review

“…Studies have confirmed the validity of the genus Allonautilus and its sister-taxon relationship with Nautilus (Bonacum et al 2011). However, they have also suggested that Nautilus pompilius comprises many evolutionarily independent lineages and there are in fact many more species present in the Indo Pacific than are currently recognized (Sinclair et al 2007(Sinclair et al , 2011Bonacum et al 2011;Williams et al 2012). These are important data because of the susceptibility of Nautilus populations to intense fishery activity (Dunstan et al 2010).…”

The Paleocene cephalopod fauna from Pebble Point, Victoria (Australia) – fulcrum between two Eras

“…New DNA work on Nautilus (Wray et al, 1995;Bonacum et al, 2010) as well as work conducted by one of the authors here (Vandepas et al, in review) has shown that species of Nautilus are, in fact, highly variable, and that rather than the currently "accepted" species Nautilus pompilius (the type species), N. macromphalus, N. stenomphalus, and N. belauensis (with N. repertus also accepted in some quarters), there is now good understanding that along the Great Barrier Reef there is a complete morphological mixture of characters that have been used to separate N. stenomphalus from N. pompilius -and that there is no difference in the COI gene between the morphologically distinct end members of what has been called N. pompilius and N. stenomphalus. In similar fashion, N. belauensis Saunders is now seen as simply a large N. pompilius, as is N. repertus.…”

The Mitochondrial Genome ofAllonautilus(Mollusca: Cephalopoda): Base Composition, Noncoding-Region Variation, and Phylogenetic Divergence

“…B. Nautilus macromphalus, New Caledonia, AMNH 94104. new genus Allonautilus containing A. scrobiculatus [Lightfoot, 1786] 4 and A. perforatus (Conrad, 1847). This generic assignment was challenged almost immediately (Harvey et al, 1999;Ward, 1999), although subsequent analyses based on molecular data (Bonacum et al, 2011) have demonstrated that Allonautilus is the sister taxon of Nautilus. Allonautilus differs from Nautilus in terms of the shape of the shell and size of the umbilicus, the thickness of the periostracum, and the number of tubercles on the hood (see fig.…”

“…Fewer than a dozen species of extant nautilids remain of a once large and widespread radiation (Teichert and Matsumoto, 1987), although the exact number of present-day species is still a subject of debate (Bonacum et al, 2011). Many of these species are known only from drift shells (House, 1987), but at least five of them, including Nautilus macromphalus Sowerby, 1849, have been caught as live animals (Saunders, 1987).…”

“…Because there are known to be extensive mitochondrial gene rearrangements within cephalopods (Akasaki et al, 2006;Kawashima et al, 2013), and because the gene arrangement of the sole sequenced nautilid (Nautilus macromphalus) was found to differ from that of the other cephalopods, it is important to determine whether the pattern observed in N. macromphalus characterized the rest of the order. Consequently, we sequenced the mitogenome of Allonautilus scrobiculatus, which appears to represent the basalmost split among extant members of the order (Bonacum et al, 2011;Bonnaud et al, 2004). Prior to this study, little molecular data were available for Allonautilus.…”