Transposable Elements in Natural Populations of Drosophila

Abstract

Publisher Summary This chapter discusses transposable elements in natural populations of Drosophila. It presents a models and data relating to the problem of the maintenance of transposable elements in randomly mating host populations. The data on the distribution of copy numbers among individuals are largely concordant with expectation. The role of the regulation of the rates of transposition and of various modes of natural selection in maintaining an equilibrium in copy numbers in the face of transpositional increase in copy number are discussed in the chapter. It also discusses the tests for the role of selection against insertional mutations and against chromosome rearrangements induced by exchange among homologous elements located at nonhomologous chromosome locations , together with theory and data on the probability distribution of element frequencies at individual chromosomal sites. It is concluded that the available population data are consistent with the notion that element abundances are largely controlled by the interaction of transpositional increase in copy number with opposing forces, although the nature of these forces is not yet clear.