Hydrobiologia

, Volume 420, Issue 1, pp 73–90 | Cite as

Molecular genetic analyses of species boundaries in the sea

  • N. Knowlton
Article

Abstract

The tools of molecular genetics have enormous potential for clarifying the nature and age of species boundaries in marine organisms. Below I summarize the genetic implications of various species concepts, and review the results of recent molecular genetic analyses of species boundaries in marine microbes, plants, invertebrates and vertebrates. Excessive lumping, rather than excessive splitting, characterizes the current systematic situation in many groups. Morphologically similar species are often quite distinct genetically, suggesting that conservative systematic traditions or morphological stasis may be involved. Some reproductively isolated taxa exhibit only small levels of genetic differentiation, however. In these cases, large population sizes, slow rates of molecular evolution, and relatively recent origins may contribute to the difficulty in finding fixed genetic markers associated with barriers to gene exchange. The extent to which hybridization blurs species boundaries of marine organisms remains a subject of real disagreement in some groups (e.g. corals). The ages of recently diverged species are largely unknown; many appear to be older than 3 million years, but snails and fishes provide several examples of more recent divergences. Increasingly sophisticated genetic analyses make it easier to distinguish allopatric taxa, but criteria for recognition at the species level are highly inconsistent across studies. Future molecular genetic analyses should help to resolve many of these issues, particularly if coupled with other biological and paleontological approaches.

sibling species taxonomy DNA electrophoresis allozymes 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Abbiata, M. & F. Maltagliati, 1996. Allozyme evidence of genetic differentiation between populations of Hediste diversicolor (Polychaeta: Nereididae) from the western Mediterranean. J. mar. biol. Ass. U.K. 76: 637–647.Google Scholar
  2. Adamkewicz, S. L. & M. G. Harasewych, 1996. Systematics and biogeography of the genus Donax (Bivalvia: Donacidae) in eastern North America. Am. malac. Bull. 13: 97–103.Google Scholar
  3. Amaral, F. D., R. S. Silva, L. Mauricio-da-Silva & A. M. Solé-Cava, 1997. Molecular systematics of Millepora alcicornis Linnaeus, 1758 and M. braziliensis Verrill, 1868 (Hydrozoa: Milleporidae) from Brazil. Proc. 8th Intl. Coral Reef Symp. 2: 1577–1580.Google Scholar
  4. Arndt, A., C. Marquez, P. Lambert & M. J. Smith, 1996. Molecular phylogeny of eastern Pacific sea cucumbers (Echinodermata: Holothuroidea) based on mitochondrial DNA sequence. Mol. Phylogenet. Evol. 6: 425–437.Google Scholar
  5. Aron, S. & A. M. Solé-Cava, 1991. Genetic evaluation of the taxonomic status of two varieties of the cosmopolitan ascidian Botryllus niger (Ascidiaceae: Botryllidae). Biochem. Syst. Ecol. 19: 271–276.Google Scholar
  6. Avise, J. C. & R. M. Ball Jr., 1990. Principles of genealogical concordance in species concepts and biological taxonomy. Oxford Surv. evol. Biol. 7: 45–67.Google Scholar
  7. Avise, J. C. & D. Walker, 1998. Pleistocene phylogeographic effects on avian populations and the speciation process. Proc. r. Soc. Lond. B 265: 457–463.Google Scholar
  8. Avise, J. C. & K. Wollenberg, 1997. Phylogenetics and the origin of species. Proc. natn. Acad. Sci. U.S.A. 94: 7748–7755.Google Scholar
  9. Avise, J. C., D. Walker & G. C. Johns, 1998. Speciation durations and Pleistocene effects on vertebrate phylogeography. Proc. r. Soc. Lond. B 265: 1707–1712.Google Scholar
  10. Backeljau, T., P. Bouchet, S. Gofas & L. de Bruyn, 1994. Genetic variation, systematics and distribution of the venerid clam Chamelea gallina. J. mar. biol. Ass. U.K. 74: 211–223.Google Scholar
  11. Bakker, F. T., J. L. Olsen & W. T. Stam, 1995a. Evolution of nuclear rDNA ITS sequences in the Cladophora albida/sericea clade (Chlorophyta). J. mol. Evol. 40: 640–651.Google Scholar
  12. Bakker, F. T., J. L. Olsen & W. T. Stam, 1995b. Global phylogeography in the cosmopolitan species Cladophora vagabunda (Chlorophyta) based on nuclear rDNA internal transcribed spacer sequences. Europ. J. Phycol. 30: 197–208.Google Scholar
  13. Baoling, W., Q. Pei-Yuan & Z. Sonling, 1991. Morphology, reproduction, ecology and allozyme electrophoresis of three Capitella sibling species in Qingdao (Polychaeta: Capitellidae). Ophelia (Suppl.) 5: 391–400.Google Scholar
  14. Barbieri, M., G. Bavestrello & M. Sarà, 1995. Morphological and ecological differences in two electrophoretically detected species of Cliona (Porifera, Demospongiae). Biol. J. linn. Soc. 54: 193–200.Google Scholar
  15. Bastrop, R., K. Jurss & C. Sturmbauer, 1998. Cryptic species in a marine polychaete and their independent introduction from North America to Europe. Mol. Biol. Evol. 15: 97–103.Google Scholar
  16. Bavestrello, G. & M. Sarà, 1992. Morphological and genetic differences in ecologically distinct populations of Petrosia (Porifera, Demospongiae). Biol. J. linn. Soc. 47: 49–60.Google Scholar
  17. Benzie, J. A. H., 1999. Genetic structure of coral reef organisms: ghosts of dispersal past. Am. Zool. 39: 131–145.Google Scholar
  18. Benzie, J. A. H., I. R. Price & E. Ballment, 1997. Population genetics and taxonomy of Caulerpa (Chlorophyta) from the Great Barrier Reef, Australia. J. Phycol. 33: 491–504.Google Scholar
  19. Bernardi, G. & U. Goswami, 1997. Molecular evidence for cryptic species among the Antarctic fish Trematomus bernacchii and Trematomus hansoni. Antarct. Sci. 9: 381–385.Google Scholar
  20. Bert, T. M. & W. S. Arnold, 1995. An empirical test of predictions of two competing models for the maintenance and fate of hybrid zones: both models are supported in a hard-clam hybrid zone. Evolution 49: 276–289.Google Scholar
  21. Bert, T. M., K. J. McCarthy, H. Cruz-Lopez & S. Bogdanowicz, 1996. Character discriminatory power, character-set congruence, and the classification of individuals from hybrid zones: an example using stone crabs (Menippe). Evolution 50: 655–671.Google Scholar
