What is the main criterion. View criteria. The geographic criterion of a species is…

A species is a collection of individuals that are similar in terms of species criteria to such an extent that they can naturally interbreed and produce fertile offspring.

A fertile offspring is one that can reproduce itself. An example of infertile offspring is a mule (a hybrid of a donkey and a horse), it is sterile.

View criteria- these are signs by which 2 organisms are compared to determine whether they belong to the same species or to different ones.

• Morphological - internal and external structure.
• Physiological and biochemical - how organs and cells work.
• Behavioral - behavior, especially at the time of reproduction.
• Ecological - a combination of factors external environment necessary for the life of the species (temperature, humidity, food, competitors, etc.)
• Geographic - area (distribution area), i.e. the area in which the species lives.
• Genetic-reproductive - the same number and structure of chromosomes, which allows organisms to produce fertile offspring.

View criteria are relative, i.e. one cannot judge the species by one criterion. For example, there are twin species (in the malarial mosquito, in rats, etc.). They do not differ morphologically from each other, but have a different number of chromosomes and therefore do not give offspring. (That is, the morphological criterion does not work [relatively], but the genetic-reproductive one works).

1. Establish a correspondence between the trait of a honey bee and the criterion of the species to which it belongs: 1) morphological, 2) ecological. Write the numbers 1 and 2 in the correct order.
A) social life
B) the difference in the size of males and females
C) development of larvae in combs
D) the presence of hair on the body
D) feeding on nectar and pollen of flowers
E) compound eyes

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2. Establish a correspondence between the trait that characterizes the agile lizard and the species criterion: 1) morphological, 2) ecological
A) the body is brown
B) eats insects
B) is inactive at low temperatures
D) respiratory organs - lungs
D) breeds on land
E) the skin does not have glands

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3. Establish a correspondence between the sign of a quick lizard and the criterion of the species that it illustrates: 1) morphological, 2) ecological
A) winter torpor
B) body length 25-28cm
B) spindle-shaped body
D) differences in the color of males and females
D) living on the edges of forests, in ravines and gardens
E) feeding on insects

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4. Establish a correspondence between the sign of the mole and the criterion of the species to which this sign belongs: 1) morphological, 2) ecological. Write the numbers 1 and 2 in the correct order.
A) the body is covered with short hair
b) very small eyes
C) digs a passage in the soil
D) front paws are wide - digging
D) eats insects
E) breeds in the nesting chamber

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1. Establish a correspondence between the characteristic of the species Wild pig (boar) and the criterion of the species to which this characteristic belongs: 1) morphological, 2) physiological, 3) ecological. Write down the numbers 1, 2 and 3 in the correct sequence.
A) The number of piglets in a brood depends on the fatness of the female and her age.
B) Pigs are active during the day.
C) Animals lead a herd life.
D) The color of individuals is from light brown or gray to black, the piglets are striped.
D) The method of obtaining food is digging the earth.
E) Pigs prefer oak and beech forests.

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2. Establish a correspondence between the characteristic of the common dolphin species (dolphin-dolphin) and the criterion of the species to which this characteristic belongs: 1) morphological, 2) physiological, 3) ecological
A) Predators, they feed on different types of fish.
B) Males are 6-10 cm larger than females.
C) Animals have mastered aquatic environment a habitat.
D) The size of the body is 160-260 centimeters.
E) Pregnancy of females lasts 10-11 months.
E) Animals lead a herd life.

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3. Establish a correspondence between the characteristic of the Asian Porcupine species and the criterion of the species to which it belongs: 1) morphological, 2) physiological, 3) ecological. Write the numbers 1, 2 and 3 in the correct order.
A) Paws are equipped with long claws.
b) Animals eat plants.
C) Pregnancy of females lasts 110-115 days.
D) The longest and sparser needles grow on the lower back of animals.
E) The female secretes milk after the birth of the cubs.
E) Animals lead night image life.

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4. Establish a correspondence between the signs of the tapeworm and the criteria of the species: 1) morphological, 2) ecological, 3) physiological. Write down the numbers 1, 2, 3 in the order corresponding to the letters.
A) body size up to 3 m
B) on the head, in addition to suckers, there are hooks
C) an adult worm lives in the human small intestine
D) reproduces parthenogenetically
D) larvae develop in the body of domestic and wild pigs
E) pork tapeworms are highly prolific

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5. Establish a correspondence between the characteristics of the blue whale species and the criteria for the species: 1) morphological, 2) physiological, 3) ecological. Write down the numbers 1-3 in the order corresponding to the letters.
A) Females breed every two years.
B) The female produces milk for seven months.
C) Whale lice and barnacles settle on the skin of whales.
D) Whalebone plates are pitch black.
E) The length of some individuals reaches 33 meters.
E) Sexual maturity of individuals occurs at four to five years.

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6. Establish a correspondence between the characteristic of a quick lizard and the criterion of the species to which it belongs: 1) morphological, 2) ecological, 3) physiological. Write down the numbers 1-3 in the order corresponding to the letters.
A) ground type limbs
B) the presence of horny scales on the skin
B) the development of the embryo in the egg
D) laying eggs on land
D) fluctuating body temperature
E) feeding on insects

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1. Establish a correspondence between examples and types of adaptation: 1) morphological, 2) ethological, 3) physiological. Write down the numbers 1, 2, 3 in the order corresponding to the letters.
A) deaf nettle resembles stinging nettle
B) a chipmunk stores food for the winter
C) the bat falls into a state of winter dormancy
D) when threatened, the opossum freezes
D) the shark has a torpedo-shaped body
E) bright coloring dart frogs

