Supporting materials from “Joint assembly and genetic mapping of the Atlantic horseshoe crab genome reveals ancient whole genome duplication.”

Atlantic horseshoe crabs (<em>Limulus polyphemus</em>) are marine arthropods with a fossil record extending back approximately 450 million years. They exhibit remarkable morphological stability over their long evolutionary history, retaining a number of ancestral arthropod traits, and are often cited as examples of living fossils. <br><br>
We constructed a genetic linkage map of this 2.7 Gbp genome by sequencing the nuclear DNA of 34 wild-collected, full-sibling embryos and their parents at a mean redundancy of 1.1x per sample. The map includes 84,307 sequence markers grouped into 1,876 distinct genetic intervals and 5,775 candidate conserved protein coding genes.