All the evidence for evolution. Evidence for the evolution of the organic world
Topic: Evidence of evolution. Embryological evidence. Morphological evidence. Paleontological evidence. Biogenetic evidence for evolution.
Target: introduce students to various groups of evidence for the evolutionary process.
Tasks: -Explore the scientific significance of the discovery in the development of embryos of traces of the distant history of systematic groups.
Assess the biogenetic law of F. Muller and E. Haeckel as embryological evidence.
Find out the significance of fossil transitional forms for science as paleontological evidence, study comparative anatomical evidence of evolution.
Type of training session: learning a new topic.
PROGRESS OF THE LESSON
I. Frontal survey on d/z (8 min):
Conversation on issues :
1.What is evolution?
2.How were scientists able to reconstruct the history of planet Earth? What methods did they use to do this?
3.What large and small segments are the entire history of our planet divided into?
4.At what time did life appear?
5.Give a general description of life in each of the five eras.
Task 1: You are offered sheets with a list of animals, plants and the largest aromorphoses. They are all numbered. Organize them into the appropriate eras as they arise. Write down the numbers.
Proterozoic
Paleozoic
Mesozoic
Cenozoic
The appearance of blue-green algaePsilophytes
Emergence of eukaryotes
Emergence of chordates
The appearance of the first mammals
Stegocephals
The emergence of sexual reproduction (meiosis)
Lobe-finned fish
The emergence of multicellular organisms
Trilobites
The emergence of photosynthesis
Dinosaurs
Mastadons
Giant ferns
Task 2. “Black box”
The guys are offered tasks from a black box.
1. In the black box there is an image of a dinosaur about which we can say this: “There was a double set of brains, and they occupied such places, one in the head, like everyone else, and the other at the beginning of the tail. This “beast” could say about himself that he was always strong in hindsight.” What animal are we talking about?(Stegosaurus)
2. By the middle of the Mesozoic, these marine animals had progressed and are now found in all marine sediments. (Ammonites)
3. In the black box there is a famous photograph taken in Scotland in 1934. Which dinosaur was called the Loch Nes monster, describe it.(Plesiosaur)
4The first fossil find of this animal was a single feather, discovered in 1861 in Bavaria. Half bird, half lizard. What kind of animal is this?(Archaeopteryx)
2. Learning new material:
Directions of evolution
biological progress
Number biological regression
Area
Differentiation
Mortality
Fertility
Division into groups. Work in groups (work with the textbook and posters)
Hypothesis: modern science has many facts proving the existence of the evolutionary process.
1 group
: Embryological evidence pp. 154-157
Evidence of the unity of origin of the organic world - (Work on posters)
2nd group
:
Paleontological evidence pp. 157-158
Biochemical evidence p. 160- (Work on posters)
3 group : Comparative anatomical (morphological). Genetic evidence pp. 158-160.Fill out the table.
Comparative proofExamples
Definition
Sample to fill out (for verification)
Comparative anatomical evidence of the evolution of the organic world
Comparative proofExamples
Definition
1.
Homologous
body shape : whale - fish
needles barberry - hawthorn
root
Organs that have a similar structure and a common origin, but perform different functions
2.
Similar
bird wings - butterflies
gills fish - crayfish
limb mole bears
Organs that are similar in appearance and perform the same functions, but have different origins
3.
Vestigial
cave fish eyes
kiwi wings
appendix
organs that are formed during embryonic development, but subsequently stop developing and remain in an underdeveloped state in adult forms
4.
Atavisms
tail
multi-nipple
facial hair
the appearance in individual organisms of a given species of characteristics that existed in distant ancestors, but were lost during evolution
5.
Transitional
euglena
platypus
echidna
fforms that combine the characteristics of several large systematic units
Conclusion: Facts of comparative anatomy revealfamily relationships between individual organisms, which provesevolution of the organic world.
1 group. Evidence of the unity of origin of the organic world .
Exercise: listen to the presentation and additional information. Write down the evidence from this group in your notebook.
Evidence of unity of origin organic world on Earth:
1) plants, animals, fungi and bacteria have a common elemental composition;
2) the unity of living things at the molecular level, expressed primarily in the presence of proteins and nucleic acids in all living beings;
3) similarity in the way biological molecules function (genetic coding, transcription, translation, DNA replication, glycolysis, etc.);
4) the universality of cellular structure and the similarity of the structure of cells of organisms from different kingdoms of the organic world;
5) unity of cell functioning, manifested in the processes of mitosis, meiosis, fertilization, etc.
Molecular evidence evolution.
This group of evidence includes the following:
A)Biochemical – fundamental similarity in the chemical composition of the intracellular environment in different organisms.
b)Genetic (molecular) - similarity in the number of chromosomes and their gene composition in related forms of organisms.
