Repeatome evolution across space and time: Unraveling repeats dynamics
in the plant genus Erythrostemon Klotzsch (Leguminosae Juss.)
Abstract
Fluctuations in genomic repetitive fractions (repeatome) are known to
impact several facets of evolution, such as ecological adaptation and
speciation processes. Therefore, investigating the divergence of
repetitive elements can provide insights into an important evolutionary
force. However, it is not clear how the different repetitive element
lineages are impacted by the ecological changes. To discuss this, we
used the Neotropical legume genus Erythrostemon (Caesalpinioideae) as a
model, given its ancient origin (~33 Mya),
lineage-specific niche conservatism, macroecological heterogeneity, and
disjunct distribution in Meso- and South American (MA and SA,
respectively) lineages. We performed a comparative repeatomic analysis
of 18 Erythrostemon species to test the impact of environmental
variables over repeats diversification. Overall, repeatome composition
was diverse, with high abundances of satDNAs and Ty3/gypsy-Tekay
transposable elements, predominantly in the MA and SA lineages,
respectively. Remarkably the first divergent lineages (E. pannosus and
E. placidus) of the MA clade preserve plesiomorphic Tekay and satDNA
patterns. This pattern was altered in the MA-sensu stricto subclade with
a striking genomic differentiation (expansion of satDNA and retraction
of Tekay) associated with the colonization of a new environment in
Central America around 20 Mya. Our data reveal that the current
species-specific Tekay pool was the result of two bursts of
amplification probably in the Miocene, with distinct patterns for the MA
and SA repeatomes. This suggests a strong role of the Tekay elements as
modulators of the genome-environment interaction in Erythrostemon,
providing macroevolutionary insights about mechanisms of repeatome
differentiation and plant diversification across space and time.