The shell-like egg case of Argonauta argo. Credit: Genome Biology and Evolution
A brand new paper in Genome Biology and Evolution signifies {that a} sort of octopus seems to have developed independently to develop one thing resembling a shell, regardless of having misplaced the genetic code that produced precise shells in its ancestors and family members.
Argonauta argo is a species of octopus that lives in tropical and subtropical open seas. Female argonauts have a protecting, spiral, shell-like egg case, which protects the eggs inside. Researchers have lengthy questioned in regards to the origin of this egg case. It appears very very similar to the shell of the generally recognized pearly nautilus (the very distant relative of the argonaut), which has a real onerous shell and lives on the ocean flooring, however that will simply be a coincidence.
While the argonaut’s egg case and the nautilus’s shell are fashioned by way of the secretion of proteins, they’re reportedly fashioned otherwise and look dissimilar on the microscopic degree. Did the egg case evolve from the shell, or did it develop independently?
By sequencing the draft genome of the species, a crew of researchers from Japan, led by Masa-aki Yoshida and Davin Setiamarga, tried to disclose the genomic background of argonauts and present how the species tailored to the open ocean and purchased its shell-like egg case. Scientists beforehand had prevented focusing on argonauts because it was tough to maintain the animals in aquaria for analysis functions. The authors right here, nonetheless, had entry to a location within the Sea of Japan that was superb for buying recent samples.
The new genome knowledge uncovered right here offers perception into a number of options associated to shell evolution and egg case formation. The researchers discovered the egg case protein-coding genes in argonauts and found that the majority of those genes weren’t used to type shells in distantly associated species, together with the nautilus. This means that whereas the distant ancestors of argonaut octopuses probably had shells, the shells did not evolve into egg instances.
“The argonaut genome is especially intriguing as a result of it reveals that the break in synteny reported within the recognized octopus genome will not be a basic trait of this group,” mentioned Yoshida and Setiamarga. “We have demonstrated that opposite to fashionable perception, cephalopods don’t essentially exhibit a definite genome evolution. We anticipate that our findings will additional the analysis of metazoan, mollusk, and cephalopod genome evolution, which has remained largely unexplored to this point.”
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More info:
Masa-aki Yoshida et al, Gene recruitments and dismissals within the argonaut genome present insights into pelagic life-style adaptation and shell-like eggcase reacquisition, Genome Biology and Evolution (2022). DOI: 10.1093/gbe/evac140
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New analysis reveals how octopuses could have developed (2022, October 26)
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