Yoda's Law and Competitive Exclusion - Lab Report Example

Yodas Law and Competitive Exclusion Individual species often adapt to their current environment in a manner that when the environment changes they rescue themselves by adapting to the competition and developing mechanisms to avoid extinction. This report seeks to explore the nature and types of competition witnessed in any natural environments and its effects on population size and distribution. The paper bases the stated explanations on experiments conducted in two different environments with a reflection to Gauses 1934 experiments. In addition, this report explores Yoda’s Law on self-thinning concepts and its implication to competitive exclusion in a given natural environment. Abiotic and biotic factors that affect plant mass-density relationship in self-thinning populations are well featured, and the extent to which they are applied. Research objectives to the experiments are further discussed with a detailed explanation to the environmental differences between the varying aquatic environments. The report sums up by covering the implications of the experimental results to a natural environment and the effects of the principles to biodiversity in the environment. Intraspecific and interspecific competition In any given environment, two or more individuals tend to share resources such as light, food, space, and oxygen. These gradually result to competition among the populations when such resources are insufficient to satisfy all their requirements. Intraspecific competition arises in a situation in which same species compete for resources such as food, breeding site and water. In this type of competition, the size of the population is determinant on availability of such resources. A good example reflects a tropical rain forest whereby frogs compete for shelter from predators during the day, and when there are numerous shelter sites, predators take fewer frogs and their population size increases. On the other hand, interspecific competition takes place in a situation in which different species compete for resources. For example, sea birds, shags and cormorants live and nest on the same type of cliff and all eat fish from the sea (Tool, Sue & Susan 34). The principle of, Law of the minimum by Liebig follows that growth is controlled not by total resources available, but by the scarcest resources identified as the limiting factor. This concept has been applied in developing ecosystem models. For instance, the growth of plants may depend on factors like; sunlight or mineral nutrients. Here, the availability of these factors may vary in the sense that, at any particular time one becomes more limiting when compared to the other (Sharma 103). Yoda’s Law and Gauses 1934 experiments Self-thinning (Yoda’s Law) relates average plant biomass to density when density-dependent mortality occurs, such that populations decline in density as biomass increases. This law asserts that the mean weight per plant increased faster than density increased by a power-law equation with an exponent -3/2 (Rockwood 136). Paradox of the plankton explains the reasons to why it is possible for such a large umber of plankton’s species to coexist in the apparent homogeneous pelagic environment. According to Gauses 1934 experiments two species competing for the same resources cannot stably co-exist under otherwise constant conditions. Gause carried experiments on populations of the protozoa Paramecium aurelia and P. caudatum in which, the growth in numbers of these populations was observed when each of the species is living alone, and when both were living together in a constant volume of nutrient medium. Gause demonstrates that given two species, with the same niche, coexist in the same ecosystem; one will be excluded from the community because of intense competition (Burton 182). The experiments sought to demonstrate the concept self-thinning whereby different species cultured under different environments with the aim of identifying patterns in their population size and distribution. Results for the experimental and the control cultures The experimental and control cultures different outcomes. Under the experimental, in day five and ten, the concentration of P. bursaria increases sharply while that of P. caudatum and P. aureria reduces significantly. In day fifteen, P. bursaria increases abundantly in experimental chemostat while P. aureria increases sharply compared to P. caudatum. However, in the twentieth day, P. aureria dominates highly in control, but with a less reduction under the experimental environment with P. bursaria greatly declining. In control environment, all the three species share bacteria and yeast as food. The species survived in all the cases because the distribution of food varied greatly. The population of P. caudatum declines compared to that P. aureria because P. aureria adapts better to using the limited food available and so grew at a faster rate when compared to the other species. Under the experimental chemostat, there are increased sources of food and competition; nevertheless, P. aureria maintains dominance indicating its quick survival and suitable feeding tactics. P. caudatum reduces compared to the control environment to indicate competition that reduces its distribution. The growth of P. bursaria is greatly favored to an extent in the experimental environment but eventually declines due to increase in competition for available resources. Role of each of the experimental components in any differences The added components in the experimental contributed significantly to the differences observed. Sand/gravel mixture on the bottom displaced the concentration of oxygen promoting the growth of yeast, which was; therefore, the most abundant food than the bacteria. On the upper side, the higher oxygen levels favored the growth of bacteria over yeast, hence bacteria food predominant in this region, hence a shift in distribution among the species. The role of the snails is to create a predator-prey system. The results of the experimental show that with the introduction of the snail, the cycles are short lived, and the system face extinction, however, as more paramecium species are added every five days, the expected cycle is observed (Sharma 105). The fish was a keystone predator that kept the strongest competitors in check. Fish feeds on snails hence helped maintain a greater number of species in the community, which affects directly to the survival of paramecium. Didinium are ravenous predators on paramecium and given an experimental environmental, paramecium benefits from safety sites from didinium, hence while the population