Why is fitness relative? The adaptability of organisms is the result of evolution

The fitness of organisms (adaptation) is a complex characteristic features, allowing them to survive in a certain environment and leave numerous strong progeny.

Adaptation to emerging conditions is influenced by the driving forces of evolution. But conditions are never constant, they change, so all adaptations are relative.

A white partridge blending into the snow is discovered by a shadow. Organisms with new traits operating within a certain range may simply die if they go beyond these boundaries. Only individuals who have adapted to the new environment through natural selection survive.

Types of adaptation of organisms

Morphological adaptations include:

Transformation of the body, namely: streamlined or flattened shape, webbed paws, thick hair.
With the help of camouflage, you can become invisible against the background of the environment, become similar in color and shape to a leaf, stone, twig (insects, fish).
With a protective and dismembering coloring, you can merge with the environment in a changing situation (brown hare, bird eggs, zebra).
Warning coloration is distinguished by bright colors, speckles, stripes, and is needed to scare away or warn of an attack (bees, snakes, ladybugs).
Warning and protecting oneself, the weaker, from a stronger one by becoming similar to it in color, body shape or behavior is called mimicry (tropical grass snake, murmuring fly, cuckoo eggs).

Among physiological adaptations highlight:

Preparing for life in changing conditions: - the camel accumulates fat; - formation of glands that eliminate excess salt (marine reptiles and birds). - location of heat and sound; - hibernation.
Behavior: - the smaller the number of cubs, the more care they take for the purpose of conservation; - formation of mating pairs during the reproduction of offspring and life in flocks with more complex conditions (birds, wolves). - scaring (cobra, grin and growl of a dog, the smell of a skunk). - imitation of a wounded or dead person, hiding (possum, frog, bird). - forethought (winter sleep, stocking of feed).
With the help of biochemical devices (special substance), the animal can defend itself or attack the enemy (poisons, antibiotic bacteria, special proteins and fats).

The nature of the adaptation of organisms

Selection by nature leaves only the most adapted alive. But the slightest changes in the environment can make those devices that served well before useless or even harmful.

As a result, those organisms that managed to adapt faster survive, and those who are late die out, giving the opportunity to form a new species. Such adaptations are formed very long time naturally and are relative, because living conditions change much faster than they appear necessary changes in animals.

Evidence for the relativity of adaptations:

methods of protection are not universal (a poisonous snake that is dangerous for some is eaten by a mongoose or a hedgehog);
in some cases instinct fails ( moth flies for nectar to a light flower, or may confuse it with fire);
an organ that is necessary in one environment is useless or harmful in another (bar-headed geese with membranes they do not need);
fish are adapted to separate oxygen from water, but on land they cannot do this; - green insects are not visible on the grass; on clean ground they will quickly be eaten.

Reasons for the adaptability of organisms

It has been established that individuals of the species will survive if they change faster, adapting to new environmental requirements. The emergence of new characters and the appearance of a new species is called phyletic speciation.

Today, the diversity of species has noticeably decreased compared to several thousand years ago. This is due to constant climate change, ice ages, volcanic eruptions, earthquakes, deterioration environmental situation, barbaric attitude of people. As a result, the most adapted organisms survive, and the main reason for adaptability belongs to natural selection.

Adaptation of organisms to their environment

To survive, you need to adapt to living conditions, and she will choose the best individuals and remove the weak. All animals live in different parts nature and their adaptive characteristics depend on this.

Laboratory work fitness of organisms

Laboratory work, with problematic situation in content, are necessary for the development of independent skills in studying and researching biological objects. The existing problem gives rise to hypotheses, versions, evidence and teaches us to draw conclusions. Each work has a goal, questions, tasks and applications. It is more convenient to display the progress of work in a table.

Example. L.r. "Adaptation to the environment."

Target: define the concept of animal adaptability, train the ability to identify adaptations.

The hoverfly fly can be found everywhere except the tundra and desert. This is a short-winged dipterous insect, similar to a wasp, but completely harmless. Hoverflies fly very quickly. Their connection with ants and bumblebees, leading a social lifestyle, has been proven.

Adaptation of organisms to environmental factors

Any living organism is affected by natural factors. TO inanimate nature include: temperature, change of day and night, seasons, soil characteristics, landscape, chemical composition air and water, noise, radiation. Organisms adapt to this, but cannot influence these conditions, which are called abiotic factors.

