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. The non-crossing of species is explained by differences in the structure of the genital organs, different periods of 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 twin of the 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.
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
Answer
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
Answer
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
Answer
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
B) digs a passage in the soil
D) front paws are wide - digging
D) eats insects
E) breeds in the nesting chamber
Answer
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.
Answer
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 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.
Answer
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 are nocturnal.
Answer
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
Answer
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.
Answer
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
Answer
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
AT) bat goes into winter dormancy
D) when threatened, the opossum freezes
D) the shark has a torpedo-shaped body
E) bright coloring of the poison dart frog
Answer
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
Answer
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
Answer
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
Answer
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 debris. (5) The larvae are white, have no legs, grow rapidly and turn into red-brown pupae. (6) The adult fly develops from the pupa.
Answer
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.
Answer
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 the night and twilight image life. (5) A litter usually has 5 to 7 babies. (6) Under natural conditions it feeds on seeds.
Answer
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) Fieldfare thrush is a large bird. (2) Thrushes live in central 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.
Answer
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.
Answer
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.
Answer
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
Answer
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.
Answer
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 of 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.
Answer
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) The flowers are small, blue, collected in a raceme inflorescence.
Answer
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.
Answer
5f. Read the text. Choose three sentences that describe the morphological criterion of the species Red clover. 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 from the male cones is carried by the wind to the female cones, where fertilization takes place.
Answer
1. Read the text. Choose three sentences that describe the genetic criteria for a species. 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.
Answer
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 the karyotype of different species provide isolation in 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.
Answer
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
Answer
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.
Answer
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 venom protects the animal both from fungi and bacteria, and from natural enemies, which can be fatally poisoned if dart frog venom comes into contact with 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.
Answer
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 the maximum growth rate of the colony occurs at an optimal temperature regime of 55-60 degrees.
Answer
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.
Answer
Answer
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
Answer
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) The only modern representative of the 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.
Answer
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) Siberian pine is very common in Western Siberia throughout the forest belt from 48 to 66 degrees north latitude, 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, the upper boundary of Siberian pine distribution 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, and avoids soils with close occurrence of permafrost.
Answer
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 of the grayling subfamily 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 Arctic Ocean, from Finland to the 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.
Answer
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 both in deciduous forests and in the taiga. (3) Adult birds feed on invertebrates, song thrushes feed their young on 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 inhabits the northern regions of the Scandinavian Peninsula and is numerous in the East European forest tundra, penetrating even into the tundra, actively spreading to the east. (6) Absent in Southern Europe, on the islands mediterranean sea, although there are biotopes suitable for song thrushes.
Answer
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 is a perennial herbaceous plant with a strong root and a long horizontal branching 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.
Answer
1. Establish a correspondence between the characteristic features of the type Bittersweet nightshade and the criteria of the species to which they belong: 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.
Answer
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) grows in forest clearings, in weedy places, along fences
C) ascorbic acid, carotene, vitamins B and K are formed in the leaves
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
Answer
© D.V. Pozdnyakov, 2009-2019
Vertyanov S. Yu.
Distinguishing supraspecific taxa is, as a rule, quite easy, but a clear distinction between the species themselves encounters certain difficulties. Some species occupy geographically separated areas of habitat (ranges) and therefore do not interbreed, but in artificial conditions give fertile offspring. Linneevskoe short definition species as a group of individuals freely interbreeding and producing fertile offspring is not applicable to organisms that reproduce parthenogenetically or asexually (bacteria and unicellular animals, many higher plants), as well as to extinct forms.
The set of distinguishing features of a species is called its criterion.
The morphological criterion is based on the similarity of individuals of the same species in terms of a set of external and internal structure. Morphological criterion is one of the main ones, but in some cases morphological similarity is not enough. The malarial mosquito was previously referred to as six non-interbreeding similar species, of which only one carries malaria. There are so-called twin species. Two species of black rats, outwardly almost indistinguishable, live separately and do not interbreed. The males of many creatures, such as birds (bullfinches, pheasants), outwardly bear little resemblance to females. Adult male and female threadtail eels are so dissimilar that for half a century scientists have placed them in different genera, and sometimes even in different families and suborders.
