Editing Peripatric speciation (section)

=== Peripatric ===
Peripatric speciation models are identical to models of [[vicariance]] (allopatric speciation).<ref name="Speciation"/>{{rp|105}} Requiring both geographic separation and time, speciation can result as a predictable byproduct.<ref>{{Citation |title=Theory and speciation |author=Michael Turelli, Nicholas H. Barton, & Jerry A. Coyne |journal=Trends in Ecology & Evolution |year=2001 |volume=16 |issue=7 |pages=330–343 |doi=10.1016/s0169-5347(01)02177-2|pmid=11403865 }}</ref> Peripatry can be distinguished from allopatric speciation by three key features:<ref name="Speciation"/>{{rp|105}}
*The size of the isolated population
*Strong [[Natural selection|selection]] caused by the dispersal and colonization of novel environments, 
*The effects of [[genetic drift]] on small populations.

The size of a population is important because individuals colonizing a new habitat likely contain only a small sample of the genetic variation of the original population. This promotes divergence due to strong selective pressures, leading to the rapid [[Fixation (population genetics)|fixation]] of an [[allele]] within the descendant population. This gives rise to the potential for genetic incompatibilities to [[evolution|evolve]]. These incompatibilities cause [[reproductive isolation]], giving rise to—sometimes rapid—speciation events.<ref name="Speciation"/>{{rp|105}} Furthermore, two important predictions are invoked, namely that geological or climatic changes cause populations to become locally fragmented (or regionally when considering allopatric speciation), and that an isolated population's reproductive traits evolve enough as to prevent interbreeding upon potential [[secondary contact]].<ref name="ST2007">{{Citation |title=Song divergence at the edge of Amazonia: an empirical test of the peripatric speciation model |author=Nathalie Seddon & Joseph A. Tobias |journal=Biological Journal of the Linnean Society |year=2007 |volume=90 |pages=173–188 |doi=10.1111/j.1095-8312.2007.00753.x|doi-access=free }}</ref>

The peripatric model results in, what have been called, progenitor-derivative species pairs, whereby the derivative species (the peripherally isolated population)—geographically and genetically isolated from the progenitor species—diverges.<ref>{{Citation |title=Progenitor-derivative species pairs and plant speciation |author=Daniel J. Crawford |journal=Taxon |year=2010 |volume=59 |issue=5 |pages=1413–1423 |doi=10.1002/tax.595008 }}</ref> A specific [[Phylogenetics|phylogenetic]] signature results from this mode of speciation: the geographically widespread progenitor species becomes [[paraphyletic]] (thereby becoming a [[paraspecies]]), with respect to the derivative species (the peripheral isolate).<ref name="Speciation"/>{{rp|470}} The concept of a paraspecies is therefore a logical consequence of the [[Species#Evolutionary species|evolutionary species concept]], by which one species gives rise to a daughter species.<ref name="AlbertReis2011">{{cite book|author=James S. Albert & Roberto E. Reis |title=Historical Biogeography of Neotropical Freshwater Fishes |url=https://books.google.com/books?id=V8kZeHxkv9oC&pg=PA316 |isbn=978-0-520-26868-5 |year=2011|publisher=University of California Press }}</ref> It is thought that the character traits of the peripherally isolated species become [[Symplesiomorphy|apomorphic]], while the central population remains [[Symplesiomorphy|plesiomorphic]].<ref name="JKFrey">{{Citation |title=Modes of Peripheral Isolate Formation and Speciation |author=Jennifer K. Frey |journal=Systematic Biology |year=1993 |volume=42 |issue=3 |pages=373–381 |doi=10.1093/sysbio/42.3.373|s2cid=32546573 }}</ref>

Modern cladistic methods have developed definitions that have incidentally removed derivative species by defining clades in a way that assumes that when a speciation event occurs, the original species no longer exists, while two new species arise; this is not the case in peripatric speciation.<ref name="Gottlieb2003"/> Mayr warned against this, as it causes a species to lose their classification status.<ref>{{Citation|title=A local flora and the biological species concept |author=Ernst Mayr |journal=American Journal of Botany |year=1992 |volume=79 |issue=2 |pages=222–238 |doi=10.2307/2445111 |jstor=2445111 }}</ref> Loren H. Rieseberg and Luc Brouillet recognized the same dilemma in plant classification.<ref>{{Citation|title=Are many plant species paraphyletic? |author=Loren H. Rieseberg and Luc Brouillet |journal=Taxon |year=1994 |volume=43 |issue=1 |pages=21–32 |doi=10.2307/1223457 |jstor=1223457 }}</ref>