1. Name the main laws of evolution.
Evolution is irreversible. Organisms that have arisen during evolution cannot return to the previous state of their ancestors.
In the process of evolution, life forms become progressively more complex.
Evolution is the process of unprogrammed development of living nature. There is no purposefulness in the process of evolution. Its movement is entirely dependent on natural selection.
Evolution reveals the relativity of the adaptability of species to their environment.
2. What are the similarities between microevolution and macroevolution?
The similarity lies in the absence of differences in the course of these processes, which allows us to consider them as two components of a single development of the organic world. Distinguish: microevolution occurs at the population level and leads to the formation of new species, while macroevolution leads to the formation of larger systematic units (above the species).
3. Why is a population called the form of existence of a species?
Because the formation of a new species occurs at the population level.
4. What role does the struggle for existence play in the evolutionary process?
The struggle for existence is carried out both between individuals of different species (interspecific struggle for existence) and between individuals of the same species (intraspecific struggle for existence). Another manifestation of the struggle for existence is the struggle with inanimate nature. As a result of the struggle for existence, some variations of traits in one individual give it a survival advantage compared to other individuals of the same species that have other variations of inherited traits. Some individuals with unfavorable variations die. Inherited traits that increase the likelihood of survival and reproduction of a given organism, transmitted from parents to offspring, will occur more and more often in subsequent generations. As a result, over a period of time, there are many such individuals with new characteristics and they turn out to be so different from the organisms of the original species that they already represent individuals of a new species.
5. Describe the main directions of evolution.
The main directions in evolution are biological progress and biological regression. Progress is an increase in the adaptability of organisms to the environment, accompanied by an increase in the number and wider distribution of the species. A decrease in the adaptability of organisms to environmental conditions, accompanied by a decrease in numbers and a narrowing of the area of distribution, is called biological regression. Biological regression is experienced by groups that were unable to adapt to changes in environmental conditions and could not withstand competition with other groups.
6. Reveal the significance of speciation in the life of nature.
As a result of speciation, new organisms appear in nature that adapt to new environmental conditions and can colonize new, previously uninhabited habitats.
7. In each line, three terms are interconnected in a certain way. Name them. Mark the fourth term that is not related to them:
Evolution, adaptation, population, speciation; (the extra term “adaptation”, the remaining terms in the line are interrelated: a population is the basic unit of evolution, which leads to the formation of new species (speciation).
Microevolution, population, fitness, macroevolution; (the term “population” is superfluous, since micro- and macroevolution are processes of increasing the fitness of organisms under environmental conditions, leading either to the formation of a new species or a structure above the species).
Idioadaptation, aromorphosis, degeneration, biological progress; (the term “degeneration” is superfluous since it is a manifestation of biological regression. All other terms refer to biological progress).
Natural selection, artificial selection, fitness, divergence. (an unnecessary term is “artificial selection”, since this is the process of a person’s purposeful selection of organisms with the necessary qualities of organisms and their subsequent reproduction).
Question 1. Name the main types of evolutionary changes.
Scientists distinguish the following types of evolutionary changes: parallelism, convergence and divergence.
Question 2. What are parallel changes, convergent, divergent?
Parallel changes (parallelism) represent the evolutionary development of related species, often having a common ancestor, caused by adaptation to similar living conditions.
With convergent changes (convergence), two or more species that are not closely related become more and more similar to each other. This type of evolutionary change is the result of adaptations to similar environmental conditions.
Divergent changes (divergence) are usually presented in the form of an evolutionary tree with diverging branches: a common ancestor gave rise to two or more forms, which, in turn, became the ancestors of many species and genera. Divergence almost always reflects increased adaptation to new living conditions.
Question 3. What is the difference between homologous structures and similar ones?
With parallel and convergent evolution, similarity in external structure can be the result of homology - origin from a common ancestor (an example is the limbs of different groups of vertebrates) or analogy - independent evolution of those organ systems that perform similar functions (for example, wings in birds and insects).
