Biochemical Genetics

, Volume 44, Issue 1–2, pp 1–17 | Cite as

Extensive Natural Hybridization Between Two Geckos, Gekko tawaensis and Gekko japonicus (Reptilia: Squamata), Throughout Their Broad Sympatric Area

  • Mamoru TodaEmail author
  • Sumio Okada
  • Tsutomu Hikida
  • Hidetoshi Ota

The status of natural hybridization between the two Japanese geckos, Gekko tawaensis and Gekko japonicus, was surveyed by use of 15 diagnostic allozyme loci. Of 438 specimens examined, 9 were identified as Fl, 1 was a first backcross with G. japonicus, and 15 were identified as more successive generations. Hybridizations were detected at 7 of the 15 localities interspersed throughout a broad sympatric area of the two species, forming a mosaic hybrid zone. A comparison of species–hybrid composition between 2-year samples from a single locality and a 5-year interval showed no evidence for progressive introgression or establishment of a hybrid swarm, despite constant emergences of Fl hybrids. Nonprevalence of the hybrid genotypes was also indicated by the analysis using hybrid index scores for all other localities examined. These results suggest that strong selection acts against hybrid genotypes. Morphological features of hybrid individuals were also provided.

Key Words

natural hybridization Gekko hybrid index introgression allozyme 



We thank H. Saito and M. Takeshima for their help in field collection. Financial support for this study was provided by a Research Fellowship of the Japan Society for the Promotion of Science for Young Scientists (9413 to MT) and a Grant-in-Aid from the Japan Ministry of Education, Science, Sports, and Culture (C-11833013 to HO), as well as by a Grant for Biodiversity Research of the Twenty-First Century COE (A14).