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2. Establish a correspondence between the characteristics of organisms and types of adaptations: 1) behavioral, 2) morphological, 3) physiological. Write down the numbers 1-3 in the order corresponding to the letters.
A) knotty stick insect
B) freezing in danger in an opossum
C) crystals of potassium oxalate on the hairs of leaves and shoots of stinging nettle
D) incubation of eggs in the mouth by tilapia
D) bright coloring of poison dart frogs
E) removal of excess water through the kidneys in the form of weakly concentrated urine by crayfish

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Choose one, the most correct option. What characteristic of the species Rosyanka rotundifolia should be attributed to the physiological criterion?
1) the flowers are regular, white, collected in an inflorescence brush
2) uses insect proteins as food
3) distributed in peat bogs
4) leaves form a basal rosette

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Choose one, the most correct option. Find the name of the view criterion in the specified list
1) cytological
2) hybridological
3) genetic
4) population

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1. Select from the text three sentences that describe the ecological criterion of the species. Write down the numbers under which they are indicated in the table. (1) The housefly is a two-winged insect that serves as food for insectivorous birds. (2) Her mouthparts are of a licking type. (3) Adult flies and their larvae feed on semi-liquid food. (4) Female flies lay their eggs on rotting organic matter. (5) The larvae are white, have no legs, grow rapidly and turn into red-brown pupae. (6) The adult fly develops from the pupa.

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2. Read the text. Choose three sentences that describe the ecological criterion of the plant species Pemphigus vulgaris. In your answer, write down the numbers under which they are indicated. (1) Pemphigus vulgaris is mainly found in the Mediterranean region of Europe and Africa. (2) Pemphigus vulgaris grows in ditches, ponds, stagnant and slow-flowing water bodies, swamps. (3) Leaves of plants are dissected into numerous thread-like lobes, leaves and stems are provided with vesicles. (4) Pemphigus flowers from June to September. (5) Flowers are yellow, 5-10 per peduncle. (6) Pemphigus vulgaris is an insectivorous plant.

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3. Read the text. Choose three sentences that describe the ecological criterion of the house mouse species. Write down the numbers under which they are indicated in the table. (1) The house mouse is a mammal of the genus Mouse. (2) Original range - North Africa, tropics and subtropics of Eurasia. (3) Settles mainly near human habitation. (4) Leads a nocturnal and twilight lifestyle. (5) A litter usually has 5 to 7 babies. (6) Under natural conditions it feeds on seeds.

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4. Read the text. Choose three sentences that describe the ecological criteria for the fieldfare thrush species. Write down the numbers under which the selected statements are indicated. (1) Field thrush - large bird. (2) Thrushes live in middle lane Russia. (3) Fieldfare thrushes settle along forest edges, in city squares and parks. (4) They feed on the ground, looking for earthworms, slugs and insects under dry leaves and moss. (5) In winter, they feed on the fruits of mountain ash, hawthorn and other berries that ripen on the bushes. (6) Fieldfare thrushes nest in small colonies ranging from 2-3 to several dozen nests.

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5. Read the text. Choose three sentences that describe the ecological criterion for the species of the cabbage white butterfly. Write down the numbers under which they are indicated. (1) The cabbage white butterfly has a mealy-white color on the upper side of the wings. (2) There are dark spots on the front pair of wings. (3) In spring and summer, the butterfly lays its eggs on the leaves of cabbage or other cruciferous plants. (4) The eggs hatch into yellow caterpillars that feed on plant leaves. (5) Caterpillars become a bright blue-green color as they grow. (6) A grown caterpillar crawls onto a tree, turns into a chrysalis, which hibernates.

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6. Read the text. Choose three sentences that describe the ecological criterion of the species Cornflower blue (sowing). Write down the numbers under which they are indicated. (1) Blue cornflower is a weed plant of the Compositae family, found in fields in grain crops. (2) Often the plant lives along roads, near forest belts. (3) An upright cornflower stem reaches up to 100 cm in height. (4) The flowers are bright blue. (5) Blue cornflower is a light-loving plant. (6) The flowers contain essential oils, tannins and other substances.

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Choose one, the most correct option. To apply an ecological criterion to the description of an animal species means to characterize
1) variability of signs within the normal range of reaction
2) a set of external signs
3) the size of its range
4) a set of intended feed

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1. Read the text. Choose three sentences that describe the morphological criterion of the rhinoceros beetle species. Write down the numbers under which they are indicated. (1) The rhinoceros beetle lives in the European part of Russia. (2) Its body is brown. (3) Sexual dimorphism is well expressed. (4) Rhinoceros beetle larvae develop in compost heaps. (5) Males have a horn on their heads. (6) Beetles can fly into the light.

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2. Read the text. Choose three sentences that describe the morphological criterion of the shrub cherry species. Write down the numbers under which the selected statements are indicated. (1) Shrub cherry is a low shrub or small tree 3-6 m high. (2) Brown bark, ellipse-shaped leaves, pointed. (3) Bush cherry is one of the ancestors of common cherry varieties. (4) Grows in Russia in the European part of the country and in the south Western Siberia. (5) The flowers are white, collected 2-3 in an umbel inflorescence. (6) Cherry blossoms in April-May, and the fruits ripen in early summer.

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3. Read the text. Choose three sentences that describe the morphological criterion for the species of oak veronica. Write down the numbers under which the selected statements are indicated. (1) Veronica oak grows in forest clearings, meadows, hillsides. (2) The plant has a creeping rhizome and a stem 10-40 cm tall. (3) Leaves with serrated edges. (4) Veronica oakwood blooms from late May to August. (5) Pollinated by bees and flies. (6) Flowers are small, of blue color collected in inflorescence raceme.