Homologous structures already in the embryonic period develop according to the same genetic programs. Similar structures perform the same functions, but do not have a common genetic basis.
Question 4. What are the main lines of evolution?
There are three main lines of evolution. Material from the site
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There are some differences among researchers in their ideas about the specific molecular mechanisms underlying mutations that are important for evolution, about the degree of influence on the evolution of individual organisms by factors such as natural selection, isolation, genetic recombination, hybridization, and the size of the breeding population. However, agreement was reached on some key points. It is absolutely clear that the primary material for evolution is changes in genes and chromosomes, that some kind of isolation is necessary for the emergence of a new species, and that natural selection ensures the preservation of some, but not all, mutations that arise. In addition, there are five basic laws of evolution recognized by almost all scientists:
Evolution occurs at different rates in different periods. Currently, it is proceeding rapidly, which is reflected in the emergence of many new forms and the extinction of many old ones.
The evolution of different types of organisms occurs at different rates. At one extreme are the brachiopods: some species have not changed at all over at least the last 500 million years - the shells of fossil brachiopods found in ancient rocks are completely identical to the shells of modern species. The other pole is occupied by humans: over the past few hundred thousand years, several species of hominids have appeared and died out. In general, evolution proceeds quickly when a new species first appears, and then gradually slows down as the group stabilizes.
New species are formed not from the most highly developed and specialized forms, but, on the contrary, from relatively simple, unspecialized forms. For example, mammals evolved not from large, specialized dinosaurs, but from a group of relatively small, unspecialized reptiles.
Evolution affects populations, not individuals, and occurs through the processes of mutation, differential reproduction, natural selection, and genetic drift.
The interaction between the environment and the object can be represented in the following form
Picture 1.
Here, arrow A shows the effect of the environment on the object being studied, and arrow B expresses the effect of the object on the external environment. Using the convenient terminology of communication theory, let us call A the channel through which the environment influences the system under study. Then, through channel B, the impact of the system (object) on the environment is realized.
Here is an example from biology. A living organism always functions in a specific environment. It can be a forest, a desert, water, a flask, etc. Through channel A, food and all external stimuli enter the body, and through channel B the body acts on the environment, changes its position in this environment, etc.
Such a concept is not idle speculation and has a deep meaning. It establishes strict relationships between objects in the world and, in fact, identifies and defines the essential causes of connection that interest us. Moreover, since every system has individual properties that characterize the connection between its input A and output B, then by observing A and B, one can know this object.
From this lesson you will learn how macroevolution differs from microevolution, get acquainted with the phenomenon of parallelism, find out what divergence and convergence are, which organs are called analogous and which are homologous. What do a man's hand, a bat's wing, a walrus' flipper, and a horse's hooves have in common? How do the eyes of mollusks and insects differ from our eyes? What is phylogeny and how is it related to our individual development - otogenesis? Is evolution reversible? Why are the body shapes of sharks, tunas, ichthyosaurs, dolphins and swimming penguins so similar?
The largest patterns that are observed within the framework of macroevolution were studied and described in the 19th and 20th centuries.
Elements of macroevolution:
- Convergence of features
- Divergence of characters
- Parallelism
Divergence- this is the accumulation of differences in the structure and functions of an organ during the process of evolution. As a result of divergence, several different organs are formed from one organ, connected by a common origin.
For example, the upper girdle of vertebrate limbs evolved into the paws and wings of reptiles, the wings of bats and birds, the fins of dolphins, the legs of ungulates, and the arms of primates.
All these organs perform different functions, but have the same origin.
Rice. 1. Homologous organs of vertebrates
Organs that were formed as a result of divergence are called homologous(Fig. 1). They are formed from similar embryonic rudiments.
Divergence provides morphological diversity of living things.
Convergence- a process inverse to divergence. This is the formation of organs that are similar in function and structure, but differ in origin.
Rice. 2. Similar organs: bird wings and butterflies
But, in fact, they developed completely independently from different ancestral forms. The requirements of the environment and the influence of natural selection determined their external similarity.
Organs that perform the same functions but have different origins are called similar(Fig. 3).
