1997 Fiscal Year Final Research Report Summary
Research on distribution and speciation of the oval squid Sepioteuthis lessoniana.
| Project/Area Number |
07660237
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General fisheries
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| Research Institution | TOKYO UNIVERSITY OF FISHERIES |
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Principal Investigator |
SEGAWA Susumu TOKYO UNIVERSITY OF FISHERIES,DEPARTMENT OF AQUATIC BIOSCIENCES,PROFESSOR, 水産学部, 教授 (30092589)
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| Project Period (FY) |
1995 – 1997
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| Keywords | Oval Squid / Cephalopods / Population Genetics / Allozyme Electrophoresis / Speciation / Biogeography / Population |
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| Research Abstract |
The oval squid, Sepioteuthis lessoniana, lives in inshore waters over a broad geographical range, covering the Indo-West Pacific. Recently, it has been appeared that S.lessoniana is a species complex composed of three sympatric AKAIKA,SHIROIKA and KUAIKA population. These three types of squid are regarded as distinctive species based on the studies of isozyme electrophoresis and reproductive biology, however, it has been impossible to segregate them from each other by conventional morphological examination. Present study attempts to presents a new character to distinguish three taxa and to clarify the population structure and distribution of the three taxa of S.lessoniana complex.
1. The present study analyzed 554 specimens of Sepioteuthis collected from 11 localities in inshore waters of southwester Japan to elucidata the distributional patterns and population structures by means of horizontal starch gel electrophoresis at 13 genetic loci encoding for ten enzymes. The results showed that each of the three taxa has a different distributional pattern.
2. Three taxa of S.lessoninana complex are safely distinguishable with characterristic arrangements of chromatophores on the funnel.
3. SHIROIKA is widely distributed in the tropical to warm temperate regions throughout southwestern Japan.
4. AKAIKA is distributed in the Ryukyu Islands and also probably occurs on the Pacific coast of Honshu, mainland Japan.
5. KUAIKA is limited to the tropical region and its latitudinal distribution suggests a close correlation with water temperature.
6. In SHIROIKA and KUAIKA,significant genetic differences were detected between the specimens from Ogasawara Islands and those from the other localities suggesting the existence of a certain barrier of panmixia between insular localities.
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