According to a new study in iScienceResearchers have sequenced the largest cephalopod genome in history. Generation of the vampire squid genome (Vampiroteuthis sp.) and comparing it with the genomes of other cephalopods, the team found that this species, combining features of an octopus, squid and cuttlefish, had ancient genome architecture and, in particular, chromosomes, indicating that the common ancestor of modern cephalopods was remarkably similar to squid.
“The vampire squid is right on the border between octopuses and squids,” said Oleg Simakov, study author and biologist at the University of Vienna, according to press release. “Its genome reveals deep evolutionary mysteries about how two strikingly different lineages could have evolved from a common ancestor.”
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Origin of cephalopods
About 300 million years ago, the ancient ancestors of modern cephalopods split into two lineages, including the modern one. Octopodiforms (octopuses) and modern Decimals (squid and cuttlefish). But the exact nature of these ancient ancestors, and whether they were more like octopuses or more like squid and cuttlefish, has long puzzled scientists.
To help unravel the mystery, the authors of a new study turned to the genome of the vampire squid, which is actually classified as an octopus, to explain the evolution of early species. cephalopods. By carefully studying the chromosome structure of vampire squid, the researchers found that this species, which combines characteristics of octopus, squid and cuttlefish, represents a link between the two lineages, retaining some chromosomal features of its common ancestors.
“Although it is classified as an octopus, the vampire squid retains genetic heritage that predates both lineages,” Emese Toth, another study author and a biologist at the University of Vienna, said in a press release. “This gives us a direct look at the earliest stages of cephalopod evolution.”
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Ancient Vampire Squid Architecture
The vampire squid genome, about four times the size of the human genome, contains an abundance of genetic material. While reviewing this material during analysis, the team was surprised to see that some parts of the species chromosomal structure have been strictly conserved or preserved over time, making the species a “genomic living fossil,” or a modern species that retains the genetics of its ancestors.
By comparing the vampire squid genome with those of other cephalopod species, the researchers concluded that the species has an ancient, squid-like chromosome architecture. While most modern octopuses lack this structure due to significant chromosomal reorganizations that occurred during their evolution, vampire squid retained this structure over time, providing important information about the origin of cephalopods.
In fact, the researchers added that the study provides strong support for the theory that modern octopuses, squids and cuttlefish evolved from a creature that was less like an octopus and more like a squid or cuttlefish, about 300 million years ago. They also said their study highlights that chromosome reorganization and restructuring may have contributed to the incredible diversity seen in modern cephalopods, which today come in all shapes and sizes, from the largest octopuses to the smallest cuttlefish.
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