All organisms have DNA and RNA at the molecular level
Contains proteins consisting of 20 amino acids.
What is universal is the genetic code and DNA replication.
Protein synthesis according to a single scheme: transcription - translation
Most people use ATP as battery molecules.
V)Cytological – similarity in the structure of cells and their functioning in representatives of related groups of organisms.
Embryological evidence for evolution
Embryology
is the science of the embryonic development of an organism.
The foundation of evolutionary comparative embryology was laid by A.O. Kovalevsky and I.I. Mechnikov.
Embryological evidence proves the degree of relatedness based on the embryonic development of an organism. Embryological data that is evidence of evolution include: Karl Baer's Law of Germinal Similarity (1828), Haeckel-Müller Biogenetic Law,
Ontogenesis (individual development of organisms) there is a brief repetition of phylogeny (historical development of organisms)
2nd group. Paleontological evidence
Paleontology is the science of animals and plants of past geological eras, studied from fossil remains. The term was proposed in 1822 by A. Blainville. The foundations of modern evolutionary paleontology were laid by V.O. Kovalevsky. Paleontology presents the following data in favor of evolution:
Information on fossil transitional forms , which have not survived to this day and are present only in the form of fossil remains. Examples of fossil transitional forms are: ancient lobe-finned fishes, seed ferns, psilophytes,beast-toothed lizard , Archeopteryx etc. The existence of transitional forms between different types and classes shows that the gradual nature of historical development is characteristic not only of lower systematic categories (species, genera, families), but also of higher categories and that they are also a natural result of evolutionary development.
Information aboutphylogenetic series , which not only show changes in the process of evolution, but also allow us to find out the reason for the evolution of certain groups of organisms. For example: the history of the development of horses during adaptation to life in the steppe plain area. Phylogenetic series convincingly show that evolution as a whole is adaptive in nature.
Answer the question:
1) Indicate the transitional forms:
fish... amphibians
spore ferns ... gymnosperms
amphibians... reptiles
reptiles...mammals
reptiles...birds
single-celled plants... single-celled animals
Biochemical evidence
Group 3 Comparative morphological evidence
Rudiments (Latin rudimentum - rudiment, fundamental principle) - these are organs that are formed during embryonic development, but later stop developing and remain in adult forms in an underdeveloped state. In other words, rudiments are organs that have lost their original significance during evolution. The presence of rudiments, as well as homologous organs, indicates a common origin of living forms. The whale's hind limbs, hidden inside the body, prove the terrestrial origin of its ancestors. The limbs of snakes are completely rudimentary. Diptera insects (flies, mosquitoes) have a rear pair of wings transformed into halteres. Vestigial organs are known in humans: the muscles that move the auricle, the third eyelid (about 150 in total).
Atavisms (lat. atavus - ancestor, progenitor) - the appearance in individual organisms of a given species of characteristics that existed in distant ancestors, but were lost during evolution. The appearance of atavistic characteristics is explained by the fact that during the development of an individual, the organizational features of the ancestors are repeated to some extent (Biogenetic Law), then violations of normal development can lead to the fact that in an adult organism the characteristics of the ancestors, which normally appear in the embryo and usually disappear, will remain for life during further development.
Among thousands of one-toed animals, there are individuals that develop three-toed limbs. There are known cases of the appearance of atavistic signs in humans: the development of additional pairs of mammary glands (multi-nipple), hair on the entire body and face, and a tail. The emergence of atavisms indicates a historical relationship between extinct and currently existing forms.
Transitional forms - fforms that combine the characteristics of several large systematic units. Example: green euglena (plant characteristics: chloroplasts, use of CO 2 ; signs of animals: flagella, light-sensitive eye.
The connection between different classes of animals indicates their common origin. Oviparous animals (platypus, echidna) are intermediate between reptiles and mammals in a number of features of their organization.
The Hoatzin is a modern bird, similar in some features to Archeopteryx. With the help of specific claws on their wings, hoatzin chicks can climb branches, and in case of danger they prefer to “sit out” in the water. Archeopteryx is half bird, half lizard. Thisextinct vertebrate of the late Solnhofen in the south . For a long time (before the appearance of other finds) it was used to reconstruct the appearance of the supposed common ancestor of birds.
Task: 2. Distribute these biological objects into 4 groups: analogues, homologues, atavisms and rudiments.
