The model of punctuated equilibrium , biology homework help
The model of punctuated equilibrium was first introduced in a paper published by the scientists Stephen Jay Gould and Niles Eldredge. The theory predicts evolutionary change, but the changes occur over short periods of time during speciation events. The populations will experience stasis, where they are living, dying, and becoming fossilized (becoming part of the fossil record); during this period you will see little observable evolution when analyzing the fossil record. There will be periods where a part of the large main population will become isolated; creating a smaller population that is separated from the main population (this could be caused by events such as geographical changes; drought.). The smaller isolated population will go through a period of rapid selection and change due to the recent change in environment and small population size. The new environment exposes the isolated species to different pressures than what it was previously adapted to. In this instance, the isolated population will go through rapid evolution over a short period of time. The small isolated populations evolution will be influenced by genetic drift. Allopatric speciation eventually leads to the formation of a new species. Due to the rapid evolution of the isolated group of species, the small population size, and their isolated location, no fossils of transitional forms are preserved in the fossil record. The isolated population may then be reintroduced to the environment of the original species. The large population of the original group and the stable environment of which they live has lead to little or no evolutionary change. The isolated population that has rapidly evolved may be reintroduced to the original population and environment, where they might out-compete the original population; this could lead to the extinction of the sister lineage. If the larger population does go extinct, the species is likely become part of the fossil record. This event could possibly reoccur with the new species.
In punctuated equilibrium the evolution happens rapidly due to allopatric speciation. The punctuated pattern shows jumps between species, with no fossil records contain transitional species to the lineage. Punctuated equilibrium pattern goes through alternating patterns of stasis and rapid change. Punctuated equilibrium and Darwin’s theory both use evolution to explain new species. Darwin’s theory of evolution uses gradual change over long periods of time, while punctuated equilibrium uses rapid evolution and extended periods of stasis. I feel that punctuated equilibrium strengthens Darwin’s theory by explaining the gaps in the fossil record; both models use evolution, but time is a fundamental difference between the two. We have found evidence that gradual change does occur; punctuated equilibrium helps fill in the gaps where gradual change cannot be explained.
Works Cited:
Prothero, Donald R. “Punctuated Equilibrium at Twenty: A Paleontological Perspective.” N.p., Autumn 1992. Web. 23 Oct. 2016.
More on Punctuated Equilibrium. (n.d.). Retrieved October 23, 2016, fromhttp://www.evolution.berkeley.edu/evosite/evo101/VIIA1bPunctuated.shtml
The article that I have chosen to analyze is, Paleontology: A monster put in its place. In the article it discusses a fossil of a newly discovered predatory dinosaur. The fossil represents the largest predatory dinosaur that has been found in Germany and belongs to a previously unknown genus. The dinosaur dates back to roughly to 163 million years ago, during the Middle Jurassic. This is the first carnivorous dinosaur that has been found during this period in Germany. Wiehenvenator albati is a megalosaur, which are the earliest large carnivorious dinosaurs that we have discovered.
The first fossilized bones and teeth of the species were discovered in 1999 Wiehengebirge quarry, which is a range of low hills south of Minden. What is interesting is that, during the Middle Jurassic there were large areas of Central Europe that lay below sea level, creating shallow waters and scattered islands.
The areas that caught my interest in this article include: Wiehenvenator is part of a group of dinosaurs that underwent rapid diversification, the location (separated islands), and the huge burst of speciation. This sounds like the perfect scenario for punctuated equilibrium to occur. We have an area where sea level changes cause drastic changes in the environment, which can lead to isolated populations. The separation of populations can lead to rapid diversification and speciation. I find it interesting that this is the first fossil of its kind, which also goes along with punctuated equilibrium; fossils during the rapid evolution of the isolated species are likely not to be found because of the rapid changes that are occurring. Could this be a species that was undergoing rapid evolution like explained in the model of punctuated equilibrium? The species could be a part of the small isolated group. During this course is the first time that I have heard of punctuated equilibrium; it really makes you think differently about how evolution could occur.
Work Cited:
Ludwig-Maximilians-Universitaet Muenchen (LMU). (2016, September 1). Paleontology: A monster put in its place. ScienceDaily. Retrieved October 23, 2016 from www.sciencedaily.com/releases/2016/09/160901093008.htm
