Determinate Evolution In The Color Pattern Of The Lady Beetles

Author : Roswell H. Johnson
Publisher :
ISBN 13 : 9781332300310
Total Pages : 114 pages
Book Rating : 4.3/5 (3 download)

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Download or read book Determinate Evolution in the Color-Pattern of the Lady-Beetles (Classic Reprint) written by Roswell H. Johnson and published by . This book was released on 2015-08-05 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: Excerpt from Determinate Evolution in the Color-Pattern of the Lady-Beetles The lady-beetles were considered desirable for this study because their variability, distribution, and taxonomy indicated that they had been recently and are probably now in an active state of evolution. The practical advantage that they could be obtained in considerable numbers from many localities and could be experimentally bred was, then, decisive in their favor. All of the American coccinellids which could be obtained in numbers and which showed a variable color-pattern were studied, viz, Hippodamini, Coccinellae, and Epilachnini, divisions employed by Casey(1899). The Epilachnini differ from the rest of the family in being leaf-eating, in having longer generations, and in hibernating necessarily in the winter; whereas the other coccinellids which eat aphids, fungus spores, and pollen will remain active during the winter in a vivarium and give many more generations. The difficulties of keeping a large and constant stock of aphids on hand and keeping the beetles free from diseases, especially such as result from dampness in the late summer and irregular temperatures in the winter, proved to be very serious and prematurely shortened many pedigrees. These difficulties also decreased the numbers which could be successfully managed. Nearly all the pedigrees, however, are given, for when too fragmentary to have much value in the study of dominance and segregation, they are, nevertheless, of value in showing the transmissibility of some characters and variation from the parent. The dorsal color-pattern in all the American species within these groups is given for the sake of completeness, although for some species but little variation data was obtainable. This fact, together with the necessity of carrying in mind the data of variation and distribution in discussing experiments upon any given species, has led me to arrange the presentation according to species, after this introductory section. Furthermore, this arrangement will be more advantageous for those whose interest in this contribution is primarily taxonomic. Every considerable new accession of data involves another revision of these tribes, since there has been so much disagreement among the authors and since the lines between varieties and species in these remarkable genera are so doubtful. I am obliged, therefore, to present a revision of my own in order to have a suitable nomenclature. Since the revision is not an end in itself, I have not given full descriptions, but only discussed and illustrated the color-pattern of the parts studied, although of course the revision is based upon many characteristics. Not having studied the structural features of the foreign species, I have not ventured to revise the genera and have simply adopted the genera as used by Casey. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works."