1. Root and rhizome
2. Limbs of a mole and mole cricket
3. Bird wing and butterfly
4. Paws of a tiger and a mole
5. Pea and grape tendrils
6. Crayfish and crab claws
7. Trapper leaves of sundew and pestle
8. Gills of crayfish and fish
9. Hawthorn and barberry thorns
10. Bat wings and a human hand
11. Whale pelvic bones
12. Three-toed horses
13. Hairy man
14. Underdeveloped mole eyes
15. The anteater lacks teeth
16. Human tail
17. Human appendix
18. Multiple nipples in humans
19. The wings of a non-flying kiwi
20. Pelvic bones in snakes
III. Consolidation
Solve the test:
1. Similar organs in plants are:
Root and rhizome (a);
Leaf and sepal (b);
Stamens and pistil (c).
2. The divergence of characters in organisms is caused by:
Modifications (a);
Combinations (b);
Mutations (c).
3. The diversity of finches is the result of:
Degeneration (a);
Aromorphosis (b);
Divergences (c).
4. The transitional form between amphibians and reptiles were:
Stegocephals (a);
Dinosaurs (b);
Animal-toothed reptiles (c).
5. For the first time they began to reproduce by seeds:
6. The transitional form between reptiles and birds is:
Pterodactyl (a);
Foreignness (b);
Archeopteryx (c).
7. Who discovered successive rows of fossil equine forms?
IN. Kovalevsky (a);
A.O. Kovalevsky (b);
Karl Baer (c).
IV. Lesson summary, homework
71. Evidence of evolution: comparative anatomical, embryological, paleontological, etc.
Paleontological evidence of evolution. Fossil remains are the basis for restoring the appearance of ancient organisms. The similarity between fossils and modern organisms is proof of their relationship. Conditions for the preservation of fossil remains and imprints of ancient organisms. The distribution of ancient, primitive organisms in the deepest layers of the earth's crust, and highly organized ones in the later layers.
Transitional forms (Archaeopteryx, wild-toothed lizard), their role in establishing connections between systematic groups. Phylogenetic series - series of successively replacing each other (for example, the evolution of a horse or elephant).
2. Comparative anatomical evidence of evolution:
1) cellular structure of organisms. Similarity in the structure of cells of organisms of different kingdoms;
2) general plan of the structure of vertebrate animals - bilateral symmetry of the body, spine, body cavity, nervous, circulatory and other organ systems;
3) homologous organs, a single structural plan, common origin, performance of various functions (skeleton of the forelimb of vertebrates);
4) similar organs, similarity of functions performed, differences in general structure and origin (gills of fish and crayfish). Lack of relationship between organisms with similar organs;
5) rudiments - disappearing organs that, in the process of evolution, have lost their significance for the preservation of the species (the first and third fingers in the wing of birds, the second and fourth fingers of a horse, the pelvic bones of a whale);
6) atavisms - the appearance of signs of ancestors in modern organisms (highly developed hair, multiple nipples in humans).
3. Embryological evidence for evolution:
1) during sexual reproduction, the development of organisms from a fertilized egg;
2) the similarity of the embryos of vertebrate animals in the early stages of their development. Formation of characteristics of a class, order, and then genus and species in embryos as they develop;
3) the biogenetic law of F. Muller and E. Haeckel - each individual in ontogenesis repeats the history of the development of its species (the body shape of the larvae of some insects is evidence of their origin from worm-like ancestors).
72. A.I. Severtsov’s teaching on phylembryogenesis.
PHYLEMBRYOGENESIS- an evolutionary change in the ontogenesis of organs, tissues and cells, associated with both progressive development and reduction. The doctrine of phylembryogenesis was developed by the Russian evolutionary biologist A.N. Severtsov. The modes (methods) of phylembryogenesis differ in the time of occurrence during the development of these structures. If the development of a certain organ in descendants continues after the stage at which it ended in the ancestors, anabolia occurs (from the Greek anabole - rise) - an extension of the final stage of development. An example is the formation of a four-chambered heart in mammals. Amphibians have a three-chambered heart: two atria and one ventricle. In reptiles, a septum develops in the ventricle (first anabolia), but in most of them this septum is incomplete - it only reduces the mixing of arterial and venous blood. In crocodiles and mammals, the development of the septum continues until the complete separation of the right and left ventricles (second anabolia). In children, sometimes, as an atavism, the interventricular septum is underdeveloped, which leads to a serious illness requiring surgical intervention.
Prolonging the development of an organ does not require profound changes in the previous stages of its ontogenesis, therefore anabolism is the most common method of phylembryogenesis. The stages of organ development preceding anabolism remain comparable to the stages of the phylogeny of ancestors (i.e., they are recapitulations) and can serve for its reconstruction (see Biogenetic law). If the development of an organ at intermediate stages deviates from the path along which its ontogenesis took place in its ancestors, deviation occurs. For example, in fish and reptiles, scales appear as thickenings of the epidermis and the underlying connective tissue layer of the skin - the corium. Gradually thickening, this anlage bends outward. Then in fish the corium ossifies, the forming bone scales pierce the epidermis and move to the surface of the body. In reptiles, on the contrary, bone is not formed, but the epidermis becomes keratinized, forming the horny scales of lizards and snakes. In crocodiles, the corium can ossify, forming the bony basis of the horny scales. Deviations lead to a more profound restructuring of ontogenesis than anabolism, so they are less common.
