. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. GROWTH AND VARIATION IN PURPURA 525 ) A* Purpura pansa I intermediate 1 s intermediate 2 D intermediate 3 ) °o p, columellaris + - LLJ Q_ < co LLJ I CO o a. + -6 -5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5 PCI-SHELL SIZE FIGURE 4. Plot of 273 shells used in PCA on the coordinates representing shell size (PC I) and shape (PC II) (see text for interpretation of these axes). All shells identified on the basis of apertural morphology as Purpura pansa are indicated by solid triangles and the region occupied by the majority of thes
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. GROWTH AND VARIATION IN PURPURA 525 ) A* Purpura pansa I intermediate 1 s intermediate 2 D intermediate 3 ) °o p, columellaris + - LLJ Q_ < co LLJ I CO o a. + -6 -5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5 PCI-SHELL SIZE FIGURE 4. Plot of 273 shells used in PCA on the coordinates representing shell size (PC I) and shape (PC II) (see text for interpretation of these axes). All shells identified on the basis of apertural morphology as Purpura pansa are indicated by solid triangles and the region occupied by the majority of these shells has been demarcated by the dotted line. All P. pansa shells within this zone are designated by small triangles while those located outside the dotted line are indicated by large triangles. Similarly, P. columellaris shells are indicated by open circles and a solid line. Intermediate shells of types 2, 3 and 4 (see text) are designated by solid, diagonally shaded and open rectangles, respectively. To further examine the variance apportioned along the shape components we repeated the PCA using a restricted range of shell sizes. This analysis included all 54 shells within the range of to + on PC I in the original analysis. As Table III shows, the PC I could still be interpreted as a size related variable although spire height and weight now contribute little to PC I. PC II now included a substantial of the variance. The loadings on the eigenvector for PC II were generally similar in magnitude and direction to PC II of the 273-shell PCA. Thus, this analysis confirmed that PC II separated shells on the relative dimensions of spire height and weight versus aperture size (both width and length). Examination of plots (not shown) again showed that P. pansa tended to have a large aperture, a low spire and are relatively light compared to P. Please note that these images are extracted from scanned page images that may have been digitally enhanced for
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
