Speciation is the process of the emergence of new biological species and their changes over time. Speciation is the process of the emergence of new biological species and their changes over time. Sympatric (biological) Allopatric (geographic) Methods of speciation: a) Allopatric b) Sympatric Geographical isolation occurs between populations. As a result, gene exchange is interrupted. The emergence of genetic differences gradually leads to the inability of individuals from disparate populations to interbreed, which causes the formation of new species. Biological isolation occurs between populations: transition to a new food supply; changes in the rhythm of activity, timing of mating, or genetic qualities (number or structure of chromosomes).
The emergence of lily of the valley species. (allopatric) The original species several million years ago, in the Tertiary period, was widespread in the deciduous forests of Eurasia. With the onset of glaciers in the Quaternary period, the single habitat of the species was torn into several parts, and the lily of the valley survived only in areas that escaped glaciation. These are the Far East, Transcaucasia, Southern Europe. After the retreat of the glacier, the lily of the valley, preserved in southern Europe, formed a new species, larger, with a wide corolla. In the Far East, another species arose - with red petioles and a waxy coating on the leaves. May lily of the valley Transcaucasian lily of the valley Keiske lily of the valley
Endemic species of finches in the Galapagos Islands. (allopatric) All Galapagos finches are descended from a single ancestor that originally migrated from South America 23 million years ago. As a result of different food sources, species differ from each other in the size and shape of the beak, plumage color and vocalization.
The emergence of tit species. (sympatric) An example of biological speciation is the formation of five species of tits. These species differ in food specialization and habitat. Thus, the great tit feeds on large insects in gardens and parks; the blue tit forages for small insects in cracks in the bark and buds of trees, the tufted tit feeds on the seeds of coniferous trees; Chickadees and Muscovites feed mainly on forest insects.
Species of cichlid fish in Lake Victoria. (sympatric) African Lake Victoria, which was formed only 12 thousand years ago, is home to more than 500 species of cichlid fish, differing from each other in morphology, lifestyle, behavior and a number of other characteristics. Molecular genetic analysis shows that they all descended from one common ancestor. African Lake Victoria, which was formed only 12 thousand years ago, is home to more than 500 species of cichlid fish, differing from each other in morphology, lifestyle, behavior and a number of other characteristics. Molecular genetic analysis shows that they all descended from one common ancestor.
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Text content of presentation slides: Speciation Speciation is the process of the emergence of new species as a result of the evolution of populations of the original species. Occurs when biological species split into two or more new species. Conditions for the implementation of speciation During speciation, natural selection operates, which adapts populations to the conditions of their environment, and reproductive isolation, which isolates the gene pools of populations and ensures the isolation of divergence of characteristics of species. Pathways of speciation From left to right - phyletic speciation; hybridogenic origin of species C, divergent speciation Phyletic speciation - transformation of existing species Hybridogenic is associated with the fusion of two existing species A and B and the formation of a new species C. The third path is due to Divergence (division) of one ancestral species into several independently evolving species. This is the path that evolution has followed. Pathways of speciation Forms of intraspecific isolation Spatial isolation occurs between populations that are far apart from each other or separated by geographic barriers. Ecological isolation - a form of biological isolation is based on the diversity of organisms in their reproductive ecology and preferred habitat. Methods of speciation: geographic ecological (allopatric) (sympatric) if isolation if isolation is geographic biological Allopatric (geographic) speciation Speciation in different territories is due to geographic (spatial) isolation. The reason for such isolation may be: *large rivers for land animals, *mountains for lowland animals, and similar obstacles that impede the migration of animals or the distribution of plant seeds. Allopatric speciation Galapagos finches Galapagos tortoises Allopatric speciation Gray ground squirrel Speckled ground squirrel They are separated by the Dnieper River Sympatric (ecological) speciation Begins with the division of a primarily single population into two or more groups of organisms, which then continue speciation. This may occur as a result of ecological specialization. Sympatric speciation Ecological isolation is observed when the habitats of different forms of one species or several closely related species, for example, forest (left) and meadow (right) pipits, do not coincide. Ecological speciation Sometimes, within a single habitat, individual populations (1-5) differ in habitat conditions. Because of this, the phenology of individuals changes, and subsequently their morphology. Sevan trout Sympatric speciation in African lakes. Victoria, which was formed 12 thousand years ago, is home to more than 500 species of cichlid fish, differing from each other in morphology, lifestyle, behavior and a number of other characteristics. Methods of sympatric speciation Polyploidization Hybridization Chromosomal rearrangements Reticulate speciation In recent decades, data has been accumulating on the third method - reticulate speciation, associated not with the divergence of characters in the population, but with the hybridization of closely related species. Such speciation has been proven for some species of lizards, fish and flowering plants. The isolation of hybrids from parental species is due to the polyploidy of hybrids. Polyploidy New species can be formed as a result of polyploidization - a sudden increase in the number of chromosomes. For example, the cultivated plum arose as a result of crossing sloe and cherry plum, with the subsequent doubling of the number of chromosomes in the hybrids.