  1. Anderson, E. (1948). Hybridization of the habitat. Evolution 2(1):1–9.CrossRefGoogle Scholar
  2. Baker, R. J., and Davis, S. K. (1989). Ribosomal-DNA, mitochondrial-DNA, chromosomal, and allozymic studies on a contact zone in the pocket gopher. Geomys. Evolution 43(1):63–75.CrossRefGoogle Scholar
  3. Barton, N. H., and Hewitt, G. M. (1985). Analysis of hybrid zones. Annu. Rev. Ecol. Syst. 16:113–148.CrossRefGoogle Scholar
  4. HAPSE (Hiba Association for the Promotion of Scientific Education) (1996). Amphibians and Reptiles in Hiroshima Prefecture, Chugoku-Shinbunsha, Hiroshima (in Japanese).Google Scholar
  5. Harrison, R. G. (1993). Hybrids and hybrid zones: Historical perspective. In Harrison, R. G. (ed.), Hybrid Zones and the Evolutionary Process, Oxford University Press, New York, pp. 3–12.Google Scholar
  6. Harrison, R. G., and Bogdanowicz, S. M. (1997). Patterns of variation and linkage disequilibrium in a field cricket hybrid zone. Evolution 51(2):493–505.CrossRefGoogle Scholar
  7. Harrison, R. G., and Rand, D. M. (1989). Mosaic hybrid zones and the nature of species boundaries. In Otte, D. and Endler, A. (eds.), Speciation and Its Consequences, Sinauer Associates, MA, pp. 111–133.Google Scholar
  8. Hewitt, G. M. (1989). The subdivision of species by hybrid zones. In Otte, D. and Endler, A. (eds.), Speciation and Its Consequences, Sinauer Associates, MA, pp. 85–110.Google Scholar
  9. Hillis, D. M., and Simmons, J. E. (1986). Dynamic change of a zone of parapatry between two species of Pholidobolus (Sauria: Gymnophthalmidae). J. Herpetol. 20(1):85–87.CrossRefGoogle Scholar
  10. Howard, D. J. (1993). Reinforcement: Origin, dynamics, and fate of an evolutionary hypothesis. In Harrison, R. G. (ed.), Hybrid Zones and the Evolutionary Process, Oxford University Press, New York, pp. 46–69.Google Scholar
  11. Howard, D. J., Waring, G. L., Tibbets, C. A., and Gregory, P. G. (1993). Survival of hybrids in a mosaic hybrid zone. Evolution 47(3):789–800.CrossRefGoogle Scholar
  12. Jiggins, C. D., and Mallet, J. (2000). Bimodal hybrid zones and speciation. Trend. Ecol. Evol. 15(6):250–255.CrossRefGoogle Scholar
  13. JME (Japan Ministry of Environment) (1979). National Survey on the Natural Environment (Vegetation): Actual Vegetation Map, JME, Tokyo.Google Scholar
  14. Kawata, H. (1980). Some notes on the gecko, Gekko tawaensis (Reptilia: Gekkonidae), of Kagawa Prefecture. Rep. Kagawa Prefectural Sci. Mus. 2:9–16 (in Japanese).Google Scholar
  15. MacCallum, C. J., Nürnberger, B., Barton, N. H., and Szymura, J. M. (1998). Habitat preference in the Bombina hybrid zone in Croatia. Evolution 52(1):227–239.CrossRefGoogle Scholar
  16. Murphy, R. W., McCollum, P. C., Gorman, G. C., and Thomas, R. (1984). Genetics of hybridizing populations of Puerto Rican Sphaerodactylus. J. Herpetol. 18(2):93–105.CrossRefGoogle Scholar
  17. Murphy, R. W., Sites, J. W., Jr., Buth, D. G., and Haufler, C. H. (1996). Proteins: Isozyme electrophresis. In Hillis, D. M., Moritz, C., and Mable, B. K. (eds.), Molecular Systematics (2nd edn.), Sinauer Associates, Sunderland, pp. 51–120.Google Scholar
  18. Okada, S., and Toda, M. (1998). New records of Gekko tawaensis from southwest Japan. Hibakagaku 189:1–12 (in Japanese with English abstract).Google Scholar
  19. Ota, H. (1996). Gekko japonicus. In Sengoku, S., Hikida, T., Matsui, M., and Nakaya, K. (eds.), The Encyclopaedia of Animals in Japan. vol. 5: Amphibians, Reptiles, Chondrichthyes, Heibonsha, Tokyo, p. 69 (in Japanese).Google Scholar
  20. Patton, J. L. (1993). Hybridization and hybrid zones in pocket gophers (Rodentia, Geomydae). In Harrison, R. G. (ed.), Hybrid Zones and the Evolutionary Process, Oxford University Press, New York, pp. 290–308.Google Scholar
  21. Pritchard, J. K., Stephens, M., and Donnelly, P. (2000). Inference of population structure using multilocus genotype data. Genetics 155(2):945–959.PubMedGoogle Scholar
  22. Schlefer, E. K., Romano, M. A., Guttman, S. I., and Ruth, S. B. (1986). Effect of twenty years of hybridization in a disturbed habitat on Hyla cinerea and Hyla gratiosa. J. Herpetol. 20(2):210–221.CrossRefGoogle Scholar
  23. Shibata, Y. (1980). Occurrences of Gekko tawaensis in Osaka Prefecture. Nat. Stud. 26(2):16–19 (in Japanese).Google Scholar
  24. Sites, J. W., Jr., Barton, N. H., and Reed, K. M. (1995). The genetic structure of a hybrid zone between two chromosome races of the Sceloporus grammicus complex (Sauria, Phrynosomatidae) in central Mexico. Evolution 49(1):9–36.CrossRefGoogle Scholar
  25. Swofford, D. L., and Berlocher, S. H. (1987). Inferring evolutionary trees from gene frequency data under the principle of maximum parsimony. Syst. Zool. 36(3):293–325.CrossRefGoogle Scholar
  26. Toda, M., Okada, S., Ota, H., and Hikida, T. (2001). Biochemical assessment of evolution and taxonomy of the two morphologically poorly diverged geckos, Gekko yakuensis and G. hokouensis (Reptilia: Squamata), in Japan, with special reference to their occasional hybridization. Biol. J. Linnean Soc. 73(1):153–165.CrossRefGoogle Scholar
  27. Toda, M., Hikida, T., Okada, S., and Ota, H. (2003). Contrasting patterns of genetic variation in the two sympatric geckos Gekko tawaensis and G. japonicus (Reptilia: Squamata) from western Japan, as revealed by allozyme analyses. Heredity 90(1):90–97.PubMedCrossRefGoogle Scholar
  28. Tokunaga, S. (1984). Morphological variation and sexual dimorphism in Gekko japonicus from Fukuoka, northern Kyushu, Japan. Jpn. J. Herpetol. 10(3):80–88.Google Scholar
  29. Wiens, J. J., and Servedio, M. R. (2000). Species delimitation in systematics: Inferring diagnostic differences between species. Proc. R. Soc. Lond. Ser. B 267:631–636.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, Inc. 2006

Authors and Affiliations

  • Mamoru Toda
    • 1
    • 3
    Email author
  • Sumio Okada
    • 2
  • Tsutomu Hikida
    • 3
  • Hidetoshi Ota
    • 1
  1. 1.Tropical Biosphere Research CenterUniversity of the RyukyusNishiharaJapan
  2. 2.Division of Environmental Biology, Faculty of Life and Environmental ScienceShimane UniversityMatsueJapan
  3. 3.Department of Zoology, Graduate School of ScienceKyoto UniversitySakyoJapan

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