Changes in the primary organ rudiments—archallaxis—occur least often. In case of deviation, recapitulation can be traced from the origin of the organ to the moment of developmental deviation. In archallaxis there is no recapitulation. An example is the development of vertebral bodies in amphibians. In fossil amphibians - stegocephalians and in modern tailless amphibians, the vertebral bodies are formed around a chord of several, usually three on each side of the body, separate anlage, which then merge to form the vertebral body. These anlages do not appear in tailed amphibians. Ossification grows above and below, covering the notochord, so that a bone tube is immediately formed, which, thickening, becomes the vertebral body. This archallaxis is the reason for the still debated question of the origin of tailed amphibians. Some scientists believe that they descended directly from lobe-finned fish, regardless of other land vertebrates. Others say that tailed amphibians diverged very early from other amphibians. Still others, neglecting the development of the vertebrae, prove the close relationship of tailed and tailless amphibians.
Organ reduction, which have lost their adaptive significance, also occurs through phylembryogenesis, mainly through negative anabolism - loss of the final stages of development. In this case, the organ either underdevelops and becomes a rudiment, or undergoes reverse development and completely disappears. An example of a rudiment is the human appendix - an underdeveloped cecum; an example of complete disappearance is the tail of frog tadpoles. Throughout its life in water, the tail grows, new vertebrae and muscle segments are added at its end. During metamorphosis, when the tadpole turns into a frog, the tail dissolves, and the process occurs in the reverse order - from the end to the base. Phylembryogenesis is the main method of adaptive changes in the structure of organisms during phylogenesis.
Embryological
In embryonic (embryo) development, organisms have characteristics of their evolutionary ancestors. For example,
- all organisms begin development from the one-cell stage (zygote);
- a two-layer embryo (gastrula) corresponds to coelenterates;
- closely related organisms have similar stages of embryonic development (similar sequence of organ formation);
- The human embryo is covered with hair and has a tail - this indicates the origin of man from animals.
Paleontological
1) Fossils and the imprints (fossils) of ancient organisms show how their historical development (evolution) proceeded.
2) Phylogenetic series- these are rows of species that successively replaced each other in the process of evolution.
3) Transitional forms(prove the origin of organisms):
- lobe-finned fish coelacanth and stegocephalus - amphibians from fish;
- Archeopteryx - birds from reptiles.
Biogeographic
Flora and fauna (FF) of volcanic islands
- very poor because it is difficult for animals and plants to get from the mainland to the new island;
- contains many endemics (species found only here).
The FF of islands that break away from the mainland is very similar to the FF of the mainland; The earlier the separation occurred, the greater the difference.
Biochemical
All living organisms on Earth are composed primarily of proteins; hereditary information is encoded in nucleic acids, the processes of replication, transcription, translation, glycolysis, etc. occur in the same way. All this testifies to the unity of the organic world.
1. Establish a correspondence between the example and the type of evidence of evolution to which this example belongs: 1) paleontological, 2) comparative anatomical
A) transitional forms
B) homologous organs
B) rudiments
D) a single structure plan of organs
D) fossils
E) atavisms
Answer
2. Establish a correspondence between the example and the type of evidence of the evolution of the animal world that it illustrates: 1) comparative anatomical, 2) paleontological
A) phylogenetic series of the horse
B) the presence of a coccyx in the human skeleton
B) bird feather and lizard scales
D) prints of Archeopteryx
D) multiple nipples in humans
Answer
3. Establish a correspondence between examples and methods of studying evolution: 1) paleontological, 2) comparative anatomical. Write numbers 1 and 2 in the order corresponding to the letters.
A) bird wing and butterfly wing
D) multiple nipples in chimpanzees
D) human appendix
Answer
4. Establish a correspondence between examples of objects and methods of studying evolution in which these examples are used: 1) paleontological, 2) comparative anatomical. Write numbers 1 and 2 in the correct order.
A) cactus spines and barberry spines
B) remains of beast-toothed lizards
B) phylogenetic series of the horse
D) multiple nipples in humans
D) human appendix
Answer
5. Establish a correspondence between the examples and evidence of evolution, which are illustrated by these examples: 1) paleontological, 2) comparative anatomical. Write numbers 1 and 2 in the order corresponding to the letters.
