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Speciation Types | Formation of New SpeciesBY: Medha Hegde | Category: Biology | Submitted: 2012-12-10 21:01:37
Article Summary: "What is Speciation? It is a elementary process responsible for the diversity of life. Understanding the common patterns and processes of speciation is fundamental to explaining the diversity of life..."
A species is the fundamental entity of biodiversity. Species is an assemblage of organisms that can inbreed in nature to generate fertile offspring. Speciation is the establishment of new species in the path of evolution. It involves the divergence of a distinct evolutionary lineage into 2 or more genetically self-regulating forms. Ernst Mayr of Harvard, one of the discoverers of synthetic theory (synthesis of mendelian genetics and Darwinian selection into a modern theory of evolutionary change) had proposed a possible mechanism back in 1942. He had suggested that speciation could occur quite fast in tiny remote populations, separated from the larger gene pool by geographic barriers. Then a small quantity of variation would be amplified by selection (the foundler's effect).
Allopatric speciation - Speciation that results when 2 or more populations of a species are isolated geographically from one another adequately that they do not interbreed. In their different niches, the 2 sets go their own evolutionary ways, gathering different gene mutations, experiencing different selective pressures, subjected to different historical events, ultimately becoming incapable of interbreeding when they come together again. For several years this was considered as the major process by which new species arose. This type of speciation occurs in 3 steps. In the first step the populations become physically split, frequently by a lengthy, slow geological process like an uplift of land, glacier movements, or waterway. Next, the unconnected populations diverge, through variations in mating strategy or utilization of their habitat. Lastly, they become reproductively separated so that they cannot interbreed and swap genes.
Peripatric speciation - It occurs when tiny groups of individuals detach from the big group and form a new species. As in the case of allopatric speciation, physical barriers make it impracticable for individuals of the groups to interbreed with one another. The key distinction between allopatric speciation and peripatric speciation is that in peripatric speciation, one group is much tinier than the other. Distinctive characteristics of the smaller groups are passed on to further generations of the group, making those traits more widespread among that group and making it unique from the others.
Parapatric speciation - In this type a species is stretched out over a huge geographic area. Even though it is possible for any individual of the species to mate with another individual, members only mate with those in their own geographic region. Similar to allopatric and peripatric speciation, dissimilar habitats influence the development of different species in parapatric speciation. In this case it is not separated by a physical barrier but the species are separated by variations in the same environment.
Sympatric speciation - Sympatric speciation results when there are no physical barriers obstructing any members of a species from mating with another and all individuals are in near proximity to one another. A novel species, perhaps based on a different food source or characteristic, seems to develop spontaneously. The theory is that some members become needy on certain aspects of an environment such as shelter or food sources while others do not.
Artificial speciation - It is the designing of new species by humans. This is executed through lab experiments, where researchers mostly work on insects like fruit flies, and in animal husbandry (animal husbandry is concerned with reproduction of livestock animals, many agricultural products, such as dairy, meat, and wool, rely on animal husbandry).
Hybrid speciation - Hybrid speciation results when hybridization among 2 species accompanies the formation of a new third species. Scientists have long thought that hybrid speciation is significant, in particular after chromosomal doubling (allopolyploidy - 2 or more complete sets of chromosomes derived from different species).New genetic information imply that hybrid speciation, is more widespread in plants and as well as in animals than considered.
Asexual speciation - Sexual reproduction may explain the subsistence of the distinct units recognized as species: interbreeding maintains consistency within populations, whereas reproductive isolation leads to genetic and phenotypic discontinuities among isolated populations. On the other hand, if similar genetic and morphological groups were found in 'asexual taxa', external ecological factors might be more important than is sexual reproduction in explaining why species exist.
Recent work has renewed interest in the role of ecological shifts( large sudden changes in ecosystems that lasts for considerable period of time) in speciation.
Speciation is a elementary process responsible for the diversity of life. Understanding the common patterns and processes of speciation is fundamental to explaining the diversity of life.
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