The mariner transposable element in natural populations of Drosophila simulans

Abstract

In cosmopolitan species, geographical variations in copy number and/or level of transposition activity have been observed for several transposable elements (TEs). Environment, history and population structure can contribute to such variation in ways that are difficult to tease apart. For the mariner element, previous studies of the geographic variation of its somatic activity in natural populations of Drosophila simulans have shown contradictory results (latitudinal clines of divergent orientations or no apparent structure). To try and resolve these inconsistencies, we gathered all available data on the mariner somatic activity of worldwide natural populations. This includes previously published results by different groups and also new data. The correlations between the level of activity and several geoclimatic factors were tested. Although no general effect of temperature was found, a relationship with the invasion history was detected. It was also shown that recent invasive populations have a higher level of activity than the putative ancestral ones. Our results strongly suggest that variability of the mariner somatic activity among natural populations of D. simulans is mainly due to populational and historical factors probably related to the recent world colonization of this species. Indeed, this activity is correlated to the main route out of Africa (the Nile route) and the recent colonization of continents such as Australia and South America.

Correlated evolution of LTR retrotransposons and genome size in the genus eleocharis

“…A greater number of TEs within a genome increases the potential to produce fecund lineages with strong abilities to evolve and adapt to various conditions [47,48]. A relationship between the latitude and activity of the mariner transposable element has already been observed in populations of Drosophila simulans [54]. The authors of that study discussed the possibility that the invasion of new stressful habitats triggered the activity of mariner , which subsequently produced variation for natural selection.…”

The struggle for life of the genome's selfish architects

“…A recent population genetics study of several TEs in plant populations of which the demographic history is known suggested that TEs diversity is influenced by demographic factors such as bottlenecks and population size fluctuations [212]. Another example comes from the invasive Drosophila simulans species, in which the level of the mariner element activity increased as the migration distance increased, probably as a result of repetitive bottlenecks [213]. However, simulation studies suggest that genetic drift is a significant force in eliminating TEs from small populations [208].…”

Transposable elements in a marginal plant population: temporal fluctuations provide new insights into genome evolution of wild diploid wheat

“…Population genetic theory assumes that the dynamics of transposable elements in natural populations reflect a balance between the tendency of these elements to increase through transposition and their removal through natural selection acting against individuals with a high element copy number [10,11]. Several studies from different biological systems indicate that the patterns of a single TE family can vary intraspecifically [12-15] and temporally [16]. Examination of the intraspecific dynamics of TEs, especially in marginal populations where microevolutionary processes are intensified [2], could considerably contribute to the understanding of key biological events such as speciation.…”