RT Journal
A1 Plessy, Charles
A1 Mansfield, Michael J.
A1 Bliznina, Aleksandra
A1 Masunaga, Aki
A1 West, Charlotte
A1 Tan, Yongkai
A1 Liu, Andrew W.
A1 Grašič, Jan
A1 del Río Pisula, María Sara
A1 Sánchez-Serna, Gaspar
A1 Fabrega-Torrus, Marc
A1 Ferrández-Roldán, Alfonso
A1 Roncalli, Vittoria
A1 Navratilova, Pavla
A1 Thompson, Eric M.
A1 Onuma, Takeshi
A1 Nishida, Hiroki
A1 Cañestro, Cristian
A1 Luscombe, Nicholas M.
T1 Extreme genome scrambling in marine planktonic Oikopleura dioica cryptic species
JF Genome Research 
JO Genome Research 
YR 2024 
FD March 01 
VO 34 
IS 3 
SP 426 
OP 440 
DO 10.1101/gr.278295.123 
UL http://genome.cshlp.org/content/34/3/426.abstract 
AB Genome structural variations within species are rare. How selective constraints preserve gene order and chromosome structure is a central question in evolutionary biology that remains unsolved. Our sequencing of several genomes of the appendicularian tunicate Oikopleura dioica around the globe reveals extreme genome scrambling caused by thousands of chromosomal rearrangements, although showing no obvious morphological differences between these animals. The breakpoint accumulation rate is an order of magnitude higher than in ascidian tunicates, nematodes, Drosophila, or mammals. Chromosome arms and sex-specific regions appear to be the primary unit of macrosynteny conservation. At the microsyntenic level, scrambling did not preserve operon structures, suggesting an absence of selective pressure to maintain them. The uncoupling of the genome scrambling with morphological conservation in O. dioica suggests the presence of previously unnoticed cryptic species and provides a new biological system that challenges our previous vision of speciation in which similar animals always share similar genome structures.