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4. Read the text. Choose three sentences that describe the morphological criterion of the species of Scots pine. Write down the numbers under which they are indicated.(1) Scotch pine is a photophilous plant. (2) When its seed germinates, five to nine photosynthetic cotyledons appear. (3) Pine is able to develop on any soil. (4) Green pine leaves are needle-shaped and arranged in pairs on short shoots. (5) The elongated shoots are arranged in whorls that form once a year. (6) Pollen with male cones carried by the wind and landed on the female cones, where fertilization takes place.

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1. Read the text. Choose three sentences that describe genetic criterion kind. Write down the numbers under which they are indicated. (1) There are a number of criteria by which one species differs from another. (2) Each species has its own specific karyotype. (3) An important feature of a species is its habitat. (4) In individuals of the same species, chromosomes have a similar structure. (5) Human somatic cells have 46 chromosomes. (6) Most mammals are sexually dimorphic.

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2. Read the text. Choose three sentences that describe the genetic criterion for the Black Rat animal species. Write down the numbers under which they are indicated. (1) It has been established that two species are hidden under the name "black rat": rats with 38 and 42 chromosomes. (2) The black rat lives in Europe, in most countries of Asia, Africa, America, Australia; its distribution is not continuous, but is associated mainly with human dwellings in port cities. (3) The ranges of such species may overlap geographically, and in the same area outwardly indistinguishable individuals of black rats may live side by side without breeding. (4) Differences in karyotype different types provide isolation during interspecific crossing, because they cause the death of gametes, zygotes, embryos or lead to the birth of infertile offspring. (5) In Europe, two races of the black rat are approximately equally distributed, of which one has a typical black-brown fur color, darker than that of the gray rat, and the other is practically blond, with a white belly, similar in color to ground squirrels. (6) Studies of the number, shape, size and structure of chromosomes make it possible to reliably distinguish twin species.

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Choose two correct answers from five and write down the numbers under which they are indicated. Which of the following is not a type criteria?
1) Genetic
2) Biocenotic
3) Cellular
4) Geographic
5) Morphological

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1. Read the text. Choose three sentences that describe the physiological criteria for the type of yellow ground squirrel. Write down the numbers under which the selected statements are indicated. (1) Yellow ground squirrel lives in desert uncultivated lands. (2) The ground squirrel feeds on the succulent parts of the steppe grasses, plant bulbs and seeds. (3) It also eats insects: locusts, grasshoppers, beetles and caterpillars. (4) A female gives birth to an average of seven cubs. (5) During the heat of summer and winter, it hibernates. (6) During hibernation, the body temperature of the animal drops to 1-2 ° C, the heart beats at a frequency of 5 beats per minute.

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2. Read the text. Choose three sentences that describe the physiological criterion for the type of animal Terrible poison dart frog. Write down the numbers under which they are indicated. (1) One of the most venomous vertebrates on Earth, these small tree frogs found in a small area of ​​southwestern Colombia, mainly in the lower tiers of rain rainforest. (2) They have bright, contrasting coloration, males and females are of the same size. (3) The skin glands of the dire dart frog secrete a mucus containing a strong poison, batrachotoxin. (4) The poison protects the animal both from fungi and bacteria and from natural enemies, which can be fatally poisoned when dart frog venom gets on the skin or mucous membranes. (5) Dart frogs are diurnal, in nature they feed mainly on ants, other small insects and mites. (6) Animals are very active, and fasting for 3-4 days can not only weaken a healthy, well-fed individual, but also cause her death.

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3. Read the text. Choose three sentences that describe the physiological criteria for the thermophilic bacterium Thiobacillus thermophilica. Write down the numbers under which they are indicated. (1) An ecologically distinct group in nature is represented by thermophilic microorganisms living in nature at temperatures from 40 to 93 degrees. (2) Hot springs North Caucasus, rich in hydrogen sulfide, are abundant with thermophilic species of thionic bacteria, such as the thiobacterium Thiobacillus thermophilica. (3) This thermophilic bacterium is capable of division and development at temperature regime from 40 to 70-83 degrees. (4) The membranes of thermophilic bacteria have high mechanical strength. (5) Thermophilic bacteria have enzymes that can function at high temperatures, providing the necessary speed chemical reactions in a cage. (6) Spores of thermophilic bacteria are much more heat resistant than spores of mesophilic forms, and maximum speed colony growth occurs at an optimal temperature of 55-60 degrees.

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4. Read the text. Choose three sentences that describe the physiological criterion of the species Silver Poplar. Write down the numbers under which they are indicated. (1) Poplars grow very quickly, reaching their final height at the age of forty. (2) The height of poplar trees ranges from 30 to 60 meters. (3) The plant does not live long, mostly up to eighty years. (4) Poplar roots are thick, strong, in many species located superficially. (5) Kidney cells form a sticky, resinous substance. (6) The wood of the tree is soft and very light, the trunk is straight, the crown can have a variety of shapes.

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2. Establish a correspondence between the characteristics and criteria of the species: 1) physiological, 2) ecological. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) herbivore
B) pregnancy within one month
B) nocturnal
D) the birth of several cubs
D) high heart rate

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1. Read the text. Choose three sentences that describe the geographical criterion for the type of tuatara. Write down the numbers under which they are indicated. (1) Single modern representative order of beak-headed reptiles. (2) Outwardly similar to a lizard, up to 75 cm long, along the back and tail there is a crest of triangular scales. (3) Before the arrival of Europeans, inhabited the North and South Islands of New Zealand. (4) At the end of the 19th century, it was exterminated and survived only on nearby islands in a special reserve. (5) Listed in the Red Book of the International Union for Conservation of Nature and natural resources(IUCN). (6) Successfully bred at the Sydney Zoo.

