Interspecific and Intraspecific Competition Among Alfalfa in in Shaded and Unshaded Pots - Research Paper Example

? Interspecific and Intraspecific Competition Among Alfalfa in Shaded and Unshaded Pots The objective of this lab was to detect the differences of interspecific and intraspecific competition in the alfalfa plant. This was accomplished by putting alfalfain combinations of 25 seeds, 50 seeds, 25 alfalfa with 25 tomato and 25 alfalfa with 25 rye. These variations were both put in pots that received the light, and ones which did not. The measure of length and weight of the germinated seeds were then recorded and compared. The outcome concluded that the length in the unshaded pots were much higher than those in the shaded, and the most competition in alfalfa was found in the 50 seed pot. Difference in weights however varied with alternating higher values in both shaded and unshaded experiments across the samples. Further, interactions among species are negative since length were longer in pure samples than in mixed samples. Introduction and Background Interactions among species of organisms within resource limited ecosystems leads to competition for the resources. Every species and individual within a species will seek to utilize the available resources for survival. This defines the concept of competition among organisms in an ecosystem that can be explored from two perspectives, intraspecific competition, and interspecific competition. While intraspecific competition occurs among organisms of the same species, interspecific competition occurs among different species. It does not happen at individual level but organisms of the same species acts as a community to gain an advantage over a competing species. Intraspecific competition may be witnessed over resources such as “food, water, breeding sites” among others such as light and shade (Toole, 2004, p. 34). One of the important principles in competition is the exclusion principle. This principle, as established by Gauss, defines the basics of survival for the fittest. It provides that when more than one species are competing for limited resources, the species that can utilize the resources most economically will have an advantage over the other species that may end up being extinguished from the ecosystem. This defines a negative competition as it leads to destruction of some ecosystems’ elements in the extinguished species. If the disadvantaged species fails to find an alternative niche for survival then they face the threat of total extinction from the immediate environment. Competition, however, plays a crucial role in determining the size of organisms in an ecosystem among other positive interactions.This leads to a maintained balance of the population sizes of different species of organisms that can be supported by resources in an ecosystem. This is because the feeding rate will highly depend on the availability of resources that translate to the number of organisms that can be sustained by the available resources (Toole, 2004, p. 34). Abiotic factors in an environment also affect chances of growth and development of individual organisms and entire species of organisms in an ecosystem. Shade, for instance, is identified to enhance chances of survival among plants with respect to predators. This is because organisms under shade enjoy a level of freedom from predators as compared to those that grow in well light areas (Kersch and Fonseca, p. 1). Even though shade enhances survival of plants, there has not been an established competition for shade among the organisms (Zobel, et al, p. 1). This paper seeks to investigate interaction between plants under shade and in light. The paper will apply statistical analysis to investigate existence of intraspecific competition and interspecific competition for shade and without shade within and among species. Experimental Designs and Results The project used primary data in which tomatoes, alpha, and rye were planted both separately and in pairs by species. The alpha species was planted with 25 seeds in one pot, 50 seeds in another, 25 seeds of alpha combined with 25 seeds of rye, as well as 25 seeds of alpha combined with 25 seeds of tomato. This was to get a good indication of both interspecific competition and intraspecific competition. After one set being left in the sun, while the other being left in the shade, measurements for height and weight were taken after two months. Simple random sampling was used. The interactions were positive since shade does not discriminate length and weights of the plants. Inferential statistics for comparison of weights and lengths of different sets of samples under light and shade indicated that measurements obtained in light and under shade are independent. This is due to the low observed p values. Deviations are, however, observed in lengths of 25 T/A vs. 25 T/A.Similarly, significant dependence in weights of plant in light and shade is observed in 25 R/A vs. 25 R/A, and 50 T vs. 50 T. These can be proven in the figures below. It is clear that the length in the light environments is higher than the shaded. When observing weight as a factor, there seems to be more competition. This is concluded from the high result comparison, especially in the 50 seed alfalfa pot. Because there is more significant weight, there must have been a more significant competition. It is also important to consider that of the 50 seeds planted, only 33 grew. Discussion The results indicate a general trend of lack of significant relationship in lengths and weights of plants grown in light and under shade. The three sets that indicate dependence can be disregarded as anomalies because they only form a small percentage of the results. There are however, significant relationships in weights and lengths of sample setunder shade experiments. Experiments done in light did not record significant relationships between sample sets. The observations made from experiments done under shade imply existence of different conditions for the plants. This difference is however absent in experiments done in light as well as paired sets of experiments done in light and under shade, an indication that presence or absence of shade does not primarily affect the lengths and weights of the plants within and among species. The significant difference in set ups under shade therefore implies existence of some other factors, other than light intensity, that affects length and weight of the plants. Conclusion The experiment concludes that there is no significant competition for shade between plants of the same species. Additionally, different species do not compete highly in a shaded environment. The difference in weights and lengths that is observed under shades is therefore attributable to the ability of the different species to adapt to the condition. Similarly, there exists difference in adaptation of plants of the same species that can be explained by presence of other factors such as nature of the seeds planted and infections by pests and diseases as well as measurement errors. Lack of competition, both intraspecific and interspecific, explains the survival of both species in the combined set ups under shade. The experiment also concludes that while plants under shade grows taller than those grown in light, weight is inconsistent between shaded and unshaded experiments. Negative interactions were further noted among species but positive interaction within rye species. There is however no dominance because the plants, based on the resulte are not competing for shade. Literature cited Kersch, Monica, and Fonseca, Carlos. ‘Abiotic factors and the conditional outcome of an ant plant mutualism.’ Ecological Society of America.Vol. 86.Issue 8. 2004. Available from: http://www.esajournals.org/doi/abs/10.1890/04-1916?journalCode=ecol. [Accessed on 28 March 2012] Zobel,Kristjan,et al. "Positive Effect Of Shade On Plant Growth: Amelioration Of Stress Or Active Regulation Of Growth Rate?." Journal Of Ecology. 100.2 (2012): 459-466. Science & Technology Collection.Web. 27 Mar. 2012. Toole, Glenn. Essential A2 Biology for OCR. London, UK: Nelson Thornes, 2004. Read More