The modern theory of evolution is a complex fusion of different biological disciplines, from the oldest and most respected systematics of plants and animals to the latest molecular biology. Whatever may appear new in the concepts, theories and methods, evolutionary theory tries to apply it to his subject. The object of evolutionary theory is extremely difficult, because the theory of evolution is studying life itself in its most universal forms, and in the development of relationships with inanimate nature. (Although we admit that from a scientific point of view, this definition of the subject of the theory of evolution is not fully faithful.) In this sense, we can say, using your very podzatertoe comparison, the theory of evolution — is the queen of biology.
And, of course, does not pass the year to evolutionary biologists did not come up, not corrected, did not refute any of the evolutionary and ecological patterns. 2012-th was no exception, and here, perhaps, we should start with the concepts and hypotheses on the origin of life — the eternal theme that excites the minds of not only scholars, but very far from science representatives of the human race. (Again, in the brackets, we note that the origins of life, perhaps in the theory of evolution are not included, but we are here at your own risk included on the basis of, could be a very naive considerations: still, is the evolution of life from what- then begin!) Any hypothesis about the origin of life is to explain some important points: first, the living organism had to copy and transmit genetic information, and secondly, it must be separated from the membrane environment, or something similar, and thirdly, it needs to have a no metabolism to build biomolecules and himself of these biomolecules.
|The scheme of the ribozyme molecule. Since similar molecules could begin life on Earth. (Figure Laguna Design.)|
As you know, one of the most popular hypotheses to explain the mechanism of the appearance of the conservation and transmission of information in living systems, has become the RNA world hypothesis. Hereditary information we fill with nucleic acids — but only with the help of proteins. However, after the discovery of ribozymes, it became clear that sometimes nucleic acids can do without any help. This prompted the creation of the RNA world hypothesis. According to her, the first molecule on Earth were RNA: they themselves backed up, and then later joined by DNA and proteins, details of which could already be recorded on nucleic media. And this year, a group of researchers from several research centers in the United States could put an interesting experiment that showed how in such RNA soup could start evolution. It was found that a mixture of ribozymes advantage given to those molecules that mimic others and not themselves. That is the evolution of the launch, the transfer of information does not necessarily have to start with the copy itself (this, incidentally, ribozymes nobody has been able to achieve.) It is important that the molecule-grandparents can work not only with his consistency, but with someone else. Here, of course, can be said about the molecular mutual, but it will be pure anthropomorphism.
Well, let us exist RNA molecules that can store and copy the information. Q: they occur in the vast ocean of the primary? Assuming that they were floating in the membrane vesicles, it turns out that, except for some complex biomolecules, RNA, in the dawn of life there are others who have organized a membrane (eg, the same lipids). However, as the experiments of scientists from the University of Pennsylvania (USA), RNA molecules could group and without slozhnosochinennyh membranes. It appeared like RNA concentrated in relatively simple mixtures of substances, dextran and polyethylene glycol: their appearance in the aqueous solution collects RNA in a limited area. Existence at the dawn of time such simple materials as dextran and polyethylene glycol, is likely. With their help, the RNA world could do without membranes.
However, not all agree to give the laurels of the founders of one life only RNA. Scientists from the University of Illinois (USA) suggest that proteins and RNAs have emerged and for a time, side by side, and only after a while, the polypeptide chains of RNA called for help. Researchers have tried to restore the genealogy and age of different fragments of the ribosome — nucleoprotein complex machine, which translates the language of nucleic bases in the amino acid sequence. It was found that the proteins that make up the ribosome, no less than the corresponding RNA fragments. Moreover, the most important reaction center of the ribosome was younger than the other parts. But even if the proteins existed before together with the RNA, the question remains: how do they maintain their structure? How they store information about themselves?
|Molecular model of a large ribosomal particles yeast in different colors to identify different proteins. (Figure Laguna Design.)|
As for the origin of metabolism, the experts from the Santa Fe Institute (USA) seems to be quite able to show convincingly that the chemical reactions by which living organisms manipulate carbon existed in ancient geochemistry, although they were rather ineffective. That is picked up by living organisms from nonliving nature something non-obvious and does not work, and for the millions of years of evolution have made this quite efficient metabolic machine. Another question, where living organisms are engaged. Conventional wisdom "Life originated in the ocean" in the past year presented counterarguments. A team of researchers, some of whom are our compatriots from MSU, quite rightly suggested that the first organisms could not survive in the salt proportions that existed in prehistoric ocean. And because the first evolutionary steps life was not done in the deep ocean and space, and on the ground, in mud puddles, the composition of which was more sparing of the first living creatures.
