Peripatric speciation
[1]: 106 Scientists observing the patterns of a species biogeographic distribution and its phylogenetic relationships are able to reconstruct the historical process by which they diverged.
[6] The founder effect is based on models that suggest peripatric speciation can occur by the interaction of selection and genetic drift,[1]: 106 which may play a significant role.
[1]: 389 Tanysiptera galatea was largely uniform in morphology on the mainland, but the populations on the surrounding islands differed significantly—referring to this pattern as "peripatric".
[1]: 389 Seeing that a species cohesion is maintained by conservative forces such as epistasis and the slow pace of the spread of favorable alleles in a large population (based heavily on J.
This promotes divergence due to strong selective pressures, leading to the rapid fixation of an allele within the descendant population.
[19] The botanist Verne Grant proposed the term quantum speciation that combined the ideas of J. T. Gulick (his observation of the variation of species in semi-isolation), Sewall Wright (his models of genetic drift), Mayr (both his peripatric and genetic revolution models), and George Gaylord Simpson (his development of the idea of quantum evolution).
[9][22] Evidence for the occurrence of this type of speciation has been found in several plant species pairs: Layia discoidea and L. glandulosa, Clarkia lingulata and C. biloba, and Stephanomeria malheurensis and S. exigua ssp.
This model contrasts with peripatric speciation by virtue of the origin of the genetic novelty that leads to reproductive isolation.
[26] Peromyscus polionotus and P. melanotis (the peripherally isolated species from the central population of P. maniculatus) arose via the centrifugal speciation model.
[30] Centrifugal speciation may have taken place in tree kangaroos, South American frogs (Ceratophrys), shrews (Crocidura), and primates (Presbytis melalophos).
[29] John C. Briggs associates centrifugal speciation with centers of origin, contending that the centrifugal model is better supported by the data, citing species patterns from the proposed 'center of origin' within the Indo-West Pacific[29] The Kaneshiro Model also provides an explanation of the mechanism of speciation during founder events as proposed by Ernst Mayr and Hampton Carson.
Such a founder colony is faced with extremely small population size which as described by the Kaneshiro Model, experiences a shift in the mating system towards and increase in frequency of less choosy females.
Eventually, a growth in population size paired with novel female mate preferences will give rise to reproductive isolation from the main population-thereby completing the speciation process.
[33] However, while laboratory experiments are ongoing and yet to be completed in support of the model, there are field observations of shifts in the mating systems that undergo population bottlenecks which demonstrate that the dynamics of sexual selection is occurring in nature and therefore, it does represent a plausible process of peripatric speciation that takes place in nature.
Drosophila species on the Hawaiian archipelago have helped researchers understand speciation processes in great detail.
It is well established that Drosophila has undergone an adaptive radiation into hundreds of endemic species on the Hawaiian island chain;[1]: 107 [35] originating from a single common ancestor (supported from molecular analysis).
[50] A host of other Hawaiian endemic arthropod species and genera have had their speciation and phylogeographical patterns studied: the Drosophila grimshawi species complex,[51] damselflies (Megalagrion xanthomelas and Megalagrion pacificum),[52] Doryonychus raptor, Littorophiloscia hawaiiensis, Anax strenuus, Nesogonia blackburni, Theridion grallator,[53] Vanessa tameamea, Hyalopeplus pellucidus, Coleotichus blackburniae, Labula, Hawaiioscia, Banza (in the family Tettigoniidae), Caconemobius, Eupethicea, Ptycta, Megalagrion, Prognathogryllus, Nesosydne, Cephalops, Trupanea, and the tribe Platynini—all suggesting repeated radiations among the islands.
M. rapaensis has been traditionally thought of as a single species; whereas this particular study found distinct genetic differences corresponding to the sequential age of the islands.
[60] In addition, a great deal of research has been conducted on several species of land snails involving chirality that suggests peripatry (with some authors noting other possible interpretations).
[1]: 111 The chestnut-tailed antbird (Sciaphylax hemimelaena) is located within the Noel Kempff Mercado National Park (Serrania de Huanchaca) in Bolivia.
The population of S. hemimelaena antbirds that reside in the isolated patch express significant song divergence; thought to be an "early step" in the process of peripatric speciation.
[14] The montane spiny throated reed frog species complex (genus: Hyperolius) originated through occurrences of peripatric speciation events.
[2] In a study of the phylogeny and biogeography of the land snail genus Monacha, the species M. ciscaucasica is thought to have speciated peripatrically from a population of M. roseni.
In addition, M. claussi consists of a small population located on the peripheral of the much larger range of M. subcarthusiana suggesting that it also arose by peripatric speciation.
[67][63] Using a phylogeographic approach paired with ecological niche models (i.e. prediction and identification of expansion and contraction species ranges into suitable habitats based on current ecological niches, correlated with fossil and molecular data), researchers found that the prairie dog species Cynomys mexicanus speciated peripatrically from Cynomys ludovicianus approximately 230,000 years ago.
North American glacial cycles promoted range expansion and contraction of the prairie dogs, leading to the isolation of a relic population in a refugium located in the present day Coahuila, Mexico.