Physiological and biochemical criterion
It is based on the similarity of the life processes of individuals of the same species. Some species of rodents have the ability to hibernate, while others do not. Many related plant species differ in their ability to synthesize and accumulate certain substances. Biochemical analysis makes it possible to distinguish between types of unicellular organisms that do not reproduce sexually. Anthrax bacilli, for example, produce proteins that are not found in other types of bacteria.
The possibilities of the physiological-biochemical criterion are limited. Some proteins have not only species, but also individual specificity. There are biochemical signs that are the same in representatives of not only different species, but even orders and types. Physiological processes can proceed in a similar way in different species. Thus, the intensity of metabolism in some arctic fish is the same as in other fish species of the southern seas.
Genetic criterion
All individuals of the same species have a similar karyotype. Individuals of different species have different chromosome sets, cannot interbreed and live in natural conditions separately from each other. Two twin species of black rats have a different number of chromosomes - 38 and 42. The karyotypes of chimpanzees, gorillas and orangutans differ in the arrangement of genes in homologous chromosomes. The differences between the karyotypes of bison and bison, which have 60 chromosomes in the diploid set, are similar. Differences in the genetic apparatus of some species can be even more subtle and consist, for example, in the different nature of the switching on and off of individual genes. The use of only a genetic criterion is sometimes insufficient. One species of weevil combines diploid, triploid and tetraploid forms, the house mouse also has different sets of chromosomes, and the gene for the human nuclear histone H1 protein differs from the homologous pea gene by only one nucleotide. Such variable DNA sequences have been found in the genomes of plants, animals and humans that people can distinguish between brothers and sisters by them.
Reproductive criterion
(Latin reproducere reproduce) is based on the ability of individuals of the same species to produce fertile offspring. An important role in crossing is played by the behavior of individuals - the mating ritual, species-specific sounds (birdsong, grasshoppers chirping). By the nature of the behavior, individuals recognize the marriage partner of their species. Individuals of similar species may not interbreed due to inconsistencies in mating behavior or inconsistencies in breeding sites. So, females of one species of frogs spawn along the banks of rivers and lakes, and the other - in puddles. Similar species may not interbreed due to differences in mating periods or mating periods when living in different climatic conditions. Different periods of flowering in plants prevent cross-pollination and serve as a criterion for belonging to different species.
Reproductive criterion is closely related to genetic and physiological criteria. The viability of gametes depends on the feasibility of conjugation of chromosomes in meiosis, and hence on the similarity or difference in the karyotypes of crossing individuals. Difference in daily physiological activity (daytime or nocturnal lifestyle) sharply reduces the possibility of crossing.
The use of only the reproductive criterion does not always make it possible to clearly distinguish species. There are species that are clearly distinguishable by morphological criteria, but which, when crossed, give fertile offspring. From birds, these are some species of canaries, finches, from plants - varieties of willows and poplars. A representative of the order of artiodactyl bison lives in the steppes and forest-steppes North America and never in natural conditions is found with the bison living in the forests of Europe. In zoo conditions, these species produce fertile offspring. Thus, the population of European bison, which was practically exterminated during the world wars, was restored. They interbreed and give fertile offspring of yaks and large cattle, polar and brown bears, wolves and dogs, sables and martens. In the plant kingdom, interspecific hybrids are even more common, among plants there are even intergeneric hybrids.
Ecological and geographical criterion
Most species occupy a certain territory (range) and an ecological niche. Buttercup caustic grows in meadows and fields, in more damp places another species is common - creeping buttercup, along the banks of rivers and lakes - burning buttercup. Similar species living in the same range may differ in ecological niches - for example, if they eat different foods.
The use of the ecological-geographical criterion is limited by a number of reasons. The range of the species may be discontinuous. The species range of the white hare is the islands of Iceland and Ireland, the north of Great Britain, the Alps and north-west Europe. Some species have the same range, such as two species of black rats. There are organisms that are distributed almost everywhere - many weeds, a number of insect pests and rodents.