  22. Beynon, C. M. & D. O. F. Skibinski, 1996. The evolutionary relationships between three species of mussel (Mytilus) based on anonymous DNA polymorphisms. J. exp. mar. Biol. Ecol. 203: 1–10.Google Scholar
  23. Blomster, J., C. A. Maggs & M. J. Stanhope, 1998. Molecular and morphological analysis of Enteromorpha intestinalis and E. compressa (Chlorophyta) in the British Isles. J. Phycol. 34: 319–340.Google Scholar
  24. Bonse, S., H. Schmidt, D. Eibye-Jacobsen & W. Westheide, 1996. Eulalaia viridis (Polychaeta: Phyllodocidae) is a complex of two species in northern Europe: results from biochemical and morphological analyses. Cah. Biol. mar. 37: 33–48.Google Scholar
  25. Borsa, P. & J. A. H. Benzie, 1993. Genetic relationships among the topshells Trochus and Tectus (Prosobranchia: Trochidae) from the Great Barrier Reef. J. moll. Stud. 59: 275–284.Google Scholar
  26. Boudry, P., S. Heurtebise, B. Collet, F. Cornette & A. Gérard, 1998. Differentiation between populations of the Portuguese oyster, Crassostrea angulata (Lamark) and the Pacific oyster, Crassostrea gigas (Thunberg), revealed by mtDNA RFLP analysis. J. exp. mar. Biol. Ecol. 226: 279–291.Google Scholar
  27. Boury-Esnault, N., M. Klautau, C. Bezac, J. Wulff & A. M. Solé-Cava, 1999. Comparative study of putative conspecific sponge populations from both sides of the Isthmus of Panama. J. mar. biol. Assoc. U.K. 79: 39–50.Google Scholar
  28. Bowen, B. W., W. S. Nelson & J. C. Avise, 1993. A molecular phylogeny for marine turtles: trait mapping, rate assessment, and conservation relevance. Proc. natn. Acad. Sci. U.S.A. 90: 5574–5577.Google Scholar
  29. Brazeau, D. A. & C. D. Harvell, 1994. Genetic structure of local populations and divergence between growth forms in a clonal invertebrate, the Caribbean octocoral Briareum asbestinum. Mar. Biol. 119: 53–60.Google Scholar
  30. Brodie, J., P. K. Hayes, G. L. Barker & L. M. Irvine, 1996. Molecular and morphological characters distinguishing two Porphyra species (Rhodophyta: Bangiophycidae). Europ. J. Phycol. 31: 303–308.Google Scholar
  31. Brown, L. D., 1995. Genetic evidence for hybridisation between Haliotis rubra and H. laevigata. Mar. Biol. 123: 89–93.Google Scholar
  32. Brown, C. J., W. W. Anderson, W. D. Burbanck & C. T. Hackney, 1988. Genetic transition between northern and southern populations of the estuarine isopod, Cyathura polita, and the discovery of a new species of Cyathura. Estuaries 11: 96–98.Google Scholar
  33. Bucklin, A., B. W. Frost & T. D. Kocher, 1995. Molecular systematics of six Calanus and three Metridia species (Calanoida: Copepoda). Mar. Biol. 121: 655–664.Google Scholar
  34. Bucklin, A., A. M. Bentley & S. P. Franzen, 1998. Distribution and relative abundance of Pseudocalanus moultoni and P. newmani (Copepoda: Calanoida) on Georges Bank using molecular identification of sibling species. Mar. Biol. 132: 97–106.Google Scholar
  35. Bucklin, A., T. C. LaJeunesse, E. Curry, J. Wallinga & K. Garrison, 1996. Molecular diversity of the copepod Nannocalanus minor: genetic evidence of species and population structure in the North Atlantic Ocean. J. mar. Res. 54: 285–310.Google Scholar
  36. Burnett, W. J., J. A. H. Benzie, J. A. Beardmore & J. S. Ryland, 1997. Zoanthids (Anthozoa, Hexacorallia) from the Great Barrier Reef and Torres Strait, Australia: systematics, evolution and a key to species. Coral Reefs 16: 55–68.Google Scholar
  37. Burton, R. S., P. D. Rawson & S. Edmands, 1999. Genetic architecture of physiological phenotypes: empirical evidence for coadapted gene complexes. Am. Zool. 39: 451–462.Google Scholar
  38. Cadman, P. S. & A. Nelson-Smith, 1993. A new species of lugworm: Arenicola defodiens sp. nov. J. mar. biol. Ass. U.K. 73: 213–223.Google Scholar
  39. Carvalho, G. R. & Ch. M. Nigmatullin, 1998. Stock structure analysis and species identification. FAO Fish. tech. Pap 376: 199–232.Google Scholar
  40. Charfi-Cheikhrouha, F., M. Laulier, E. Hamelin & J.-P. Mocquard, 1998. Genetic differentiation and evolutionary process of speciation in the Idotea chelipes complex (Crustacea, Isopoda). Genet. Sel. Evol. 30: 289–303.Google Scholar
  41. Collins, T. M., K. Frazer, A. R. Palmer, G. J. Vermeij & W. M. Brown, 1996. Evolutionary history of northern hemisphere Nucella (Gastropoda, Muricidae): molecular, morphological, ecological, and paleontological evidence. Evolution 50: 2287–2304.Google Scholar
  42. Comesaña, A. S., J. E. Toro, D. J. Innes & R. J. Thompson, 1999. A molecular approach to the ecology of a mussel (Mytilus edulis-M. trossulus) hybrid zone on the east coast of Newfoundland, Canada. Mar. Biol. 133: 213–221.Google Scholar
  43. Côrte-Real, H. B. S. M., S. J. Hawkins & J. P. Thorpe, 1996a. An interpretation of the taxonomic relationship between the limpets Patella rustica and P. piperata. J. mar. biol. Ass. U.K. 76: 717–732.Google Scholar
  44. Côrte-Real, H. B. S. M., S. J. Hawkins & J. P. Thorpe, 1996b. Population differentiation and taxonomic status of the exploited limpet Patella candei in the Macaronesian islands (Azores, Madeira, Canaries). Mar. Biol. 125: 141–152.Google Scholar
  45. Coyne, J. A. & H. A. Orr, 1997. 'Patterns of speciation in Drosophila' revisited. Evolution 51: 295–303.Google Scholar
  46. Cracraft, J., 1989. Speciation and its ontology: The empirical consequences of alternative species concepts for understanding patterns and processes of differentiation. In Otte, D. & J. A. Endler (eds), Speciation and its Consequences. Sinauer, Sunderland, Massachusetts: 28–59.Google Scholar
  47. Craddock, C., W. R. Hoeh, R. G. Gustafson, R. A. Lutz, J. Hashimoto & R. J. Vrijenhoek, 1995. Evolutionary relationships among deep-sea mytilids (Bivalvia: Mytilidae) from hydrothermal vents and cold-water methane/sulfide seeps. Mar. Biol. 121: 477–485.Google Scholar
  48. Cunningham, C. W., N. W. Blackstone & L. W. Buss, 1992. Evolution of king crabs from hermit crab ancestors. Nature 355: 539–542.Google Scholar
  49. Dalby, J. E. Jr., 1997. Reproductive and electrophoretic evidence for genetic maintenance of dimorphism in the ascidian Pyura stolonifera near Melbourne, Australia. Ophelia 47: 227–243.Google Scholar
