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The chromosomes of the Didelphidae (Marsupialia) and their evolutionary significance

Biological Journal of the Linnean Society

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Abstract

One hundred and seventy-seven specimens of American didelphids, representing 9 genera and 22 species have been studied for their chromosomal constitution. Didelphids are very conservative in chromosomal complements. All of the studied species can be sorted into one of three kinds of karyotypes: 2n= 14 (three species of Didelphis, one of Lutreolina, two of Philander, and one of Chironectes), 2n = 14 (eight species of Marmosa, one of Metachirus, three of Caluromys, and one of Dromiciops), and 2n= 18 (three species of Monodelphis). These karyotypes are stable, showing only minor variations within each basic pattern. It is concluded that chromosomals evolution in the Didelphidae proceededs from low numbers to higher numbers by a process of centromeric fissioning complemented by some pericentric inversions and/or translocations. The pattern of karyotypic stability is consistent with bradytely at the organismic level of evolution. This is explained by a low rate of regulatory genetic evolution promoted by epistatic selection favouring the retention of chromosomal arrangements highly advantageous for overall adaptation.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
The chromosomes of the Didelphidae (Marsupialia) and their evolutionary significance
Series title:
Biological Journal of the Linnean Society
Volume
9
Issue:
2
Year Published:
1977
Language:
English
Publisher:
U.S. Fish and Wildlife Service
Contributing office(s):
Patuxent Wildlife Research Center
Description:
191-216
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Biological Journal of the Linnean Society
First page:
191
Last page:
216
Number of Pages:
26