Environmental Science IP 1 Essay Example | Topics and Well Written Essays - 500 words

Environmental Science IP 1 - Essay Example One of the classical examples of this type of the ecosystem is the Amazon basin of South America. It has four distinctive layers; firstly it has forest floor. This is the bottom strata or layer that is highly obscured from receiving sunlight. Only plants that are adapted to low temperatures can survive here. Besides the layer of plants, it has a decaying plant and animal matter. Notably, the rate of decaying is high because of the humid and warm conditions. The second layer is made up of understory layer; this is found between the forest floor and canopy layers. Small animals and birds find suitable habitat within it because it consists of shade-tolerant shrubs, large woody vines, and herbs. Up to 5% of the sunlight reaches this zone (Lewis, 2009). Canopy layer makes the primary area of this ecosystem. It has largest trees of 35-45 meters high which are broad-leafed and dominant. It has the highly dense flora including the epiphytes, bromeliads, mosses and lichen. Most of these epiphytic plants are attached to the branches and trunks of trees.it has diverse fauna, then the emergent layer. Besides the majority of avian species including the spider monkey, hornbill, African parrot among others are found within this layer. Lastly, the emergent layer forms the last part of this ecosystem. Unlike the canopy, this region is made up of a small number of huge trees that reaches above 45-55 meters. Hence, this part rise just above the canopy layer. Tropical rainforest is often dynamic, their structure keeping changing. Like other ecosystems, both biotic and abiotic factors affects its existence. Biotic factors include organism that ensures decomposition of the animal and plants. These fungi, bacteria, and other microscopic organisms help to provide balanced carbon cycle. Also, autotrophs and consumers such as heterotrophs such as antelope and gazelles feed on plants and herbs and thus their lives are dependent on producers. Abiotic

Tracing Genetic Ancestry in Humans Research Paper

Tracing Genetic Ancestry in Humans - Research Paper Example Before the advent of molecular technology, ancestral lineage is based on the recollection of and stories passed by the oldest living family member to the younger family members. People born from the same continent also have some attachment, as it seems logical to think they could have come from the same ancestors because of the proximity of their parents with one another. Now, DNA analysis becomes a way of objectively verifying those theories. By comparing the nucleotide sequences of samples against a sequence database from more than 75, 000 indigenous and traditional populations from all over the world, (Biological and Environmental Research Information System, 2010), DNA sequence unique to people from a certain continent, country, town, village or family may be identified (Rotimi, 2003). These populations are each composed of people living within a particular region for several generations and maintaining the same culture (Biological and Environmental Research Information System, 2 010). Anyone who would like to determine his or her group of origin can thus look for these unique sequences in his or her own genome. An example of a population seeking to define their ancestral origin and the populations that have the same ancestors is African-Americans. Certainly, the parallelism in their experiences with slavery and obvious similarities in appearance motivate the effort of linking African-Americans with modern-day Africans. The results of many DNA studies suggest that the common female (140, 000 years old) and male (60, 000 years old) ancestors of modern humans are from Africa. Migration started 65, 000 years ago, when they populated southern Asia, China, Java and Europe (Biological and Environmental Research Information System, 2010). Such movement has caused a modern human population, such as African-American, to be genetically-diverse. For example, African-Americans can have a European Y-chromosome because of the historical admixture of African farming employ ees to European plantation owners (www.rootsforreal.com). As well, in a study of scientists from the University of Pennsylvania and Cornell University analyzing the genetic make-up of 365 African-Americans, 203 people from 12 West African populations, and 400 Europeans from 42 countries, it was found that African-Americans had as little as 1% and as much as 99% West African ancestry. The genetic sequences implicating West African origin was also found to be similar to those of Igbo and Yoruba from Nigeria and Bantu-speaking populations in Western Africa. In addition, their median proportion of European ancestry is 18.5%. Specifically, mitochondrial DNA (mtDNA) origin (mothers) were mostly African, while the Y chromosome (fathers) were African or European (http://www.physorg.com/news180632039.html, 2010). Which tools can be used to determine such ancestral connections? Let us start with the most superficial. If an individual would like to verify connections between him or her and an alleged relative, he or she can request for a DNA fingerprinting test. Using certain sequences at 16 chromosomes, the possibility of a blood relationship is calculated (www.rootsforreal.com). As mentioned earlier, matching mtDNA and/or Y-chromosome with the database of samples from different populations can be done to determine ancestral roots. These