A) the remains of a beast-toothed lizard
B) imprints of Archeopteryx on rocks
C) the presence of a tail in humans
D) phylogenetic series of the horse
D) phylogenetic series of the elephant
E) multiple nipples in humans
Answer
1. Select three sentences from the text that describe paleontological evidence for evolution. Write down the numbers under which they are indicated. (1) The history of the development of the organic world on Earth is preserved in the form of fossil remains. (2) It has been proven that proteins in closely related groups of organisms are similar in amino acid composition. (3) For example, hemoglobin in humans and chimpanzees is identical, but between human and gorilla hemoglobin there are differences in two amino acids. (4) It is known that the structural plan of terrestrial vertebrates is the same in different classes. (5) Transitional forms from algae to higher plants have been discovered - these are psilophytes. (6) In the animal kingdom, the evolution of many groups has been restored, and phylogenetic series have been compiled.
Answer
2. Read the text. Select three sentences that identify paleontological methods for studying evolution. Write down the numbers under which they are indicated. (1) Transitional forms are organisms that combine characteristics of both ancient and young groups of large systematic taxa. (2) Rhiniophytes were the first land plants. (3) V.O. Kovalevsky created a phylogenetic series of the horse and proved the gradual nature of the evolutionary process. (4) By comparing the flora and fauna of different continents, scientists reconstruct the course of evolution. (5) Lake Baikal is home to many endemic species.
Answer
Choose one, the most correct option. What stage of embryonic development does the structure of freshwater hydra correspond to?
1) blastula
2) gastrula
3) neurule
4) zygote
Answer
Choose one, the most correct option. Reptiles originated from
1) lobe-finned fish
2) stegocephals
3) ichthyosaurs
4) Archeopteryx
Answer
1. Select three sentences from the text that describe embryological evidence of evolution. Write down the numbers under which they are indicated in the table. (1) There is a connection between ontogeny and the historical development of a species - phylogeny. (2) Representatives of close systematic groups exhibit similarities in the structure and functions of many organ systems. (3) F. Müller and E. Haeckel formulated the biogenetic law “Ontogenesis is a short and rapid repetition of phylogeny.” (4) The repetition of characteristics is explained by the fact that at different stages of embryo development the preserved genes of distant ancestors are turned on. (5) Evolution is supported by rudiments, organs that have lost their significance for the species. (6) Rudiments include the presence of coccygeal vertebrae and hair on the human limbs.
Answer
2. Read the text. Select three sentences that indicate embryological methods for studying evolution. Write down the numbers under which they are indicated.
(1) The body of the chordate embryo is divided into the head, trunk, and caudal sections. (2) Gill slits are formed in the embryo. (3) The development of the embryo goes through the stages of blastula, gastrula, neurula. (4) Humans have vestigial organs. (5) Human embryonic cells have 46 chromosomes.
Answer
3. Select three sentences from the text “Evidence for Evolution” that describe embryological evidence. Write down the numbers under which they are indicated.
(1) At the early stages of development, embryos of different classes of the same type have a similar structure. (2) Individuals of the same class of animals are similar in internal and external structure. (3) In accordance with the biogenetic law, “Ontogenesis is a short and rapid repetition of phylogeny.” (4) In all multicellular tissue animals, ontogenesis begins with the fragmentation of the zygote with the formation of the blastula, gastrula, and neurula. (5) The presence of rudiments and atavisms in animals serves as evidence of the evolution of species. (6) Human rudiments include the presence of coccygeal vertebrae, hair, and wisdom teeth. (7) Human atavisms include thick hair all over the body and multiple nipples.
Answer
Choose one, the most correct option. Embryological evidence for evolution includes
1) fossil remains
2) the birth of people with an increased number of caudal vertebrae
3) hair of a human embryo
4) similarities in the structure of the limbs of birds and mammals
Answer
1. Establish a correspondence between the examples and the evidence of evolution to which they correspond: 1) embryological, 2) comparative anatomical. Write numbers 1 and 2 in the correct order.
A) chimpanzee ontogeny begins with the zygote
B) a bird’s wing and a mole’s paw are homologous organs
C) rudiments of the pelvic girdle of a whale and the limbs of a python
D) the presence of gill slits in the mammalian embryo
D) blastula stage in vertebrate ontogenesis
Answer
2. Establish a correspondence between examples and evidence of evolution: 1) comparative anatomical, 2) embryological. Write numbers 1 and 2 in the order corresponding to the letters.