Adaptations to changes in nature by humans (anthropogenic factor) are of no small importance for the survival of animals. While in natural communities, all living inhabitants of the planet, are divided into groups with similar signs of adaptation to a particular environmental factor. These changes can be expressed both externally and internally, with a change in the nature of behavior.

For example, body temperature depends on weather conditions in most representatives of the animal world. These are cold-blooded animals. They react either by decreasing or increasing their metabolic rate. When they slow down, they experience suspended animation, which helps conserve energy. In warm-blooded species, the temperature is always constant and does not affect metabolism. There are predators that hunt during the day, and there are those that only come out at night. Pets are active mainly during the daytime.

Examples of the fitness of organisms

The horse can run quickly with the help of wide, comfortable hooves. Felines are able to sneak up silently, retracting their claws. Birds made their bodies lighter for flight by getting rid of the bladder, one ovary, teeth and acquiring wings with different plumage.

Insects - caterpillars have adapted to become similar to a plant leaf or twig. Crocodiles have special glands near their eyes that help remove excess salt. The camel stores fat in its humps, the breakdown of which releases water. Polar bear retains heat with a layer subcutaneous fat and thick fur, wide paws allow them to walk on thin ice.

Study of the fitness of organisms

Initially, during the reign of religion, it was argued that all life on Earth was created by the existing wise God. That nature itself could not do this. The Creator created everyone so that they could do what is assigned to them. K. Linnaeus also adhered to this theory.

J.B. Lamarck argued that all organisms are born with the ability to change, and throughout their lives they can only improve these skills. Thus, new species with beneficial properties arise. But this theory does not explain the different colors of bird eggs and the benefits of spines for a hedgehog.

C. Darwin expressed an opinion; “... if an animal or plant can survive a sharp change in climate or other conditions, then its descendants will become the most common.” A new trait that appears is passed on to the offspring if it promotes survival.

Modern scientists, studying adaptation, have come to the conclusion that any useful variability occurs later than the right time. Some new signs even cause harm to the animal in suddenly changed conditions.

Pronghorns rank second among all animals in terms of running speed. But a special feature is the muscles that change the slope of the coat. This ability helps in hot or cold weather. And most importantly, seeing the danger, the observer fluffs the hair of his butt, which is immediately noticed by the entire herd.
The secret of toothfish, an Antarctic fish, is that with the help of a special protein that acts as antifreeze, its blood remains unfrozen even at a temperature of minus 2 degrees.
Even a bear will envy the African fish Protoptera, which can sleep for up to 4 years. She is a lungfish, having, along with gills, also a pulmonary system.
The water-carrying toad sleeps in his mucus shelter, waiting for another rain, as many as seven.
The vulture bird is not only a nurse - it eats carrion, and can also cool its body by urinating on its plumage.

Conclusions

Every organism in the best possible way adapted to the conditions where it has to live. This change only serves where it was purchased and is therefore considered relative. Natural selection leaves individuals only with those traits that have withstood the greatest deviation in the significance of a certain environmental factor.

The emergence of adaptation of organisms.
The main reason for the appearance of various adaptations of living organisms to their environment is selection. For example, it is known that the partridge is a forest bird. Depending on its habitat, it has various adaptations: a) shortening of the beak in connection with obtaining food from under the snow and leaf litter: b) the appearance of horny folds at the ends of the fingers to facilitate movement on thick snow cover; c) expansion, rounding of the wings for rapid lifting into the air (the ancestors of the partridge did not have such a structure).
To further spread, the fruits and seeds of plants also underwent various changes. These are hooks, spines with which they are attached to animals, or light fluff that is scattered by the wind.
The emergence of adaptation in plants and animals - characteristic phenomenon, but in any case, fitness does not appear immediately. As a result of long evolutionary process individuals appear with special characteristics adapted to environmental conditions.
Features of adaptation in structure, color, body shape and behavior are clearly visible in the example of an aquatic mammal - the dolphin. The pointed shape of the body allows it to move easily and freely in the water. different directions. The dolphin's speed reaches 40 km/h. And in birds, indicators of fitness for flight are the presence of feathers covering the body; absence of ears and teeth; the ability to turn the head 180"; lightness of bones; rapid digestion of food in the stomach, etc.
Many animals have such advanced adaptations that they are difficult to distinguish from their environment. The body shape, coloring of fish and animals living in dense thickets of algae help them successfully hide from enemies.

