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Mayr's definition of a species is based on the genetic isolation of populations.
A ... difficulty which confronts us in our attempt at a species definition is that
there is, in nature, a great diversity of different kinds of species. Even if we do
not consider such aberrant phenomena as the apomictic species in plants and
the strains of bacteria, there is, even among animals, a great variety of different
taxonomic situations which are generally classified as species. The question as to
whether the species of birds, of corals, or protozoa, and of intestinal worms are
the same kind of evolutionary phenomena is entirely justified. . . It may not be exaggeration if I say that there are probably as many species concepts as there are
thinking systematists and students of speciation. [(Mayr 1942: 114-115)]
A species consists of a group of population which replace each other
geographically or ecologically and of which the neighboring ones intergrade
or interbreed wherever they are in contact or which are potentially capable of
doing so (with one or more of the populations) in those cases where contact is
prevented by geographical or ecological barriers.
Or shorter: Species are groups of actually or potentially interbreeding
natural populations, which are reproductively isolated from other such groups.
[Systematics and the Origin of Species, 1942: 120]
Wiki User
∙ 15y ago
Wiki User
∙ 9y agoHe approached the problem of species with a new definition for the concept. His definition says a species is a "group that can breed only among themselves."
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How did Dobzhansky and Mayr explain the origin of species?
In the 1930s, Dobzhansky and Mayr explained that species originate through allopatric speciation.
How does the existence of an archipelago promote speciation?
An archipelago is basically a group of islands. Speciation according to the Biological Species Concept by Ernest Mayr, is -- populations whose members can interbreed and produce viable, fertile offspring. For example, the Galapagos finches studied by Charles Darwin. Some live on different parts of the archipelago and so have different features, adapting to their environment. These different feature obviously get passed down and are more frequent in future populations because those finches with this specific adaptation lived and reproduced better. So since there are different islands, there are different finch speciation and so the geographic isolation promotes speciation.
Who are all Cytologists and their contribution?
Visual discovery of chromosomes. Textbooks have often said that chromosomes were first observed in plant cells by a Swiss botanist named Karl Wilhelm von Nägeli in 1842.[1] However, this opinion has been challenged, perhaps decisively, by Henry Harris, who has freshly reviewed the primary literature.[2] In his opinion the claim of Nägeli to have seen spore mother cells divide is mistaken, as are some of his interpretations. Harris considers other candidates, especially Wilhelm Hofmeister, whose publications in 1848-9 include plates which definitely show mitotic events.[3][4] Hofmeister was also the choice of Cyril Darlington. The work of other cytologists such as Walther Flemming, Eduard Strasburger, Otto Bütschli, Oskar Hertwig and Carl Rabl should definitely be acknowledged. The use of basophilic aniline dyes was a new technique for effectively staining the chromatin material in the nucleus. Their behavior in animal (salamander) cells was later described in detail by Walther Flemming, who in 1882 "provided a superb summary of the state of the field".[5][6] The name chromosome was invented in 1888 by Heinrich von Waldeyer. However, van Beneden's monograph of 1883 on the fertilised eggs of the parasitic roundworm Ascaris megalocephala was the outstanding work of this period.[7] His conclusions are classic: * Thus there is no fusion between the male chromatin and the female chromatin at any stage of division... * The elements of male origin and those of female origin are never fused together in a cleavage nucleus, and perhaps they remain distinct in all the nuclei derived from them. [tranl: Harris p162] "It is not easy to identify who first discerned chromosomes during mitosis, but there is no doubt that those who first saw them had no idea of their significance... [but] with the work of Balbiani and van Beneden we move away from... the mechanism of cell division to a precise delineation of chromosomes and what they do during the division of the cell." [8] Van Beneden's master work was closely followed by that of Carl Rabl, who reached similar conclusions. [9] This more or less concludes the first period, in which chromosomes were visually sighted, and the morphological stages of mitosis were described. Coleman also gives a useful review of these discoveries.[10] Nucleus as the seat of heredity. The origin of this epoch-making idea lies in a few sentences tucked away in Ernst Haeckel's Generelle Morphologie of 1866.[11] The evidence for this insight gradually acumulated until, after twenty or so years, two of the greatest in a line of great German scientists spelt it out. August Weismann proposed that the germ line was separate from the soma, and that the cell nucleus was the repository of the hereditary material, which he proposed was arranged along the chromosomes in a linear manner. Furthermore, he proposed that at fertilisation a new combination of chromosomes (and their hereditary material) would be formed. This was the explanation for the reduction division of meiosis (first described by van Beneden). Chromosomes as vectors of heredity. In a series of outstanding experiments, Theodor Boveri gave the definitive demonstration that chromosomes were the vectors of heredity. His two principles were: : The continuity of chromosomes : The individuality of chromosomes. It was the second of these principles which was so original. He was able to test the proposal put forward by Wilhelm Roux, that each chromosome carries a different genetic load, and showed that Roux was right. Upon the rediscovery of Mendel, Boveri was able to point out the connection between the rules of inheritance and the behaviour of the chromosomes. It is interesting to see that Boveri influenced two generations of American cytologists: Edmund Beecher Wilson, Walter Sutton and Theophilus Painter were all influenced by Boveri (Wilson and Painter actually worked with him). In his famous textbook The Cell, Wilson linked Boveri and Sutton together by the Boveri-Sutton theory. Mayr remarks that the theory was hotly contested by some famous geneticists: William Bateson, Wilhelm Johannsen, Richard Goldschmidt and T.H. Morgan, all of a rather dogmatic turn of mind. Eventually complete proof came from chromosome maps - in Morgan's own lab! [12]
In the biological species concept of Ernst Mayr what aspect of a population is critical to determining a species?
interbreeding capabilities
How did Ernst Walter Mayr contributed to the current theory of evolution?
He was a systemist who contributed to the neodarwinian synthesis. He was the man who came up with the biological species concept.
How is species defined as the biological species concept?
Organisms are the same species if the have the potential, or actually interbreed one with another. Does not apply to all organisms. Bacteria being an example of this. Is not as strong a concept as once it was as it did not adequately address hybridization.
How did dobzhansky and mayr explain the origin of species in the 1930's?
In the 1930s, Dobzhansky and Mayr explained that species originate through allopatric speciation.
The term species was coined by?
Ernst Mayr
How did Dobzhansky and Mayr explain the origin of species?
In the 1930s, Dobzhansky and Mayr explained that species originate through allopatric speciation.
How are dobzhanskys and mayr's ideas about the orgin of species similar to Darwin's?
they thought the evolution of a new species is linked to environmental changes
How are Dobzhansky and Mayr's ideas about the origin of species similar to Darwins?
They thought the evolution of new species is linked to environmental changes
How are Dobzhansky's and Mayr's ideas about the origin of species similar to Darwin's?
they thought the evolution of new species is linked to environmental changes
How are dobzhansky and mayr's idea about the origin of species similar to Darwin's?
they thought the evolution of new species is linked to environmental changes
How are Dobzhansky and mayr's idea about the origin of species similar to Darwins?
They thought the evolution of new species is linked to environmental changes
How are dobzhansky and mayr idea about the origin of species similar to Darwin's?
they thought the evolution of new species is linked to environmental changes