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2. Read the text. Choose three sentences that describe the geographical criterion for the type of plant Siberian cedar pine. Write down the numbers under which they are indicated. (1) Siberian cedar pine, or Siberian cedar- one of the species of the genus Pine; evergreen tree, reaching 35-44 m in height and 2 m in trunk diameter. (2) Cedar is very common in Western Siberia throughout the forest belt from 48 to 66 degrees N, and in Eastern Siberia due to permafrost, the northern border of the range deviates sharply to the south. (3) In Siberia, it prefers sandy and loamy soils, but can also grow on stony substrates and sphagnum bogs. (4) In Central Altai upper bound distribution of cedar lies at an altitude of 1900-2000 m above sea level. (5) Siberian cedar also grows in Mongolia and northern China. (6) Siberian cedar pine is frost-resistant, shade-tolerant, demanding on heat, air and soil moisture, avoids soils with close occurrence of permafrost.

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3. Read the text. Choose three sentences that describe the geographical criterion for the type of animal European grayling. Write down the numbers under which they are indicated. (1) European grayling - freshwater fish subfamilies of graylings of the salmon family, weighing up to seven kilograms. (2) The life of these fish is associated with a certain water temperature, so grayling is not found in grassy places, deep coastal bays and fiords. (3) This species of fish lives in the basins of the White and Baltic Seas, in the basin of the North Arctic Ocean, from Finland to Tyumen region. (4) Smaller graylings live in the rivers, their weight barely reaches the weight of more than 1 kg. (5) Fish, making seasonal migrations in search of food, reach the upper reaches of the Dniester, Volga and Ural rivers. (6) Grayling is also found in the large northern lakes of the European part of Russia - Onega, Ladoga and some other reservoirs, in which it chooses rocky, less often sandy shallows.

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4. Read the text. Choose three sentences that describe the geographical criterion for the species of the Song Thrush. Write down the numbers under which they are indicated. (1) The song thrush is a small songbird of the thrush family found in Europe, Asia Minor and Siberia. (2) The song thrush inhabits various types of forests and is equally numerous in deciduous forests, and in the taiga. (3) Adult birds feed on invertebrates, song thrushes feed their chicks with various insects and small worms, and in autumn they eat various berries and fruits. (4) The range of the song thrush characterizes it as a northern, cold-resistant bird, choosing forests with young spruce or juniper for nesting sites. (5) Actively populates northern regions Scandinavian Peninsula and numerous in the East European forest-tundra, penetrating even into the tundra, actively settled to the east. (6) Absent in Southern Europe, on the islands mediterranean sea, although there are biotopes suitable for song thrushes.

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1. Read the text. Select three sentences that describe the biochemical criterion for the species Stinging nettle. Write down the numbers under which they are indicated. (1) Stinging nettle - perennial herbaceous plant with a powerful root and a long horizontal branched rhizome. (2) Nettles are protected from being eaten by herbivores by stinging hairs found on all parts of the plant. (3) Each hair is a large cell. (4) The wall of the hair contains silicon salts, which make it brittle. (5) The content of formic acid in the cell sap of the hairs does not exceed 1.34%. (6) Young nettle leaves contain many vitamins, so they are used as food.

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1. Establish a correspondence between the characteristic features of the type Bittersweet nightshade and the criteria of the species to which they are referred: 1) morphological, 2) ecological, 3) biochemical. Write down the numbers 1-3 in the order corresponding to the letters.
A) Poisonous substances are formed and accumulated in the plant.
B) Ripe berries contain a lot of sugar.
C) The berries are bright red in color.
D) The flowers are lilac, have the correct shape.
D) Plants are common in vegetable gardens and river banks.
E) Plant height - 30-80 centimeters.

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2. Establish a correspondence between the features and criteria of the species Stinging nettle: 1) ecological, 2) morphological, 3) biochemical. Write down the numbers 1-3 in the order corresponding to the letters.
A) a perennial plant with a strong root and a long rhizome
B) is growing clearings, in weedy places, along fences
B) is formed in the leaves ascorbic acid, carotene, vitamins B and K
D) nettle blooms from early summer to early autumn
D) flowers are small, unisexual, with a greenish perianth
E) potassium oxalate accumulates in leaf cells

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Morphological criterion reflects the external and internal similarity of individuals of the same species.

So, black and white crows belong to different species, which can be determined by their appearance. But organisms that belong to the same species may differ from each other in some signs and properties. However, these differences are very small compared to those observed in individuals of different species. Meanwhile, there are species that have an external resemblance, but cannot interbreed with each other. These are the so-called twin species. So, in Drosophila, the malarial mosquito and the black rat, two twin species have been established. Twin species are also found in amphibians, reptiles, birds, and even mammals. Therefore, the morphological criterion is not decisive for the differentiation of species. However, for a long time this criterion was considered the main and the only one in determining species (Fig. 39).

At the core physiological criterion lies the similarity of life processes in individuals of each species, especially reproduction.

Representatives of different species do not interbreed, and if they interbreed, they do not give offspring. Non-crossing of species is explained by differences in the structure of the genital organs, different terms reproduction and other reasons. However, in nature there are cases when certain types of plants (poplar, willow), birds (canaries) and animals (hares) can interbreed and produce offspring. This also indicates that one physiological criterion is also not enough to distinguish between species.

Under this criterion understand the specific environmental conditions in which they live and to which individuals of a particular species have adapted. For example, a poisonous buttercup grows in fields and meadows, a creeping buttercup grows in damp places, along the banks of rivers, reservoirs, and in swampy places a burning ranunculus.

This criterion refers to the set of chromosomes, structure and coloration characteristic of each species. One double view black rat has 38, the other has 42 chromosomes. Although the genetic criterion is characterized by some constancy, this similarity is relative, since differences in the number and structure of chromosomes can be observed within a species. In addition, the number of chromosomes may be the same in different species. For example, cabbage and radish each have 18 chromosomes.