A typical example of similar organs is the eyes of cephalopods and vertebrates. These organs were formed independently over hundreds of millions of years, and in the end they turned out to be almost identical, differing only in details.
Rice. 3. Similar organs: eyes of a mollusk (octopus or squid) and humans
The third element in the transformation process is something between divergence and convergence, parallelism- a process when an organ, as a result of divergence, turns into many homologous organs. But then, in the course of evolution, these homologous organs again begin to perform a common function.
For example, the trunk and shoulder girdles of vertebrates have yielded many homologous variants. Ungulates, birds, fish, and reptiles were formed from identical skeletal elements, but then, in the process of evolution, some of them acquired the same characteristics for the second time (Fig. 4).
Rice. 4. An example of parallelism in the evolution of body shape in cartilaginous fish (shark), reptiles (ichthyosaur) and mammal (dolphin)
For example, the bodies of an ichthyosaur, a shark and a dolphin (and even a penguin swimming in the water) are very similar and were formed from the same skeletal elements, but along completely different evolutionary paths.
The ancestors of ichthyosaurs were lizards, the ancestors of dolphins were herbivorous land mammals, penguins were birds, and the ancestors of sharks were ancient cartilaginous fish.
Evolution follows three main paths: by divergence, by convergence and by parallelism.
The process of historical development of a species is called phylogeny.
An important stage in understanding evolution was the formulation of “ basic phylogenetic law» Ernest Haeckel.
“Ontogenesis is an accelerated repetition of phylogeny” E.G. Haeckel.
Haeckel clearly demonstrated that organisms in the process of embryonic development repeat all the stages that the species went through in the process of evolutionary development (see video). It is important to understand that we are talking about a repetition of the embryonic stages of ancestral forms.
In the human embryo, at different stages of ontogenesis, you can see gills, a heart tube and other signs of the embryos of our distant ancestors.
Another important law of phylogeny is "the law of irreversibility of evolution." Despite the presence of convergence, the similarity of different species is never complete.
The evolutionary process, due to the extreme complexity of living organisms, cannot create an exact copy of either an existing species or an extinct one. Each species of living organisms is unique.
So, we have learned that as a result of evolution, homologous organs can be formed through divergence, and similar organs can be formed through convergence. Found out that ontogenesis repeats the stages of phylogenesis and that each species of living organisms is unique.
Bibliography
- A.A. Kamensky, E.A. Kriksunov, V.V. Beekeeper. General biology, grades 10-11. - M.: Bustard, 2005. Download the textbook from the link: ( )
- D.K. Belyaev. Biology 10-11 grade. General biology. A basic level of. - 11th edition, stereotypical. - M.: Education, 2012. - 304 p. ()
- V.B. Zakharov, S.G. Mamontov, N.I. Sonin, E.T. Zakharova. Biology 11th grade. General biology. Profile level. - 5th edition, stereotypical. - M.: Bustard, 2010. - 388 p. ()
- IN AND. Sivoglazov, I.B. Agafonova, E.T. Zakharova. Biology 10-11 grade. General biology. A basic level of. - 6th edition, expanded. - M.: Bustard, 2010. - 384 p. ()
Homework
- What is evolution? How is macroevolution different from microevolution?
- What consequences of macroevolution do you know?
- What organs are called homologous? Give examples.
- What organs are called analogous? Give examples.
- What is parallelism?
- Using the human body as an example, discuss with friends and relatives the phenomena of homology, analogy and parallelism.
- Biological Dictionary ().
- All biology ().
- Internet portal Bio.fizteh.ru ().
- Biology ().
- Internet portal Sochineniya-referati.ru ().
>> Basic patterns of evolution
Basic laws of evolution.
1. What is evolution?
2. What facts support the doctrine of evolution?
When constructing phylogenetic series, evolutionary biologists, in addition to paleontological data, widely use the comparative method, with which they establish similarities in the structure of organisms, their biochemical reactions, reproductive characteristics or other properties by which one can judge the paths of development of a group from a common ancestor.
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