Phyletic Gradualism Research Paper

phyletic gradualism and punctuated equilibrium

Science 101
IP # 2
Olivia Altamirano
February 24, 2014
There are numerous mis-conceptions concerning punctuated equilibrium. In the year of 1972, Stephen Jay Gould and Niles Eldredge introduced the idea of punctuated equilibrium, a far-reaching notion in the time. Currently, the relational importance of punctuated and gradual patterns of evolution is a topic for continuing debates and exploration. Contrary to the claims of Eldredge and Gould, Darwin was not a "phyletic gradualist” (Theobald, 2013).
Definition of Phyletic gradualism: Relating to the hereditary descent of a species or its development over time (Encarta Dictionary).
The differences
and similarities are sometimes difficult to decipher…

Charles Darwin’s innovative approach to evolution was to collect tiny dissimilar samples over extended periods until a different species was born. In Darwin’s studies, he found phyletic gradualism and punctuated equilibrium are dissimilar and similar in the ways which the evolution of a species can occur. Forms of species can evolve by only one or the other, or occasionally both. Researchers believe that species with a shorter evolution grew by punctuated equilibrium and others with a lengthier evolution changed by gradualism.
Darwin presumed that if evolution is gradual then there should be a documentation of fossils in small incremental change within a species. He believed that evolution was a slow and gradual process. He did not believe this process to be "perfectly smooth," but rather, "stepwise," with a species evolving and accumulating small variations over long periods. Darwin assumed that if evolution is gradual then there should be a record in fossils of small incremental change within a species (Perkins, University of Vermont. 2013).
Gradualism is selection and variation that happens more gradually, hence the name “Gradualism” (Evolution. (n.d.). Although, over a short period (and it is hardly noticeable), small variations fit an organism slightly better to its environment and they are selected to the difference.
“How did the tiger get its stripes: gradualism or punctuated equilibrium?
We do not know whether the tiger got its stripes through gradualism or punctuated equilibrium, but in order to explain both concepts, here is how it could have happened through each. Assume that stripes are helpful because they help the tiger to camouflage, blend in with the tall grasses where it lives, so that it can sneak up on its prey, (what it eats) and not be noticed. Scientists were studying fossils and they found that some species have their evolution almost "mapped out" in fossils. For others they found a few, very different species along the evolutionary course, but very few or no fossils of "in between" organisms. In addition, when dating the fossils, scientists saw that in some species, change was very slow, but in others, it must have occurred rapidly to be able to produce such change over such a short amount of time. The scientists reasoned that there had to be another way that evolution could have happened that was quicker and had fewer intermediate species, so the idea of punctuated equilibrium was formed ” (Evolution.
(n.d.).
Darwin blamed lack of transitional forms on gaps in the fossil record, a good assertion, because the chances of each of those critical changing forms having been preserved as, fossils are very small.
However, in 1972, evolutionary scientists Stephen Jay Gould and Niles Eldredge proposed another explanation for the numerous gaps in the fossil record. They suggested that the "gaps" were real, representing periods of stasis in morphology. They termed this mode of evolution "punctuated equilibrium." This means that species are generally morphologically stable, changing little for millions of years. This leisurely pace is "punctuated" by a rapid burst of change that results in a new species (Perkins, University of Vermont. 2013).
Phyletic gradualism was proposed by Charles Darwin, stating: “Natural selection gradually changes the average features of a species by preferentially, removing less fit individuals from the breeding stock. If this process continues long enough, a single species may change imperceptibly into a new species. The original species therefore undergoes phyletic extinction. Evolutionary change occurs all the time and is not concentrated in lineage-splitting speciation event. The absence of missing links is a result of the many breaks in the rock record. If stratigraphic sequences were more complete, we should find more missing links.”
The debates will continue for as long as scientists, religious and anthroplogists continue to research. Theory, beliefs
and discovery…’

REFERENCES

Bar-Yam, S. (n.d.). Evolution. Evolution. Retrieved from http://necsi.edu/projects/evolution/cover/evolution_cover.html
The Editors of Encyclopædia Britannica. (n.d.). Web sites: Phyletic gradualism (anthropology). Encyclopedia Britannica Online. Retrieved from http://www.britannica.com/topic/458494/websites
Evolution. (n.d.). Evolution. Retrieved from http://necsi.edu/projects/evolution/evolution/grad%2Bpunct/evolution_grad%2Bpunct.html
Gradual Change Vs. Punctuated Equilibrium : The Study of Change Over Time : Evolution 101 : University of Vermont. (n.d.). Gradual Change Vs. Punctuated Equilibrium : The Study of Change Over Time : Evolution 101 : University of Vermont. Retrieved from http://www.uvm.edu/perkins/evolution/darwin/?Page=record/plas.html&SM=record/recordmenu.html
Theobald, D. (2013, October 9). All you need to know about Punctuated Equilibrium (almost). All You Need to Know about Punctuated Equilibrium (almost). Retrieved from http://theobald.brandeis.edu/pe.html