Speciation.
Speciation
1.Definition, basic concepts
2. Paths of speciation (according to E. Mayr)
3.Main methods of speciation
Speciation is a qualitative stage of the evolutionary process leading to the emergence of new species, as a result of which the newly emerged species loses all connections with the original parent species.
Currently, there is a huge diversity of species on Earth, their total number is several million, and over the entire existence of life on Earth, scientists believe there were 50-100 times more of them.
Ernst Walter Mayr
American evolutionary scientist who, in 1964, in the book “Population, Species, Evolution,” identified the main paths of speciation.
Pathways of speciation (according to E. Mayr)
The main pathways of speciation (according to Mayr).
From left to right – phyletic speciation; hybridogenic origin of the species (C), divergent speciation.
Eohippus
Modern horse
Interspecific hybrid
wolf and dog (wolf-dog)
Interspecific hybrid
grizzly bear and polar bear
Divergence (divergence of characters) is the division of one ancestral form into several new systematic categories (species, genera, families, etc.). The divergence principle proves that
similar organisms arose from a common ancestor.
The divergent formation of species occurs due to increased competition between related forms for similar conditions of existence.
|
III. Chromosomal (mesh) |
I. Geographical (allopatric) speciation (Latin allo - different and patria - homeland) - occurs as a result of spatial isolation of the parent species, provides the possibility of morphological divergence, which can occur under the influence of several factors (the most common method).
Observed when the original range of a species is divided by various natural barriers. As a result, separated populations cannot interbreed freely with each other, resulting in different subspecies.
Geographical isolation
Subspecies of brown trout
Trout is an anadromous fish of the salmon family. Length up to 1 m, weighs up to 13 kg; Caspian salmon – up to 51 kg. It lives in the coastal waters of the seas of Europe, including the Black, Caspian, Baltic and Aral seas. It goes to rivers to spawn. Valuable object of fishing and breeding. Freshwater forms of brown trout.
The differences between the species of finches living on the neighboring Galapagos Islands prompted Charles Darwin to come up with the idea of the origin of species, and since then the birds have been called Darwin's finches.
Big
ground finch
Thick-billed
tree finch
Warbler finch
II. Ecological (sympatric) speciation (Latin sim - together and patria - homeland) - arises as a result of differences in living conditions (ecological isolation) within the range of the original species.
Ecological isolation is observed when the habitats of different forms of one species or several closely related species, for example, forest (left) and meadow (right) pipits, do not coincide.
Environmental insulation
Species diversity of cichlids
Ecological races
Weevil
big pine
Oak weevil
III. Chromosomal (network) speciation - occurs as a result of changes in the number and shape of chromosomes, which often leads to the non-breeding of the new form with the parent species. It is often called sudden.
Forms of chromosomal speciation
Polyploidy
In plants, a rare method of chromosomal speciation occurs—hybridization followed by polyploidy.
Through hybridization of sloe and cherry plum followed by polyploidy, a cultivated plum arose.
Plum fruit
Cherry plum fruits
Sloe fruit
Large leaf rose with 14
chromosomes
Large leaf rose with 28
chromosomes
Tiger salamander
Ambytoma sp.
Mole voles
Slide 1
Slide 2
Speciation is the process of the emergence of new species. What is meant by appearance? What criteria are used to characterize the properties of a species?
Slide 3
Speciation is a qualitative stage of the evolutionary process. This means that microevolution ends with the formation of species and macroevolution begins.
Slide 4
The diversity of species that exists in nature is enormous; their total number is several million. Since the emergence of life on Earth, the number of species that have ever existed, experts believe, is probably 50-100 times greater.
