Convergent adaptive evolution in marginal environments: unloading transposable elements as a common strategy among mangrove genomes

Several clades of mangrove trees independently invade the interface between land and sea at the margin of woody plant distribution. As phenotypic convergence among mangroves is common, the possibility of convergent adaptation in their genomes is quite intriguing. To study this molecular convergence,...

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Bibliographic Details
Published in:The New phytologist 2018-01, Vol.217 (1), p.428-438
Main Authors: Lyu, Haomin, He, Ziwen, Wu, Chung‐I, Shi, Suhua
Format: Article
Language:English
Subjects:
Adaptation
Adaptation, Physiological - genetics
adaptive evolution
Avicennia - genetics
Avicennia - physiology
Convergence
convergent evolution
Environment
Evolution
Evolution & development
Genome Size
Genome, Plant - genetics
Genomes
genomic parasite
Long terminal repeat
mangrove
Mangrove trees
Mangroves
marginal habitat
Parasites
Retroelements - genetics
Rhizophoraceae - genetics
Rhizophoraceae - physiology
Size reduction
Terminal Repeat Sequences - genetics
transposon
Unloading
Woody plants
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Summary:Several clades of mangrove trees independently invade the interface between land and sea at the margin of woody plant distribution. As phenotypic convergence among mangroves is common, the possibility of convergent adaptation in their genomes is quite intriguing. To study this molecular convergence, we sequenced multiple mangrove genomes. In this study, we focused on the evolution of transposable elements (TEs) in relation to the genome size evolution. TEs, generally considered genomic parasites, are the most common components of woody plant genomes. Analyzing the long terminal repeat-retrotransposon (LTR-RT) type of TE, we estimated their death rates by counting solo-LTRs and truncated elements. We found that all lineages of mangroves massively and convergently reduce TE loads in comparison to their nonmangrove relatives; as a consequence, genome size reduction happens independently in all six mangrove lineages; TE load reduction in mangroves can be attributed to the paucity of young elements; the rarity of young LTR-RTs is a consequence of fewer births rather than access death. In conclusion, mangrove genomes employ a convergent strategy of TE load reduction by suppressing element origination in their independent adaptation to a new environment.
ISSN:0028-646X
1469-8137
DOI:10.1111/nph.14784