动物造模,脊椎动物 z-bo 2020-09-26 305

　　Scientists at the University of Nottingham have shown in a new study that animals (including fertility) may evolve faster. This research challenges traditional theories about how certain vertebrate species have evolved.

　　A study published in the journal Science by scientists from the University of Nottingham challenged long-term perceptions of the evolution of certain vertebrate species. A study conducted by Dr. Martin Luce and Dr. Andrew Johnson, genetics and cell development experts in the School of Life Sciences,

　　Medical Research Council (MRC) funding, discovered the genetic evolution of species, including fecundity. It proved to be faster. fast. As a result, they tested a new theory that early developmental events can significantly change the structure and evolution of vertebrate bodies.

　　The original theory was put forward by Dr. Johnson 10 years ago. His view is that the relationship between the germ line (that is, the hereditary germ cells that produce sperm and eggs) and somatic cells (the cells that make up an organism) also affects species diversity. .. He believes that when a species evolves a substance called bacteria, the germ cells are unique, thereby removing the restriction on somatic cell development and enhancing the ability of the species to evolve. Therefore, it is worth noting that vertebrates such as frogs, fruit flies and birds do not look like their ancestors, but they evolve faster than their ancestors.

　　New appearance welcome to implant

　　In the early stages of animal development, embryonic daughter cells are dedicated to producing primordial germ cells (PGC). Primordial germ cells develop into sperm or eggs. The remaining cells develop into somatic cells. This is a term used to describe all the body tissues that make up a person. The germ line is an immortal cell line that can control the fertilized egg to form a new embryo for several generations. On the other hand, somatic cells are passed down from generation to generation. The most classical biological importance is to explain the role of natural selection in determining genetic compatibility, leading to the so-called "most appropriate survival". create

　　There are two known methods for

　　PGC. One is the preformed theory of evolution theory. A substance called egg cell reproductive material is directly inherited by certain cells of the embryo, and the reproductive material regulates these cells to become PGCs. Another method is that PGC is independent of reproductive development. In this case, secretion signals from certain somatic cells induce the formation of PGC, which is called progressive.

　　Dr Johnson said: "Biologists are used to thinking about how adult physical characteristics affect natural selection and the formation of new species. The role of evolutionary embryonic mechanisms and how they affect species diversity. It is not clear whether it will promote."

　　The new computer program tests the hypothesis recently published by Dr. Ruth. He said: "To study the effect of reproduction quality on sequence changes. In order to observe as many sequences as possible, 12 million sequences from 165 different species were analyzed and processed, including mammals and reptiles, amphibians and fish."

　　Ruth and graduate student Terry Evans wrote a computer program to process sequences and test hypotheses. They use epigenetics to compare the DNA sequences of fertile species with relatives. So, for example, we compared the DNA of amphibious sal (apparent pi) and frog (fertility). Unexpectedly, they found that certain reproductive quality sequences changed much faster than those without reproductive sequences. Therefore, frogs evolve faster than sal. Similar comparisons of fish and reptiles confirmed the same pattern. This shows that it is a universal feature of animal evolution. These results indicate that reproductive quality can develop faster and therefore has the advantage of selectivity. In addition, they also support the idea that the relationship between germ cell development and somatic cells in the animal world will affect the formation of species diversity.

　　Dr. Johnson said: "The theory Martin and I were looking for was not what we expected. This study shows that fertile animals can evolve faster. Evolution is usually considered a gradual process. This work is not the case. It shows that the evolution of reproductive quality will lead to explosive radiation of species. Importantly, the speed of evolution is accelerating, so the genetic similarity sex coefficient between species may be different from the expected genetic relationship. This has a wide range of biological effects.

　　But there is a price to pay for the evolution of reproductive quality. The first interesting thing is that the early discovery of animal embryos (including fertility) is different from embryos using epigenetics. In fact, the body structure of these adult animals is Their "typical vertebrates". Is different. Therefore, we use Sal as an experimental model. It is a "typical vertebrate" and has no fertility. We have discovered a mechanism that can control the development of the in mammalian embryos. However, this is not seen in the development of "normal" vertebrates. Therefore, the evolution of fertility leads to a dead end in evolution. In other words, sal amphibians can evolve into reptiles and then into mammals. Frogs can only evolve into other frogs. There are many types of frogs, but there are still only frogs. Therefore, researchers believe that sal can be used as a model for future human development research.