RT Journal Article
SR Electronic
T1 Annelid functional genomics reveal the origins of bilaterian life cycles
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2022.02.05.479245
DO 10.1101/2022.02.05.479245
A1 Yan Liang
A1 Francisco M. Martín-Zamora
A1 Kero Guynes
A1 Allan M. Carrillo-Baltodano
A1 Yongkai Tan
A1 Giacomo Moggioli
A1 Océane Seudre
A1 Martin Tran
A1 Kate Mortimer
A1 Nicholas M. Luscombe
A1 Andreas Hejnol
A1 Ferdinand Marlétaz
A1 José M. Martín-Durán
YR 2022
UL http://biorxiv.org/content/early/2022/02/06/2022.02.05.479245.abstract
AB Indirect development with an intermediate larva exists in all major animal lineages1, and thus larvae are central to most scenarios for animal evolution2–12. Yet how larvae evolved remains disputed. Here we show that changes in the timing of trunk formation underpin the diversification of larvae and bilaterian life cycles. Combining chromosome-scale genome sequencing with transcriptomic and epigenomic profiling in the slow-evolving oweniid Owenia fusiformis13, we found that different genes and genomic regulatory elements control the development of its feeding larva and adult stage. First, O. fusiformis embryos develop into an enlarged anterior domain that forms larval tissues and the adult head, as posterior growth and trunk patterning is deferred to pre-metamorphic stages. These traits also occur in the so-called “head larvae” of other bilaterians14,15, with whom O. fusiformis larva shows extensive transcriptomic similarities. Conversely, animals with non-feeding larvae and gradual metamorphoses, such as the annelid Capitella teleta, start trunk differentiation during embryogenesis, like direct developers. Together, our findings suggest that the ancestral temporal decoupling of head and trunk formation, as retained in extant “head larvae”, allowed larval evolution in Bilateria, questioning prevailing scenarios that propose either co-option10,11 or innovation12 of gene regulatory programmes to explain larva and adult origins.Competing Interest StatementThe authors have declared no competing interest.