A) rudiments of the third century in humans
B) formation of gill pouches in the human embryo
B) homologous organs - the wing of a bird and the flipper of a whale
D) formation of a secondary mouth in the developmental stage of a chordate animal
D) the beginning of ontogenesis from the zygote
E) a unified plan for the structure of the limbs of vertebrates
Answer
Choose one, the most correct option. The formation of lungs and fins of a special structure in the process of evolution in lobe-finned fish made it possible to consider them as ancestors
1) bony fish
2) cartilaginous fish
3) amphibians
4) reptiles
Answer
Choose one, the most correct option. The presence of a tail in a human embryo at an early stage of development indicates
1) mutations that have arisen
2) manifestation of atavism
3) disruption of fetal development in the body
4) the origin of man from animals
Answer
Choose three correct answers out of six and write down the numbers under which they are indicated. What embryological evidence of evolution supports human kinship with other vertebrates?
1) formation of gill slits at the embryo
2) the presence of 46 chromosomes in the cells of the human embryo body
3) development of the caudal region in the embryo
4) presence of homologous organs
5) development of vestigial organs
6) division of the body into the head, trunk, and caudal sections
Answer
Establish a correspondence between the evidence of evolution and the sciences: 1) paleontology, 2) comparative morphology. Write numbers 1 and 2 in the correct order.
A) body shapes of whales and sharks
B) fern fossils
B) dinosaur remains
D) homologous organs of the frog and monitor lizard
D) phylogenetic series of the horse
E) reduced perianth in willow
Answer
1. Establish a correspondence between the example and the group of evidence for the evolution of animals: 1) paleontological, 2) embryological. Write numbers 1 and 2 in the order corresponding to the letters.
A) shellfish fossils
B) skeletal remains of a mammoth
B) gill slits in chordates
D) insect larva in amber
D) neural tube in fish
E) notochord in vertebrates
Answer
2. Establish a correspondence between examples and methods of studying evolution: 1) paleontological, 2) embryological. Write numbers 1 and 2 in the order corresponding to the letters.
A) formation of gill arches in human ontogenesis
B) remains of beast-toothed lizards
B) phylogenetic series of the horse
D) similarity of embryos of vertebrate classes
D) comparison of the flora of the Permian and Triassic periods
Answer
Establish a correspondence between examples and evidence of evolution: 1) comparative anatomical, 2) paleontological, 3) embryological. Write numbers 1-3 in the order corresponding to the letters.
A) the presence of gill slits in the embryos of chordates
B) human appendix
C) the remains of beast-toothed lizards
D) rudiments of the pelvic girdle of a whale
D) stages of blastula, gastrula, neurula in the development of multicellular animals
E) phylogenetic series of elephants
Answer
Choose two correct answers out of five and write down the numbers under which they are indicated. What research methods are used to study evolutionary processes?
1) hybridological
2) physiological
3) paleontological
4) comparative anatomical
5) polyploidization
Answer
© D.V. Pozdnyakov, 2009-2019
Back in the first half of the 19th century. a number of data were obtained indicating the unity of the entire organic world. These include the discovery of the cellular structure of plants, animals and humans. The outstanding French zoologist J. Cuvier established uniform structural plans in each type of animal.
Comparative anatomical evidence of evolution
All vertebrates have bilateral symmetry, a body cavity, a spine, a skull, and two pairs of limbs. The heart of all vertebrates is located on the ventral side, and the nervous system is on the dorsal side, it consists of the brain and spinal cord. The unity of the building plan in each type indicates the unity of its origin.
Bilateral symmetry - the left half of the body is a reflection of the right
Homologous organs
After the publication of Darwin's works, comparative anatomy received an impetus for development and, in turn, made a significant contribution to the development of Darwinism.
Establishing the homology of organs played an important role. Homologous organs can perform different functions and, therefore, differ somewhat in structure, but are built according to the same plan and develop from the same embryonic rudiments.
These are the forelimbs of all vertebrates: the leg of a rabbit, the wing of a bat, the flipper of a seal, the hand of a person. The skeleton of each of these organs has a shoulder, a forearm consisting of two bones, a carpal bone, a metacarpus and a phalanges of the fingers. The same applies to the hind limbs. It was found that the mammary glands are homologous to sweat glands, the jaws of crustaceans to their limbs, the hair of mammals to the feathers of birds and the scales of reptiles, the teeth of mammals to the scales of sharks, parts of a flower (pistil, stamens, petals) to leaves, etc.
Unlike homologous similar bodies may be similar in structure, since they perform homogeneous functions, but do not have a common structural plan of common origin. Examples of these include insect wings, bird wings, crustacean gills, and fish gills. In plants, cactus spines (modified leaves) and rose thorns (outgrowths of the skin) are similar. They do not play a role in establishing related relationships between organisms.
Atavisms and rudiments
To prove evolution matters atavistic organs, which were inherent in distant ancestors and are not normally found in modern organisms. Naturally, such features indicate phylogenetic relationship. Examples of atavism are the appearance of lateral toes in a horse, striping in domestic pigs; cervical fistula (formation homologous to gill slits in lower chordates), caudal appendage, profuse hairiness of the entire body in humans.
