Derpy from the side and hellish from below, the lamprey is the destruction of the Great Lakes fishing industry. Jawless fish and blood sucker, the lamprey is often considered an ancestral early vertebrate for its rudimentary morphology and larval stage of life. Now, a team of researchers has written a new study on fossilized lamprey larvae from the Devonian period that they say shows that the evolution of lamprey occurred differently than previously thought. This would mean that we would have to change our history of vertebrate origin.
The researchers’ paper was published Wednesday in the journal Nature. His argument depends on the life cycle of the lamprey. Modern lamprey larvae, called amocoets, are blind filters, which then transform into their predatory and noodly adult self. Both biologists and paleontologists have seen that the larval stage of parrots was a relic of the evolution of early vertebrates, and a sign that the lamprey could be relied upon as a living fossil that helps explain where all the vertebrates came from. animals with blankets. But recent team described lamprey fossils for babies that are not amocoets (these fossils look like smaller versions of adult lampreys) suggest that that larval stage was a later evolutionary adaptation, unique to lampreys.
“Now it looks like lampreys are weird,” Tetsuto Miyashita, a paleontologist at the Canadian Museum of Nature and lead author of the paper, said in a video call. “[The lamprey] it seems primitive, more primitive than these fish without extinct jaws. But it was the other way around. “
Miyashita’s team describes four different species of ancient lamprey from Africa and North America, ranging from 360 to 310 million years ago. At the time, the localities of Montana, Illinois, and South Africa (where eel-like lamps were excavated) were shallow seas; a habitat different from the freshwater that mixes the most today.
G / O Media may receive a commission
Non-amputated fossil lamps were not a smaller group of adult lampreys, according to the team, as some of the fossilized fish even have yolk sacs attached to the body. If this were only in one place, “we would have thought we were seeing this extensive and specialized and strange lamprey lineage that did what it did and perhaps lost the larval stage of filtration,” Miyashita said. “But species after species after species, through four different lineages of fossil lamps, show the same thing.”
The authors propose that the larval stage of the amocoquet was an adaptation that the lamprey developed to move to freshwater environments where they now thrive too well. Throughout the twentieth century, numerous efforts have been made to control the invasive lamprey population in the Great Lakes. First observed in Lake Ontario in 1835, lightning spread to other large lakes in the mid-20th century. Now, the established population wreaks havoc on lake trout, whitefish, ciscoes and other fish species, catching them with their suckers and ending their deaths. In the 1960s, the annual catch of fish in the Great Lakes was 2% of its previous average; a dramatic nose attributed to lampreys.
“These species, like the lamprey, which we think are‘ ancient fish ’have been evolving the same way we have had and are not frozen in time,” Jera said.miah Smith, a University of Kentucky biologist who was not affiliated with the recent article, in an email. “More generally, the study clearly shows that it is important to consider alternatives to widely accepted evolutionary scenarios and how new data sets continue to shape our understanding of the deep evolutionary history of the vertebrate lineage.”
For an alternative candidate to a vertebrate ancestor, the researchers propose armored Devonian fish called ostracoderms, which closely resemble warblers going to war.
“Lights are not the swimming time capsules we once thought they were,” co-author Michael Coates, a biologist at the University of Chicago, told a Canadian Nature Museum Press release. “They remain important and essential to understanding the deep history of vertebrate diversity, but we must also recognize that they have also evolved and specialized on their own.”
This story was updated to include comments from Jeramiah Smith.