Speciation

Example of Speciation

Example of an extinct animal

    In my last blog I spoke about phylogenetic trees and how organisms are placed upon the diagram. This blog I will be speaking a bit more in depth as to why the organism earned their spot on the cladogram or phylogenetic tree. The reason to why they earned a spot on both diagrams is due to speciation. Speciation is the evolutionary process by which new biological species arise. Hence, being able to place them on a phylogenetic tree according to when they arose. When speaking about speciation is vital to not forget extinction because it also plays an important role in the evolutionary process. Extinction occurs when a species is dying out or is completely terminated. So a good way to distinguish the two is to remember that speciation is when 1 species goes to 2 species and extinction is when 1 species goes to 0 species. Speciation and extinction have been happening throughout the entire history of Earth. Although, the rates of speciation and extinction can be very random at times. Speciation has tendencies to be slow or as described in punctuated equilibrium, can happen at any given moment followed by certain periods of nothing. Moments of ecological stress, extinction rates are extremely rapid and can be seen before your eyes, and mass extinctions are followed by adaptive radiation. Adaptive radiation is simply the rapid evolution of species when they're exposed to new environments.

       Species are groups of individuals capable of interbreeding or exchanging genetic information to produce fertile offspring. Speciation occurs when two populations diverge from a common ancestors and become reproductively isolated. Reproductive isolation is when two populations that live in the same environment are unable to reproduce because their genes are no longer able to interbreed. Although speciation can happen by different processes, reproductive isolation must be maintained so species can remain distinct. Speciation creates a diversity in life formations. Species are spread throughout the earth which causes a geographical barrier, for example species on land and species who live in the ocean. Also pre- and post-zygotic mechanisms can maintain this reproductive isolation and also prevents gene flow. So the main thing to grasp is that new species arise from reproductive isolation over time.

Darwin's Finches

       Something interesting to know is that even today population are continuing to evolve. Everyday is a new day of possibility for species to speciate or become extinct. There is scientific evidence to back this up. Scientific evidence has also proved that evolution has occurred in all species. Take Grants' observation of darwin's finches for example in the Galapagos for example. The "Grants'" are a married couple who have recently studied and observed the continuation of evolution happening on the Galapagos Island. They saw how the finches of the birds are still evolving from when darwin studied them. This is a directional phenotypic change in population.     




SOURCES

"Darwin's Finches." Wikipedia. Wikimedia Foundation, 10 Nov. 2014. Web. 11 Oct. 2014.

"Speciation." Evolution 101:. N.p., n.d. Web. 09 Oct. 2014.

"007 - Speciation and Extinction." Bozemanscience. N.p., n.d. Web. 11 Oct. 2014.