Explanations of Phyletic Gradualism and Punctuated Equilibrium Assignment

Explanations of Phyletic Gradualism and Punctuated Equilibrium - Assignment Example (A Dictionary of Ecology, 2004) According to this theory, new species crop up by the conversion of an inherited populace into its customized descendants. This transformation is steady and slow and engrosses huge numbers typically the whole ancestral inhabitants and their geographical series (Eldredge and Gould, 1972). Punctuated equilibrium In 1972, a new theory was anticipated by Eldredge and Gould to explicate the development of species. According to this hypothesis, evolution takes place in small rapid speciation disintegrations and the new species initiate in geological instants and persevere in stasis for extended period. There exists dissimilarity between phyletic gradualism and punctuated equilibrium because the former one states that uniformity prevails in the evolutionary process through slow and gradual transformation of large of complete pedigree. Sporadic record of fossil was the main issue discussed by this theory. The time interval for which specie subsists in a distinc tive appearance is long as compared to the time period in which transition occur from parent specie to its descendents. When a part of populace is segregated from the remaining population, then the smaller part of population undergoes particular deviations which are much slighter then the variations in the population left behind. The environmental factors like climate, the geological location and the reserves when combine with these variations, result in rapid evolution process. Moreover, rapid dispersion and evolution of descendent species from parent species can be resulted from considerable alteration in the daughter species. Few descendent species may be generated by the ancestral specie during its whole time span of life. Genetic homeostasis and gene stream from distant range are responsible for the periods of relative stasis because due to it large populations do not alter much (Elsberry, 1996). Several studies and researches have illustrated that concept of punctuated equilib rium supports long history of life on the planet. Prediction about fossil record by Punctuated equilibrium Punctuated equilibrium composes following predictions about fossil record: The geographic speciation of ancestral population along with environmental and biological diffusion would result in geographically unexpected emergence of the descendant species ubiquitously apart from the area where the evolutionary process took place. Due to this reason, it takes a long time to find the species which go through the splitting process. The pattern of fossil record consists of geographic and stratigraphic components. The intermediary fossils between ancestral species and its descendants for the peripatric speciation will be restricted in the geographic section. As the species transformation time period is petite therefore the geographic existence of fossil record will be concise (Elsberry, 1996). Evidences supporting the two theories The exposure of gradual evolution of taxa from one cate gory to a further one in fossil record supports phyletic gradualism theory which states that evolution occurs by gradual change. But this evidence of gradual evolution is restricted to limited number of taxa therefore, most of the studies and evidences support punctuated equilibrium hypothesis. Long periods of stasis along with rapid and small durations of morphological

Childhood Obeasity Research Proposal Example | Topics and Well Written Essays - 2000 words

Childhood Obeasity - Research Proposal Example The overwhelming evidence of prevalence of unhealthy obese lifestyle among the American youth originates a serious issue related to health. Children with obesity have to cope with numerous diseases linked with obesity that are discussed in this paper. Some of the research presented in this paper also deals with the factors that explain why the incidence of obesity is increasing among the American youth. Increase in the availability of affordable junk foods and sedentary lifestyle are also highlighted in the paper that contribute to incidence of obesity. Some factors that make it difficult to decrease the likelihood of obesity in the youth are also identified in the paper and backed up with authentic evidence. 1. Introduction: For the past many years, research reports have been illuminating that more and more children are getting overweight owing to the increased adaptation of sedentary lifestyle and increased consumption of junk food and sugar beverages. Childhood obesity presents on e of the greatest health challenges to the world. Obesity is especially drastic and devastating for the youth owing to the many other diseases it develops like emotional disturbances, heart problems, type 2 diabetes, and increased blood pressure. Over the past years, decrease in the prices of beverages and fast food has made it convenient for the youth to consume these readymade products excessively. Affordability of such foods that are high in calories, fat, and sugar has made the likelihood of obesity among youth all the more potent. There are numerous alarming side effects associated with this growing epidemic which are highly capable of destroying the futures of many children. The rate of obesity among the American youth is so markedly high that according to a report by Robert Wood Johnson Foundation Center to Prevent Childhood Obesity, â€Å"today, more than 23 million U.S. children and teens—nearly one in three young people—are either overweight or obese.† (Thompson, 2010). What aggravates the situation is that only a minimal percentage of youth is on diet that meets the national recommendations and even less percentage of youth considers the necessary 60 minute daily physical activity presently in America. Outdoor activity has been almost completely replaced with television and video games, and this greatly increases the incidence of obesity among the American youth. 2. Research review: a. Prevalence of obesity in the American youth: (Thompson, 2010) mentions that â€Å"obesity is becoming a problem at an earlier age, with 24.4 percent of children ages 2 to 5 already obese or overweight.† The problem of childhood obesity is prevalent in the American youth irrespective of race, religion, family income, and location. Still, some populations or communities are at more risk of childhood obesity than others because of their unhealthy lifestyle and increased consumption of foods that go against the recommended healthy diet. Some pa rticular races like Blacks, American Indians, and Latinos are at more risk of childhood obesity than other races owing to genetic factors. Sedentary lifestyle and social environments play more active role in increasing childhood obesity incidence than the genetic factors. Obesity significantly destroys the futures of many children because the adverse disease it brings with itself, cause a serious setback to such children. This epidemic