Vestigial These are organs that have lost their function but remain in adult animals. They usually remain in their infancy. The remains of the pelvic bones are vestigial in the legless yellow-bellied lizard and in cetaceans. They serve as evidence of the origin of these animals from ancestors who had developed limbs. In humans, the vestigial organs are:
- The coccyx is the remnant of the caudal vertebrae;
- rudimentary ear muscles indicating that human ancestors had a movable auricle.
On the rhizomes of fern, wheatgrass, and lily of the valley, you can find scales - rudiments of leaves.
Comparative anatomical studies of modern progressive and primitive forms make it possible to detect transitional forms. The marine animal Balanogloss combines the characteristics of animals such as echinoderms and chordates. The lancelet has a number of characteristics that bring it closer on the one hand to echinoderms and hemichordates (balanoglossus), and on the other hand to vertebrates, with which it belongs to the same type of chordates.
Among modern mammals, there are monotremes (which have a cloaca and lay eggs during reproduction, like reptiles), marsupials and placentals. Comparison of them indicates that mammals are related to reptiles and that the evolution of mammals went from animals that lay eggs, to viviparous forms with a still underdeveloped placenta, and, finally, to animals that give birth to well-formed young.
Embryological evidence for evolution
Even before the publication of Darwin’s main work, Academician of the Russian Academy of Sciences K.M. Baer established that the embryos of various animals are more similar to each other than the adult forms. Darwin saw this pattern as important evidence of evolution. He believed that in embryonic development the characteristics of ancestors should be repeated.
In the post-Darwinian period, the connection between ontogenesis and phylogeny was confirmed by numerous studies. Russian scientists A.O. Kovalevsky and I.I. Mechnikov established that in all multicellular organisms (invertebrates, starting with worms and vertebrates), three germ layers are formed, from which all organs are subsequently formed. This confirms the unity of origin of the entire animal world.
A comparison of the development of embryos of all classes of vertebrates shows their great similarity in the early stages of development, it concerns both external and internal structure (notochord, organs of the circulatory and excretory systems). As development progresses, the similarity decreases, and signs of a class, then order, genus and species begin to emerge. This confirms the relationship of all chordates.
Based on embryological studies carried out on objects from various types of animals, F. Muller and E. Haeckel (independently of each other) formed the biogenetic law.
The condensed formulation of the biogenetic law reads: ontogeny is a brief repetition of phylogeny.
Further embryological studies showed that the biogenetic law is valid only in general terms. In fact, there is not a single stage of development in which the embryo completely repeats the structure of any of its ancestors. The embryo of a bird or mammal never completely replicates the structure of a fish, but at a certain stage of development it develops gill slits and gill arteries. In ontogenesis, the structure of the embryos, rather than the adult forms of the ancestors, is repeated. In mammalian embryos, it is not the gill apparatus of adult fish that is formed, but only the anlage of the gill apparatus of fish embryos.
It has been established that in embryonic development not only organs associated with the repetition of characteristics are formed, but also temporary organs that ensure the existence of embryos in the conditions in which they undergo development.
Academician A.N. Severtsov clarified and supplemented the provisions of the biogenetic law. He proved that in the process of ontogenesis there is a loss of certain stages of historical development, a repetition of the embryonic stages of the ancestors, and not adult forms, and the occurrence of changes and mutations that the ancestors did not have. New hereditary characteristics that change the structure of the adult organism and the direction of evolution appear at different periods of embryonic development. The later in the process of embryonic development new characteristics arose, the more fully the biogenetic law manifests itself.
Paleontological evidence of evolution
Darwin believed that it was paleontology, the study of the fossil remains of the Earth's former inhabitants, that should provide the most compelling evidence in favor of evolution. Darwin was acutely aware of the lack of information about transitional forms, fossil organisms that combine the characteristics of ancient and younger groups belonging to different classes and types.
Evidence of evolution using the horse as an example
The first most compelling paleontological evidence of evolution was obtained by V.O. Kovalevsky (1842-1883). He managed to figure out the successive stages of the origin of equids, to which the horse belongs. The earliest ancestor of the horse, found in sediments of the Tertiary period, was about 30 cm high, had four toes on the front legs and three on the hind legs. He moved, relying on all the phalanges of his fingers, which was an adaptation to living in swampy areas. His food consisted of fruits and seeds.
Further, due to climate change, forests became less and less and at the next stage of evolution, the ancestors of the horse found themselves in open areas such as steppes. This led to the survival of those capable of fast running (to escape from predators), which was achieved by lengthening the limbs and reducing the support surface, i.e. reducing the number of fingers in contact with the soil.