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Riteria of the species. The features by which one species can be distinguished from another are called species criteria.

The basis of the morphological criterion is the similarity of the external and internal structure between individuals of the same species. This criterion is the most convenient and is therefore widely used in taxonomy.

However, individuals within a species sometimes differ so greatly that it is not always possible to determine which species they belong to by morphological criteria alone. At the same time, there are species that are morphologically similar, but individuals of these species do not interbreed. These are twin species that researchers are discovering in many systematic groups. So, under the name “black rat”, two twin species are distinguished, having karyotypes of 38 and 42 chromosomes each. It has also been established that under the name " malarial mosquito» There are up to 15 outwardly indistinguishable species, previously considered one species. About 5% of all species of insects, birds, fish, amphibians, worms are twin species.

The physiological criterion is based on the similarity of all vital processes in individuals of the same species, primarily the similarity of reproduction. Individuals of different species, as a rule, do not interbreed, or their offspring are sterile. For example, in many species of Drosophila fly, the sperm of a foreign species triggers an immune response, which leads to the death of spermatozoa in the female genital tract. At the same time, there are species in nature whose individuals interbreed and produce fertile offspring (some species of canaries, finches, poplars, willows).

The geographical criterion is based on the fact that each species occupies a certain territory or water area, called the range. It can be larger or smaller, intermittent or continuous (Fig. 1.2). However, a huge number of species have overlapping or overlapping ranges. In addition, there are species that do not have clear distribution boundaries, as well as cosmopolitan species that live on vast expanses of land on all continents or the ocean (for example, plants - shepherd's purse, medicinal dandelion, types of pondweed, duckweed, reed, synanthropes - bed bedbug, red cockroach, housefly). Therefore, the geographical criterion, like the others, is not absolute.

Environmental criterion is based on the fact that each species can exist only under certain conditions, performing its own

functions in a certain biogeocenosis. So, for example, the caustic buttercup grows in floodplain meadows, the creeping buttercup grows along the banks of rivers and ditches, the burning buttercup grows in wetlands. There are, however, species that do not have a strict ecological confinement. These include many weeds, as well as species under human care: indoor and cultivated plants, pets.

The genetic (cytomorphological) criterion is based on the difference between species according to karyotypes, i.e., the number, shape, and size of chromosomes. The vast majority of species are characterized by a strictly defined karyotype. However, this criterion is not universal. First, in many species the number of chromosomes is the same and their shape is similar. For example, some species of the legume family have 22 chromosomes (2n = 22). Secondly, within the same species, individuals with a different number of chromosomes can occur, which is the result of genomic mutations (poly- or aneuploidy). For example, goat willow can have a diploid (38) or tetraploid (76) chromosome number.

The biochemical criterion makes it possible to distinguish species according to the composition and structure of certain proteins, nucleic acids and others. Individuals of one species have a similar DNA structure, which leads to the synthesis of identical proteins that differ from proteins of another species. However, some bacteria, fungi, higher plants DNA composition was very similar. Consequently, there are twin species in terms of biochemical characteristics.

Thus, only taking into account all or most of the criteria makes it possible to distinguish individuals of one species from another.

The question of species and species criteria occupies a central place in the theory of evolution and is the subject of numerous studies.research in the field of systematics, zoology, botany and otherSciences. And this is understandable: a clear understanding of the essencespecies is necessary to elucidate the mechanisms of evolutionary process.

A strict generally accepted definition of the species has not yet been developed.nerd. In biological encyclopedic dictionary we are onwe go to the following definition of the form:

“A species is a set of populations of individuals capable of interbreedingwith the formation of fertile offspring inhabiting a certainarea, which have a number of common morphophysiological signs and remote from other similar groups of individuals in practiceby the complete absence of hybrid forms.

Compare this definition with the one in your textbook.(textbook by A.A. Kamensky, § 4.1, p. 134).

Let us explain the concepts that occur. in the view definition:

area- the area of ​​distribution of a given species or population in nature.

population(from lat. “Pop uius " - people, population) - totalthe number of individuals of the same species with a common gene pool and occupationcovering a certain territory - an area.

gene pool- the totality of genes that individuals haveof this population.

Consider the history of the development of views on the species in biology.

The concept of species was first introduced into science by an English botanist John Ray inXVII century. Foundational work on the species problemwas written by a Swedish naturalist and naturalistCarl Linnaeus in XVIII centuryin which he proposed the firstscientific definition of the species, clarified its criteria.

K. Linnaeus believed that the species is a unigreasy, really existing unit of living matter, morphologically homogeneous and unchanging . All individuals of the species, according to the scientist, have a typical morphological appearance, and variations are random deviations. , the result of an imperfect implementation of the idea of ​​the form (a kind of deformity). Scientistbelieved that species are unchanging, nature is unchanging. The idea is unchangedof nature rested on the concept of creationism, according towhich all things were created by God. Applied to biologyLinnaeus expressed this concept in his famous formulamule “There are as many kinds as there are different forms that the Infinite creature".

Another concept belongs Tom Baptiste Lamarck- ledto whom the French naturalist. According to his concept, the views are real Not exist, is a purely speculative concept invented forto make it easier to consider a larger number ofindividuals, because, according to Lamarck, “in nature there is noanything but individuals. Individual variability is continuous, therefore, the boundary between species can be drawn here and there - where it is more convenient.

The third concept was prepared in the first quarter XIX century. She was justified Charles Darwin and subsequent biologistmi. According to this concept, species have an independent reality. Viewheterogeneous, is a system of subordinate units. WITHamong them, the basic elementary unit is the population. Species, by Darwin, change, they are relatively constant and areultatum of evolutionary development .

Thus, the concept of "species" has a long history of formation in biological science.

