Myrceugenia fernandeziana (Myrtaceae) is a dominant, apparently anemophilous, tree endemic to Masatierra Island in the Juan Fernandez archipelago. These islands provide a natural laboratory for investigations of relationships within and among populations of threatened/vulnerable species. Leaf morphology was used to compare 25 populations from a diversity of habitats. Allozyme analyses were conducted for a subset of 15 of these populations. Leaf shape, described by elliptic Fourier analyses, allows recognition of distinct subsets of populations (also recognized by allozymes) and a number of leaf characters show evidence of geographically-based (southeast to northwest) clinal variation on the island. Morphological distances among populations are not correlated with geographic distances but allozyme distances among populations are correlated with geographic distances. There is a positive, but not statistically significant, correlation between allozyme and morphological distances. In addition, there is no apparent connection between patterns of allozyme or morphological differences and the habitats in which the populations occur. These results are not consistent with models based on localized adaptation, suggest panmixis, perhaps based on anemophily and broad dispersal, and suggest that conservation strategies must be based on sampling multiple populations within and among habitat types.

Communicating Editor: Thomas G. Lammers