Mechanism of speciation
The process by which a new species develops from the existing species is known as speciation. 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. A species can be defined as one or more populations of interbreeding organisms that are reproductively isolated in nature from all other organisms. When populations no longer interbreed, they are thought to be separate species. There are four geographic modes of speciation in nature, based on the extent to which speciating populations are isolated from one another: allopatric, peripatric, Parapatric, and sympatric. Speciation may also be induced artificially, through animal husbandry, agriculture, or laboratory experiments. Allopatric speciation: It is regarded as the most common type of speciation. It involves the physical separation of a species into two groups. This may occur due to climatic changes, movement of tectonic plates leading to the fragmentation of a mass of land, or eruption of a land mass, formation of waterways, or due to the presence of an impassable mountain range. Parapatric mode of speciation: It occurs due to partial spatial isolation of populations, and is characterized by a small overlap in their ranges as well as significant gene flow amongst the populations. However, the gene flow reduces due to changes in the local conditions, and the two populations become reproductively isolated. Sympatric mode of speciation: It involves the formation of new species due to a genetic divergence among a few members of the species inhabiting a single geographic area. Unlike the other modes of speciation, here genetic divergence does not arise due to increase in geographic distance, but occurs within the same niche. Peripatric speciation was Proposed by Ernst Mayr. In this type of speciation, a small group of members inhabiting a peripheral region of the range undergo reproductive isolation to form a new species. Many a time, it is considered to be a variation of allopatric speciation.
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Mechanism of speciation
- 1. Dr. P.B.Reddy M.Sc,M.Phil,Ph.D, FIMRF,FICER,FSLSc,FISZS,FISQEM PG DEPARTMENT OF ZOOLOGY GOVERTNAMENT PG COLLEGE, RATLAM.M.P reddysirr@gmail.com Mechanism of speciation
- 3. Multiply, vary, let the strongest live and the weakest die.” ― Charles Darwin
- 4. 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.
- 5. The process by which a new species develops from the existing species is known as speciation. 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. A species can be defined as one or more populations of interbreeding organisms that are reproductively isolated in nature from all other organisms. When populations no longer interbreed, they are thought to be separate species. There are four geographic modes of speciation in nature, based on the extent to which speciating populations are isolated from one another: allopatric, peripatric, Parapatric, and sympatric. Speciation may also be induced artificially, through animal husbandry, agriculture, or laboratory experiments.
- 6. 3 steps of speciation Speciation has been observed as a three-stage process: 1. Isolation of populations. 2. Divergence in traits of separated populations (e.g. mating system or habitat use). 3. Reproductive isolation of populations that maintains isolation when populations come into contact again (secondary contact). Types of isolating mechanisms Ecological Isolation. ... Temporal Isolation. ... Behavioral Isolation. ... Mechanical or Chemical Isolation. ... Geographical Isolation. Basic mechanisms of evolution Describe the four basic causes of evolution: natural selection, mutation, genetic drift, and gene flow.
- 7. Allopatric speciation: It is regarded as the most common type of speciation. It involves the physical separation of a species into two groups. This may occur due to climatic changes, movement of tectonic plates leading to the fragmentation of a mass of land, or eruption of a land mass, formation of waterways, or due to the presence of an impassable mountain range. Parapatric mode of speciation: It occurs due to partial spatial isolation of populations, and is characterized by a small overlap in their ranges as well as significant gene flow amongst the populations. However, the gene flow reduces due to changes in the local conditions, and the two populations become reproductively isolated. Sympatric mode of speciation: It involves the formation of new species due to a genetic divergence among a few members of the species inhabiting a single geographic area. Unlike the other modes of speciation, here genetic divergence does not arise due to increase in geographic distance, but occurs within the same niche. Peripatric speciation was Proposed by Ernst Mayr. In this type of speciation, a small group of members inhabiting a peripheral region of the range undergo reproductive isolation to form a new species. Many a time, it is considered to be a variation of allopatric speciation.
- 8. Modes of Speciation Allopatric Speciation VS Sympatric Speciation
- 10. Pre-zygotic barriers are obstacles that are present before an egg can be fertilized. Post-zygotic barriers mean the animals mated but no offspring occurred after they did so. It can also mean the offspring is a hybrid and is not viable, sterile or both.