Types of adaptability:

Protective (camouflage) coloring and its types.
Instinctive adaptation.
Caring for offspring.
Physiological adaptation.

Rice. 21. Adaptation of moths by changing color to the corresponding colors of the tree trunk: 1 - equal number of marked dark and light butterflies; 2 - light tree trunk; 3 - increase in the number of light butterflies; 4 - increase in the number of dark butterflies; 5 - dark tree trunk

1. Protective (camouflage) coloring and its types. Protective coloring is an adaptation of organisms that live openly and may be accessible to enemies. Birds that incubate eggs on the ground (grouse, partridge, quail, etc.) blend into the surrounding background. A bird sitting motionless on a nest is almost invisible to its enemies. The eggs, which have a pigmented shell, and the chicks hatching from them are also hardly noticeable. U large predators, whose eggs are inaccessible to enemies, or in birds that lay eggs high on rocks or bury them. into the ground, the protective color of the shell does not develop. Butterfly caterpillars are usually green, the color of the leaves, or dark, the color of the bark. Bottom fish(stingray, flounder) are often colored to match the color of sand.
Desert animals are usually sandy-yellow in color. A monochromatic protective color is characteristic of insects (locusts), lizards, saigas, and lions. Depending on the time of year, many animals change color. For example, the Arctic fox, white hare, and partridge are white in winter. U day butterflies protective coloring on the lower part of the wings, and on the upper part of the wings of the night ones, so during the day they become noticeable to enemies and may die (the lower part of the wings is light). The protective coloring can also be observed in the shape of insects: the pupa of butterflies on a branch is very similar to a bud; a larva attached to a branch in a motionless state, similar to a tree branch, etc.
Protective coloring is especially useful in the initial stages individual development organism (eggs, larva, chick). Protective coloring is necessary for animals that move slowly or have entered a state of rest.
Many animals are able to quickly change color depending on the color of their environment, and this ability is inherited. For example: chameleon, flounder, agama.

Types of protective coloring:

protective painting;
attractive coloring;
threatening coloring;
imitation coloring.

1. Protective warning paint characteristic of poisonous, stinging or burning insects. For example, birds never peck a ladybug (red, yellow, brown, dark red, striped) because of the toxic, bitter yellowish liquid it secretes (Fig. 22). If the chicks accidentally peck this beetle, then next time they do not approach it. The carrion beetle secretes an unpleasant, burning liquid and is bright red striped in color. The coloring of bees, bumblebees, wasps, and poisonous snakes protects them from predators. Protective coloring also depends on the behavior of some insects and animals. Sometimes crawling beetles freeze in moments of danger. A bittern nesting in the reeds, accidentally seeing an enemy, stretches its neck, raises its head up and freezes. Warning coloration in animals is combined with behavior that scares away predators.

Rice. 22. Warning coloring: 1 - ladybug; 2 - blister

2. Attractive coloring. This coloration is especially important during breeding. The bright colors of red butterflies, blue-winged grasshoppers, jerboas, and the plumage of male birds attract females during the breeding season. IN ordinary days the color blends into the environment and becomes invisible to enemies (Fig. 23).

Rice. 23. Attractive coloring: 1 - red sash; 2 - blue-winged filly; 3 - jerboa

3. Menacing coloring. When in danger, animals take a threatening pose. For example, in moments of danger, a cobra raises its head straight, inflates its neck and takes a threatening pose; The darkling beetle raises its abdomen and emits an unpleasant odor. The long-eared roundhead instantly opens the folds of skin on its head and freezes with its mouth open. On the open wings of the praying mantis there are spots similar to eyes. In case of danger, by opening its wings, the praying mantis scares away its enemy. Moths have the same spots (Fig. 24).

Rice. 24. Menacing coloring: ocular spots on the wings of a butterfly (1) in a threat pose look like the eyes of an elf owl (2)

4. Imitating coloring -mimicry(Greek mimikos - “imitation”). This is the imitation of animals and plants by living organisms or certain inanimate objects environment. The warning coloration of unprotected organisms resembles one or more species. For example, in body shape, size, and bright color, a cockroach is similar to a ladybug. The body shape of the seahorse and fish resembles algae. White butterfly unpleasant smell, with its bright colors imitates inedible butterflies from the heliconid family (Fig. 25), and flies imitate wasps. Similarity non-venomous snakes with poisonous ones helps them protect themselves from enemies and survive.

