Plant Systematics and Evolution

, Volume 214, Issue 1–4, pp 29–47 | Cite as

Allozyme variation in relation to morphology and taxonomy inMedicago sect.Spirocarpos subsect.Intertextae (Fabaceae)

  • Ernest Small
  • Suzanne I. Warwick
  • Brenda Brookes
Article

Abstract

Medicago intertexta andM. ciliaris have been controversially recognized as separate species. The only reliable diagnostic character, gland-tipped trichomes on the fruits inM. ciliaris, is controlled by presence of a single dominant allele, and such one-character taxonomies are debatable. Contributing to the difficulty,M. muricoleptis andM. granadensis, the other two species ofMedicago sectionSpirocarpos subsectionIntertextae, are sometimes confusingly similar toM. intertexta or to each other. Allozyme differences provided 95% verification of the suitability of the gland-tipped trichome character for separatingM. intertexta andM. ciliaris, thus corroborating their recognition as separate taxa. Several measures of allozyme variation indicated thatM. intertexta is more polymorphic than its sister species. Heterozygosity was also highest inM. intertexta, suggestive of a higher outcrossing rate, which is also consistent with larger floral size. Heterozygosity ofM. intertexta was concentrated in Sicily and nearby countries. Taxonomic difficulties in identifying SicilianM. intertexta are well known, and may be the result of interspecific hybridization and introgression.Medicago muricoleptis differed from the above two species in the frequency of several alleles, whileM. granadensis possessed numerous unique alleles consistent with its complete absence of genetic exchange with the other three substantially interfertile species.

Key words

Fabaceae Medicago Systematics evolution allozymes isozymes 

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Copyright information

© Springer-Verlag 1999

Authors and Affiliations

  • Ernest Small
    • 1
  • Suzanne I. Warwick
    • 1
  • Brenda Brookes
    • 1
  1. 1.Eastern Cereal and Oilseed Research Centre, Research BranchAgriculture and Agri-Food Canada, Central Experimental FarmOttawaCanada

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