The problem of species definition sometimes grows into a complex scientific problem and is solved using a set of criteria. Thus, a species is a collection of individuals occupying a certain area and possessing a single gene pool that ensures hereditary similarity of morphological, physiological, biochemical and genetic traits, in natural conditions interbreeding and producing fertile offspring.
1. What is a view?
Answer. Species (lat. species) - a taxonomic, systematic unit, a group of individuals with common morphophysiological, biochemical and behavioral characteristics, capable of interbreeding, producing fertile offspring in a number of generations, regularly distributed within a certain range and similarly changing under the influence of environmental factors. Species - a really existing genetically indivisible unit of the living world, the main structural unit in the system of organisms.
2. What types of plants and animals do you know?
Answer. Plant species: European bathing suit, Altai anemone, two-leafed love, needle-leaved carnation, venus slipper, etc.
Types of animals: Brown bear, Siberian roe deer, common lynx, pine marten, black polecat, European mink. striped chipmunk, flying squirrel, gray partridge, black grouse and others.
Questions after § 53
1. Define a species.
Answer. A biological species is a set of individuals that have the ability to interbreed with the formation of fertile offspring; inhabiting a certain area; having a number of common morphological and physiological features and similarities in their relationship with the biotic and abiotic environment.
Biological species is not only a systematic category. This is a holistic and isolated element of wildlife from other species. The integrity of a species is manifested in the fact that its individuals can live and reproduce only by interacting with each other due to the mutual adaptations of organisms developed in the process of evolution: the peculiarities of the coordination of the structure of the maternal organism and the embryo, signaling and perception systems in animals, the common territory, the similarity of life habits and reactions to seasonal climate changes, etc. Species adaptations ensure the preservation of the species, although sometimes they can damage individual individuals. River perch, for example, feeds on their own young, due to which the species survives with a lack of food, even despite the loss of part of the offspring. Each species exists in nature as a historically emerged integral formation.
2. What kind of criteria do you know?
Answer. Characteristic features and the properties by which some species differ from others are called species criteria.
Morphological criterion is the similarity of the external and internal structure of organisms. Carl Linnaeus, for example, defined species as whole groups of organisms distinct from others. life forms on the basis of the structure. In other words, the presence of structural features that make a certain group of organisms similar to each other and at the same time different from all other groups is the criterion for classifying them as a given species.
Individuals within a species are sometimes so variable that it is not always possible to determine the species by morphological criteria alone. There are species morphologically similar. These are twin species that are open in all systematic groups. For example, in black rats, two twin species are known - with 38 and 49 chromosomes; the malarial mosquito has 6 twin species, and the small loach fish, which is widespread in fresh water, has 3 such species. Twin species are found among the most various organisms: fish, insects, mammals, plants, however, individuals of such twin species do not interbreed.
A genetic criterion is a set of chromosomes characteristic of each species; their strictly defined number, size and shape, DNA composition. The chromosome set is the main species trait. Individuals of different species have different sets of chromosomes, so they cannot interbreed and are reproductively limited from each other in natural conditions.
The physiological criterion is the similarity of the body's reactions to external influences, the rhythms of development and reproduction. This criterion is based on the similarity of all life processes, and above all reproduction. Representatives of different species, as a rule, do not interbreed or their offspring are sterile. However, there are exceptions. For example, dogs can produce offspring by mating with wolves. Hybrids of some species of birds (canaries, finches), as well as plants (poplars, willows) can be fruitful. Consequently, the physiological criterion is also insufficient to determine the species belonging of individuals.
An ecological criterion is a position characteristic of a species in natural communities, its relations with other species, sets of environmental factors necessary for existence.
Geographic criterion - the area of distribution, a certain area occupied by a species in nature.
The historical criterion is the commonality of ancestors, a single history of the emergence and development of the species.
3. What is the integrity of the species, how does it manifest itself?
Answer. View is an integral system. The view is a single integral system. The integrity of the species is ensured by its isolation from other species due to a specific chromosome set (reproductive isolation).
The integrity of a species is also determined by the bonds that its individuals form in populations and subspecies. Relationships between males and females, parents and their offspring, individuals different ages in a flock, herd and colony, they allow them to successfully reproduce, take care of offspring, provide protection from enemies, etc. The whole set of connections ensures the existence of the species as an integral system.
