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Download (3398Kb) - ePrints Soton - University of Southampton

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Fig. 4.7. Hierarchical cluster analysis <strong>of</strong> the data on adult size, egg size and Gonad<br />

Index, based on the Normalized Euclidean distance measure.<br />

Group B contains 17 species, which present large adult size (major radius 100-200<br />

mm), large egg size (diameters from 470 to 1182 µm), and low Gonad Index (3.17 to<br />

6.4).<br />

Four species with small egg size were included in this cluster. This occurred<br />

because the analysis considered them similar to the other species in having a large<br />

adult size and low Gonad Index; however it is evident that two <strong>of</strong> these species:<br />

Stichastrella rosea (O.F. Müller) and Astropecten irregularis (Pennant) clearly belong<br />

to a group <strong>of</strong> shallow-water species with small egg size, high fecundity and<br />

planktotrophic development together with Luidia sarsi Düben and Koren, which was<br />

separated by the analysis as an outlier because <strong>of</strong> its very high Gonad Index. These<br />

three species are found in the upper slope zone at 150-700 m, as defined by Howell et<br />

al. (2002).<br />

79

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