I heard on the news today that a deep sea fish called the Sea Robin is supposedly a breakthrough in evolutionary understanding of the human upright stance. I am not sure how they come to thins conclusion as the “limbs” do not appear to have muscles and at that depth the fish must have some kind of bouyancy to counteract the deep sea pressure.
Apparently they use the same gene sequence as (plays a role in) the human limb?
Any comments?
Richard
A link to the article would be helpful.
It’s all over the news, but here is a link to a science blog that may be more reputable
Walking Fish
Basically you only have to put in “Walking Fish” to get the News version.
From what I have read it is not as sensational as the news would have us believe, These fish have been on the science radar for a while
Richard
A link to the peer reviewed paper:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10592820/
Abstract:
A major goal in biology is to understand how organisms evolve novel traits. Multiple studies have identified genes contributing to regressive evolution, the loss of structures that existed in a recent ancestor. However, fewer examples exist for genes underlying constructive evolution, the gain of novel structures and capabilities in lineages that previously lacked them. Sea robins are fish that have evolved enlarged pectoral fins, six mobile locomotory fin rays (legs) and six novel macroscopic lobes in the central nervous system (CNS) that innervate the corresponding legs. Here, we establish successful husbandry and use a combination of transcriptomics, CRISPR-Cas9 editing, and behavioral assays to identify key transcription factors that are required for leg formation and function in sea robins. We also generate hybrids between two sea robin species with distinct leg morphologies and use allele-specific expression analysis and gene editing to explore the genetic basis of species-specific trait diversity, including a novel sensory gain of function. Collectively, our study establishes sea robins as a new model for studying the genetic basis of novel organ formation, and demonstrates a crucial role for the conserved limb gene tbx3a in the evolution of chemosensory legs in walking fish.
From the scientific paper:
I’m not sure what depth has to do with it, but sea robins do have swim bladders that allow them to move up and down in a water column. A lot of fish have swim bladders.
Sequence changes to tbx3a in Prionotus carolinus resulted in the limb changes. The homologous gene in humans and other tetrapods is also involved in developing limbs. The sequences are not the same, but the function is similar.
It’s a separate issue, but in case you are wondering how fish and some aquatic mammals withstand extreme pressures:
The sea robin is an example of a fish that uses its fins in sort of walking on the seafloor, not just in swimming. (Batfish and mudskippers are other examples.) While their existence has long been known, the genetic analyses are new. The fact that some of the same genes were independently used by sea robins and land vertebrates in modifying limbs makes the fish an interesting comparison. Beyond that, headline hype is a problem.
For some reason my botany study group (that met regularly in a hot tub) found that term humorous. Once when one of the guys climbed out of the tub to go get some cold beers, but slipped and landed on his read end on the (wet) deck, someone hollered, “Dude, you need a gain of function!” We laughed so hard there was no studying done for half an hour.
One day in lifeguard training we were doing sunken swimmer search-and-recover drills during a thunderstorm, which made keeping formation, then diving again, three times as hard as on a calm lake. I remember wishing for some swim bladders!
In a comedy movie I watched years ago there was a scene where divers came up bringing a container with specimens that had been collected at depth and then the container sealed. They paid recognition to the pressure change by having a fish explode as it was removed from the container.
Most notably, there is a “walking fish” in California, called the Grunion that leaps onto the beach sand in order to mate and produce young.
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