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Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within lineages. Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book On the Origin of Species. He also identified sexual selection as a likely mechanism, but found it problematic.
Thomas Hunt Morgan was an American evolutionary biologist, geneticist, embryologist, and science author who won the Nobel Prize in Physiology or Medicine in 1933 for discoveries elucidating the role that the chromosome plays in heredity.
Ornithology is a branch of zoology that concerns the "methodological study and consequent knowledge of birds with all that relates to them." Several aspects of ornithology differ from related disciplines, due partly to the high visibility and the aesthetic appeal of birds. It has also been an area with a large contribution made by amateurs in terms of time, resources, and financial support. Studies on birds have helped develop key concepts in biology including evolution, behaviour and ecology such as the definition of species, the process of speciation, instinct, learning, ecological niches, guilds, island biogeography, phylogeography, and conservation.
Allopatric speciation – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow.
Bird vocalization includes both bird calls and bird songs. In non-technical use, bird songs are the bird sounds that are melodious to the human ear. In ornithology and birding, songs are distinguished by function from calls.
Erwin Friedrich Theodor Stresemann was a German naturalist and ornithologist. Stresemann was an ornithologist of extensive breadth who compiled one of the first and most comprehensive accounts of avian biology of its time as part of the Handbuch der Zoologie. In the process of his studies on birds, he also produced one of the most extensive historical accounts on the development of the science of ornithology. He influenced numerous ornithologists around him and oversaw the development of ornithology in Germany as editor of the Journal für Ornithologie. He also took an interest in poetry, philosophy and linguistics. He published a monograph on the Paulohi language based on studies made during his ornithological expedition to the Indonesian island.
Haldane's rule is an observation about the early stage of speciation, formulated in 1922 by the British evolutionary biologist J.B.S. Haldane, that states that if in a species hybrid only one sex is inviable or sterile, that sex is more likely to be the heterogametic sex. The heterogametic sex is the one with two different sex chromosomes; in therian mammals, for example, this is the male.
Genetics and the Origin of Species is a 1937 book by the Ukrainian-American evolutionary biologist Theodosius Dobzhansky. It is regarded as one of the most important works of the modern synthesis, and was one of the earliest. The book popularized the work of population genetics to other biologists, and influenced their appreciation for the genetic basis of evolution. In his book, Dobzhansky applied the theoretical work of Sewall Wright (1889–1988) to the study of natural populations, allowing him to address evolutionary problems in a novel way during his time. Dobzhansky implements theories of mutation, natural selection, and speciation throughout his book to explain habits of populations and the resulting effects on their genetic behavior. The book explains evolution in depth as a process over time that accounts for the diversity of all life on Earth. The study of evolution was present, but greatly neglected at the time. Dobzhansky illustrates that evolution regarding the origin and nature of species during this time in history was deemed mysterious, but had expanding potential for progress to be made in its field.
Nikolai Konstantinovich Koltsov was a Russian biologist and a pioneer of modern genetics. Among his students were Nikolay Timofeeff-Ressovsky, Vladimir Pavlovich Efroimson, A.S. Serebrovsky, and Nikolay Dubinin. Along with his students, he demonstrated the fine structure of genes, and examined the structure of the cell and pioneered the idea of a cytoskeleton. His career was cut short in Stalinist Russia due to the entanglement of Marxist ideology and interpretations that genetics was a science that supported racism, fascism and eugenics. He died unexpectedly following government persecution and there are allegations that he was executed.
The mechanisms of reproductive isolation are a collection of evolutionary mechanisms, behaviors and physiological processes critical for speciation. They prevent members of different species from producing offspring, or ensure that any offspring are sterile. These barriers maintain the integrity of a species by reducing gene flow between related species.
H. Allen Orr is the Shirley Cox Kearns Professor of Biology at the University of Rochester.
The Bateson–Dobzhansky–Muller model, also known as Dobzhansky–Muller model, is a model of the evolution of genetic incompatibility, important in understanding the evolution of reproductive isolation during speciation and the role of natural selection in bringing it about. The theory was first described by William Bateson in 1909, then independently described by Theodosius Dobzhansky in 1934, and later elaborated in different forms by Herman Muller, H. Allen Orr and Sergey Gavrilets.