The next evolutionary event, which in the past year of special attention of researchers — is the emergence of multicellular organisms. This episode is, so to speak, to the fundamental issues raised, and what fundamental problem, the harder it is for her to find a consistent theory. Multicellularity has obvious advantages, but what made the ancient unicellular move to this state? Especially in today's world is not such a unicellular downtrodden and fading group: just remember bacteria and oceanic plankton. Ingenious explanation offered by researchers from the University of California at Berkeley (USA), worked with hoanoflagellyatami which is believed to stand on the line between single and multicellular organisms. According to scientists, the ancestors of multicellular united by bacteria, but rather due to some substances that contain bacteria. Single-celled bacteria were fed, and that the substance that was contained in the bacteria, glued multicellular together in a colony. Not too appetizing hypothesis, if you think about it.
|Hoanoflagellaty single (left) and colony forming bacteria after feeding (right) (photo by Rosanna A. Alegado / University of California, Berkeley).|
Another surprising result were scientists from the University of Minnesota (USA), which evolved from unicellular yeast to multicellular formation … just 60 days. The driving force here was the gravity: to quickly settle to the bottom, the yeast cells are united with their families, and in the resulting clusters of different cells behave differently, that is demonstrating the main features of the emerging multi-cellular "identity." But the most surprising thing here, of course, supercompressed timelines are for this to happen. Well, most, perhaps, surprising hypothesis about the origin of multicellularity came from the pen of Stuart Newman of New York Medical College (USA). Dear Professor compared the basic building blocks that have a variety of animals, with viscoelastic chemical substances and concluded that the first multicellular formed under the action of physical and chemical forces, which do not affect the single cells, but inevitably comes into its own when the cells pleases unite.
In general, the theory of evolution has recently become extremely wide use experimental methods, however, it would seem, are associated with the evolution of the millions and millions of years of experiments, which can there be? Nevertheless, researchers suddenly realized who they believe will experiment mysteries of evolution. Assistants were bacteria and yeast: by highest rate of reproduction they can show evolutionary patterns for a reasonable time, we just need to plan the experiment. And with the help of these microscopic helpers last year was able to verify a number of key evolutionary concepts that still exist only in the form of speculative reasoning. For example, researchers from the University of Michigan (USA) were able to compare the concept of genetic mutation and phenotypic trait concept. The virus formed a new feature for the four mutations, bacteria, this required more than fifty. What is important here is not so much the absolute number (of course, for different organisms and different features it will not be the same), but the very method for assessing the interaction of genes in the formation of the trait and the number of mutations, which are expected to get them. And again with the help of bacteria were able to see the whole evolutionary cycle: 56,000 generations of bacteria and 20 years of the experiment allowed scientists to observe the formation of the three stages of the trait and compare them with phenotypic changes.
In turn, the yeast helped researchers from the University of Auckland (New Zealand) to confirm experimentally one of the main concepts in biology, sexual reproduction from an evolutionary point of view is better than asexual. However, one could argue that all these experiments are put on very specific sites, bacteria and unicellular fungi and their evolution can go other ways. But, as it turned out, at least in bacteria, new species are formed in the same way as animals — due to genetic diversity within a population, which is manifested by changing environmental conditions. That is, there is no need to invent some own bacteria, separate evolution.
|Baker's yeast — one of the main "workhorse" of modern biology (Dennis Kunkel Microscopy.)|
Certainly, not to mention an experiment researchers from the University of Rhode Island (USA), who have managed to see the evolution is not in a test tube, not in bacteria, and among lizards. Scientists to think to check whether in fact an evolutionary-genetic effect, called the founder effect, when dispersing small population caught between a rock and a hard place — natural selection and its own modest means (because of settling) gene pool. So, for several years, researchers have observed firsthand the struggle between the two evolutionary factors that previously existed only in theory. True, one must admit that with the experimental conditions zoologists luck at their disposal to islands cleared of most of the fauna of the strongest hurricane.
|Lizards of the genus anoles became participants of the unique evolutionary experiment. (Photo by Jim Merli.)|
In other news on obscheevolyutsionnyh laws should note two posts on the molecular mechanisms of evolution. At Stanford (USA) in the example stickleback was confirmed well-known conjecture that b? Most of evolutionary change is reshuffling existing genes rather than creating new ones. That is, create several types of genetic script to life, of which one is working, while others are sleeping. If there is a need, it switches between the genetic make — due to mutations in the DNA sequences of several managers. That's right, according to scientists, sticklebacks were able to quickly move from the sea into the salt water. And so, by the way, could be a man: according to some researchers, we are different from monkeys first way to control genes.
In another study published by scientists from the Massachusetts Institute of Technology (USA), said that the main tool of molecular evolution, the basic molecular mechanism for adaptation of species to the environment, can be an alternative RNA splicing. In any case, according to the results of this research group, the different species differ from each other not so much the activity of genes, how many ways of alternative splicing.