Sometimes the most experienced biologists are at a dead end, determiningwhether these individuals belong to the same species or not . Why is that happens, are there precise and strict criteria thatcould resolve all doubts?

Species criteria are traits by which one species differs.comes from another. They are also isolation mechanisms.interbreeding, independence, independently hundreds of species.

We know that one of the main features of biological matter on our planet is discreteness. It's in expressed in the fact that it is represented by separate species, notinterbreeding with each other, isolated from each other gogo.

The existence of a species is ensured by its genetic unity.(individuals of the species are able to interbreed and produce viable fertile offspring) and its genetic independence (impossiblethe possibility of interbreeding with individuals of another species, not viablestability or sterility of hybrids).

The genetic independence of the species is determined by the totalits characteristic features: morphological, physiological, biochemical, genetic, lifestyle, behavior, geographical distribution, etc. This is Crete series of the species.

View criteria

Morphological criterion

Morphological criterion is the most convenient and noticeable, thereforeand is now widely used in the taxonomy of plants and animals.

We can easily distinguish by the size and color of the plumage of a largespotted woodpecker from green woodpecker, lesser spotted woodpecker and yellow(black woodpecker), great tit from crested, long-tailed, blueand chickadees, meadow clover from creeping and lupine, etc.

Despite the convenience, this criterion does not always “work”. You can’t use it to distinguish between twin species, practicallymorphologically different. There are many such species among malarialmosquitoes, fruit flies, whitefish. Even birds have 5% of twin species, andThere are 17 of them in one row of North American crickets.

The use of morphological criteria alone canlead to erroneous conclusions. So, K. Linnaeus in particularexternal structure attributed the male and female mallard ducks to different species. Siberian hunters identified five variations based on the color of fox fur: gray foxes, moths, crosses, black-brown and black. In England, 70 species of butterflies, along with individuals with a light color, also have themes.nye morphs, the number of which in populations began to increase inconnection with forest pollution. Polymorphism is a widespreadphenomenon. It occurs in all species. It also affects those features by which species differ. In lumberjack beetles, for example, in barbeled flowersexact, found in late spring on a bathing suit, in addition to tiIn the peak form, up to 100 color aberrations occur in populations. In the days of Linnaeus, the morphological criterion was the main one, sincewaist that there is one typical form for the species.

Now that it is established that a species can have many forms, such asthe logical concept of species is discarded and the morphological criterion is notalways satisfies scientists. However, it must be recognized that this criterionis very convenient for systematizing species, and in most determinants of animals and plants it plays a major role.

Physiological criterion

Physiological features of various types of plants and bellynyh are often a factor that ensures their genetic selfvalue. For example, in many fruit flies, the sperm of individuals of a foreign speciesYes, it causes an immunological reaction in the female genital tract, which leads to the death of spermatozoa. Hybridization of various species andsubspecies of goats often leads to a violation of the periodicity of the fetuswearing - the offspring appears in winter, which leads to his death. Crossbreedsthe study of different subspecies of roe deer, for example, Siberian and European,sometimes leads to the death of females and offspring due to large size fetus.

Biochemical criterion

Interest in this criterion has emerged in recent decades in connection withdevelopment of biochemical research. It is not widely used, since there are no specific substances characteristiconly for one species and, in addition, it is very laborious and far not universal. However, they can be used in cases wherewhen other criteria do not work. For example, for two twin speciesbutterflies from the genus Amata (A. p h e g ea and A. g ugazzii ) diagnosticand signs are two enzymes - phosphoglucomutase and esterase-5, allowing even identify hybrids of these two species. IN Lately widely used comparative study of the composition of DNK in practical taxonomy of microbes. The study of the composition of DNA allowed to revise the phylogenetic system of various groups microorganisms. The developed methods make it possible to compare the compositionDNA in bacteria preserved in the depths of the earth and now livingforms. For example, a comparison was made of the composition of DNA in a lyingabout 200 million years in the thickness of salts of the Paleozoic bacterium pseudosalt-loving monads and in living pseudomonads. The composition of their DNA turned out to be identical, and biochemical properties are similar.

Cytological criterion

The development of cytological methods has allowed scientists to investigate theRmu and the number of chromosomes in many species of animals and plants. A new direction has appeared - karyosystematics, which has introduced somecorrections and clarifications to the phylogenetic system built on the basis of morphological criteria. In some cases, the number of chromosomes serves characteristic feature kind. Karyological analysis allowed, for example, to streamline the taxonomy of wild mountain sheep, whichry different researchers identified from 1 to 17 species. The analysis showedthe presence of three karyotypes: 54 chromosome - in mouflons, 56romosome - in argali and argali and 58-chromosome - in the inhabitantsmountains Central Asia- urials.

However, this criterion is not universal. First, atmany different species have the same number of chromosomes and their shape is similar. Secondly, individuals with different numbers of chromosomes may occur within the same species. These are the so-called chromosomal and genomicpolymorphism. For example, goat willow has a diploid - 38 and a tetraploid the new number of chromosomes is 76. In silver carp, there are populations with a setrum chromosomes 100, 150, 200, while their normal number is 50. In the rainbow trout, the number of chromosomes varies from 58 to 64, in the White Seadi meet individuals with 52 and 54 chromosomes. In Tajikistan on the siteonly 150 km long, zoologists discovered a population of mole voles with a set of chromosomes from 31 to 54. In gerbils from different places habitats, the number of chromosomes is different: 40 - in Algerian gerbils skian populations, 52 in Israeli and 66 in Egyptian. To infusion current time, intraspecific chromosomal polymorphism was found in 5% of ctotal genetically studied species of mammals.

Sometimes this criterion is incorrectly interpreted as genetic. Undoubtedly, the number and shape of chromosomes is an important feature that prevents crossbreedingof individuals of different species. However, this is rather a cytomorphologicalcue criterion, since we are talking about intracellular morphology: the numberand the shape of chromosomes, and not about the set and structure of genes.