At the same time, selection was aimed at adapting to feeding on steppe grasses. Folded teeth appeared with a large chewing surface necessary for grinding tough plant foods. Consistently, the middle finger became larger and larger, and the side fingers became smaller and smaller. As a result, the fossil horse, like the modern one, had only one toe on each leg, on the tip of which it rested. The height has increased to 150 cm. The entire body structure is well adapted for living in open steppe areas.
Other transitional forms
After research by V.O. Kovalevsky, it was possible to establish the phylogenetic series of many other animals: proboscis, carnivores, mollusks.
Currently, the geological history of the Earth has been studied in some detail. It is known that in the most ancient layers remains of various types of invertebrates are found, and only in later layers do remains of vertebrates appear. It has been established that the younger the layers, the closer the remains of plants and animals are to modern ones.
Transitional forms have also been discovered. An important find was Archeopteryx, a first bird that retains a number of reptile characteristics. Signs of a bird:
- general view;
- the presence of feathers;
- resemblance of the hind limbs to the tarsus.
Signs of reptiles:
- Presence of caudal vertebrae;
- teeth;
- abdominal ribs
A transitional form between reptiles and mammals has been found - wild-toothed lizards (theriodonts), which are similar to mammals in the structure of the skull, spinal column, and limbs. If in reptiles all teeth are of the same type, then in theriodonts there is a differentiation of teeth into incisors, canines, and molars, which gave rise to calling these fossil lizards animal-toothed.
In the fossil state, seed ferns were found, combining some of the characteristics of ferns and some of gymnosperms. This serves as evidence of the origin of seed plants from pteridophytes.
Evolution is the irreversible process of development of any system, as a result of which new structures and new functions arise. In biology, the term “evolution” (from Lat. evolutio- development, deployment) was first used by the Swiss naturalist Charles Bonnet in 1762 in one of his embryological works.
According to modern concepts, biological evolution is an irreversible and, to a certain extent, directed historical development of living nature, accompanied by changes in the genetic composition of populations, the formation of adaptations, the formation and extinction of species, transformations of biogeocenoses and the biosphere as a whole.
Thus, the very concept of “evolution” includes at least two aspects: adaptation genesis and the formation of taxa.
There are numerous evidences of the evolution of the organic world of the Earth, which are also methods for studying evolution. Classic evidence of evolution includes paleontological, comparative anatomical and comparative embryological.
1. Paleontological . Pre-existing organisms leave behind various forms of fossil remains: fossils, prints, skeletons, traces of activity. These remains can be used to trace changes in groups of organisms over time. Reconstructed phylogenetic series equidae, proboscis, some mollusks. Many transitional forms between modern groups of organisms have been discovered. However, due to the incompleteness of the fossil record, it is not always possible to reconstruct the course of evolution.
2. Comparative morphological . The organ systems of modern organisms form a series of sequential changes. For example, in modern organisms it is possible to trace the fate of individual bones of the brain and visceral skull. Comparative biochemical evidence is close to comparative morphological evidence. For example, in modern organisms it is possible to trace changes in the structure of hemoglobin. However, there are also gaps in these series, since not all transitional forms have survived to our time.
3. Comparative embryological . During embryonic development, embryos often exhibit similarities with the embryos of ancestral forms. For example, in all vertebrates, internal gills (or their rudiments - gill pouches) appear in the early stages of development.
Based on law of germinal similarity was formulated biogenetic law of Müller–Haeckel, which briefly states: “ Ontogenesis (individual development) is a quick and brief repetition of phylogeny (historical development)" However, in these series of embryonic development, the similarity between embryos is only the most general; not all signs appear. For example, the embryos of amniotes (reptiles, birds and mammals) do not develop external gills characteristic of anamnia larvae (fish and amphibians), and the development of gill slits stops at the gill pouch stage. Therefore, the biogenetic law in the interpretation of Müller-Haeckel is limited.
In the course of evolution, evolutionary transformations of ontogenetic processes associated with adaptations of adult (mature) organisms are observed. During such transformations, new organs may appear, but old organs may also be lost (completely or turn into rudiments). In this case, the following may change: the initial mass of the organ rudiment, the place and time of organ formation. These transformations can occur at different stages of ontogenesis: at the earliest (laying down of the notochord, neural tube), middle (laying down of scales in fish, feathers in birds, modification of plant shoots) and late (reduction of the tail in tadpoles, formation of a four-chambered heart in birds and mammals). , change in leaf shape). When organs change in the later stages of ontogenesis, a phylogenetic law can operate.
Currently, to study the evolutionary development of a particular group of organisms, a whole range of methods is used: biogeographical, ecological, genetic, molecular biological, immunological, biochemical, as well as methods of paleoecology, comparative physiology and ethology; Computer modeling methods are widely used.