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Three sympatric karyomorphs in the fish Astyanax fasciatus (Teleostei, Characidae) do not seem to hybridize in natural populations.

Abstract：

:Ninety individuals of the characid fish Astyanax fasciatus (Cuvier, 1819) were collected at Água da Madalena stream (Botucatu, São Paulo, Brazil) and analyzed for diploid chromosome number 2n and karyotype composition as well as for the chromosomal location of the 5S and 18S ribosomal DNA (rDNA). Whereas no chromosome differences were associated with sex, three different karyomorphs with diploid chromosome numbers 2n=46, 2n=48 and 2n=50 were found. No intermediate 2n numbers were discovered. The 2n=50 karyomorph showed some differences in 18S rDNA location compared to the two other karyomorphs. Finally, all specimens with the 2n=46 karyomorph showed the presence of a partly heterochromatic macro supernumerary chromosome, which was absent in all individuals with the two other karyomorphs. All these results suggest that indviduals of the three different karyomorphs are not likely to hybridize in the examined populations. Our findings strongly suggest the presence of three separate species (sensu biological species concept) easily diagnosed on the basis of differences in the diploid chromosome numbers and other chromosomal markers.

journal_name

Comp Cytogenet

journal_title

Comparative cytogenetics

authors

Ferreira-Neto M,Artoni RF,Vicari MR,Moreira-Filho O,Camacho JP,Bakkali M,de Oliveira C,Foresti F

doi

10.3897/CompCytogen.v6i1.2151

subject

Has Abstract

pub_date

2012-01-24 00:00:00

pages

29-40

issue

1

eissn

1993-0771

issn

1993-078X

journal_volume

6

pub_type

杂志文章

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