4. Why is it important to preserve species in nature?
Answer. Biological diversity on the planet is the presence on it of a large number of species of all kingdoms: animals, plants, fungi. The task of preserving them is one of the main ones in ecology. Planet Earth is really rich, therefore, a person is obliged to protect this wealth, at least so that it goes to the next generations of people. So that grandchildren and great-grandchildren can see wonderful animals, beautiful corners of nature, they can use medicinal plants. Any plant, animal (even the smallest) is part of the biogeocenosis, and in general, is included in the entire ecosystem of the Earth. The body participates in the circulation of substances, being a link in the food chain. Plants, which are producers, synthesize nutrients using solar energy. Consumers consume the energy accumulated by plants and other animals, deritophages “utilize” dead animals, and decomposers finally decompose nutrient residues. Thus, each organism occupies a certain place in nature and performs a certain role. The disappearance of one link can cause the disappearance of several more, changing the entire chain. There will be not only impoverishment the food chain, but also a violation of the balance of species in the ecosystem. Some species may increase disproportionately in numbers and cause ecological disaster. How, for example, an unprecedented breeding of locusts can deprive the harvest of entire areas. By preserving the richness of species on the planet, we thus maintain the stability of ecosystems, ensure the safety of life of all species, including human life. In addition, scientists want to preserve the genetic information of each species, with the expectation of future technologies that will allow them to recreate animal world of the past, for example, in isolated recreations (parks), to recreate species of animals and plants that are extinct and are now dying out.
View (lat. species) is a taxonomic, systematic unit, a group of individuals with common morphophysiological, biochemical and behavioral characteristics, capable of interbreeding, producing fertile offspring in a number of generations, regularly distributed within a certain range and similarly changing under the influence of environmental factors. A species is a really existing genetically indivisible unit of the living world, the main structural unit in the system of organisms, a qualitative stage in the evolution of life.
For a long time it was believed that any species is a closed genetic system, that is, there is no exchange of genes between the gene pools of two species. This statement is true for most species, but there are exceptions to it. So, for example, lions and tigers can have common offspring (ligers and tigers), the females of which are fertile - they can give birth both from tigers and lions. Many other species are also interbred in captivity, which do not naturally interbreed due to geographic or reproductive isolation. Crossing (hybridization) between different species can also occur in natural conditions, especially in the case of anthropogenic disturbances of the habitat that violate the ecological mechanisms of isolation. Especially often plants hybridize in nature. A noticeable percentage of species of higher plants is of hybrid origin - they were formed during hybridization as a result of partial or complete merging of parental species.
Basic view criteria
1. Morphological criterion of the species. It is based on the existence of morphological features characteristic of one species, but absent in other species.
For example: in an ordinary viper, the nostril is located in the center of the nasal shield, and in all other vipers (nosed, Asia Minor, steppe, Caucasian, viper) the nostril is shifted to the edge of the nasal shield.
At the same time, there are significant individual morphological differences within species. For example, the common viper is represented by a variety of color forms (black, gray, bluish, greenish, reddish and other shades). These features cannot be used to distinguish species.
2. geographical criterion. It is based on the fact that each species occupies a certain territory (or water area) - a geographical range. For example, in Europe, some species of the malarial mosquito (genus Anopheles) inhabit the Mediterranean, others - the mountains of Europe, Northern Europe, Southern Europe.
However, the geographical criterion is not always applicable. The ranges of different species may overlap, and then one species smoothly passes into another. In this case, a chain of vicarious species (superspecies, or series) is formed, the boundaries between which can often be established only through special studies (for example, herring gull, black-backed gull, western, Californian).
3. ecological criterion. Based on the fact that two species cannot occupy the same ecological niche. Therefore, each species is characterized by its own relationship with the environment.
However, within the same species, different individuals can occupy different ecological niches. Groups of such individuals are called ecotypes. For example, one ecotype of Scotch pine inhabits swamps (marsh pine), another - sand dunes, the third - leveled areas of forest terraces.
A set of ecotypes that form a single genetic system (for example, capable of interbreeding with each other to form full-fledged offspring) is often called an ecospecies.
