Trabajo presentado en el International Congres on Transposable Elements (ICTE 2016), celebrado en Saint Malo (Francia) del 16 al 19 de abril de 2016.Drosophila melanogaster is an excellent model organism to study
adaptation to novel environments, as it has undergone a recent expansion
from its origins in Africa to virtually the entire globe. A recent genome-wide
screen surprisingly found signatures of adaptation in transposable element
(TE) mutations, however, this study was based on a partial dataset of TEs
that were sampled only in North American populations. In this work, we
analyze all euchromatic TEs identified in three out-of-Africa populations:
one North American (DGRP) and two European, Italian and Swedish. We
identify 41 candidate adaptive TEs with significantly different frequencies
within and outside of Africa, which doubles the number of candidate
TEs for out-of-Africa adaptation compared to the previous study. 70.3%
of these TEs showed signals of positive selection using the iHS statistic,
and include the two TEs that have already been functionally validated.
We find that most of these candidate TEs for out-of-Africa adaptation are
inserted inside genes or at less than 1 kb distance, and we show that stress
response and olfaction are over-represented in this set of genes. Our results
highlight the important role of TEs in genome evolution, and shed light
to the understanding of the phenotypes involved in adaptation to novel
environments in natural populations.N