Jürgen Haffer was a German ornithologist, biogeographer, and geologist. He is most remembered for his theory of Amazonian forest refugia during the Pleistocene that would have contributed to speciation and the diversification of the biota.
The scientific study of speciation — how species evolve to become new species — began around the time of Charles Darwin in the middle of the 19th century. Many naturalists at the time recognized the relationship between biogeography and the evolution of species. The 20th century saw the growth of the field of speciation, with major contributors such as Ernst Mayr researching and documenting species' geographic patterns and relationships. The field grew in prominence with the modern evolutionary synthesis in the early part of that century. Since then, research on speciation has expanded immensely.
Reinforcement is a process within speciation where natural selection increases the reproductive isolation between two populations of species by reducing the production of hybrids. Evidence for speciation by reinforcement has been gathered since the 1990s, and along with data from comparative studies and laboratory experiments, has overcome many of the objections to the theory. Differences in behavior or biology that inhibit formation of hybrid zygotes are termed prezygotic isolation. Reinforcement can be shown to be occurring by measuring the strength of prezygotic isolation in a sympatric population in comparison to an allopatric population of the same species. Comparative studies of this allow for determining large-scale patterns in nature across various taxa. Mating patterns in hybrid zones can also be used to detect reinforcement. Reproductive character displacement is seen as a result of reinforcement, so many of the cases in nature express this pattern in sympatry. Reinforcement's prevalence is unknown, but the patterns of reproductive character displacement are found across numerous taxa, and is considered to be a common occurrence in nature. Studies of reinforcement in nature often prove difficult, as alternative explanations for the detected patterns can be asserted. Nevertheless, empirical evidence exists for reinforcement occurring across various taxa and its role in precipitating speciation is conclusive.
Laboratory experiments of speciation have been conducted for all four modes of speciation: allopatric, peripatric, parapatric, and sympatric; and various other processes involving speciation: hybridization, reinforcement, founder effects, among others. Most of the experiments have been done on flies, in particular Drosophila fruit flies. However, more recent studies have tested yeasts, fungi, and even viruses.
Drosophila silvestris is a large species of fly in the family Drosophilidae that are primarily black with yellow spots. As a rare species of fruit fly endemic to Hawaii, the fly often experiences reproductive isolation. Despite barriers in nature, D. silvestris is able to breed with D. heteroneura to create hybrid flies in the laboratory.
Michael Gordon Ritchie is a British evolutionary biologist and professor at the University of St Andrews. He is known for his work on speciation. He served as editor-in-chief of the Journal of Evolutionary Biology from 2011 to 2017, and Vice-President of the Society for the Study of Evolution from 2004 to 2005.
Vladimir Vladimirovich Sakharov was a Soviet cytogeneticist who studied mutagenesis by radiation with applications to agricultural and human genetics. He was a professor at the K. A. Timiriazev Agricultural Academy.
References
- ↑ Veprintsev, Boris N. (1980). "Wildlife sound recording in the soviet union". Comparative Biochemistry and Physiology Part A: Physiology. 67 (3): 321–328. doi:10.1016/S0300-9629(80)80003-X.
- ↑ Marler., P. (1952-07-01). "Variation in the Song of the Chaffinch Fringilla Coelebs". Ibis. 94 (3): 458–472. doi:10.1111/j.1474-919x.1952.tb01845.x. ISSN 1474-919X.
- ↑ Radick, Gregory (2007). The Simian Tongue: The Long Debate about Animal Language. University of Chicago Press. p. 251.
- 1 2 3 Krementsov, Nikolai (2007). "A Particular Synthesis: Aleksandr Promptov and Speciation in Birds". Journal of the History of Biology. 40 (4): 637–682. doi:10.1007/s10739-007-9123-y. JSTOR 29737515. S2CID 85078250.
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