2024-03-01 カリフォルニア大学サンタバーバラ校(UCSB)
hoto Credit:Marcelo Rojas González via iNaturalist
The shell of the variable tonicia is covered in complex, image-forming eyes.
<関連情報>
- https://news.ucsb.edu/2024/021384/unraveling-mystery-chiton-visual-systems
- https://www.science.org/doi/10.1126/science.adg2689
視覚系の経路依存的進化の形態学的基盤 A morphological basis for path-dependent evolution of visual systems
REBECCA M. VARNEY, DANIEL I. SPEISER HTTPS://ORCID.ORG/0000-0001-6662-3583, JOHANNA T. CANNON, MORRIS A. AGUILAR, […], AND TODD H. OAKLEY
Science Published:29 Feb 2024
DOI:https://doi.org/10.1126/science.adg2689
Editor’s summary
Established morphological traits can direct trait evolution along particular trajectories in a process known as path dependence. Varney et al. explored this process in two lineages of chitons that have evolved two different visual systems, eye spots and shell eyes (see the Perspective by Sumner-Rooney). They found that lineages with more nerve openings in their shell evolved eye spots, whereas those with fewer openings evolved shell eyes. —Sacha Vignieri
Abstract
Path dependence influences macroevolutionary predictability by constraining potential outcomes after critical evolutionary junctions. Although it has been demonstrated in laboratory experiments, path dependence is difficult to demonstrate in natural systems because of a lack of independent replicates. Here, we show that two types of distributed visual systems recently evolved twice within chitons, demonstrating rapid and path-dependent evolution of a complex trait. The type of visual system that a chiton lineage can evolve is constrained by the number of openings for sensory nerves in its shell plates. Lineages with more openings evolve visual systems with thousands of eyespots, whereas those with fewer openings evolve visual systems with hundreds of shell eyes. These macroevolutionary outcomes shaped by path dependence are both deterministic and stochastic because possibilities are restricted yet not entirely predictable.