  50. Davidson, S. K. & M. G. Haygood, 1999. Identification of sibling species of the bryozoan Bugula neritina that produce different anticancer bryostatins and harbor distinct strains of the bacterial symbiont 'Candidatus Endobugula sertula.' Biol. Bull. 196: 273–280.Google Scholar
  51. Dayton, C., A. C. Santayana & J. M. Lacson, 1994. Genetic evidence for reproductive isolation of the recently described unicornfish Naso caesius and its sibling N. hexacanthus. Mar. Biol. 118: 551–554.Google Scholar
  52. De Queiroz, K., 1998. The general lineage concept of species, species criteria, and the process of speciation. In Howard, D. J. & S. H. Berlocher (eds), Endless Forms: Species and Speciation. Oxford University Press, New York: 57–75.Google Scholar
  53. Degnan, B. M. & M. F. Lavin, 1995. Highly repetitive DNA sequences provide evidence for a lack of gene flow between two morphological forms of Herdmania momus (Ascidiacea: Stolidobranchia). Mar. Biol. 124: 293–299.Google Scholar
  54. Denis, F., D. Jollivet & D. Moraga, 1993. Genetic separation of two allopatric populations of hydrothermal snails Alviniconcha spp. (Gastropoda) from two south-western Pacific back-arc basins. Biochem. Syst. Ecol. 21: 431–440.Google Scholar
  55. Duffy, J. E., 1996. Species boundaries, specialization, and the radiation of sponge-dwelling alpheid shrimp. Biol. J. linn. Soc. 58: 307–324.Google Scholar
  56. Dutton, P. H., S. K. Davis, T. Guerra & D. Owens, 1996. Molecular phylogeny for marine turtles based on sequences of the ND4–leucine tRNA and control regions of mitochondrial DNA. Mol. Phylogenet. Evol. 5: 511–521.Google Scholar
  57. Edmands, S., 1996. The evolution of mating systems in a group of brooding sea anemones (Epiactis). Invert. Reprod. Devel. 30: 227–237.Google Scholar
  58. Embley, T. M. & E. Stackebrandt, 1997. Species in practice: exploring uncultured prokaryote diversity in natural samples. In Claridge, M. F., H. A. Dawah & M. R. Wilson (eds), Species: the Units of Biodiversity. Chapman & Hall, London: 61–81.Google Scholar
  59. Felder, D. L. & J. L. Staton, 1994. Genetic differentiation in trans-Floridian species complexes of Sesarma and Uca (Decapoda: Brachyura). J. Crust. Biol. 14: 191–209.Google Scholar
  60. Ferris, M. J. & B. Palenik, 1998. Niche adaptation in ocean cyanobacteria. Nature 396: 226–228.Google Scholar
  61. Foltz, D. W., 1997. Hybridization frequency is negatively correlated with divergence time of mitochondrial DNA haplotypes in a sea star (Leptasterias spp.) species complex. Evolution 51: 283–288.Google Scholar
  62. Fong, P. P. & R. L. Garthwaite, 1994. Allozyme electrophoretic analysis of the Hediste limnicola-H. diversicolor-H. japonica species complex (Polychaeta: Nereididae). Mar. Biol. 118: 463–470.Google Scholar
  63. France, S. C., 1994. Genetic population structure and gene flow among deep-sea amphipods, Abyssorchomene spp., from six California continental borderland basins. Mar. Biol. 118: 67–77.Google Scholar
  64. France, S. C. & T. D. Kocher, 1996. Geographic and bathymetric patterns of mitochondrial 16S rRNA sequence divergence among deep-sea amphipods, Eurythenes gryllus. Mar. Biol. 126: 633–643.Google Scholar
  65. Fuseya, R. & S.Watanabe, 1996. Genetic variability in the mud crab genus Scylla (Brachyura: Portunidae). Fish. Sci. 62: 705–709.Google Scholar
  66. Galis, F. & J. A. J. Metz, 1998. Why are there so many cichlid species? Trends Ecol. Evol. 13: 1–2.Google Scholar
  67. Gamenick, I., M. Abbiati & O. Giere, 1998. Field distribution and sulphide tolerance of Capitella capitata (Annelida: Polychaeta) around shallow water hydrothermal vents off Milos (Aegean Sea). A new sibling species? Mar. Biol. 130: 447–453.Google Scholar
  68. Garcia-Rodriguez, A. I., B. W. Bowen, D. Domning, A. A. Mignucci-Giannoni, M. Marmontel, R. A. Montoya-Opina, B. Morales-Vela, M. Rudin, R. K. Bonde & P. M. McGuire, 1998. Phylogeography of the West Indian manatee (Tirchechus manatus): how many populations and how many taxa? Mol. Ecol. 7: 1137–1149.Google Scholar
  69. Gardner, J. P. A., 1996. The Mytilus edulis species complex in southwest England: effects of hybridization and introgression upon interlocus associations and morphometric variation. Mar. Biol. 125: 385–399.Google Scholar
  70. Gardner, J. P. A., 1997. Hybridization in the sea. Adv. mar. Biol. 31: 1–78.Google Scholar
  71. Geller, J. B., E. D. Walton, E. D. Grosholz & G. M. Ruiz, 1997. Cryptic invasions of the crab Carcinus detected by molecular phylogeography. Mol. Ecol. 6: 901–906.Google Scholar
  72. Goff, L. J., D. A. Moon & A. W. Coleman, 1994. Molecular delineation of species and species relationships in the red algal agarophytes Gracilariopsis and Gracilaria (Gracilariales). J. Phycol. 30: 521–537.Google Scholar
  73. Grahame, J., S. L. Hull, P. J. Mill & R. Hemingway, 1997. Discovering unrecognized diversity among marine molluscs. In Ormond, R. F. G., J. D. Gage & M. V. Angel (eds), Marine Diodiversity: Patterns and Processes. Cambridge University Press, Cambridge: 293–318.Google Scholar
  74. Grassle, J. P. & J. F. Grassle, 1976. Sibling species in the marine pollution indicator Capitella (Polychaeta). Science 192: 567–569.Google Scholar
  75. Greenberg, N., R. L. Garthwaite & D. C. Potts, 1996. Allozyme and morphological evidence for a newly introduced species of Aurelia in San Francisco Bay, California. Mar. Biol. 125: 401–410.Google Scholar
  76. Hare, M. P. & J. C. Avise, 1998. Population structure in the American oyster as inferred by nuclear gene genealogies. Mol. Biol. Evol. 15: 119–128.Google Scholar
  77. Hellberg, M. E. & V. D. Vacquier, 1999. Rapid evolution of fertilization selectivity and lysin cDNA sequences in teguline gastropods. Mol. Biol. Evol. 16: 839–848.Google Scholar
  78. Hinrichs, K.-U., J. M. Hayes, S. P. Sylva, P. G. Brewer & E. F. DeLong, 1999. Methane-consuming archaebacteria in marine sediments. Nature 398: 802–805.Google Scholar
  79. Hoelzel, A. R., M. Dalheim & S. J Stern, 1998. Low genetic variation among killer whales (Orcinus orca) in the eastern North Pacific and genetic differentiation between foraging specialists. J. Heredity 89: 121–128.Google Scholar
