Isozyme variation and alleged progenitor-derivative relationships in theMedicago murex complex (Fabaceae) |
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Authors: | Ernest Small Suzanne I Warwick Brenda Brookes |
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Institution: | (1) Centre for Land and Biological Resources Research, Agriculture Canada, Research Branch, Central Experimental Farm, K1A OC6 Ottawa, Ont., Canada |
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Abstract: | Chromosomal studies ofMedicago lesinsii (n = 8) and its close relativeM. murex (n = 7) have led to the competing hypotheses that the latter is derived directly from the former, or that both originated from a common ancestor. In contrast to the relatively variableM. murex, M. lesinsii proved to be almost uniform isozymically, except that most populations of Greece differed by one allele from plants of the remainder of the range. This Greek variant ofM. lesinsii was indistinguishable from one of the isozyme variants ofM. murex. The greater level of allozyme variation inM. murex was consistent with its greater ecological amplitude and competitive ability. Also, this suggests thatM. murex is unlikely to have originated directly from the less variableM. lesinsii. The data suggest that either both species originated from a common ancestor, or that the n = 8 species evolved from the n = 7 species, a mode of chromosome evolution not previously hypothesized for the genus. |
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Keywords: | Angiosperms Fabaceae Medicago murex M lesinsii Systematics evolution isozymes chromosomes |
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