The population genetics of Armeria maritima (Mill.) Willd. on the River South Tyne, UK

Abstract

A. maritima inland in England and Wales is largely confined to metal‐rich soils, where it has probably evolved metal tolerance. Similar populations are found in Belgium, Germany and Poland. Numerous large populations occur on river terraces beside the rivers South Tyne and Tyne in Northumberland. These terraces were mostly formed between 1850 and 1940, and have high levels of toxic heavy metals which result from mining activities within the catchment. It is probable that A. maritima occurred on naturally metalliferous soils high in the Pennine catchment prior to mining, and colonized metalliferous river terraces downstream after 1850. In comparison with the British populations of subspecies maritima, the Tyne populations are unique in being polymorphic for scape hairiness. This character is also found in European mine populations. The Tyne populations also share with European mine populations some degree of self‐fertility, but selfing was insufficient to give rise to detectable excesses of the papillate morph. Nevertheless, in at least one population, excesses of papillates may occur. The papillate morphs tend to be more self‐fertile than the cob morph. The recessive homozygous papillate phenotypes flower later, and tend to predominate in the densest parts of the population It is suggested that heterotic genes may be linked to the loci studied. This may account for the late dowering and high density of homozygous phenotypes. Copyright © 1989, Wiley Blackwell. All rights reserved