  80. Howard, D. J., R. W. Preszler, J. Williams, S. Fenchel & W. J. Boecklen, 1997. How discrete are oak species: Insights from a hybrid zone between Quercus grisea and Quercus gambelii. Evolution 51: 747–755.Google Scholar
  81. Hrincevich, A. W. & D. W. Foltz, 1996. Mitochondrial DNA sequence variation in a sea star (Leptasterias spp.) species complex. Mol. Phylogenet. Evol. 6: 408–415.Google Scholar
  82. Huber, B. T., J. Bijma & K. Darling, 1997. Cryptic speciation in the living planktonic foraminifer Globigerinella siphonifera (d'Orbigny). Paleobiology 23: 33–62.Google Scholar
  83. Hughes, R. N., 1989. A Functional Biology of Clonal Animals. Chapman & Hall, London.Google Scholar
  84. Hummel, H., M. Wolowicz & R. H. Bogaards, 1994. Genetic variability and relationships for populations of Cerastoderma edule and of the C. glaucum complex. Neth. J. Sea Res. 33: 81–89.Google Scholar
  85. Hutchinson, G. E., 1975. Variations on a theme by Robert Mac-Arthur. In Cody, M. L. & J. M. Diamond (eds), Ecology and Evolution of Communities. Belknap Press of Harvard University Press, Cambridge: 492–521.Google Scholar
  86. Irawan, B., A. Kijima & Y. Fujio, 1993. Genetic divergence among the three species of estuarine crab, Helice tridens, H. japonica and Chiromantes dehaani (Sesarminae, Grapsidae; Decapoda). Tohoku J. agric. Res. 43: 101–110.Google Scholar
  87. Izuka, T., S. Segawa & T. Okutani, 1996. Biochemical study of the population heterogeneity and distribution of the oval squid Sepioteuthis lessoniana complex in southwestern Japan. Am. malacol. Bull. 12: 129–135.Google Scholar
  88. Jackson, J. B. C. & A. H. Cheetham, 1994. Phylogeny reconstruction and the tempo and mode of speciation in cheilostome Bryozoa. Paleobiology 20: 407–423.Google Scholar
  89. Johnson, M. S. & R. L. Cumming, 1995. Genetic distinctness of three widespread and morphologically variable species of Drupella (Gastropoda, Muricidae). Coral Reefs 14: 71–78.Google Scholar
  90. Kenyon, J. C., 1997. Models of reticulate evolution in the coral genus Acropora based on chromosome numbers: parallels with plants. Evolution 51: 756–767.Google Scholar
  91. King, G. M., C. Giray & I. Kornfield, 1995. Biogeographical, biochemical and genetic differentiation among North American saccoglossids (Hemichordata; Enteropneusta; Harrimaniidae). Mar. Biol. 123: 369–377.Google Scholar
  92. Kirby, R. R., R. J. Berry & D. A. Powers, 1997. Variation in mitochondrial DNA in a cline of allele frequencies and shell phenotype in the dog-whelk Nucella lapillus (L.). Biol. J. linn. Soc. 62: 299–312.Google Scholar
  93. Kirsten, J. H., C. J. Dawes & B. J. Cochrane, 1998. Randomly amplified polymorphism detection (RAPD) reveals high genetic diversity in Thalassia testudinum Banks ex Konig (Turtlegrass). Aquat. Bot. 61: 269–287.Google Scholar
  94. Klautau, M., A. M. Solé-Cava & R. Borojevic, 1994. Biochemical systematics of sibling sympatric species of Clathrina (Porifera: Calcarea). Biochem. Syst. Ecol. 22: 367–375.Google Scholar
  95. Klautau M., C. A. M. Russo, C. Lazoski, N. Boury-Esnault, J. P. Thorpe & A. M. Solé-Cava, 1999. Does cosmopolitanism result from overconservative systematics? A case study using the marine sponge Chondrilla nucula. Evolution 53: 1414–1422.Google Scholar
  96. Knowlton, N., 1993. Sibling species in the sea. Ann. Rev. Ecol. Syst. 24: 189–216.Google Scholar
  97. Knowlton, N. & J. B. C. Jackson, 1993. Inbreeding and outbreeding in marine invertebrates. In Thornhill, N. W. (ed.), The Natural History of Inbreeding and Outbreeding. University of Chicago Press, Chicago: 200–249.Google Scholar
  98. Knowlton, N. & L. A. Weigt, 1997. Species of marine invertebrates: a comparison of the biological and phylogenetic species concepts. In Claridge, M. F., H. A. Dawah & M. R. Wilson (eds), Species: the Units of Biodiversity. Chapman & Hall, London: 199–219.Google Scholar
  99. Knowlton, N. & L. A. Weigt, 1998. New dates and new rates for divergence across the Isthmus of Panama. Proc. r. Soc. Lond. B 265: 2257–2263.Google Scholar
  100. Knowlton, N., L. A. Weigt, L. A. Solórzano, D. E. K. Mills & E. Bermingham, 1993. Divergence in proteins, mitochondrial DNA, and reproductive compatibility across the Isthmus of Panama. Science 260: 1629–1632.Google Scholar
  101. Kojima, S., R. Segawa, J. Hashimoto & S. Ohta, 1997. Molecular phylogeny of vestimentiferans collected around Japan, revealed by the nucleotide sequences of mitochondrial DNA. Mar. Biol. 127: 507–513.Google Scholar
  102. Kornfield, I., A. B. Williams & R. S. Steneck, 1995. Assignment of Homarus capensis (Herbst, 1792), the Cape lobster of South Africa, to the new genus Homarinus (Decapoda: Nephropidae). U.S. natn. Mar. Fish. Serv. Fish. Bull. 93: 97–102.Google Scholar
  103. Kyle, C. J. & E. G. Boulding, 1998. Molecular genetic evidence for parallel evolution in a marine gastropod, Littorina subrotundata. Proc. r. Soc. Lond. B 265: 303–308.Google Scholar
  104. Lacson, J. M., 1994. Fixed allele frequency differences among Palauan and Okinawan populations of the damselfishes Chrysiptera cyanea and Pomacentrus coelestis. Mar. Biol. 118: 359–365.Google Scholar
  105. Lacson, J. M. & S. Clark, 1995. Genetic divergence of Maldivian and Micronesian demes of the damselfishes Stegastes nigricans, Chrysiptera biocellata, C. glauca and C. leucopoma. Mar. Biol. 121: 585–590.Google Scholar
  106. Lacson, J. M. & S. G. Nelson, 1993. Genetic distances among fishes of the genus Siganus (Siganidae) from the western Pacific Ocean. Mar. Biol. 116: 187–192.Google Scholar
  107. Lasker, H. R., K. Kim & M. A. Coffroth, 1996. Reproductive and genetic variation among Caribbean gorgonians: the differentiation of Plexaura kuna, new species. Bull. mar. Sci. 58: 277–288.Google Scholar
  108. Laulier, M., 1989. Génétique et systématique évolutives du complexe d'espèces Spaeroma hookeri Leach, Sphaeroma levii Argano et Sphaeroma rugicauda Leach (Crustacés, Isopodes Flabellifères). 2. Variabilité génétique, distances génétiques et allèles diagnostiques. Gen. Sel. Evol. 21: 131–145.Google Scholar
