Hidden genomic structure and widespread structural polymorphism across environmental gradients in the spiny sea star Marthasterias glacialis
Abstract
Genomic regions of reduced recombination can preserve linkage among co-adapted alleles, facilitating local adaptation despite high connectivity. Such regions—often generated by chromosomal inversions—may be especially important in highly dispersive marine taxa yet remain poorly documented in echinoderms. Here, we combined a chromosome-level reference genome with genome-wide ddRAD-seq from 296 Marthasterias glacialis individuals across 19 Atlantic–Mediterranean locations to quantify population structure and scan for recombination-suppressed haploblocks. Genome-wide neutral markers showed significant population differentiation together with evidence of high connectivity, revealed by the presence of inter-ecoregion migrants. Additionally, we identified 16 polymorphic haploblocks with patterns consistent with putative chromosomal inversions spanning 18.6% of the genome. Haploblock haplotypes were strongly environmentally and geographically structured and contained genes with key functions in stress response, osmoregulation and thermal tolerance. Haplotype distributions also paralleled previously described mitochondrial lineages despite nuclear gene flow, consistent with a model of ancient divergence followed by secondary contact. Overall, our results suggest a role for widespread structural polymorphism in adaptive differentiation in Echinodermata, providing a framework for linking echinoderm genome rearrangements to ecological divergence. Marthasterias glacialis thus emerges as a promising system to explore how structural variation contributes to adaptation and genome evolution in highly dispersive organisms.
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BibTeX
@article{martinhuete2026hidden,
title = {{Hidden genomic structure and widespread structural polymorphism across environmental gradients in the spiny sea star Marthasterias glacialis}},
author = {Marta Martín-Huete and Aurora García-Berro and Claire Mérot and Rocio Pérez-Portela and Carlos Leiva Sisnieguez},
journal = {Proceedings of the Royal Society B: Biological Sciences},
year = {2026},
month = aug,
doi = {10.1098/rspb.2026.0791},
url = {https://hal.science/hal-05744069v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Hidden genomic structure and widespread structural polymorphism across environmental gradients in the spiny sea star Marthasterias glacialis
AU - Marta Martín-Huete
AU - Aurora García-Berro
AU - Claire Mérot
AU - Rocio Pérez-Portela
AU - Carlos Leiva Sisnieguez
PY - 2026
DA - 2026/08/19
JO - Proceedings of the Royal Society B: Biological Sciences
DO - 10.1098/rspb.2026.0791
UR - https://hal.science/hal-05744069v1
AB - Genomic regions of reduced recombination can preserve linkage among co-adapted alleles, facilitating local adaptation despite high connectivity. Such regions—often generated by chromosomal inversions—may be especially important in highly dispersive marine taxa yet remain poorly documented in echinoderms. Here, we combined a chromosome-level reference genome with genome-wide ddRAD-seq from 296 Marthasterias glacialis individuals across 19 Atlantic–Mediterranean locations to quantify population structure and scan for recombination-suppressed haploblocks. Genome-wide neutral markers showed significant population differentiation together with evidence of high connectivity, revealed by the presence of inter-ecoregion migrants. Additionally, we identified 16 polymorphic haploblocks with patterns consistent with putative chromosomal inversions spanning 18.6% of the genome. Haploblock haplotypes were strongly environmentally and geographically structured and contained genes with key functions in stress response, osmoregulation and thermal tolerance. Haplotype distributions also paralleled previously described mitochondrial lineages despite nuclear gene flow, consistent with a model of ancient divergence followed by secondary contact. Overall, our results suggest a role for widespread structural polymorphism in adaptive differentiation in Echinodermata, providing a framework for linking echinoderm genome rearrangements to ecological divergence. Marthasterias glacialis thus emerges as a promising system to explore how structural variation contributes to adaptation and genome evolution in highly dispersive organisms.
SN - 0080-4649
ER -