Friday, April 5, 2013

Ecological Speciation

Ecological Speciation by Patrick Nosil is a book with a red cover with a picture of a fish on its cover. An entire book dedicated to explaining "ecological speciation", its components, outstanding problems and current developments should definitely be comprehensive.  The book was written during Nosil's yearlong stay at the institute of advanced study at Berlin, Germany. It has been praised for its clarity and utility to even graduate students who are just entering the field.

While the book was published in 2012, this 2005 paper in Ecology letters gives a good premise to the book. The idea behind ecological speciation is the action of divergent selection that is due to ecological reasons which leads to the evolution of barriers to gene flow leading to the formation of new species. This process is broken down into its 3 constituents, ecologically divergent selection, barrier to gene flow or reproductive isolation and a "genetic" mechanism which links these two.

Why should the mechanism linking divergent selection and reproductive isolation be genetic? Depending on the comprehensiveness of this "genetic" mechanism, could one think of links other than pleiotropy or linkage?. For example, would a scenario that involves speciation (formation of barriers to gene flow) due to some other mechanism expedited by divergent selection be part of ecological speciation? It might be worth thinking about it while reading the chapter thats devoted to the mechanisms linking selection and isolation.

Concepts such as immigrant inviability and isolation by adaptation are also covered. Adaptive speciation is considered a special case of ecological speciation which requires frequency-dependent disruptive selection in sympatry or parapatry. Disruptive selection involves selection for opposite phenotypes within a single population while divergent selection involves selection for opposite phenotypes in different populations.

The book is made up of 9 chapters divided into 3 parts covering 280 pages. So this should definitely be a interesting read.