  109. Lazoski, C., S. Peixinho, C. A. M. Russo & A. M. Solé-Cava, 1999. Genetic confirmation of the specific status of two sponges of the genus Cinachyrella (Porifera: Spirophorida: Demospongiae) in the southwest Atlantic. Mem. Queensland Mus. 44: 299–306.Google Scholar
  110. Lee, S.-C. & H.-L. Cheng, 1996. Genetic difference between two snappers, Lutjanus ophuysenii and L. vitta (Teleostei: Lutjanidae). Ichthyol. Res. 43: 340–344.Google Scholar
  111. Lessios, H. A., 1998. The first stage of speciation as seen in organisms separated by the Isthmus of Panama. In Howard, D. J. & S. H. Berlocher (eds), Endless Forms: Species and Speciation. Oxford University Press, New York: 186–201.Google Scholar
  112. Lessios, H. A. & J. S. Pearse, 1996. Hybridization and introgression between Indo-Pacific species of Diadema. Mar. Biol. 126: 715–723.Google Scholar
  113. Lessios, H. A. & J. R. Weinberg, 1994. Genetic and morphological divergence among morphotypes of the isopod Excirolana on the two sides of the Isthmus of Panama. Evolution 48: 530–548.Google Scholar
  114. Lessios, H. A., B. D. Kessing & D. R. Robertson, 1998. Massive gene flow across the world's most potent marine biogeographic barrier. Proc. r. Soc. Lond. B 265: 583–588.Google Scholar
  115. Lessios, H. A., J. R. Weinberg & V. R. Starczak, 1994. Temporal variation in populations of the marine isopod Excirolana: how stable are gene frequencies and morphology? Evolution 48: 549–563.Google Scholar
  116. Lessios, H. A., G. R. Allen, G. M. Wellington & E. Bermingham, 1995. Genetic and morphological evidence that the eastern Pacific damselfish Abudefduf declivifrons is distinct from A. concolor (Pomacentridae). Copeia 1995: 277–288.Google Scholar
  117. Levy, J. A. & M. B. Conceição, 1989. Biochemical evidences for two sibling species of genus Myliobatis (Chondrichthyes: Myliobatidae) in south Brazil. Comp. Biochem. Physiol. 94B: 687–690.Google Scholar
  118. Lindstrom, S. C. & K. M. Cole, 1992. A revision of the species of Porphyra (Rhodophyta: Bangiales) occurring in British Columbia and adjacent waters. Can. J. Bot. 70: 2066–2075.Google Scholar
  119. Liu, L. L., D. W. Foltz & W. B. Stickle, 1991. Genetic population structure of the southern oyster drill Stramonita (= Thais) haemostoma. Mar. Biol. 111: 71–79.Google Scholar
  120. Lopez, J. V. & N. Knowlton, 1997. Discrimination of species in the Montastraea annularis complex using multiple genetic loci. Proc. 8th Intl. Coral Reef Symp. 2: 1613–1618.Google Scholar
  121. Lopez, J. V., R. Kersanach, S. A. Rehner & N. Knowlton, 1999. Molecular determination of species boundaries in corals: genetic analysis of the Montastraea annularis complex using amplified fragment length polymorphisms and a microsatellite marker. Biol. Bull. 196: 80–93.Google Scholar
  122. Maggs, C. A. & B. A. Ward, 1996. The genus Pikea (Dumontiaceae, Rhodophyta) in England and the north Pacific: comparative morphological, life history, and molecular studies. J. Phycol. 32: 176–193.Google Scholar
  123. Maggs, C. A., S. E. Douglas, J. Fenety & C. J. Bird, 1992. A molecular and morphological analysis of the Gymnogongrus devoniensis (Rhodophyta) complex in the north Atlantic. J. Phycol. 28: 214–232.Google Scholar
  124. Manchenko, G. P. & V. I. Kulikova, 1996a. Allozyme and colour differences between two sibling species of the heteronemertean Lineus torquatus from the Sea of Japan. Mar. Biol. 125: 687–691.Google Scholar
  125. Manchenko, G. P. & V. I. Kulikova, 1996b. Enzyme and colour variation in the hoplonemertean Tetrastemma nigrifrons from the Sea of Japan. Hydrobiologia 337: 69–76.Google Scholar
  126. Manchenko, G. P & V. I. Radashevsky, 1993. Genetic differences between two sibling species of the Polydora ciliata complex (Polychaeta: Spionidae). Biochem. Syst. Ecol. 21: 543–548.Google Scholar
  127. Manchenko, G. P & V. I. Radashevsky, 1994. Genetic differences between two allopatric sibling species of the genus Polydora (Polychaeta: Spionidae) from the west Pacific. Biochem. Syst. Ecol. 22: 767–773.Google Scholar
  128. Manchenko, G. P & V. I. Radashevsky, 1998. Genetic evidence for two sibling species within Polydora cf. ciliata (Polychaeta: Spionidae) from the Sea of Japan. Mar. Biol. 131: 489–495.Google Scholar
  129. Manchenko, G. P., A. V. Moschenko & V. S. Odintsov, 1993. Biochemical genetics and systematics of Millepora (Coelenterata: Hydrozoa) from the shore of South Vietnam. Biochem. Syst. Ecol. 21: 729–735.Google Scholar
  130. Marko, P. B., 1998. Historical allopatry and the biogeography of speciation in the prosobranch snail genus Nucella. Evolution 52: 757–774.Google Scholar
  131. Mayden, R. L., 1997. A hierarchy of species concepts: the denouement in the saga of the species problem. In Claridge, M. F., H. A. Dawah & M. R. Wilson (eds), Species: the Units of Biodiversity. Chapman & Hall, London: 381–424.Google Scholar
  132. Mayr, E., 1963. Animal Species and Evolution. Harvard University Press, Cambridge, Massachusetts.Google Scholar
  133. Mayr, E. & P. D. Ashlock, 1991. Principles of Systematic Zoology, 2nd edn. McGraw Hill, New York.Google Scholar
  134. McClure, M. R. & I. F. Greenbaum, 1994. Biochemical variation in Alpheus (Decapoda, Caridea, Alpheidae) from the coast of Texas: evidence for cryptic species. Southwest. Nat. 39: 63–66.Google Scholar
  135. McFadden, C. S., 1999. Genetic and taxonomic relationships among Northeastern Atlantic and Mediterranean populations of the soft coral Alcyonium coralloides. Mar. Biol. 133: 171–184.Google Scholar
  136. McFadden, C. S., R. K. Grosberg, B. B. Cameron, D. P. Karlton & D. Secord, 1997. Genetic relationships within and between clonal and solitary forms of the sea anemone Anthopleura elegantissima revisited: evidence for the existence of two species. Mar. Biol. 128: 127–139.Google Scholar
  137. McMillan, W. O., L. A. Weigt & S. R. Palumbi, 1999. Color pattern evolution, assortative mating, and genetic differentiation in brightly colored butterflyfishes (Chaetodontidae). Evolution 53: 247–260.Google Scholar
  138. Medina, M., E. Weil & A. M. Szmant, 1999. Examination of the Montastraea annularis species complex (Cnidaria: Scleractinia) using ITS and COI sequences. Mar. Biotechnol. 1: 89–97.Google Scholar
