Abstract
Transposable elements (TEs), acting as symbiotic entities within host
genomes, their landscapes represent a pivotal subject in evolutionary
discourse. Previous investigations on the impact of ecological niches on
the shaping of TE landscapes have yielded inconsistent conclusions. This
study assessed the effect of ecological niches on the dynamics of TEs,
employing pollinating fig wasps and non-pollinating fig wasps (NPFWs)
residing in the syconia of figs as models. Our findings reveal a
significantly positive correlation between TE content and genome size,
exhibiting conspicuous phylogenetic signal. Significant differences
emerge in the quantity, total length, and family types of TEs between
pollinators and NPFWs. Notably, pollinators exhibit ‘dormant’ TE
landscapes characterized by inactivity along with rapid decay
attributable to smaller effective population sizes. This results in only
a few remnants persisting over nearly a million years. Despite the
relaxed selection pressure on pollinators in an effort to prolonging TE
retention, their abundance remains limited. In contrast, NPFWs exhibit
‘aggressive’ TE landscapes, marked by the continual generation of new
insertions. The larger effective population sizes contribute to
decelerating the decay of TEs, as demonstrated by the substantial TE
accumulation in the last one million years. These observed dynamics are
intrinsically linked to the distinctive ecological niche provided by
figs. TE remains suggest a functional role in facilitating pollinators’
adaptation to stress induced by their niche. Numerous cis-regulatory
modules that originate from TEs and locate near genes involved in
processing environmental information, which emphasizes their potential
functional significances.