| 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. |
| Genre: | Article |
| ProdID: | 5223634 |
| Citation Author: | Reig, O.; Gardner, A.L.; Bianchi, N.O.; Patton, J.L. |
| Citation Contributing Office: | Patuxent Wildlife Research Center |
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| Citation End Page: | 216 |
| Citation Issue: | 2 |
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| Citation Language: | English |
| Citation Larger Work Title: | Biological Journal of the Linnean Society |
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| Citation Number Of Pages: | 26 |
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| Citation Phsyical Description: | 191-216 |
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| Citation Publisher: | U.S. Fish and Wildlife Service |
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| Citation Search Results Text: | The chromosomes of the Didelphidae (Marsupialia) and their evolutionary significance; 1977; Article; Journal; Biological Journal of the Linnean Society; Reig, O.; Gardner, A.L.; Bianchi, N.O.; Patton, J.L. |
| Citation Start Page: | 191 |
| Citation Volume: | 9 |
| Citation Year: | 1977 |
| Type: | citation/reference |
| Text: | The chromosomes of the Didelphidae (Marsupialia) and their evolutionary significance; 1977; Article; Journal; Biological Journal of the Linnean Society; Reig, O.; Gardner, A.L.; Bianchi, N.O.; Patton, J.L. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DOCUMENT): | http://www3.interscience.wiley.com/journal/119628039/abstract |
| Date Other: | Wed, 16 Jun 2010 12:19 -0500 |
| Publisher: | U.S. Fish and Wildlife Service |
