Fig. 5

Discriminant Function analysis of phenotypic diversity among 24 populations of Arctic charr in lava caves. Phenotypic diversity was estimated as (a) body shape and (b) head shape using landmarks-based geometric morphometric of body morphology and discriminant function analysis. Each point represents the average body/head shape of fish in a given population. Numbers refer to the cave numbers as described in Table 1. The deformation grids show the average morphology of fish/head in a population with a 3-time magnification, at the extremes. The genetic cluster that the majority of fish in a population were assigned to is indicated by the color of the average body shape point (main geographic area: V=Vindbelgur; H=Haganes, and subarea W = west; E = east; N = north; C = central; S = south; see Table 1 and Fig. 3 for details). The morph from the lake is refered to as “Krús”. Double arrows indicate movements of tagged fish between the caves (i.e. migrants). Fish from connected caves (double arrows) showed variable similarities in body and head shape. For instance, fish from caves 1 and 2 (10 migrants) were phenotypically similar in body shape, but in other cases (caves 7 and 25 with 19 migrants) were very different. The differences between fish from caves 25 and 7 were even more marked for head shape