Overview

• Teams at the Wellcome Sanger Institute and the Institute of Evolutionary Biology sequenced the species for the first time, with results published in Current Biology.
• The karyotype consists of 227 pairs of unusually small autosomes plus two large sex chromosomes that largely resisted fragmentation.
• Comparative and Hi-C analyses indicate the extreme count arose through repeated chromosome fissions rather than whole-genome duplication.
• Fragmentation sites were enriched in loosely packed, transcriptionally active A chromatin and depleted in densely packed B regions.
• Researchers estimate the increase from roughly 24 to 229 pairs occurred in about three million years, focusing next on implications for adaptation, conservation in North Africa, and parallels to cancer-associated rearrangements.