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The evolutional significance of the chromosomes of Aphididae
Author(s) -
Shinji Orihay
Publication year - 1931
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/jmor.1050510204
Subject(s) - biology , bivalent (engine) , aphididae , ploidy , meiosis , aphid , karyotype , chromosome , genus , b chromosome , zoology , genetics , botany , homoptera , chemistry , organic chemistry , gene , metal , pest analysis
An investigation into the number of chromosomes in thirty‐seven species of Aphidiae belonging to twenty‐seven geaera has shown that there is but one sex chromosome in the male cells of all but one species of Aphididae. That exceptional species is Euceraphis betulae Koch. The number of chromosomes and body characters are so closely correlated that we can safely judge the evolutional scale of any aphid by its number of chromosomes. In Aphididae the least number of chromosomes seems to be the most primitive. The number of chromosomes varies with the genera. The highest number is 18 11 + X = 37 chromosomes, the lowest being 2 11 + X = 5 (diploid in male). The increase in the number of chromosomes seems to have been brought about by transverse divisions of the primitive chromosomes. The genus Tuberolachnus with 3 11 + X = 4 elements (♂) represents altogether different chromosomes characters from the genus Pterochlorus with 8 elements. In the genera Periphyllus and Calaphis there are species with a small m ‐element which is bivalent.