Invertebrate Systematics Invertebrate Systematics Society
Systematics, phylogeny and biogeography

Reconstructing a radiation: the chiton genus Mopalia in the north Pacific

Ryan P. Kelly A B C E and Douglas J. Eernisse D

A Columbia University, New York, USA.

B American Museum of Natural History, New York, USA.

C Present address: Stanford University, Hopkins Marine Station, Pacific Grove, California, USA.

D California State University, Fullerton, California, USA.

E Corresponding author. Email:

Invertebrate Systematics 22(1) 17-28
Submitted: 13 June 2006  Accepted: 13 December 2007   Published: 18 March 2008


The chiton genus Mopalia Gray, 1847 is highly speciose despite showing little morphological differentiation. Many of the 24 extant species are conspicuous, large-bodied and ecologically important today, but pre-Pleistocene fossils for the genus are rare. Here, we use a combined analysis of four gene regions (16S and COI mtDNA, 18S and 28S rDNA) to estimate the phylogenetic relationships for Mopalia species and use the inferred phylogeny to analyse the group’s biogeography and patterns of speciation. We then use these molecular data to distinguish between two alternative interpretations of the fossil record, as there is a large temporal gap between the oldest fossils tentatively identified as Mopalia and the next oldest fossils (Miocene versus Plio-Pleistocene). Based on the estimated substitution rates from a wide variety of other marine animals, we conclude that the observed rates in Mopalia are consistent with a Miocene origin for the genus. Given this age for the group and assuming a molecular clock, most speciation events in Mopalia are inferred to have occurred on average ~5 Mya. The phylogenetic results indicate that most of the speciation events leading to extant species must have occurred along the western North American coast, though there appear to have been multiple spreading events across the Pacific. When considered along with results for the many other near-shore taxa that have similar distributions to Mopalia, our findings suggest the emergence of a coherent historical biogeography of the northern Pacific.

Additional keywords: Mollusca, neogene, phylogeny, polyplacophora, speciation.


Amano K. Vermeij G. J. 1998 Origin and biogeographic history of Ceratostoma (Gastropoda: Muricidae). Venus (Tokyo) 57 209 223

Amano K. Vermeij G. J. 2003 Evolutionary adaptation and geographic spread of the Cenozoic buccinid genus Lirabuccinum in the North Pacific. Journal of Paleontology 77 863 872

Barron J. A. 2003 Planktonic marine diatom record of the past 18 My: appearances and extinctions in the Pacific and Southern Oceans. Diatom Research 18 203 224

Bremer K. 1994 Branch support and tree stability. Cladistics 10 295 304

Briggs J. C. 2006 Proximate sources of marine biodiversity. Journal of Biogeography 33 1 10 DOI

Collin R. 2003 Worldwide patterns in mode of development in calyptraeid gastropods. Marine Ecology Progress Series 247 103 122 DOI

Collins T. M. Frazier K. Palmer A. R. Vermeij G. J. Brown W. M. 1996 Evolutionary history of Northern Hemisphere Nucella (Gastropoda, Muricidae): molecular, morphological, and paleontological evidence. Evolution 50 2287 2304 DOI

Dawson M. N. 2001 Phylogeography in coastal marine animals: a solution from California? Journal of Biogeography 28 723 736 DOI

Dawson M. N. Jacobs D. K. 2001 Molecular evidence for cryptic species of Aurelia aurita (Cnidaria, Scyphozoa). The Biological Bulletin 200 92 96 DOI

Dawson M. N. Louie K. D. Barlow M. Jacobs D. K. Swift C. C. 2002 Comparative phylogeography of sympatric sister species, Clevelandia ios and Eucyclogobius newberryi (Teleostei, Gobiidae), across the California Transition Zone. Molecular Ecology 11 1065 1075 DOI

Durham J. W., and MacNeil F. S. (1967). Cenozoic migrations of marine invertebrates through the Bering Strait region. In ‘The Bering Land Bridge’. (Ed. D. M. Hopkins.) pp. 326–349. (Stanford University Press: Stanford, CA, USA.)

Eernisse D. J., Clark R. N., and Draeger A. (2007). Chitons (Mollusca: Polyplacophora). In ‘Light’s Manual of Intertidal Invertebrates of the Central California Coast’. (Eds S. F. Light, R. I. Smith and J. T. Carlton.) pp. 701–713. (University of California Press: Berkeley, CA, USA.)