4. Molecular genetic criterion. Based on the degree of similarity and difference in nucleotide sequences in nucleic acids. As a rule, "non-coding" DNA sequences (molecular genetic markers) are used to assess the degree of similarity or difference. However, DNA polymorphism exists within the same species, and different species can be characterized by similar sequences.
5. Physiological and biochemical criterion. It is based on the fact that different species can differ in the amino acid composition of proteins. At the same time, protein polymorphism exists within a species (for example, intraspecific variability of many enzymes), and different species can have similar proteins.
6. Cytogenetic (karyotypic) criterion. It is based on the fact that each species is characterized by a certain karyotype - the number and shape of metaphase chromosomes. For example, all hard wheats have 28 chromosomes in the diploid set, and all soft wheats have 42 chromosomes. However, different species can have very similar karyotypes: for example, most species of the cat family have 2n=38. At the same time, chromosomal polymorphism can be observed within the same species. For example, in elks of Eurasian subspecies 2n=68, and in elks of North American species 2n=70 (in the karyotype of North American elks there are 2 less metacentrics and 4 more acrocentrics). Some species have chromosome races, for example, in a black rat - 42 chromosome (Asia, Mauritius), 40 chromosome (Ceylon) and 38 chromosome (Oceania).
7. reproductive criterion. It is based on the fact that individuals of the same species can interbreed with each other with the formation of fertile offspring similar to their parents, and individuals of different species living together do not interbreed with each other, or their offspring are sterile.
However, it is known that interspecific hybridization is often common in nature: in many plants (for example, willows), a number of fish species, amphibians, birds and mammals (for example, a wolf and a dog). At the same time, within the same species, there may be groupings that are reproductively isolated from each other.
8. ethological criterion. Associated with interspecies differences in behavior in animals. In birds, song analysis is widely used for species recognition. By the nature of the sounds produced, different types of insects differ. Different types North American fireflies differ in the frequency and color of light flashes.
9. Historical (evolutionary) criterion. Based on the study of the history of a group of closely related species. This criterion is complex in nature, since it includes a comparative analysis of modern species ranges (geographical criterion), a comparative analysis of genomes (molecular genetic criterion), a comparative analysis of cytogenomes (cytogenetic criterion), and others.
None of the considered species criteria is the main or the most important one. For a clear separation of species, it is necessary to carefully study them according to all criteria.
Due to unequal environmental conditions, individuals of the same species within the range break up into smaller units - populations. In reality, a species exists precisely in the form of populations.
Species are monotypic - with a weakly differentiated internal structure, they are characteristic of endemics. Polytypic species are characterized by a complex intraspecific structure.
Within species, subspecies can be distinguished - geographically or ecologically isolated parts of a species, individuals of which, under the influence of environmental factors in the process of evolution, have acquired stable morphophysiological features that distinguish them from other parts of this species. In nature, individuals of different subspecies of the same species can freely interbreed and produce fertile offspring.
species name
The scientific name of a species is binomial, that is, it consists of two words: the name of the genus to which the given species belongs, and the second word, called the species epithet in botany, and the species name in zoology. The first word is a singular noun; the second is either an adjective in the nominative case, agreed in gender (masculine, feminine or neuter) with a generic name, or a noun in the genitive case. The first word is capitalized, the second is lowercase.
- Petasites fragrans- the scientific name of a species of flowering plants from the genus Butterbur ( Petasites) (the Russian name of the species is Fragrant Butterbur). The adjective is used as a specific epithet Fragrans("fragrant").
- Petasites fominii- the scientific name of another species from the same genus (Russian name - Fomin Butterbur). The Latinized surname (in the genitive case) of the botanist Alexander Vasilyevich Fomin (1869-1935), a researcher of the flora of the Caucasus, was used as a specific epithet.
Sometimes entries are also used to designate indeterminate taxa at species rank:
- Petasites sp.- the entry indicates that the taxon at the rank of species, belonging to the genus, is meant Petasites.
- Petasites spp.- entry means that all taxa in the rank of species included in the genus are meant Petasites(or all other taxa in the rank of species included in the genus Petasites, but not included in any given list of such taxa).
