ISSN:
1573-5117
Keywords:
Turbellaria
;
chromosomal polymorphism
;
mixoploidy
;
differentiation of karyotype
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Although the chromosomal number of Polycelis (Seidlia) auriculata Ijima et Kaburaki is basically 2n = 6, this species shows remarkable chromosomal polymorphisms in different populations. Among worms collected at 30 stations in the central part of Japan's Main Island and in Hokkaido, we found five new karyotypes, considered to be variations of tetraploidy and diploidy: 4n?fis1. + 1 = 3SM + 2A + 3T1 + 2T2 + 4M = 14, 4n?fis2.(B) = 2SM + 2A + 4T1 + 2T2 + 4M + (0−2B) = 14 –16, 4n?fis2. + 1 = 2SM + 2A + 4T1 + 2T2+5M= 15, 4n?fis2.−2 = 2SM + 2A + 4T1 + 4M = 12, and 2nM- = 2SM + 2A = 4 (where SM = submetacentric; A = acrocentric; T1 and T2 = telocentric; M = metacentric; B = B-chromosome; fis1. and fis2. = occurrence of one or two centric fissions, respectively; and M- = deletion of a metacentric chromosome). These karyotypes exist singly in one individual or as various mixoploids within the same individual. No individual having only karyotype 2nM- has yet been found. This brings the total number of known karyotypes in P. auriculata to 17; these can be arranged in an order that we believe reflects their evolution.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00027595
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