Rice. 25. Imitative coloration: the white butterfly (T) is similar to the poisonous heliconid butterfly (2)

Examples of imitative plant coloring.
Imitative coloration in plants is necessary to attract or intimidate animals. Usually there is no nectar on the belozor flower. To attract insects, it is similar to a honey plant. Insects, landing on a flower, contribute to its pollination. The flowers of the insectivorous plant (Nepenthes) are brightly colored. Insects, landing on a flower, instantly fall into a “trap” and die. An orchid resembles the female of some insects in its flower shape and smell, so male insects involuntarily land on the flower and pollinate it.
Mimicry arises “under the control” of natural selection. Its occurrence is associated with the accumulation of small beneficial mutations in edible species in conditions of their cohabitation with inedible ones. One of the main weapons of defense against enemies and adaptive characteristics is: in beetles and crabs - chitinous cover, in mollusks - shells, in crocodiles - scales, in armadillos and turtles - shells, in hedgehogs and porcupines - quills.

Fitness. Protective coloration. Protective painting. Attractive coloring. Menacing coloring. Imitative coloring (mimicry).

Main reason various adaptations of organisms to environmental conditions is selection.
Protective coloration is an adaptation necessary to protect organisms leading an open lifestyle from enemies.
Protective coloration is a type of protective coloration characteristic of poisonous, stinging, burning insects.
Attractive coloration is a type of protective coloration during the reproduction period of organisms.
Menacing coloring is a way of protecting animals from enemies by adopting a threatening pose.
Imitation of living organisms and inanimate objects of the environment is an adaptation of organisms that are unable to defend themselves or are inactive.
What characteristics of organisms determine fitness?
How does fitness occur?
Name the types of protective coloring.
Give an example of protective paint.

What organisms are characterized by imitative coloration?
Give examples that prove the usefulness of attractive colors.
What are examples of mimic coloration in plants?

Exercise
Have you ever encountered insects in nature that freeze when touched? Pay attention to their actions, immobility. Pay attention to insects that produce an unpleasant odorous odor. Compare them. This activity will help you become more familiar with the protective and threatening colors of animals.
Try to complete the task.
What type of protective coloration are these examples? Enter in capital letters accordingly: “ZShch” - protective; "PR" - attractive; "PD" is imitative.

Ladybug. 5. Nepenthes (insectivorous plant).
Butterfly. 6. Bittern.
Darkling beetle. 7. Male pheasant.
Sea horse. 8. Praying Mantis.

Having explained the origin of species on the basis of natural selection as a grandiose and all-encompassing process of successive changes in adaptations, Darwin's theory also explained the phenomenon of the purposeful structure of organic forms. The forms of devices as a reflection of expediency are infinitely varied: the swim bladder in the body of a fish is filled with air and lightens the weight of its body; it is more convenient to cross swamps on long legs with widely spaced toes, like a heron, or with wide hooves, like an elk; Jumping animals have more developed hind limbs (kangaroo, grasshopper, frog). Animals that lead an underground lifestyle have spade-shaped limbs and are adapted for digging the ground. There are expedient adaptations in plants and animals to daily and annual fluctuations in temperature and humidity.

Adherents of idealistic views and ministers of the church saw in the phenomena of the adaptability of organisms and their purposeful structure an expression of the general harmony of nature, supposedly emanating from its creator. C. Darwin's theory rejects any participation in the emergence of adaptations of supernatural forces; it convincingly proved that all animals and flora Since its appearance, it has been improving along the path of expedient adaptations to living conditions: water, air, sunlight, gravity. The amazing harmony of living nature, its perfection is created by nature itself: the struggle for survival. This struggle is the force that gives strength to roots, sophisticated beauty to flowers, causes a bizarre mosaic of leaf arrangement and sharpens teeth, gives powerful muscle strength, visual acuity, hearing and sense of smell to many animals.

