. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 88 H. E. EWING. The results obtained for these last 4 generations of subline II are further illustrated in Fig. 9 and Table IX. Older plants, therefore, cause a remarkable diminution in the size of Aphis avence individuals. Perhaps it is because these aphids are not able to extract as much food from the harder tissues of older plants, but it may be due to a change in the nature of the juices sucked from the food plant, or due to both of these causes. The Effects of Selection for 44 Generations on a Fluctuating Variation. The
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 88 H. E. EWING. The results obtained for these last 4 generations of subline II are further illustrated in Fig. 9 and Table IX. Older plants, therefore, cause a remarkable diminution in the size of Aphis avence individuals. Perhaps it is because these aphids are not able to extract as much food from the harder tissues of older plants, but it may be due to a change in the nature of the juices sucked from the food plant, or due to both of these causes. The Effects of Selection for 44 Generations on a Fluctuating Variation. The results of selection in the whole subline n are shown graphically in Fig. 10. Here we have plotted the exact lengths of each individual selected, scale X5O, and also the lengths re- presenting each fraternal mean, plotted to the same scale. The barred vertical columns repre- sent the lengths of the individuals selected, and the solid vertical columns represent the lengths expressed by the fraternal means. These two kinds of columns are arranged in the diagram Fig. 10 so that the two belonging to the same generation come in pairs, the number of the genera- tion being given at the top of the dotted vertical guide line. The curved arrows, each of which passes from the top of the column representing the length of the individual selected, to the top of the column representing the length of the mean of its offspring in the next generation, shows the amount of regression, or di- gression, as the case may be, for the fraternal mean in question. If we examine this figure we find that with but a single excep- tion there is a dropping of the fraternal mean downward. The. FIG. 9. Plotted results of selection in the last four generations of isola- tion No. ii. Curves plotted on the same plan as in Figs. 7 and Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may n
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