E tological criterion

For some animal species, a mechanism that preventsbaptism and leveling the differences between them are especiallybenignity of their behavior, especially in mating season. Partner recognition own species and rejection of courtship attempts by males of another speciesbased on specific stimuli - visual, auditorychemical, tactile, mechanical, etc.

In the widespread genus warblers, different species are very similarlive on top of each other morphologically, in nature they cannot be distinguished either by color or by size. But they all differ very well in song and by habits. The song of the willow warbler is complex, similar to the song of the chaffinch, only without his final knee, and the song of the chiffchaff is aboutstenky monotonous whistles. Numerous twin species of ameRican fireflies of the genus P hotinus were first identified bydifferences in their light signals. Male fireflies in flight flashes of light, the frequency, duration and alternation of whichspecific to each species. well known but that a number of species of orthoptera and homopterans living within,of the same biotope and breeding synchronously, differ onlythe nature of their calling signals. Such double species with acousticreproductive isolation are found, for example, in crickets, skating fillies, cicadas and other insects. Two closely related species of Americantoads also do not interbreed because of differences in the call of males.

Differences in demonstrative behavior often play a decisive role in reproductive isolation. For example, related species of Drosophila flies fromdiffer in the specifics of the ritual of courtship (according to the nature of the vibrationwings, leg trembling, whirling, tactile contacts). Two closespecies - herring gull and klusha have differences in the degree of pronouncedhundreds of demonstrative poses, and seven species of lizards of the genus S se1horns s differ in the degree of raising the head when courting sexual partners.

Environmental criterion

Behavioral features are sometimes closely related to the ecological specifics of the species, for example, to the peculiarities of nest construction. Three species of our common tits nest in hollows deciduous trees, predominantly birches. great tit in the Urals chooses usually deep a hollow in the lower part of a birch or alder trunk, formed in a re as a result of rotting of the knot and adjacent wood. This hollow is inaccessible to woodpeckers, crows, or predatory mammal. Tit moskovka populates frost cracks in the trunks of birch and alder. Hathe egg prefers to build a hollow itself, plucking cavities into rottenold trunks of birch and alder, and without this time-consuming procedure, she will not lay eggs.

Features of the lifestyle inherent in each species determineits position, its role in the biogeocenosis, that is, its ecologicalniche. Even the closest species, as a rule, occupy different econiches, that is, they differ in at least one or two ecological signs.

Thus, the econiches of all our species of woodpeckers differ in the nature of their diet. Great spotted woodpecker feeds on larch seeds in winter tsy and pines, crushing cones in their "forges". black woodpeckerzhelna extracts barbel larvae and gold beetles from under the bark and from woodfir, and the small spotted woodpecker hammers soft alder wood or extracts nase lumps from the stems of herbaceous plants.

Each of the 14 species of Darwin's finches (named afterC. Darwin, who first paid attention to them), living on the Galapagos islands, has its own specific eco-niche, which differs from others primarily in the nature of food and ways of obtaining it.

Neither the ecological nor the ethological crite discussed aboverii are not universal. Very often individuals of the same species, but oncepopulations differ in a number of lifestyle featuresand behaviour. And vice versa, different species, even very distant ones, in the systemchemically, may have similar ethological characteristicsor play the same role in the community (for example, the role of a herbivorous mammal and insects, say, such as locusts, are quite comparable).

Geographic criterion

This criterion, along with the ecological one, takes the second (after the morphological) place in most determinants. When determining many species of plants, insects, birds, mammals and othergroups of organisms whose distribution is well studiedThe distribution of the range plays a significant role. In subspecies, the ranges, as a rule, do not coincide, which ensures their reproductive isolation and, in fact,, their existence as independent subspecies. many kindsoccupy different ranges (such species are called allopatric And). But a vast number of species have overlapping or overlappingexpanding ranges (sympatric species). In addition, there are typeshaving clear boundaries of distribution, as well as braid speciesmopolitans living on vast expanses of land or ocean. INdue to these circumstances, the geographical criterion cannot be universal.

Genetic criterion

Genetic unity of the species and, accordingly, genetic isolationit from other species - the main criterion of the species, the main speciesa sign due to a complex of features of the structure and lifeactivities of this species. Genetic compatibilitybridge, similarity of morphological, physiological, cytologicaland other signs, the same behavior, living together - all thiso creates the necessary conditions for successful reproduction andspecies production. At the same time, all these traits provide geneticisolation of a species from other similar species. For example, oncelychia in the song of thrushes, warblers, warblers, finches and finches, deafand common cuckoo prevent the formation of mixed pairs,despite the similarity of their coloration and ecology (hybrids are almost never found in birds with a specific song). Even in those cases I, when, despite isolation barriers, interbreeding occurredthe formation of individuals of different species, a hybrid population, as a rule, does not arise, since a number of post-populationisolation mechanisms. The most important of them is the death of male gametes (genetical incompatibility), death of zygotes, non-viability of thereeds, their sterility, finally, the inability to find a sexualpartner and produce viable fertile offspring. We know thatEach species has its own set of specific features. An interspecific hybrid will have characters intermediate betweenfeatures of the two original parental forms. His song, for example will not be understood by either a chaffinch or a finch if it is a hybrid of these species, and he will not find a sexual partner. In such a hybrid,the formation of gametes, the finch chromosomes contained in its cells “do notfind the chromosomes of the finch and, not finding a homologous partner, do notconjugate. As a result, gametes with a disturbed set are formed.chromosomes, which are usually not viable. And as a resultThis hybrid will be sterile.