Estes J. A. Steinberg P. D. 1988 Predation, herbivory, and kelp evolution. Paleobiology 14 19 36

Estes J. A. Lindberg D. A. Wray C. 2005 Evolution of large body size in abalones (Haliotis): patterns and implications. Paleobiology 14 19 36

Folmer O. Black M. Hoeh W. Lutz R. Vrijenhoek R. 1994 DNA Primers for amplification of mitochondrial cytochrome c oxidase subunit I from diverse metazoan invertebrates. Molecular Marine Biology and Biotechnology 3 294 299

Gladenkov A. Y. Oleinik A. E. Marincovich L. Jr Barinov K. B. 2002 A refined age for the earliest opening of Bering Strait. Palaeogeography, Palaeoclimatology, Palaeoecology 183 321 328

Hellberg M. E. 1998 Sympatric sea shells along the sea’s shore: the geography of speciation in the marine gastropod Tegula. Evolution 52 1311 1324 DOI

Hellberg M. E. 2006 No variation and low synonymous substitution rates in coral mtDNA despite high nuclear variation. BMC Evolutionary Biology 6 24 DOI

Hellberg M. E. Vacquier V. D. 1999 Rapid evolution of fertilization selectivity and lysin cDNA sequences in teguline gastropods. Molecular Biology and Evolution 16 839 848

Hendry A. P. Wenburg J. K. Bentzen P. Volk E. C. Quinn T. P. 2000 Rapid evolution of reproductive isolation in the wild: evidence from introduced salmon. Science 290 516 518

Herbert T. D. Schuffert J. D. Andreasen D. Heusser L. Lyle M. Mix A. Ravelo A. C. Stott L. D. Herguera J. C. 2001 Collapse of the California Current during glacial maxima linked to climate change on land. Science 293 71 76 DOI

Hickman C. S. (2003). Evidence for abrupt Eocene–Oligocene molluscan faunal change in the Pacific Northwest. In ‘From Greenhouse to Icehouse: The Marine Eocene–Oligocene Transition’. (Eds D. R. Prothero, L. C. Ivany and E. A. Nesbitt.) pp. 71–87. (Columbia University Press: New York, USA.)

Hillis D. M. Dixon M. T. 1991 Ribosomal DNA: molecular evolution and phylogenetic inference. The Quarterly Review of Biology 66 411 543 DOI

Huelsenbeck J. P. Ronquist F. 2001 MRBAYES: Bayesian inference of phylogeny. Bioinformatics 17 754 755 DOI

Huelsenbeck J. P. Larget B. Miller R. E. Ronquist F. 2002 Potential applications and pitfalls of Bayesian inference of phylogeny. Systematic Biology 51 673 688 DOI

Itoigawa J. 1993 Miocene palaeogeography of the Mizunami Group of the Tono region, central Japan. Palaeogeography, Palaeoclimatology, Palaeoecology 100 209 215 DOI

Itoigawa J. Nishimoto H. 1975 Miocene Polyplacophora assemblage from the Mizunami group, central Japan (first report). Bulletin of the Mizunami Fossil Museum 2 35 50

Itoigawa J. Shibata H. Nishimoto H. Okumura Y. 1981 Miocene fossils of the Mizunami group, central Japan 2. Molluscs, part 1. Bulletin of the Mizunami Fossil Museum 3A 1 53

Itoigawa J. Shibata H. Nishimoto H. Okumura Y. 1982 Miocene fossils of the Mizunami group, central Japan 2. Molluscs, part 2. Bulletin of the Mizunami Fossil Museum 3B 303 310

Jablonski D., Roy K., and Valentine J. W. (2003). Evolutionary macroecology and the fossil record. In ‘Macroecology: Concepts and Consequences’. (Eds T. M. Blackburn and K. J. Gaston.) pp. 368–390. (Blackwell Science: Oxford, UK.)

Jacobs D. K. Haney T. A. Louie K. D. 2004 Genes, diversity, and geologic process on the Pacific Coast. Annual Review of Earth and Planetary Sciences 32 601 652

Jones A. G. Moore G. I. Kvarnemo C. Walker D. Avise J. C. 2003 Sympatric speciation as a consequence of male pregnancy in seahorses. Proceedings of the National Academy of Sciences of the United States of America 100 6598 6603 DOI

Kelly R. P. Sarkar I. N. Eernisse D. J. Desalle R. 2007 DNA barcoding using chitons (genus Mopalia). Molecular Ecology Notes 7 177 183 DOI

Knowlton N. 2000 Molecular genetic analyses of species boundaries in the sea. Hydrobiologia 420 73 90 DOI

Lessios H. A. Kessing B. D. Pearse J. S. 2001 Population structure and speciation in tropical seas: global phylogeography of the sea urchin Diadema. Evolution 55 955 975 DOI

Levin L. A. 2006 Recent progress in understanding larval dispersal: new directions and digressions. Integrative and Comparative Biology 46 282 297 DOI

Losos J. B. Glor R. E. 2003 Phylogenetic comparative methods and the geography of speciation. Trends in Ecology & Evolution 18 220 227 DOI

Lyle M. Barron J. A. Bralower T. J. Huber M. Olivarez Lyle A. Ravelo A. C. Rea D. K. Wilson P. A. in press The Pacific Ocean and the Cenozoic evolution of climate. Reviews of Geophysics

Maddison D. R., and Maddison W. P. (2003). ‘MacClade: Analysis of Phylogeny and Character Evolution, Version 4.06.’ (Sinauer: Sunderland, MA, USA.)

