week 5 blog

Specialization can be formed by three different ways these three ways are called allotropic,peripatetic, and parametric During allopatric speciation, a population splits into two geographically isolated allopatric populations (for example, by habitat fragmentation building in the wild life The isolated populations then undergo genotypic and/or phenotypic divergence as they (a) become subjected to dissimilar selective pressures or (b) they independently undergo genetic drift. When the populations come back into contact, they have evolved such that they are reproductively isolated and are no longer capable of exchanging genes.

In peripatric speciation, new species are formed in isolated, small peripheral populations that are prevented from exchanging genes with the main population. It is related to the concept of a founder affect, since small populations often undergo bottlenecks. genetic drift is often proposed to play a significant role in peripatric speciation.

Observed instances

• Mayr bird fauna
• The Australian bird petrocia multicolor
• Reproductive isolation occurs in populations of drosophila subject to population bottlenecking

Thelondon underground mosqutoe is a variant of the mosquito Culex pipiens that entered in the london underground in the nineteenth century. Evidence for its speciation include genetic divergence, behavioral differences, and difficulty in mating. n parapatric speciation, the zones of two diverging populations are separate but do overlap. There is only partial separation afforded by geography, so individuals of each species may come in contact or cross the barrier from time to time, but reduced fitness of the hertrozygous leads to selection for behaviours or mechanisms that prevent breeding between the two species.

Ecologists refer to parapatric and peripatric speciation in terms of ecological niches. A niche must be available in order for a new species to be successful.