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Marine Biology

, Volume 127, Issue 3, pp 359–367 | Cite as

Genetic stock structure of the swordfish (Xiphias gladius ) inferred by PCR-RFLP analysis of the mitochondrial DNA control region

  • S. Chow
  • H. Okamoto
  • Y. Uozumi
  • Y. Takeuchi
  • H. Takeyama

Abstract

Restriction fragment length polymorphism (RFLP) analysis was performed on PCR amplified DNA fragments containing the control region of the swordfish (Xiphias gladius Linnaeus, 1758) mitochondrial DNA. A total of 456 individuals comprising 13 local samples (six Pacific, three Atlantic, the Mediterranean Sea, two Indian Ocean and the Cape of Good Hope) were surveyed with four endonucleases (Alu I, Dde I, Hha I and Rsa I), yielding a total of 52 composite genotypes. Within-sample genotypic diversity (H) was high ranging from 0.702 to 0.962 with a value of 0.922 for the pooled sample. Significant geographic variation in the frequencies of genotypes and restriction patterns was revealed. The Mediterranean sample was highly distinct from all other samples. Further, Rsa I digestion revealed high levels of polymorphism in all but the Mediterranean samples, indicating that exogenous swordfishes rarely enter that body of water. Heterogeneity between the North and South Atlantic samples was significant, both of which differed from those of the Pacific. In contrast, the Indian Ocean samples were not significantly different from the samples of South Atlantic and Pacific. Genetic differentiation among the Pacific samples was low. The results indicate that the world-wide swordfish population is genetically structured not only among, but also within ocean basins and suggest that gene flow is restricted despite the absence of geographic barriers.

Keywords

Indian Ocean Restriction Fragment Length Polymorphism Control Region Ocean Basin Genetic Stock 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • S. Chow
    • 1
  • H. Okamoto
    • 1
  • Y. Uozumi
    • 1
  • Y. Takeuchi
    • 1
  • H. Takeyama
    • 2
  1. 1.National Research Institute of Far Seas Fisheries, Shimizu, Shizuoka 424, JapanJP
  2. 2.Tokyo University of Agriculture and Technology, Koganei, Tokyo 184, JapanJP

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