Tropical Africa as a cradle for horizontal transfers of transposable elements between species of the genera Drosophila and Zaprionus

Abstract

We have recently reported numerous cases of horizontal transfers of transposable elements between species of drosophilids. These studies revealed a substantial number of horizontal transfers between species of the subgroup melanogaster of the genus Drosophila and between these species and species of the genus Zaprionus. In this review, these transfers and similar, previously reported events are discussed and reanalysed to portray the interrelationships between the species that allowed the occurrence of so many horizontal transfers. The paper also addresses problems that may arise in drawing inferences about the time period during which the horizontal transfers occurred and the factors that may be associated with these transfers are discussed.

Keywords: :

• Zaprionus subgenus
• horizontal transfer ages
• introgression
• melanogaster subgroup
• retrotransposons
• transposons

Acknowledgments

The author is grateful N. Setta for comments during the preparation of this article and for making available 11 sequences of the retrotransposon Copia extracted from the D. melanogaster genome. The data produced in the C.M.A.C laboratory cited in this work were supported by grants from the Brazilian Agencies CNPq (Conselho Nacional de Desenvovimento Científico e Tecnológico) and FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) and the CAPES-COFECUB International Cooperation Program.

Figures and Tables

Figure 1

Figure 2

Table 1 Comparative analysis of Ks and estimation of the average divergence time (Mya) from the common ancestor sequence of 12 sequences of the retrotransposon Copia in D. melanogaster.

Table 2 Mean values of the HT ages (Mya) of LTR retrotransposons between groups of species differing by degrees of evolutionary relatedness calculated according to the equation r = kS/2T (r = 0.01125)