Of more particular evolutionary research related to the development of separate groups of animals, we can recall the work of researchers from the Smithsonian Tropical Research Institute (U.S.) and Wageningen University (Netherlands), who concluded that the rodents through their thieving habits of prehistoric forests saved from extinction. And researchers from Monash University in Australia have tried to calculate how long it takes evolution to turn into an elephant and a mouse back — and then was struck by its slowness evolution. And, of course, a separate issue — this is the origin and evolution of man himself. About the transition from ape to man and his evolutionary-genetic causes can be found in the next article. Here it is worth mentioning the experiment, researchers from Trinity College (Ireland), which are using a simulation of evolution showed that the complex social life goes hand in hand with the development of large neural systems. That is, roughly speaking, better brain development occurs in the community.
However, separated from the apes, and formed the first civilization, man is not released from the power of evolution and natural selection. For example, scientists from the University of Sheffield (UK) showed the influence of natural selection on the example of human population dynamics in several Finnish villages. It turned out that even in a monogamous society is evolutionary changes in traits that can be seen for several hundred years. We can assume that in the modern world, with the development of medicine, contraception, and so on and so forth, no place, not only for the old, traditional communities, but for evolution. However, researchers from the University of Groningen (Netherlands) claim that natural selection is still valid even in the important from the point of view of aesthetics and fashion option, as the growth: while modern men and women prefer high partners evolution favors tall men, but women are stunted.
|In prehistoric times, it is older women caring about other people's children lengthened the human life. (Photo by Barry Lewis.)|
For a long time, the phenomenon of menopause could not find an explanation from the scientists. Man — one of the rare exceptions among the animals, our individual female with a certain age lose the ability to produce offspring. This strange and irrational evolutionary strategy seems to have found its explanation in the theory: the menopause need to take care of my grandmother could offspring of their children, thereby enhancing its survival. It is through the menopause, according to researchers from Turkuskogo University (Finland), an elderly woman can give their time and energy to her daughter or daughter-that is focused on their own kids. This hypothesis has existed before, but this time it was tested for the human population. Caring grandmother bore fruit — Anthropology of the University of Utah and the University of California at Los Angeles (both — the U.S.) have confirmed that due to grandmothers people are living longer.
Above we called evolutionary theory queen biology. Evil tongues might say that it is in the full sense of the queen, using the results and methods of other areas, it does not give anything in return in terms of practical use: any of it as from goat milk (can not be represented entirely evolutionary matter, be possible in terms of genetic engineering). This is not true: the conclusions in the theory of evolution, may be useful to other more practical areas. That is a remarkable example of the cancer center researchers named H. Lee Moffitt (USA) published a paper in which it is through the theory of evolution explains the surprising ability of cancer cells to resist chemotherapy. In fact, the researchers treated tumors as a population, which is governed by the evolutionary and environmental laws. If the hypothesis is correct, the oncologists to cope with cancer, you need to be radically revised approaches to treatment. And perhaps it is due to the theory of evolution we would ever conquer cancer. (Note that the assimilation of cancer population is not such a radical step — up from last year's work, in which the cancer was likened to a single body, and offered perhaps the role of our ancestors.)
|Is it possible to cure cancer with Darwin? (Photo by Moredun Animal Health.)|
Other results of evolutionary studies, which can be useful from a practical point of view, we can mention that, as climate change plays into the hands of parasites, as well as the genealogy of evil Ebola and Lassa, who were much older than the thought of them. Both would be useful to epidemiologists and all the doctors who would give a lot for that to know what to expect from future infection.
In fact, as is easily seen, the modern theory of evolution is more reminiscent of a ghost, an elusive entity that occurs at the interface of different disciplines, from psychology to immunology. So it makes sense to speak not so much of a single discipline as an evolutionary approach, which can be a powerful weapon in the knowledge of the natural world — no matter whether it be abstract and high mystery of origin of life or of the "low-lying" day-to-immunological health issues .
|Zlatokrot (Photo Inspector Lewis).|
However, despite all the greatness and power of the evolutionary approach, it does not always fire. And the passing year gave us two interesting examples where evolutionary biologists could only shrug. The first — the bacteria out of the cave Lechuga, in the U.S. state of New Mexico. Local microbes were able to acquire resistance to most modern antibiotics, although there have been isolated from the environment in the last thousand years, — a phenomenon that can not be explained by evolutionary-genetic point of view. The second number is zlatokrot: the emergence of this amazing animal shimmering golden fur can not be explained by any evolutionary necessity, and the scientists have to say that in this case we are dealing with a "by-product, and any other useless evolutionary transformations."