  139. Metz, E. C. & S. R. Palumbi, 1996. Positive selection and sequence rearrangements generate extensive polymorphism in the gamete recognition protein bindin. Mol. Biol. Evol. 13: 397–406.Google Scholar
  140. Metz, E. C., G. Gomez-Gutierrez & V. D. Vacquier, 1998a. Mitochondrial DNA and bindin gene sequence evolution among allopatric species of the sea urchin genus Arbacia. Mol. Biol. Evol. 15: 185–195.Google Scholar
  141. Metz, E. C., R. Robles-Sikisaka & V. D. Vacquier, 1998b. Nonsynonymous substitution in abalone sperm fertilization genes exceeds substitution in introns and mitochondrial DNA. Proc. natn. Acad. Sci. U.S.A. 95: 10676–10681.Google Scholar
  142. Miller, K. J. & J. A. H. Benzie, 1997. No clear genetic distinction between morphological species within the coral genus Platygyra. Bull. mar. Sci. 61: 907–917.Google Scholar
  143. Miya, M. & M. Nishida, 1997. Speciation in the open ocean. Nature 389: 803–804.Google Scholar
  144. Mokady, O., S. Rozenblatt, D. Graur & Y. Loya, 1994. Coral-host specificity of Red Sea Lithophaga bivalves: interspecific and intraspecific variation in 12S mitochondrial ribosomal RNA. Mol. mar. Biol. Biotechnol. 3: 158–164.Google Scholar
  145. Monteiro, F. A., A. M. Solé-Cava & J. P. Thorpe, 1997. Extensive genetic divergence between populations of the common intertidal sea anemone Actinia equina from Britain, the Mediterranean and the Cape Verde Islands. Mar. Biol. 129: 425–433.Google Scholar
  146. Moore, L. R., G. Rocap & S. W. Chisolm, 1998. Physiology and molecular phylogeny of coexisting Prochlorococcus ecotypes. Nature 393: 464–467.Google Scholar
  147. Muricy, G., A. M. Solé-Cava, J. P. Thorpe & N. Boury-Esnault, 1996. Genetic evidence for extensive cryptic speciation in the subtidal sponge Plakina trilopha (Porifera: Demospongiae: Homoscleromorpha) from the western Mediterranean. Mar. Ecol. Prog. Ser. 138: 181–187.Google Scholar
  148. Mustaquim, J., 1988. Electrophoretic variation of isozymes in Polydora ciliata complex (Polychaeta: Spionidae). Comp. Biochem. Physiol. 91B: 197–205.Google Scholar
  149. Odorico, D. M. & D. J. Miller, 1997. Variation in the ribosomal internal transcribed spacers and 5.8 S rDNA among five species of Acropora (Cnidaria; Scleractinia): patterns of variation consistent with reticulate evolution. Mol. Biol. Evol. 14: 465–473.Google Scholar
  150. Ó Foighil, D. & M. J. Smith. 1996. Phylogeography of an asexual marine clam complex, Lasaea, in the northeastern Pacific based on Cytochrome Oxidase III sequence variation. Mol. Phylogenet. Evol. 6: 134–142.Google Scholar
  151. Oliverio, M., 1995. Larval development and allozyme variation in east Atlantic Columbella (Gastropoda: Prosobranchia: Columbellidae). Sci. mar. 59: 77–86.Google Scholar
  152. Olsen, J. L., W. T. Stam, P. V. M. Bot & C. Van den Hoek, 1987. scDNA-DNA hybridization studies in Pacific and Caribbean isolates of Dictyosphaeria cavernosa (Chlorophyta) indicate a long divergence. Helgoländer Wiss. Meeresunters 41: 377–383.Google Scholar
  153. Olsen, J. L., M. Valero, I. Meusnier, S. Boele-Bos & W. T. Stam, 1998. Mediterranean Caulerpa taxifolia and C. mexicana (Chlorophyta) are not conspecific. J. Phycol. 34: 850–856.Google Scholar
  154. Ovenden, J. R., J. D. Booth & A. J. Smolenski, 1997. Mitochondrial DNA phylogeny of red and green rock lobsters (genus Jasus). Mar. freshwat. Res. 48: 1131–1136.Google Scholar
  155. Palumbi, S. R. 1994. Genetic divergence, reproductive isolation, and marine speciation. Ann. Rev. Ecol. Syst. 25: 547–572.Google Scholar
  156. Palumbi, S. R. & J. A. H. Benzie, 1991. Large mitochondrial DNA differences between morphologically similar penaeid shrimp. Mol. mar. Biol. Biotech. 1: 27–34.Google Scholar
  157. Palumbi, S. R., G. Grabowsky, T. Duda, L. Geyer & N. Tachino, 1997. Speciation and population genetic structure of tropical Pacific sea urchins. Evolution 51: 1506–1517.Google Scholar
  158. Parsons, K. E. & R. D. Ward, 1994. Electrophoretic and morphological examination of Austrocochlea constricta (Gastropoda: Trochidae): a species complex. Aust. J. mar. Freshwat. Res. 45: 1065–1085.Google Scholar
  159. Peek, A. S., R. G. Gustafson, R. A. Lutz & R. C. Vrijenhoek, 1997. Evolutionary relationships of deep-sea hydrothermal vent and cold-water seep clams (Bivalvia: Vesicomyidae): results from mitochondrial cytochrome oxidase subunit I. Mar. Biol. 130: 151–161.Google Scholar
  160. Pillmann, A., G. W. Woolcott, J. L. Olsen, W. T. Stam & R. J. King, 1997. Inter-and intraspecific genetic variation in Caulerpa (Chlorophyta) based on nuclear rDNA ITS sequences. Europ. J. Phycol. 32: 379–386.Google Scholar
  161. Planes, S. & P. J. Doherty, 1997. Genetic relationships of the colour morphs of Acanthochromis polyacanthus (Pomacentridae) on the northern Great Barrier Reef. Mar. Biol. 130: 109–117.Google Scholar
  162. Ponder, W. F. & G. A. Clark, 1988. A morphological and electrophoretic examination of 'Hydrobia buccinoides', a variable brackish-water gastropod from temperate Australia (Mollusca: Hydrobiidae). Aust. J. Zool. 36: 661–690.Google Scholar
  163. Pont-Kingdon, G., N. A. Okada, J. L. Macfarlane, C. T. Beagley, C. D. Watkins-Sims, T. Cavelier-Smith, G. D. Clark-Walker & D. R. Wolstenholme, 1998. Mitochondrial DNA of the coral Sarcophyton glaucum contains a gene for a homologue of bacterial MutS: a possible case of gene transfer from the nucleus to the mitochondrion. J. mol. Evol. 46: 419–431.Google Scholar
  164. Potter, D., T. C. Lajeunesse, G. W. Saunders & R. A. Anderson, 1997. Convergent evolution masks extensive biodiversity among marine coccoid picoplankton. Biodiv. Conserv. 6: 99–107.Google Scholar
  165. Quesada, H., C. Gallagher, D. A. G. Skibinski & D. O. F. Skibinski, 1998. Patterns of polymorphism and gene flow of genderassociated mitochondrial DNA lineages in European mussel populations. Mol. Ecol. 7: 1041–1051.Google Scholar
  166. Rappé, M. S., M. T. Suzuki, K. L. Vergin & S. J. Giovannoni, 1998. Phylogenetic diversity of ultraplankton plastid small-subunit rRNA genes recovered in environmental nucleic acid samples from the Pacific and Atlantic coasts of the United States. Apl. envir. Microbiol. 64: 294–303.Google Scholar