Marincovich L. Jr Gladenkov A. Y. 1999 Evidence for an early opening of the Bering Strait. Nature 397 149 151

Marko P. B. 1998 Historical allopatry and the biogeography of speciation in the prosobranch snail genus Nucella. Evolution 52 757 774 DOI

McCartney M. A. Keller G. Lessios H. A. 2000 Dispersal barriers in tropical oceans and speciation in Atlantic and eastern Pacific sea urchins of the genus Echinometra. Molecular Ecology 9 1391 1400 DOI

Meyer C. P. 2003 Molecular systematics of cowries (Gastropoda: Cypraeidae) and diversification patterns in the tropics. Biological Journal of the Linnean Society 79 401 459 DOI

Ogasawar K. 2003 Mollusca: Polyplacophora and allied taxa. Palaeontological Society of Japan Special Papers 41 277 278

Oleinik A. E., and Marincovich L.Jr (2003). Biotic response to the Eocene–Oligocene Transition: gastropod assemblages in the high-latitude North Pacific. In ‘From Greenhouse to Icehouse: The Marine Eocene–Oligocene Transition’. (Eds D. R. Prothero, L. C. Ivany and E. A. Nesbitt.) pp. 36–56. (Columbia University Press: New York, USA.)

Palumbi S. R. (1996). Nucleic acids II: the polymerase chain reaction. In ‘Molecular Systematics’. (Eds D. M. Hillis, C. Moritz and B. K. Mable.) pp. 205–247. (Sinauer Associates: Sunderland, MA, USA.)

Posada D. Crandall K. A. 1998 ModelTest: testing the model of DNA substitution. Bioinformatics 14 817 818

Reid D. G. (1996). ‘Systematics and Evolution of Littorina.’ (Dorset Press: Dorchester, UK.)

Ronquist F. Huelsenbeck J. P. 2003 MRBAYES 3: Bayesian phylogenetic inference under mixed models. Bioinformatics 19 1572 1574 DOI

Roy K. Jablonski D. Valentine J. W. 1995 Thermally anomalous assemblages revisited: patterns in the extraprovincial latitudinal range shifts of Pleistocene marine mollusks. Geology 23 1071 1074 DOI

Saito H. Okutani T. 1991 Taxonomy of Japanese species of the genera Mopalia and Plaxiphora (Polyplacophora: Mopaliidae). The Veliger 34 172 194

Sanderson M. J. 2002 Estimating absolute rates of molecular evolution and divergence times: a penalized likelihood approach. Molecular Biology and Evolution 19 101 109

Schroth W. Jarms G. Streit B. Schierwater B. 2002 Speciation and phylogeography in the cosmopolitan marine moon jelly, Aurelia sp. BMC Evolutionary Biology 2

Squires R. L. (2003). Turnovers in marine gastropod faunas during the Eocene–Oligocene Transition. In ‘From Greenhouse to Icehouse: the Eocene–Miocene Transition’. (Eds D. R. Prothero, L. C. Ivany and E. A. Nesbitt.) pp. 14–35. (Columbia University Press: New York, USA.)

Sullivan J. Joyce P. 2005 Model selection in phylogenetics. Annual Review of Ecology and Systematics 36 445 466 DOI

Swofford D. L. (2003). ‘PAUP*. Phylogenetic Analysis Using Parsimony (*and Other Methods), Version 4.0.’ (Sinauer Associates: Sunderland, MA, USA.)

Tamura K. Dudley J. Nei M. Kumar S. 2007 MEGA4: Molecular Evolutionary Genetics Analysis, software version 4.0. Molecular Biology and Evolution 24 1596 1599 DOI

Valentine J. W. 1980 Camalu: A Pleistocene terrace fauna from Baja California. Journal of Paleontology 54 1310 1318

Vermeij G. J. (2001). Community assembly in the sea: geologic history of the living shore biota. In ‘Marine Community Ecology’. (Eds M. D. Bertness, S. D. Gaines and M. E. Hay.) pp. 39–60. (Sinauer Associates: Sunderland, MA, USA.)

Vermeij G. J. (2005). Invasion as expectation: a historical fact of life. In ‘Species Invasions: Insights into Ecology, Evolution, and Biogeography’. (Eds D. F. Sax, J. J. Stachowicz and S. D. Gaines.) pp. 309–339. (Sinauer Associates, Inc.: Sunderland, MA, USA.)

Wares J. P. Cunningham C. W. 2001 Phylogeography and historical ecology of the North Atlantic intertidal. Evolution 55 2455 2469

Zwickl D. J. (2006). Genetic algorithm approaches for the phylogenetic analysis of large biological sequence datasets under the maximum likelihood criterion. PhD Thesis, University of Texas, Austin, TX, USA.

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