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CLINAL MORPHOLOGICAL VARIATION OF ALLIUM SCHŒNOPRASUM IN EASTERN NORTH AMERICA
Author(s) -
Tardif Bernard,
Morisset Pierre
Publication year - 1990
Publication title -
taxon
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 81
eISSN - 1996-8175
pISSN - 0040-0262
DOI - 10.2307/1223088
Subject(s) - taxon , biology , population , habitat , geography , longitude , ecology , mantel test , latitude , panama , zoology , genetic variation , demography , geodesy , sociology
Summary Nineteen populations of Allium schœnoprasum L., distributed throughout the region between Lévis (near Québec City) and western Newfoundland, Canada, were sampled for a study of morphological variation. These populations overlapped the eastern Canadian ranges of var. laurentianum Fern. (an endemic taxon of eastern North America) and var. sibiricum (L.) Hartm. (a circumboreal taxon). Twenty morphological characters were measured on 20 plants from each population. Kruskal‐Wallis tests showed that (1) all the characters exhibited very significant differences between populations, and (2) 17 characters were different between habitats. Principal coordinate analyses, based on the 14 characters related more strongly to locality than to habitat, showed that similarity values were generally higher between populations from the same region. Using populations from both ends of the geographic gradient as a priori defined groups, canonical discriminant and classification analyses indicated that the overall variation pattern of A. schœnoprasum was clinal on a longitudinal gradient. The proportion of plants per population classified in one or the other group changed gradually along that gradient, and longitude alone accounted for most of the variance in mean population discriminant scores. Populations from Newfoundland and the eastern part of the Gaspé Peninsula, corresponding to var. laurentianum , are different from native populations of the upper St. Lawrence estuary region (var. sibiricum ), but the clinal variation between these two extremes casts doubts on the need of retaining var. laurentianum in future taxonomic treatments of that species. Present variation patterns of A. schœnoprasum in eastern North America are interpreted as resulting from widespread introgression, following secondary contacts between two population systems that survived Wisconsin glaciation in refugia situated around the Gulf of St. Lawrence and in southern New England, respectively.