Slide 5
Speciation pathways
Pathways of speciation. From left to right – phyletic speciation; hybridogenic origin of species C, divergent speciation
Slide 6
The first is the transformation of existing species (phyletic speciation). The second path is associated with the fusion of two existing species A and B and the formation of a new species C (hybridogenic origin). The third path is due to the divergence (division) of one ancestral species into several independently evolving species. This is the path that evolution has followed.
Slide 7
Each species is a closed genetic system. Representatives of different species do not interbreed, and if they interbreed, they either do not produce offspring, or these offspring are infertile. Therefore, divergent speciation must be preceded by the emergence of isolated populations within the ancestral species.
Slide 8
Forms of intraspecific isolation
Spatial isolation occurs between populations that are widely separated from each other or separated by geographic barriers. Ecological isolation - a form of biological isolation is based on the diversity of organisms in their reproductive ecology and preferred habitat.
Slide 9
Long-term intraspecific isolation leads to the fact that each population evolves independently. This leads to genetic differences. Populations are becoming less and less similar to each other in a number of morphological, physiological and behavioral characteristics, which leads to the emergence of biological mechanisms of isolation and speciation.
Slide 10
Methods of speciation
Slide 11
Allopatric (geographic) speciation
From the Latin words allo - different and patria - homeland. The most common method provides the possibility of morphological divergence, which can occur under the influence of several factors.
Slide 12
Living conditions in geographic isolates can vary significantly. Natural selection will lead to morphological divergence of these populations due to adaptation to different living conditions. The most favorable conditions for adaptive radiation develop on groups of islands (archipelagos) located at a considerable distance from the mainland.
Slide 13
Adaptive radiation is the emergence of several species from one ancestor, associated with the development of adaptations to various environmental conditions.
Slide 14
Flowerbirds turned out to be the first birds to inhabit the Hawaiian archipelago. The lack of competition with other species caused a rapid adaptive radiation: finding themselves in favorable conditions, flower girls formed various species that differed in food preferences and, in accordance with them, the shape of the beak.
Treecrest Sicklebeak
Parrot flower girl
Slide 15
The differences between the species living on neighboring islands prompted Charles Darwin to come up with the idea of the origin of species, and since then the birds have been called Darwin's finches.
Warbler finch
Thick-billed Tree Finch
Great Ground Finch
Slide 16
One of the species of alluring crabs - Uca tetragonon lives in the part of the coast that is flooded during high tide, among fragments of shells and fragments of dead corals; it can also be found on sandy and silty soils. The second crab, Uca perplexa, lives only on muddy soils.
Uca perplexa Uca tetragonon
Slide 17
The most striking examples of geographic speciation are complexes of closely related species that form ring habitats. The range of the great white-headed gull complex covers a wide ring of the northern hemisphere of the globe. Within the complex, up to 15 different forms are distinguished, differing in the color of the back and wings, the color of the legs and the periorbital ring.
Slide 18
CLASSIFICATION OF ISOLATING MECHANISMS
Presented in printouts on desks in the form of a table. In the proposed classification, isolating mechanisms are arranged in the sequence of their entry into action: if some turn out to be imperfect, others begin to work. Typically, for each pair of closely related species, several isolating mechanisms can be identified. At the same time, for reliable reproductive isolation, their entire spectrum is not needed; two or three are often enough.
Slide 19
Mallards and pintails often nest side by side with each other, inhabiting freshwater bodies of woodland. Mixed couples are not uncommon in zoos. Most of the eggs in their clutches are unfertilized, but fertilized eggs hatch into fully viable and fertile hybrids. The mating behavior of hybrids is disrupted, making it difficult for them to form a mating pair in natural conditions.
Pintail. Mallard
Slide 20
Ring habitat of gulls. There are two species of gulls living on the shores of the North and Baltic seas: the herring gull and the laughing black gull. These two species combine with each other at the other edge of their range, forming a chain of related populations
Slide 21
Sympatric (biological) speciation
Occurs within the range of the original species as a result of biological isolation. It is carried out on the basis of a territorially unified population, which has clearly distinct forms of individuals. The emergence of new species can occur in various ways
Slide 22
For example, in the African Lake Victoria, which was formed only 12 thousand years ago, more than 500 species of cichlid fish live, differing from each other in morphology, lifestyle, behavior and a number of other characteristics.
Slide 23
Species arising through sympatric speciation are often called “ecological races.”