The raven is distributed almost throughout the northern hemisphere: it occursalmost throughout Europe, Asia, excluding Southeast, in NorthAfrica and North America. Everywhere he leads a settled way of life. Inhabits forests, deserts and mountains. In treeless areas keeps atrocks, coastal cliffs of river valleys. Mating and mating gamesin the south of the country are celebrated in the first half of February, in the north - inMarch. Couples are constant. Nests are usually placed on the tops of tall trees. In clutch from 3 to 7, more often 4-6, eggs are bluish-green in color. ki with dark markings.

Raven is an omnivorous bird. His main food is carrion, which he oftenfinds everything in landfills and slaughterhouses. Eating carrion, he performslike a sanitary bird. It also feeds on rodents, eggs,and chicks, fish, various invertebrates, and placesmi and grains of cereals.

The crow in general physique resembles a crow, but significantlysmaller than it: weighs from 460 to 690 g.

The described species is interesting in that, according to the color of the plumage, it breaks upinto two groups: gray and black. The hooded crow is well knownnew two-tone color: head, throat, wings, tail, beak and legs are black, the rest of the plumage is gray. Black Crow is all black, with a metallic blue and purple sheen.

Each of these groups has a local distribution. The gray crow is widespread in Europe, Western Asia, the black crow is widespread in Central and Western Europe, on the one hand, and in Central and Eastern Asia and North America, on the other.

The crow inhabits the edges and outskirts of forests, gardens, groves, thickets of river valleys, less often rocks and slopes of coastal cliffs. It is partly sedentary, partly migratory bird.

In early March, in the southern parts of the country and in April-May in the northern and eastern parts, egg laying begins. The clutch usually contains 4-5 pale green, bluish-green or partially green eggs with dark spots and speckles. The crow is an omnivorous bird. From animals, she eats various invertebrates - beetles, ants, mollusks, as well as rodents, lizards, frogs and fish. From plants, it pecks grains of cultivated cereals, seeds of spruce, field bindweed, bird buckwheat, etc. In winter, it feeds mainly on garbage.

White Hare and European Hare

The genus of hares proper, which includes the hare and hare, as well as another 28 species , quite numerous. The most famous hares in Russia are hare and hare. White hare can be found on the territory from the coast of the Arctic Ocean to the southern border of the forest zone, in Siberia - to the borders with Kazakhstannom, China and Mongolia, and on Far East- from Chukotka to and North Korea. The hare is also common in the forests of Europe, as well as in the east of Northern America. Rusak lives in the territory European Russia from Kareliasouth of the Arkhangelsk region to the southern borders of the country, in Ukraine and in the Zakavcasier. But in Siberia, this hare lives only in the south and west of Lake Baikal.

Belyak got its name due to snow-white winter fur. Only the tips of his ears remain black all year round. Rusak, in some northern areas, also brightens greatly by winter, but it never happens to be snow-white. And in the south it does not change color at all.

The hare is more adapted to life in open landscapes, since it is larger than the white hare, and it runs better. At short distances, this hare can developspeed up to 50 km/h. The hare's paws are wide, with dense pubescence to fall less into loose forest drifts. And the hare already has paws, because on open places snow, as a rule, is hard, packed, "trodden down by the wind."

The body length of the hare is 45-75 cm, weight - 2.5-5.5 kg. The ears are shorter than those of the hare. The body length of the hare is 50-70 cm, weight up to 5 (sometimes 7) kg.

breed hares usually two, and in the south three or even four times a year. Wu harebelyakovs in the output can be two, three five, seven hares, and the hare- usually only one or two hares. Browns begin to taste grass two weeks after birth, and whites even faster - a week later.

In biology, a species is a certain set of individuals that have a hereditary similarity of physiological, biological and morphological features, are able to freely interbreed and produce viable offspring. Species are stable genetic systems, because in nature they are separated by some series of barriers from each other. Scientists distinguish between them according to a number of basic features. Usually, the following species criteria are distinguished: morphological, geographical, ecological, genetic, physico-biochemical.

Morphological criterion

Such signs are the main ones in this system. Morphological criteria species are based on external differences between individual groups of animals or plants. This condition subdivides into species organisms that clearly differ from each other in internal or external morphological features.

Geographic criteria of the species

They are based on the fact that representatives of each stable genetic system live within limited spaces. Such areas are called areas. However, the geographical criterion has some shortcomings. It is not universal enough for the following reasons. First, there are some cosmopolitan species that are distributed all over the planet (for example, the orca whale). Secondly, in many biological aggregates, the ranges coincide geographically. Thirdly, in the case of some too rapidly dispersing populations, the ranges are very variable (for example, a sparrow or a house fly).

Ecological criterion of the species

It is assumed that each species is characterized by certain characteristics, such as the type of food, timing of reproduction, habitat, and everything that determines the ecological niche it occupies. This criterion is based on the assumption that the behavior of some animals differs from the behavior of others.

Genetic criterion of the species

This takes into account the main property of any species - its genetic isolation from others. Plants and animals of different stable genetic systems almost never interbreed. Of course, a species cannot be completely isolated from the influx of genes from related species. However, at the same time, he generally retains the constancy of his genetic composition over a really long period of time. It is in the genetic component that the clearest differences between representatives of different biological populations lie.

Physico-biochemical criteria of the species

Such criteria also cannot serve as an absolutely reliable way to distinguish between species, since fundamental biochemical processes
occur in similar groups in the same way. And in the environment of each individual species there is a certain number of adaptations to certain living conditions, which affects the change in biochemical processes.

conclusions

Thus, according to some single criterion, it is very difficult to distinguish between species. The belonging of an individual to any particular species should be determined only through a comprehensive comparison according to a number of criteria - all or at least the majority. Individuals that occupy a certain territory and are able to freely interbreed with each other are a species population.