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Cytotaxonomy of 41 Species of Neotropical Cichlidae
Kenneth W. Thompson
Vol. 1979, No. 4 (Nov. 28, 1979), pp. 679-691
Stable URL: http://www.jstor.org/stable/1443877
Page Count: 13
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Chromosome morphology for 40 species and diploid counts for 41 species of neotropical Cichlidae were prepared using colchicine treated gill epithelial squashes. Gross chromosomal evolution among this group appears to have been somewhat conservative with the majority of the species retaining the putative ancestral diploid number of 48. The most parsimonious description of karyotypic evolution among the neotropical Cichlidae indicates a common ancestor with 2N = 48 subtelocentric-telocentric chromosomes which gave rise, probably through pericentric inversions, to the most common present day arrangement which was designated as the 'A' karotype. The rarer 'B' karotype which was dominated by metacentrics was evolved either from the primitive state or from the 'A' by centric fusions. The karyotypic data does not significantly contradict the generally accepted evolutionary scheme for these fishes. However, an interesting correlation between the probable geographic center of origin and the number of metacentrics within Cichlasoma was noted. It was concluded that the South American autochthons (Cichlasoma and probable derived genera) showed an evolutionary trend toward the accumulation of metacentrics while Middle American representatives of this group did not.