Slide 24
Regular mowing of the grass in mid-summer led to the formation of two ecological races of this plant, differing in flowering times: the spring race has yellow flowers, and the autumn race has orange flowers. The ripening of seeds in the third form of the rattle is timed to coincide with the harvest
Great rattle Alectorophus major
Slide 25
The willow leaf beetle has two ecological races - “willow” and “birch”. Beetles and larvae of the willow race are able to feed only on willow leaves; the birch race can feed on both birch and willow.
Slide 26
CHROMOSOMAL SPECIATION
Associated with a change in the number and shape of chromosomes, which often leads to the uncrossability of the new form with the parent species. It is often called sudden. In this way, new species can arise in organisms capable of self-fertilization, vegetative or same-sex reproduction (parthenogenesis). This type of speciation is most common in plants, but it is also found in some groups of animals - mollusks, insects, fish, amphibians and reptiles.
Slide 29
Another, more rare method of chromosomal speciation occurs in plants - through hybridization followed by polyploidy. It was in this way - through the hybridization of sloe and cherry plum with subsequent polyploidy - that the cultivated plum arose.
Slide 30
Chromosomal speciation is possible in those groups of animals that are capable of same-sex reproduction (parthenogenesis): the development of eggs without fertilization. Closely related species that arose in this way are found, for example, in salamanders of the genus Ambistoma.
Tiger salamander Ambytoma sp.
Slide 31
In rodents, it is not uncommon for closely related species to differ in the number and shape of chromosomes. For example, in mole voles (Ellobius talpinus) there are 16 forms that are outwardly indistinguishable from each other, but differ in the number of chromosomes (from 32 to 54). Some of the forms are able to interbreed with each other and produce fertile offspring, while others have reproductive isolation.
Mole mole Ellobius talpinus
Slide 32
Homework
Paragraph 40 Answer the questions: Name the main ways of speciation. What factors can lead to isolation of populations? How does long-term isolation affect the genetic structure of isolated populations? What mechanisms are allopatric speciation based on? Give examples of allopatric speciation. When does sympatric speciation occur? Give examples.
Slide 33
Used sources
Copyright ©Fig. E.N. Bukvareva.. http://evolution2.narod.ru/evo19.htm http://afonin-59-bio.narod.ru/4_evolution/4_evolution_lec/evol_lec_09.htm Materials of the Darwin Museum Ponomareva I.N., Kornilova O.A., Chernova N.M. Fundamentals of general biology: Textbook for 9th grade students of general education institutions/Under the general editorship of Prof. I.N. Ponomareva. – M.: Ventana-Graf, 2004. Lenagold.Clipart.ru
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Speciation processes
Speciation is a qualitative stage of the evolutionary process. Speciation is the process of the emergence of new species.
Ernst Walter Mayr is an American evolutionary scientist who, in 1964, in his book “Population, Species, Evolution,” identified the main pathways of speciation.
THE FIRST PATH OF SPECIATION This is the process of transformation of one species into another, the transformation of an ancestor species into a descendant species over long periods of time without the formation of daughter species.
SECOND PATHWAY OF SPECIATION divergent speciation Allopatric geographical Sympatric biological
MICROEVOLUTION - evolutionary processes occurring in populations based on Hereditary variability Natural selection Result - the formation of new species
Geographical (allopatric) speciation. From the Latin words allo - different and patria - homeland.
I. SPATIAL-TERRITORIAL ISOLATION Initial population Beginning of speciation: formation of a barrier Emergence of reproductive isolation Completion of speciation
Diversity of Darwin's finches in the Galapagos Islands
II. DISTRIBUTION OF THE SPECIES OVER A WIDE TERRITORY Dandelion officinalis Dandelion kok-sagyz
Biological (sympatric) speciation.
I. ECOLOGICAL RACES Great pine weevil Oak weevil
II. RAPID CHANGE OF GENOTYPE Hybridization followed by polyploidy. Through hybridization of sloe and cherry plum followed by polyploidy, a cultivated plum arose. Plum fruits Cherry plum fruits Sloe fruits + =
Lesson outline "Processes of speciation"
Lesson outline "Processes of Speciation", a biology lesson in the 10th grade using the textbook "General Biology", edited by D.K. Belyaev, P.M. Borodin, N.N. Vorontsov. Used together with a present...
Speciation is the result of microevolution.
Geographic speciation: isolation, range gap, divergence, range expansion. Examples: lily of the valley, hare, rye and wheat, Madagascar island, Darwin's finches. Ecological speciation: ...
