For millions of years, laying eggs was the primary means for snails, but at some point in the last 100,000 years, a group of marine snails began to abandon their eggs and give birth alive. Ta. This switch happened in an evolutionary blink of an eye, and scientists have now discovered that it was caused by about 50 genetic changes. The rare opportunity to study the genetic structure of evolutionary change has revealed that the secret lies not in one giant leap, but in the accumulation of many gradual changes.
that Littorina saxatilis Being a living snail is almost the only obvious characteristic that distinguishes it from its egg-laying neighbors. Because it shows a wide variety of shell types and habitats. This may explain why it is one of the most misidentified organisms on Earth. guardian.
To better understand how these marine snails are differentiated at the genetic level, a research team led by Sean Stankowski, a postdoctoral researcher at the Austrian Institute of Science and Technology (ISTA), examined the snail family tree. Ta. L. saxatilis Its close relatives using whole genome sequences. By doing so, it became clear that The ability to give birth to live offspring is associated with 50 genetic changes scattered throughout the snail’s genome, and the degree of interbreeding between snails has made them easier to identify. L. saxatilisrange, which could lead to genetic exchange across species.
“In this case, all this cross-breeding has mixed up the genetic backgrounds, giving us an opportunity to find the genes involved in the evolution that gave rise to life.” Professor Roger Butlin a professor in the School of Biological Sciences at the University of Sheffield told IFLScience. “That’s why the genes involved in the creation of life stand out from the background.”
They are both Littorina saxatilis, but the larger snail is one ecotype adapted to defend against crab attack, and the smaller snail is a second ecotype adapted to live in areas exposed to strong waves.
Image credit: Sophie Webster
Tracing back a wealth of genetic information reveals that living offspring of marine snails emerged gradually over the past 100,000 years through the accumulation of a series of mutations. However, it is still unclear which of these gradual changes played a pivotal role in the remarkable changes in reproductive strategy.
“I don’t think we can say at this point which specific traits were required for survival,” Butlin continued. But we wonder if some of them are probably involved in other things that come with live breeding, such as changing to breeding all year round instead of just one season. is thinking. ”
The reason for this behavior is that by laying eggs alive, the young snails are less likely to dry out, be crushed, or be eaten before they hatch, which may be beneficial to the snails. There is sex. But that doesn’t mean it didn’t come at some cost to the parents.
“Additional investment in offspring would almost certainly have placed new demands on the snail’s anatomy, physiology, and immune system,” Stankowski said in the paper. statement. “Many of the genomic regions we have identified may be involved in responding to these types of challenges.”
The wide range of shell types and habitats of Littorina snails may be the result of allowing them to adapt to diverse environmental conditions in the living state. This has led to the evolution of many “ecotypes” that differ in size, shape, and behavior.
Image credit: Fredrik Pleijel
Understanding how such large changes occur in evolution occurs so slowly and across a wide range of species, many of which have become extinct, that we rarely have the opportunity to explore. A team of researchers at the University of Sheffield said this rare example of studying the genetic structure of evolutionary change shows that radical innovations occur through gradual steps, and can take a large amount of time to establish surprising new capabilities. No genetic leap is needed, he says.
This not only tells us about major evolutionary changes in the past, such as how feathers led to flight, but also how future changes will occur in response to climate change, etc. You can also find out if it exists. It is unlikely that they will adapt the thermoregulation necessary to survive it.
“Discovering and studying recent evolutionary changes in how marine snails give birth will allow us to understand these major changes and apply our methods to many other evolutionary changes.” Butlin wrote in another paper. statement.
“Our results will change the way biologists look at large evolutionary transitions, shifting the focus from large evolutionary leaps to understanding the incremental benefits of small evolutionary steps. They may also help other adaptations. It will also help others analyze the genetic and historical basis of traits, which is important at a time when many organisms are being forced to rapidly adapt to a changing world.”
The research will be published in a journal science.