Abstract
The mutualistic lifestyle of pollinating fig wasps and fig trees
provides an excellent model for studying ecological and adaptive
evolution issues. Transposable elements (TEs), as an important component
of the genomes, are powerful driver for organisms to adapt to
environment. Here, the genomic TEs of six pollinating fig wasps and five
non-pollinating fig wasps were analyzed in the characteristics of
composition and their effects on genome size, the historical burst
patterns and their association with effective population size and
paleoclimate changes, to infer the role of TEs in environmental
adaptation in fig wasps. Compared with non-pollinators, pollinators’ TEs
showed a significantly different burst state with less types and amount,
shorter lengths, and lower contents in the genomes. The recent smaller
effective population size and contractive demography failed to cause
pollinators to accumulate more TEs, while the large number of TEs
accumulated in non-pollinators positively correlated with their
population expansion. The major TEs burst peaks in the history of
pollinators highly overlapped with the warmer times in the Coolhouse in
geological history. TEs located in the major peak period were mostly
inserted near genes related to environment information processing such
as Circadian entrainment pathway, and might act as CRMs (cis-regulatory
modules) to regulate the conjunctive genes in response to paleoclimate
changes in pollinators. These results revealed the molecular basis of
the fig wasp’s response to changes in the syconia microenvironment and
paleoclimate macroenvironment from the perspective of genomic TEs.