. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 44 L. R. McEDWARD AND K. H. MORGAN -OT2 C Volume (Ml) ( Volume (ull r 12-5 I 10 5 g 5 I Figure 6. Plots of egg volume and energy content for the 38 species of echinoderms with planktotrophic or lecithotrophic development. Panels show different regression models fit to the data and the 95% confidence belts around the regression line. A. linear regression; B, power function; C, full allometric model: D. polynomial model. planktonic food particles, brooders retain the offspring on or in the bo
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 44 L. R. McEDWARD AND K. H. MORGAN -OT2 C Volume (Ml) ( Volume (ull r 12-5 I 10 5 g 5 I Figure 6. Plots of egg volume and energy content for the 38 species of echinoderms with planktotrophic or lecithotrophic development. Panels show different regression models fit to the data and the 95% confidence belts around the regression line. A. linear regression; B, power function; C, full allometric model: D. polynomial model. planktonic food particles, brooders retain the offspring on or in the body of the parent and therefore have the potential to provide nutrition to the developing young. Scaling relationships among free-spawners Among free-spawning species, linear regression explains 84% of the variance in egg energy content in this sample of 38 species (Fig. 6). The best-fit linear regression passes through the origin (the intercept confidence interval in- cludes zero) and has a slope of (Table 5). The power function and the allometric models each explain 88% of the variance. Their slopes () are not different from the slope of the linear regression, and their scaling exponents () are not significantly different from 1. This indicates that energy content increases roughly in proportion to egg vol- ume. The predictive power of these scaling relationships does not improve substantially by restricting the analysis to de- velopment modes without offspring retention. Eggs that differ by /xl in volume have different predicted energy contents. Note that this is still more than half of the entire range of egg sizes in these two modes of develop- ment. How good is this? Volume is the most useful measure of egg size for comparison with content, but it is not easy to visualize. Biologists routinely report egg size as diameter because it is easy to measure and it is what one sees in an optical section under the microscope. Obviously, the diam- eter differe
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
