Peripatric speciation

Peripatric speciation is a form of speciation, the formation of new species through evolution.

Peripatric and peripatry are terms from biogeography, referring to organisms whose ranges are closely adjacent but do not overlap, being separated where these organisms do not occur – for example a wide river or a mountain range.

The turnover in this group is clearly marked at the species level .< ref > Statistical analysis of marine losses at this time suggests that the decrease in diversity was caused more by a sharp increase in extinctions than by a decrease in speciation .< ref > The K – T boundary record of dinoflagellates is not as well-understood, mainly because only microbial cysts provide a fossil record, and not all dinoflagellate species have cyst-forming stages, thereby likely causing diversity to be underestimated.

His theory of peripatric speciation ( a more precise form of allopatric speciation which he advanced ), based on his work on birds, is still considered a leading mode of speciation, and was the theoretical underpinning for the theory of punctuated equilibrium, proposed by Niles Eldredge and Stephen Jay Gould.

The direct evidence suggests there was a migration of H. erectus out of Africa, then a further speciation of H. sapiens from H. erectus in Africa.

This might lead to the erroneous belief that speciation was involved in the observed evolution of the peppered moth.

A year before their 1972 Eldredge and Gould paper, Niles Eldredge published a paper in the journal Evolution which suggested that gradual evolution was seldom seen in the fossil record and argued that Ernst Mayr's standard mechanism of allopatric speciation might suggest a possible resolution.

When Eldredge and Gould published their 1972 paper, allopatric speciation was considered the " standard " theory of speciation.

In 2008 a speciation gene causing reproductive isolation was reported.

Despite this, Huxley strongly supported Darwin on evolution ; though he called for experiments to show whether natural selection could form new species, and questioned if Darwin's gradualism was sufficient without sudden leaps to cause speciation.

Statistical analysis of marine losses at this time suggests that the decrease in diversity was caused more by a decrease in speciation than by an increase in extinctions .< ref >

As part of the disagreement about whether natural selection alone was sufficient to explain speciation, George Romanes coined the term neo-Darwinism to refer to the version of evolution advocated by Alfred Russel Wallace and August Weismann with its heavy dependence on natural selection.

Therefore, it seems that speciation could have occurred when the rats colonized southwest India, which was a primary country where Romans obtained their spices.

This geological history probably contributed to the dramatic cichlid speciation that characterises its ecology, as well as that of other African Great Lakes, although some researchers dispute this, arguing while Lake Victoria was at its lowest between 18, 000 and 14, 000 years ago, and it dried out at least once during that time, there is no evidence of remnant ponds or marshes persisting within the desiccated basin.

As part of the disagreement about whether natural selection alone was sufficient to explain speciation, George Romanes coined the term neo-Darwinism to refer to the version of evolution advocated by Alfred Russel Wallace and August Weismann with its heavy dependence on natural selection.

He was skeptical of the reality of sympatric speciation believing that geographical isolation was a prerequisite for building up intrinsic ( reproductive ) isolating mechanisms.

By applying a molecular clock to the amount of mitochondrial DNA sequence divergence between the two, it was estimated that Troglodytes pacificus and Troglodytes troglodytes last shared a common ancestor approximately 4. 3 million years ago, long before the glacial cycles of the Pleistocene, thought to have promoted speciation in many avian systems inhabiting the boreal forest of North America.

The post-Darwin concept of human speciation was unacceptable to those forming the Anthropological Society.

Sewall Wright was the first to attach this significance to random drift and small, newly isolated populations with his shifting balance theory of speciation.

Statistical analysis of marine losses at this time suggests that the decrease in diversity was mainly caused by a sharp increase in extinctions, rather than a decrease in speciation .< ref >

Haffer proposed the explanation for speciation was the product of rainforest patches being separated by stretches of non forest vegetation during the last glacial period.

Yoshimaro Yamashina examined those specimens in Japanese museums in 1948, and decided that the Mariana Mallard was an example of hybrid speciation, and was descended from the Mallard and the Pacific Black Duck's Palau subspecies ( Anas superciliosa pelewensis ).

If the population is panmixic, then Geospiza conirostris exhibits a balanced genetic polymorphism and not, as originally supposed, a case of nascent sympatric speciation.

Changes in the genes regulating development have also been proposed as being important in producing speciation through large and relatively sudden changes in animals ' morphology.

Genetic drift is often proposed to play a significant role in peripatric speciation.

A number of models have been proposed to account for this mode of speciation.

Genetic drift is often proposed to play a significant role in peripatric speciation.

These included the concept of warning colouration in animals, and the Wallace effect, a hypothesis on how natural selection could contribute to speciation by encouraging the development of barriers against hybridization.

It is for this reason that gene flow strongly acts against speciation, by recombining the gene pools of the groups, and thus, repairing the developing differences in genetic variation that would have led to full speciation and creation of daughter species.

Contrary to the claims of some antievolution proponents, evolution of life forms beyond the species level (" macroevolution ", i. e. speciation ) has indeed been observed and documented by scientists on numerous occasions.

Punctuated equilibrium originated as a logical extension of Ernst Mayr's concept of genetic revolutions by allopatric and especially peripatric speciation as applied to the fossil record.

Allopatric speciation suggests that species with large central populations are stabilized by their large volume and the process gene flow.

During allopatric ( from the ancient Greek allos, " other " + Greek patrā, " fatherland ") speciation, a population splits into two geographically isolated populations ( for example, by habitat fragmentation due to geographical change such as mountain building ).

In parapatric speciation, there is only partial separation of the zones of two diverging populations afforded by geography ; individuals of each species may come in contact or cross habitats from time to time, but reduced fitness of the heterozygote leads to selection for behaviours or mechanisms that prevent their inter-breeding.

Sympatric speciation driven by ecological factors may also account for the extraordinary diversity of crustaceans living in the depths of Siberia's Lake Baikal.

Grant ) and his current colleagues in British Columbia, were once thought to provide an intriguing example best explained by sympatric speciation.

Therefore the first four chapters lay out his case that selection in nature, caused by the struggle for existence, is analogous to the selection of variations under domestication, and that the accumulation of adaptive variations provides a scientifically testable mechanism for evolutionary speciation.

It has been established that 15 % of angiosperm and 31 % of fern speciation events are accompanied by ploidy increase.

For example, data from species-level phylogenetic and biogeographic studies tell us that the Amazonian fish fauna accumulated incrementally over a period of tens of millions of years, principally by means of allopatric speciation, and in an arena extending over most of the area of tropical South America ( Albert & Reis 2011 ).

This is an example of the parapatric speciation model described by Ernst Mayr.

This is due to a pseudogene's shared ancestry with a functional gene: in the same way that Darwin thought of two species as possibly having a shared common ancestry followed by millions of years of evolutionary divergence ( see speciation ), a pseudogene and its associated functional gene also share a common ancestor and have diverged as separate genetic entities over millions of years.

Progressive creationists point to multiple destructive events in the Earth's history ( such as meteoric impacts and large-scale global volcanic activity ) and geological evidence for rapid subsequent speciation as evidence for distinct, typically limited intervention by a Creator.