caa a22 4500 386393257 CHVBK 20180307112127.0 cr unu---uuuuu 161130e198910 xx s 000 0 eng 10.1017/S0016672300028482 doi S0016672300028482 pii (NATIONALLICENCE)cambridge-10.1017/S0016672300028482 A study of ten families of transposable elements on X chromosomes from a population of Drosophila melanogaster [Elektronische Daten] Data were collected on the distribution of ten families of transposable elements among fourteen X chromosomes isolated from a natural population of Drosophila melanogaster, by means of in situ hybridization to polytene chromosomes. It was found that, with the exception of roo, the copy number per chromosome followed a Poisson distribution. There was no evidence for linkage disequilibrium, either within or between families. Some pairs of families of elements were correlated with respect to the identity of the sites that were occupied in the sample, although there was no evidence for a correlation with respect to the sites at which elements attained relatively high frequencies. Elements appeared to be distributed randomly along the distal part of the X chromosome. There was, however, a strong tendency for elements to accumulate at the base of the chromosome. Element frequencies per chromosome band were generally low, except at the base of the chromosome where bands in subdivisions 19E and 20A sometimes had high frequencies of occupation. These results are discussed in the light of models of the population dynamics of transposable elements. It is concluded that they provide strong evidence for the operation of a force or forces opposing transpositional increase in copy number. The accumulation of elements at the base of the chromosome is consistent with the idea that unequal exchange between elements at non-homologous sites is such a force, although other possibilities cannot be excluded at present. The data suggest that the rate of transposition per element per generation is of the order of 10−4, for the elements included in this study. Copyright © Cambridge University Press 1989 Charlesworth Brian Department of Ecology and Evolution, The University of Chicago, 1103 E. 57th St, Chicago, IL 60637, USA Lapid Angela Department of Ecology and Evolution, The University of Chicago, 1103 E. 57th St, Chicago, IL 60637, USA Genetical Research Cambridge University Press 54/2(1989-10), 113-125 0016-6723 54:2<113 1989 54 GRH https://doi.org/10.1017/S0016672300028482 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0016672300028482 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Charlesworth Brian Department of Ecology and Evolution, The University of Chicago, 1103 E. 57th St, Chicago, IL 60637, USA NATIONALLICENCE 700 1- Lapid Angela Department of Ecology and Evolution, The University of Chicago, 1103 E. 57th St, Chicago, IL 60637, USA NATIONALLICENCE 773 0- Genetical Research Cambridge University Press 54/2(1989-10), 113-125 0016-6723 54:2<113 1989 54 GRH CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge