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<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>Alfred Gardner</dc:contributor>
  <dc:contributor>N. O. Bianchi</dc:contributor>
  <dc:contributor>James L. Patton</dc:contributor>
  <dc:creator>O. Reig</dc:creator>
  <dc:date>1977</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;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: 2&lt;/span&gt;&lt;i&gt;n&lt;/i&gt;&lt;span&gt;= 14 (three species of&amp;nbsp;&lt;/span&gt;&lt;i&gt;Didelphis,&lt;/i&gt;&lt;span&gt;&amp;nbsp;one of&amp;nbsp;&lt;/span&gt;&lt;i&gt;Lutreolina,&lt;/i&gt;&lt;span&gt;&amp;nbsp;two of&amp;nbsp;&lt;/span&gt;&lt;i&gt;Philander,&lt;/i&gt;&lt;span&gt;&amp;nbsp;and one of&amp;nbsp;&lt;/span&gt;&lt;i&gt;Chironectes)&lt;/i&gt;&lt;span&gt;, 2&lt;/span&gt;&lt;i&gt;n =&lt;/i&gt;&lt;span&gt;&amp;nbsp;14 (eight species of&amp;nbsp;&lt;/span&gt;&lt;i&gt;Marmosa,&lt;/i&gt;&lt;span&gt;&amp;nbsp;one of&amp;nbsp;&lt;/span&gt;&lt;i&gt;Metachirus,&lt;/i&gt;&lt;span&gt;&amp;nbsp;three of&amp;nbsp;&lt;/span&gt;&lt;i&gt;Caluromys,&lt;/i&gt;&lt;span&gt;&amp;nbsp;and one of&amp;nbsp;&lt;/span&gt;&lt;i&gt;Dromiciops),&lt;/i&gt;&lt;span&gt;&amp;nbsp;and 2&lt;/span&gt;&lt;i&gt;n&lt;/i&gt;&lt;span&gt;= 18 (three species of&amp;nbsp;&lt;/span&gt;&lt;i&gt;Monodelphis).&lt;/i&gt;&lt;span&gt;&amp;nbsp;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.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1111/j.1095-8312.1977.tb00265.x</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Oxford Academic</dc:publisher>
  <dc:title>The chromosomes of the Didelphidae (Marsupialia) and their evolutionary significance</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>