Adaptability as an expression of expediency is manifested in everything. For example, predators have claws, fangs, beaks, and poisonous teeth, from which it can be very difficult for the victim to escape. But in the struggle for life, means of defense were also developed: some respond to force with force, others are saved by their legs, others developed shells, shells, needles, etc. Many weak and defenseless insects, being harmless or edible, for many years the actions of natural selection took on the color and shape of hornets and wasps and became similar to poisonous or inedible forms. Their imitative coloring or shape is at the same time protective, since it coincides with the background of the environment: it makes predators invisible and helps them sneak up on prey, and it gives hunted species the opportunity to hide from enemies. If the insects pursued by birds were not colored to match the color of green grass or tree bark, they would be exterminated by birds. The plumage of the tundra partridge merges with the tone of the rocks and peaks covered with lichens, the woodcock is invisible among the dried and fallen oak leaves, etc. The ability of animals to take on a “threatening” or “frightening” color and pose is of a pronounced adaptive nature: in the caterpillar wine hawkmoth there are eye-like spots in front; at the moment of danger, it raises the front part of the body, thereby scaring away the birds.

Various adaptations exclude the possibility of self-pollination in most plants, allow them to distribute fruits and seeds, or, thanks to their spines, resist being eaten by herbivores. The aroma and bright color of flowers arose as adaptations to attract insects, which, visiting the flowers, cross-pollinate these plants, or as an adaptation to more efficient absorption sun rays a certain length.

Protective coloration. Protective coloration is developed in species that live openly and may be accessible to enemies. This coloration makes the organisms less noticeable against the background of the surrounding area. Some have a bright pattern (the coloring of a zebra, tiger, giraffe) - alternating light and dark stripes and spots. This dismembering coloring seems to imitate the alternation of spots of light and shadow.

Disguise. Camouflage is a device in which the body shape and color of an animal blends in with surrounding objects. For example, the caterpillars of some butterflies resemble twigs in body shape and color.

Mimicry. Mimicry is the imitation of a less protected organism of one species by a more protected organism of another species. This imitation can manifest itself in body shape, coloring, etc. Thus, some types of non-venomous snakes and insects are similar to poisonous ones. Mimicry is the result of selection of similar mutations in various types. It helps unprotected animals survive and helps preserve the body in the struggle for existence.

Warning (threatening) coloring Species often have bright, memorable colors. Having once tried to taste an inedible ladybug or a stinging wasp, the bird will remember their bright color for the rest of its life.

(Based on materials from Andrey Ivanov’s personal page)

In the doctrine of natural selection, Darwin not only materialistically substantiated the fitness of organisms (their expedient structure), but also showed it relative character. Thus, warning and protective coloring and various other protective devices do not affect all pursuers, but, having devices, individuals are less likely to be attacked. Those with stings - wasps, bees, hornets - are easily eaten by flycatchers and bee-eaters. A flying fish, jumping out of the water into the air, deftly escapes from predatory fish, but the albatross takes advantage of this, overtaking its prey in the air. The tortoise's shell is a good defense, but the eagle lifts it into the air and throws it onto the rocks; the shell breaks and the eagle eats the turtle.

Every animal and plant cannot be fully adapted to all conditions that have developed throughout life on Earth. Any adaptation persists as long as it is supported by natural selection, but disappears as soon as it ceases to be useful. As an example of a change in adaptations, one can cite the development of protective coloration in the birch moth butterfly.

Thus, the basis of Darwin's theory is the doctrine of natural selection - the main and guiding factor of evolution. In the struggle for existence on the basis of hereditary variability, there is a consistent change of adaptations and the survival of the fittest, the diversity of forms of living nature increases, the process of speciation takes place and the general progressive development of the plant and animal world takes place. In this theory, two problems were resolved: the mechanism of speciation and the origin of the purposefulness of the organic world.

Adaptability of organisms as a result of evolution (T.A. Kozlova, V.S. Kuchmenko. Biology in tables. M., 2000)

Fitness indicators	Plants	Animals
Methods of obtaining food	The absorption of water and mineral salts is ensured by the intensive development of roots and root hairs; absorption of solar energy is carried out most successfully by wide and thin leaves; capture and digestion of insects and small amphibians by marsh plants	Eating leaves on tall trees; capture using a trap net and lying in wait for food items; the special structure of the mouthparts ensures catching insects from long, narrow burrows, biting grass, and catching flying insects; Grasping and holding prey predatory mammals and birds
Anti-eating	They have spines that provide protection from herbivores; contain toxic substances; the rosette shape of the leaves is not available for grazing	They escape by running quickly; have needles, shells, a repellent odor, and other protection; protective coloring saves in certain conditions
Adaptation to abiotic factors (cold)	Falling leaves; cold resistance; conservation; vegetative organs in the soil	Flight to the south; thick wool; hibernation; subcutaneous fat
Expansion into new territories	Light, winged seeds; tenacious hooks	Bird flights; animal migration
Reproduction efficiency	Attracting pollinators: flower color, smell	Attracting a sexual partner: bright plumage, sexual attractants

What features does it have? How is the relative fitness of a cactus, chameleon, or turtle manifested?