  167. Reid, D. G., E. Rumbak & R. H. Thomas, 1996. DNA, morphology and fossils: phylogeny and evolutionary rates of the gastropod genus Littorina. Phil. Trans. r. Soc., Lond. B 351: 877–895.Google Scholar
  168. Rice, D. W., 1998. Marine mammals of the world: systematics and distribution. Soc. mar. Mamm. Spec. Publ. 4.Google Scholar
  169. Rice, S. A. & J. L. Simon, 1980. Intraspecific variation in the pollution indicator polychaete Polydora ligni (Spionidae). Ophelia 19: 79–115.Google Scholar
  170. Ridgway, T. M., B. A. Stewart, G. M. Branch & A. N. Hodgson, 1998. Morphological and genetic differentiation of Patella granularis (Gastropoda: Patellidae): recognition of two sibling species along the coast of southern Africa. J. Zool., Lond. 245: 317–333.Google Scholar
  171. Rieseberg, L. H. & C. R. Linder, 1999. Hybrid classification: insights from genetic map-based studies of experimental hybrids. Ecology 80: 361–370.Google Scholar
  172. Rodríguez-Trelles, F., J. R. Weinberg & F. J. Ayala, 1996. Presumptive rapid speciation after a founder event in a laboratory population of Nereis: allozyme electrophoretic evidence does not support the hypothesis. Evolution 50: 457–461.Google Scholar
  173. Rogers, A. D., J. P. Thorpe & R. Gibson, 1995. Genetic evidence for the occurrence of a cryptic species with the littoral nemerteans Lineus ruber and L. viridis (Nemertea: Anopla). Mar. Biol. 122: 305–316.Google Scholar
  174. Rohner, M., R. Bastrop & K. Jurss, 1997. Genetic differentiation in Hediste diversicolor (Polychaeta: Nereididae) for the North Sea and Baltic Sea. Mar. Biol. 130: 171–180.Google Scholar
  175. Romano, S. L. & S. R. Palumbi, 1997. Molecular evolution of a portion of the mitochondrial 16S ribosomal gene region in scleractinian corals. J. mol. Evol. 45: 397–411.Google Scholar
  176. Rossi, A. R., M. Capula, D. Crosetti, L. Sola & D. E. Campton, 1998. Allozyme variation in global populations of striped mullet, Mugil cephalus (Pisces: Mugilidae). Mar. Biol. 131: 203–212.Google Scholar
  177. Rowan, R., 1998. Diversity and ecology of zooxanthellae on coral reefs. J. Phycol. 34: 407–417.Google Scholar
  178. Russo, C. A. M., A. M. Solé-Cava & J. P. Thorpe, 1994. Population structure and genetic variation in two tropical sea anemones (Cnidaria, Actinidae) with different reproductive strategies. Mar. Biol. 119: 267–276.Google Scholar
  179. Sanjuan, A., M. Pérez-Losada & E. Rolán, 1997. Allozyme evidence for cryptic speciation in sympatric populations of Nassarius spp. (Mollusca: Gastropoda). J. mar. biol. Ass. U.K. 77: 773–784.Google Scholar
  180. Sarà, M., G. Corriero & G. Bavestrello, 1993. Tethya (Porifera, Demospongiae) species coexisting in a Maldivian coral reef lagoon: taxonomical, genetic and ecological data. Mar. Ecol. 14: 341–355.Google Scholar
  181. Sarver, S. K., M. C. Landrum & D. M. Foltz, 1992. Genetics and taxonomy of ribbed mussels (Geukensia spp.). Mar. Biol. 113: 385–390.Google Scholar
  182. Sarver, S. K., J. D. Silberman & P. J. Walsh, 1998. Mitochondrial DNA sequence evidence supporting the recognition of two subspecies or species of the Florida spiny lobster Panulirus argus. J. Crust. Biol. 18: 177–186.Google Scholar
  183. Sato, M. & Y. Masuda, 1997. Genetic differentiation in two sibling species of the brackish-water polychaete Hediste japonica complex (Nereididae). Mar. Biol. 130: 163–170.Google Scholar
  184. Schmidt, H. & W. Westheide, 1997. RAPD-PCR experiments confirm the distinction between three morphologically similar species of Nerilla (Polychaeta: Nerillidae). Zool. Anz. 236: 277–285.Google Scholar
  185. Schneider-Broussard, R. & J. E. Neigel, 1997. A large subunit mitochondrial ribosomal DNA sequence translocated to the nuclear genomes of two stone crabs. Mol. Biol. Evol. 14: 156–165.Google Scholar
  186. Schneider-Broussard, R., D. L. Felder, C. A. Chlan & J. E. Neigel, 1998. Tests of phylogeographic models with nuclear and mitochondrial DNA sequence variation in the stone crabs, Menippe adina and Menippe mercenaria. Evolution 52: 1671–1678.Google Scholar
  187. Schneppenheim, R. & R. Weigmann-Haass, 1986. Morphological and electrophoretic studies of the genus Themisto (Amphipoda: Hyperiidea) from the South and North Atlantic. Polar Biol. 6: 215–226.Google Scholar
  188. Schreiber, A., M. Eisinger & V. Storch, 1996. Allozymes characterize sibling species of bipolar Priapulida (Priapulus, Priapulopsis). Polar Biol. 16: 521–526.Google Scholar
  189. Schubart, C. D., R. Diesel & S. B. Hedges, 1998. Rapid evolution to terrestrial life in Jamaican crabs. Nature 393: 363–365.Google Scholar
  190. Shaklee, J. B. & P. Bentzen, 1998. Genetic identification of stocks of marine fish and shellfish. Bull. mar. Sci. 62: 589–621.Google Scholar
  191. Shank, T. M., R. A. Lutz & R. C. Vrijenhoek, 1998. Molecular systematics of shrimps (Decapoda: Bresiliidae) from deep-sea hydrothermal vents, I: Enigmatic 'small orange' shrimp from the Mid-Atlantic Ridge are juvenile Rimicaris exoculata. Mol. mar. Biol. Biotechnol. 7: 88–96.Google Scholar
  192. Solé-Cava, A. M. & N. Boury-Esnault, 1999. Patterns of intra and interspecific divergence in marine sponges. Mem. Queensland. Mus. 44: 591–602.Google Scholar
  193. Solé-Cava, A. M. & J. P. Thorpe, 1992. Genetic divergence between colour morphs in populations of the common intertidal sea anemones Actinia equina and A. prasina (Anthozoa: Actiniaria) in the Isle of Man. Mar. Biol. 112: 243–252.Google Scholar
  194. Solé-Cava, A. M., J. P. Thorpe & J. G. Kaye, 1985. Reproductive isolation with little genetic divergence between Urticina (= Tealia) felina and U. eques (Anthozoa: Actiniaria). Mar. Biol. 85: 279–284.Google Scholar
  195. Stevens, P. M., 1990. A genetic analysis of the pea crabs (Decapoda: Pinnotheridae) of New Zealand. I. Patterns of spatial and hostassociated genetic structuring in Pinnotheres novaezelandiae Filhol. J. exp. mar. Biol. Ecol. 141: 195–212.Google Scholar
  196. Stiller, J. W. & J. R. Waaland, 1993. Molecular analysis reveals cryptic diversity in Porphyra (Rhodophyta). J. Phycol. 29: 506–517.Google Scholar