of didinium reduces that of paramecium recovers to expand its carrying capacity. Aquatic macrophytes compete for the same nutrients just like the paramecium. Algae, on the other hand, enhance a symbiotic relationship with paramecium (Burton 179). What are the biological reasons why this relationship exist Yes, these results do support the equation. Abiotic and biotic factors affect plant mass-density relationship in self-thinning population. The physical environment is a primary key determinant of the overall net primary production. In a natural stressful environment, plants are forced to cope with several limiting factors such as limited water supply, nutrient’s sterility, salinity and shade, which influence plant competitive potential and consequently population dynamics. In an environment rich in water and nutrients, plants primarily compete for space and light by stretching their shorts while in harsh environmental conditions with limited water and nutrients, plants always increase root allocations to compete for resources under the ground. Competition is another factor, which affects plants density in the sense that when there is high competition amongst plants species in a given niche, the resources shared become limited, which eventually reduces the population density and when there are abundant resources amongst the same plant species the plants density increases (Capinera 906). Biological reason why this relationship may not apply The biological reason to why the relationship may not apply is that the relationship only applies to the final stage of the postulated progression of growth and competition. The relationship, however, does not apply after some of the plants have started to die off through the competition for space (Burton 183). Discuss the results in the contexts of the research objectives The objective of the experiments was to determining how different species in any natural environment responded to competition and its effect on population size and distribution. The experiment demonstrates that species that adapted well eliminated those that failed in population and that when species occupy different niches they all survive. The results of the experiment pointed out that when species compete for limited resources, the species that utilize the resources effectively eliminates the other species and that given a heterogeneous environment the risk of competitive exclusion is reduced on the basis that key predators keep the number of competitors in check and consequently maintain the survival of the weak species. Moreover, the experiment seeks to explain the effects of competition on both population size and distribution. Competition forces the species to occupy different regions any ecological environment than regions with stiff and unmatchable competition whereas some species adapt to their habitat and eventually surviving. Specifically which species were most affected by the experimental treatment? The P. aureria and P. bursaria species was most affected by the experimental treatment. The P. aureria significantly increases in size and distribution over the other species an indication that the species quickly and suitably adapts to a competitive environment. In the case of P. bursaria its population increases but declines after a certain period because of the increase in competition and a reduction in the resources available. Reasons for the observed differences Under control aquatic environment, the three species share bacteria and yeast as food. To begin with, P. aureria adapts better to using the limited food available and so grew at a faster rate in size and distribution compared to P. caudatum. By observing the results of the experimental aquatic environment, P. aureria develops better survival and feeding mechanisms and significantly demonstrates and increase in size and population. On the other hand, P. bursaria shows a sharp increase in concentration and declines after a certain period compared to the other species. These observations are influenced by the factors in the experimental environment, which favors the growth and distribution of P. bursaria, but eventually, decline because of predators and competition for limited resources. What implication do these results have for natural populations? These results signify size and distribution of a population species in any ecological environment due to competition. To begin with, the results, demonstrate that no two species have the capability of inhabiting the same niche indefinitely when resources are limited. In essence, only one that effectively utilizes the resources effectively eliminates the other. Secondly, competition in any natural environment results to changes in distribution of populations with most species thriving in regions with less competition. Increased competition for resources affects the population size of species, which ultimately affects the overall population density of species. Those species that adapt effectively to their environment increase in size and distribution, and ultimately their density population increases compared to species that adapt slowly to environmental changes (Tool, Sue & Susan 35). How biodiversity is affected in a natural environment based on these principles In a natural environment, the ability to adapt and persist depend on, interactions between existing species. Most species adapt to their current environment in the sense that when the environment changes individual population may decline, and if the changes are more severe the population may face extinction. However, some population can respond to the pressure and return to healthy abundances. Competition may reduce population abundances and will likely lower the potential for evolutionary rescue. However, competition can also facilitate selective pressure, promote and increase the speed rate for niche expansion and eventually, increase the rate of evolution enabling different species to adapt newer conditions much faster (Huston & Alan 233). Works Cited Burton, Richard. Biology by Numbers: An Encouragement to Quantitative Thinking. London: Cambridge University Press, 2012. Print. Capinera, John. Encyclopedia of Entomology, Vol. 2. UK: Cengage Learning, 2008. Print. Huston, Michael. & Alan, Huston. Biological Diversity: The Coexistence of Species. London: Cambridge University Press, 2008. Print. Rockwood, Larry. Introduction to Population Ecology. London: John Wiley & Sons, 2011. Print. Sharma, Patrick. Ecology and Environment. London: Cambridge University Press, 2009. Print. Toole, Glenn. Sue, Toole. & Susan, Margaret. Essential A2 Biology for OCR. UK: Nelson Thornes, 2012. Print. Read More