Organisms and the external environment

Each individual species of living beings has its own habitat. Within its limits there are various factors, which have special characteristics, for example, a certain air temperature, soil or water salinity, certain inhabitants.

To survive in a particular environment, an organism must adapt to it. The one who does this as efficiently as possible will be able to survive and have offspring. Plants, animals, and even humans have evolved various tools to help them adapt.

These tools were formed gradually. Species that had some advantage in structure or color survived better than others in certain conditions. Useful traits were inherited and became more pronounced. Over time, the desired characteristics became characteristic of all representatives of the species or population.

Relative nature of fitness

Adaptation is the presence in animals or plants of characteristics that correspond to their lifestyle and the environment in which they find themselves. For example, the body of fish is streamlined and covered with mucus to make it easier to move in water. Arctic bears are white in color to blend in with their environment as much as possible.

However, the developed auxiliary mechanisms among representatives of living nature are not absolute, but relative. Why is fitness relative? It's simple. If the body adapts to specific environmental conditions, then it may be unprepared for other conditions. usually change faster than organisms, which need at least several generations to change.

The relative nature of fitness is also manifested in the fact that, having a reliable means of protection from some enemies (bright colors, thorns or poison), you can get caught in the nets of others. Thus, the venom of many snakes affects small prey and repels large mammals, however, does not stop hedgehogs and mongooses that feed on snakes. Detailed examples Let's look at it further.

cacti

An excellent example of survival in harsh conditions demonstrate plants They thrive in an environment that is unbearable for many living creatures. Plants are common in deserts and semi-deserts, mountains, savannas, and arid forests.

The powerful fleshy stem allows it to accumulate a lot of moisture from the air, and the spines prevent it from evaporating. In addition, sharp spines scare away those who want to feast on the cactus. Strongly developed roots reaching deep groundwater, saturate the plant with water.

Thus, the plant is fully prepared for life in regions where precipitation is extremely rare. The relative nature of the cactus's adaptability lies in the fact that when conditions change, for example, when prolonged rainfall occurs, the plant may die from excessive water intake into the body.

In indoor conditions, all the benefits of the cactus are lost and become neutral. The powerful stem and thorns will no longer carry those functions important for survival, only the aesthetic aspect will remain.

Chameleons

Chameleons spend most of their time on trees; flexible limbs help chameleons climb them. The animals' fingers are fused, forming two almost opposite groups (they look like a claw), the tail is twisted and long - all this makes it easy to grasp branches and move along them.

The relative fitness of a chameleon lies precisely in its color. The natural color of the animal camouflages it as much as possible with its environment, making it invisible to predators. But chameleons often change color, using it as a means of communication.

Some species can be repainted in almost all colors. This is how they express their reaction to changes in lighting, humidity or the appearance of other animals. At the moment of danger, the “lizard” experiences stress and can turn bright red or yellow, giving itself away, instead of merging with the situation and hiding.

Turtles

Reptiles unique in their structure are turtles. The body of animals is in a dense shell, covered with skin or horny scutes. It is a bit like a shell, as it consists of an upper and lower part.

The turtle is not just located inside the shell, it is a single whole with it. Upper part The “frame” is fused with the animal’s spine, the lower part is formed by the collarbone and abdominal ribs. It is impossible to get the turtle out of the “house” without crippling it.

In case of danger, the animal hides its head and limbs inside. How does the relative nature of fitness manifest itself in this case? Predators cannot chew the shell or pick the turtle out of it. But the eagles lift it high above the ground, release it so that the shell breaks, and then eat their prey.

Conclusion

The fitness of organisms is the correspondence between their external and internal structure, behavior in the environment in which they live. It is formed during a long historical process and is important factor evolution.

The relative nature of fitness is that characteristic features the body can help it only in certain conditions and situations. When changing external factors devices can be ineffective and sometimes even harm their owner.