  197. Stobart, B. & J. A. H. Benzie, 1994. Allozyme electrophoresis demonstrates that the scleractinian coral Montipora digitata is two species. Mar. Biol. 118: 183–190.Google Scholar
  198. Sturmbauer, C., J. S. Levinton & J. Christy, 1996. Molecular phylogeny analysis of fiddler crabs: test of the hypothesis of increasing behavioral complexity in evolution. Proc. natn. Acad. Sci. U.S.A. 93: 10855–10857.Google Scholar
  199. Sundberg, P. & S. Andersson, 1995. Random amplified polymorphic DNA (RAPD) and intraspecific variation in Oerstedia dorsalis (Hoplonemertea, Nemertea). J. mar. biol. Ass. U.K. 75: 483–490.Google Scholar
  200. Swanson, W. J. & V. D. Vacquier, 1998. Concerted evolution in an egg receptor for a rapidly evolving abalone sperm protein. Science 281: 710–712.Google Scholar
  201. Takabayashi, M., D. Carter, S. Ward & O. Hoegh-Guldberg, 1998. Inter-and intra-specific variability in ribosomal DNA sequence in the internal transcribed spacer region of corals. In Greenwood, J. G. & N. J. Hall (eds), Proceedings of the Australian Coral Reef Society 75 Anniversary Conference. University of Queensland, Brisbane: 237–244.Google Scholar
  202. Tam, Y. K., I. Kornfield & F. P. Ojeda, 1996. Divergence and zoogeography of mole crabs, Emerita spp. (Decapoda: Hippidae), in the Americas. Mar. Biol. 125: 489–497.Google Scholar
  203. Tatarenkov, A. & K. Johannesson, 1998. Evidence of a reproductive barrier between two forms of the marine periwinkle Littorina fabalis (Gastropoda). Biol. J. linn. Soc. 63: 349–365.Google Scholar
  204. Taylor, E. B. & J. J. Dodson, 1994. A molecular analysis of relationships and biogeography within a species complex of Holarctic fish (genus Osmerus). Mol. Ecol. 3: 235–248.Google Scholar
  205. Templeton, A. R., 1989. The meaning of species and speciation: a genetic perspective. In Otte, D. & J. A. Endler (eds), Speciation and its Consequences. Sinauer, Sunderland, Massachusetts: 3–27.Google Scholar
  206. Thollesson, M., 1998. Discrimination of two Dendronotus species by allozyme electrophoresis and the reinstatement of Dendronotus lacteus (Thompson, 1840) (Nudibranchia, Dendronotoidea). Zool. Scr. 27: 189–195.Google Scholar
  207. Thorpe, J. P., 1983. Enzyme variation, genetic distance and evolutionary divergence in relation to levels of taxonomic separation. In Oxford, G. S. & D. Rollison (eds), Protein Polymorphism: Adaptive and Taxonomic Significance. Academic Press, London: 131–152.Google Scholar
  208. Thorpe, J. P. & A. M. Solé-Cava, 1994. The use of allozyme electrophoresis in invertebrate systematics. Zool. Scr. 23: 3–18.Google Scholar
  209. Todaro, M. A., J. W. Fleeger, Y. P. Hu, A. W. Hrincevich & D. W. Foltz, 1996. Are meiofaunal species cosmopolitan? Morphological and molecular analysis Xenotrichula intermedia (Gastrotricha: Chaetonotida). Mar. Biol. 125: 735–742.Google Scholar
  210. Tuttle, R. D. & R. Lindahl, 1980. Genetic variability in 3 cooccurring forms of the starfish genus Othilia (= Echinaster). Experientia 36: 923–925.Google Scholar
  211. Väinölä, R. & J. K. Vainio, 1998. Distributions, life cycles and hybridization of two Mysis relicta group species (Crustacea: Mysida) in the northern Baltic Sea and Lake Båven. Hydrobiologia 368: 137–148.Google Scholar
  212. Van Oppen, M. J. H., J. L. Olsen & W. T. Stam, 1995a. Genetic variation within and among North Atlantic and Baltic populations of the benthic alga Phycodrys rubens (Rhodophyta). Europ. J. Phycol. 30: 251–260.Google Scholar
  213. Van Oppen, M. J. H., B. L. Willis & D. J. Miller, 1999. Atypically low rate of cytochrome b evolution in the scleractinian coral genus Acropora. Proc. r. Soc. Lond. B 266: 179–183.Google Scholar
  214. Van Oppen, M. J. H., S. G. A. Draisma, J. L. Olsen & W. T. Stam, 1995b. Multiple trans-Arctic passages in the red alga Phycodrys rubens: evidence from nuclear rDNA ITS sequences. Mar. Biol. 123: 179–188.Google Scholar
  215. Van Oppen, M. J. H., H. Klerk, J. L. Olsen & W. T. Stam, 1996. Hidden diversity in marine algae: some examples of genetic variation below the species level. J. mar. biol. Assoc. U.K. 76: 239–242.Google Scholar
  216. Van Soosten, C., H. Schmidt & W. Westheide, 1998. Genetic variability and relationships among geographically widely separated populations of Petitia amphophthalma (Polychaeta: Syllidae). Results from RAPD-PCR investigations. Mar. Biol. 131: 659–669.Google Scholar
  217. Veron, J. E. N., 1995. Corals in space and time: The Biogeography and Evolution of the Scleractinia. University of New SouthWales Press, Sydney.Google Scholar
  218. Ward, R. D. & P. M. Grewe, 1994. Appraisal of molecular genetic techniques in fisheries. Rev. Fish Biol. Fish. 4: 300–325.Google Scholar
  219. Watanabe, K., K. Numachi, M. Goto, S. Wada, T. Kobayashi & T. Kamaishi, 1994. Genetic differentiation of two forms of flatfishes, genus Pleuronichthys in Kiisuido channel waters off the Pacific coast of central Japan, by restriction analysis of mitochondrial DNA. Nippon Suisan Gakkaishi 60: 515–520.Google Scholar
  220. Weber, L. I. & R. Galleguillos, 1991. Morphometric and electrophoretic evidences for two species of the genus Liopetrolisthes 90 (Crustacea: Decapoda: Porcellanidae) and some aspects of their variability. Comp. Biochem. Physiol. 100B: 201–207.Google Scholar
  221. Weil, E. & N. Knowlton, 1994. A multi-character analysis of the Caribbean coral Montastraea annularis (Ellis and Solander, 1786) and its two sibling species, M. faveolata (Ellis and Solander, 1786) and M. franksi (Gregory, 1895). Bull. mar. Sci. 55: 151–175.Google Scholar
  222. Wray, C. G., N. H. Landman, W. B. Saunders & J. Bonacum, 1995. Genetic divergence and geographic diversification in Nautilus. Paleobiology 21: 220–228.Google Scholar
  223. Yeatman, J. & J. A. H. Benzie, 1994. Genetic structure and distribution of Photololigo spp. in Australia. Mar. Biol. 118: 79–87.Google Scholar

Copyright information

© Kluwer Academic Publishers 2000

Authors and Affiliations

  • N. Knowlton
    • 1
    • 2
  1. 1.Marine Biology Research Division – 0202; Scripps Institution of OceanographyUniversity of California San DiegoLa JollaU.S.A.
  2. 2.Smithsonian Tropical Research InstituteBalboaRepublic of Panama

Personalised recommendations