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The geographic expression of morphological variation in Xiphophora gladiata ssp. Gladiata was examined throughout the range of the taxon. The spatial scales on which this variation occurred were identified using nested analyses of variance (ANOVA) on 14 morphometric characters from 1224 plants collected at 12 sites. These characters were remarkably homogeneous in the scales at which their variation was expressed. The greater part of the morphological variation in X. gladiata ssp. Gladiata (over 90% for most characters) was expressed between adjacent primary clumps: that is, over scales of about 100 mm. Since it was previously shown that the clumps of plants are themselves spatially discrete, the spatial expression of morphology in this taxon forms a true mosaic with abrupt between-cells boundaries. Much of the remaining variation in most characters was expressed at a scale of about 300 km. At intermediate scales, that is, over a few meters and (in most characters) a few kilometers, there appears to be negative additional variance. In effect, the mixture of clumps at these scales tends to be a uniform rather than a random selection of the available morphological variety of clumps within each region. This observed pattern is compared and contrasted with those previously found in the confamilial species Fuscous distichus and F. evanescens. [ABSTRACT FROM AUTHOR]

The geographic expression of inter-regional morphological in Xiphophora gladiata ssp. gladiata was examined using a combination of discriminant function analyses, canonical correlation analysis and liner regression analysis. The pattern of that expression is an irregularly-stepped cline over scales of hundreds of kilometers, superimposed on a weak complex of microclines driven by exposure and (perhaps) other locally-varying environmental factors. The large-scale irregular cline is probably a response to the physico-chemical characteristics of regional water masses. [ABSTRACT FROM AUTHOR]