Sections: Biology

Lesson objectives:

repetition and consolidation of knowledge about the driving forces of evolution;
to form the concept of the adaptability of organisms to their environment, knowledge about the mechanisms of adaptation as a result of evolution;
continue to develop the skills to use knowledge of theoretical laws to explain phenomena observed in living nature;
develop specific knowledge about adaptive features structure, body coloring and behavior of animals.

Equipment:

Table “Adaptability and its relative nature”, photographs, drawings, collections of plant and animal organisms, cards for performing tests, presentation.

1. Repetition of the material studied:

In the form of a frontal conversation, it is proposed to answer questions.

a) Name the only guiding driving force of evolution.
b) What is the supplier of material for selection in the population?
c) It is known that hereditary variability, which supplies material for selection, is random and not directed. How does natural selection become directional?
d) Give an explanation from an evolutionary point of view for the following expression: “It is not individual genes that are subject to selection, but entire phenotypes. The phenotype is not only an object of selection, but also plays the role of a transmitter of hereditary information in generations.”

As the question is posed, its text is displayed on the screen (a presentation is used)

2. The teacher brings the conversation to the formulation of the topic of the lesson.

In nature, there is a discrepancy between the ability of organisms to reproduce unlimitedly and limited resources. Is this the reason...? the struggle for existence, as a result of which the individuals most adapted to environmental conditions survive. (Display the diagram on the screen, students write it down in a notebook)

So, one of the results of natural selection can be called the development of adaptations in all living organisms - adaptations to the environment, i.e. fitness is the result of the action of natural selection under given conditions of existence.

(Message about the topic of the lesson, writing in a notebook)

Think and try to formulate what is the essence of adaptation to environmental conditions? (Together with the students, the teacher gives a definition of fitness, which is written down in a notebook and displayed on a slide screen)

Adaptability of organisms or adaptations- a set of those features of their structure, physiological processes and behavior that provide for a given species the possibility of a specific lifestyle in certain environmental conditions.

What do you think is the importance of fitness for organisms?

Meaning: adaptability to environmental conditions increases the chances of organisms to survive and remain large number offspring. (Write in notebook, display slide on screen)

The question arises, how are adaptations formed? Let's try to explain the formation of an elephant's trunk from the point of view of C. Linnaeus, J.B. Lamarck, C. Darwin.

(On the screen is a photograph of an elephant and the wording of the question posed)

Probable student answers:

According to Linnaeus: the fitness of organisms is a manifestation of original expediency. The driving force is God. Example: God created elephants, like all animals. Therefore, from the moment of their appearance, all elephants have a long trunk.

According to Lamarck: the idea of the innate ability of organisms to change under the influence of the external environment. The driving force of evolution is the desire of organisms for perfection. Example: elephants, when getting food, were forced to constantly stretch their upper lip to get food (exercise). This trait is inherited. This is how the long trunk of elephants came into being.

According to Darwin: among the many elephants there were animals with trunks different lengths. Those of them with a slightly longer trunk were more successful in obtaining food and surviving. This trait was inherited. So, gradually, there arose long trunk elephants.

Which explanation is more realistic? Let's try to describe the mechanism by which adaptations arise. (Scheme on screen)

3. Variety of adaptations.

On the students' desks are drawings and collections illustrating the various adaptations of organisms to environment. Work in pairs or groups. Students describe adaptations, name them themselves or with the help of the teacher. These devices appear on the screen as the conversation progresses.

1. Morphological adaptations(changes in body structure).

streamlined body shape in fish and birds
membranes between the toes of waterfowl
thick fur in northern mammals
flat body in bottom fish
creeping and cushion-shaped form in plants in northern latitudes and high mountain areas

2. Camouflage: body shape and color blend with surrounding objects (slide).

(Seahorse, stick insects, caterpillars of some butterflies).

3. Patronizing coloring:

developed in species that live openly and may be accessible to enemies (eggs of openly nesting birds, grasshopper, flounder). If the background of the environment is not constant depending on the season of the year, the animals change their color (white hare, brown hare).

4. Warning color:

Very bright, characteristic of poisonous and stinging forms (wasps, bumblebees, ladybugs, rattlesnakes). Often combined with demonstrative scaring behavior.

5. Mimicry:

similarity in color and body shape of unprotected organisms with protected ones (hoverflies and bees, tropical snakes and poisonous snakes; Snapdragon flowers look like bumblebees - insects are trying to establish mating relationships, which promotes pollination; eggs laid by the cuckoo). Mimics never outnumber the original species. Otherwise, the warning coloring will lose its meaning.

6. Physiological adaptations:

adaptability of life processes to living conditions.

accumulation of fat by desert animals before an attack dry season(camel)
glands that eliminate excess salts in reptiles and birds that live near the sea
water conservation in cacti
rapid metamorphosis in desert amphibians
thermolocation, echolocation
state of partial or complete suspended animation

7. Behavioral adaptations:

changes in behavior in certain conditions

caring for offspring improves the survival of young animals and increases the stability of their populations
formation of separate pairs in mating season, and in winter they form flocks. What makes food and protection easier (wolves, many birds)
deterrent behavior (bombardier beetle, skunk)
freezing, feigning injury or death (opossums, amphibians, birds)
precautionary behavior: hibernation, food storage

8. Biochemical adaptations:

associated with the formation in the body of certain substances that facilitate the defense of enemies or attacks on other animals

poisons of snakes, scorpions
antibiotics for fungi and bacteria
crystals of potassium oxalate in the leaves or spines of plants (cactus, nettle)
special structure of proteins and lipids in thermophiles (resistant to high temperatures)

and psychrophilic (cold-loving), allowing organisms to exist in hot springs, volcanic soils, and permafrost conditions.

Relative nature of adaptations.

It is suggested that you pay attention to the table: hare. Invisible to predators in the snow, clearly visible against the background of tree trunks. Together with the students, other examples are given: moths collect nectar from light flowers, but also fly towards the fire, although they die in the process; poisonous snakes are eaten by mongooses and hedgehogs; If you water a cactus too much, it will die.

What conclusion can be drawn?

Conclusion: any device is useful only in the conditions in which it was formed. When these conditions change, adaptations lose their value or even cause harm to the body. Therefore, fitness is relative.

When studying the topic, we relied on the teachings of Charles Darwin on natural selection. It explained the mechanism by which organisms adapt to their living conditions and proved that fitness is always relative.

4. Consolidation of knowledge.

There are test sheets and answer cards on the students' desks.

Option 1.

1. A phenomenon that serves as an example of camouflage coloring:

a) coloration of sika deer and tiger;
b) spots on the wings of some butterflies, similar to the eyes of vertebrates;
c) the similarity of the color of the wings of the pierida butterfly with the color of the wings of the inedible heliconid butterfly;
d) coloring of ladybugs and Colorado potato beetles.

2. How modern science explains the formation of organic expediency:

a) is the result of the active desire of organisms to adapt to specific environmental conditions;
b) is the result of natural selection of individuals that turned out to be more adapted than others to environmental conditions due to the presence of randomly occurring hereditary changes in them;
c) is the result of direct influence external conditions on the development of corresponding characteristics in organisms;
d) it was initially predetermined at the moment the creator created the main types of living beings.

3. Phenomenon. An example of which is the similarity between the lionfly and wasps in the color of the abdomen and the shape of the antennae:

a) warning coloring;
b) mimicry;
V) adaptive coloration;
d) camouflage.

4. Example of protective coloring:

5. Example of warning coloring:

a) bright red color of the rose flower;

d) similarity in color and body shape.

Option 2.

1. The main effect of natural selection:

a) increasing the frequency of genes in the population that ensure reproduction over generations;
b) increasing the frequency of genes in the population that ensure wide variability of organisms;
c) the appearance in the population of genes that ensure the preservation of characteristics of the species in organisms;
d) the appearance in the population of genes that determine the adaptation of organisms to living conditions;

2. Example of protective coloring:

a) green coloration of the singing grasshopper;
b) green color of leaves in most plants;
c) bright red color ladybug;
d) similarity in the color of the abdomen of the hoverfly and the wasp.

3. Masking example:

a) green coloration of the singing grasshopper;
b) similarity in the color of the abdomen of the hoverfly and the wasp;
c) bright red color of the ladybug;

4. Example of warning coloring:

a) bright red color of a rose flower;
b) the ladybug has a bright red color;
c) similarity in color between the hoverfly and the wasp;
d) similarity in color and body shape of the moth caterpillar with the knot.

5. Example of mimicry:

a) green coloration of the singing grasshopper;
b) the ladybug has a bright red color;
c) similarity in the color of the abdomen of the hoverfly and the wasp;
d) similarity in color and body shape of the moth caterpillar with the knot.

Answer card: