BIO153 –Assignment 2
1- The two hypotheses displayed in the given literary piece belong to the two lineages including Porifera and Cnetophora. Cnetophora is assumed a sister group to all other animals and the second argument states opposite of this claim supporting the Porifera-sister tree approach.
i) First hypothesis: Advanced physiology including muscles, epithelia and nerves evolved independently in the two separate lineages of animals (in the antecedents of Cnidaria and Bilateria and phylum Ctenophora).
ii) Second hypothesis: Ctenophora is abstractedly linked to phylum Bilateria and Cnidaria instead of similar characteristics.
The first hypothesis is a supportive hypothesis of conventional Cnetophore sister tree which is mainly accepted by the experts. The Ctenophora-sister tree approach claims Cnetophora a rapidly evolving phylum. The second theory altered the whole scene claiming that Cnetophora, an advanced level phylum is more close to simple Porifera, instead of its high similarity with other lineages. This novel hypothesis opened doors to new controversies, and most of the experts called it an error of using scarce phylogenetic models. According to the experts, the taxa between the series would have lost several features in the course of progression that caused a scarcity of information about intermediates on a long branch (Telford, Moroz and Halanych 286-287.
2-
First Hypothesis
Second Hypothesis
The paragraph is taken from a secondary source (Guides.library.utoronto.ca).
Based on the information on the given link there are multiple criteria assigned to a secondary source. The given section fulfilled several points that verified its source as a secondary source. It cannot be a primary source because the paragraph neither contained any new result which has appeared first time in literature nor was any new experiment conducted by the author. The article contains the information that is previously described by others and compiled by the author in this segment. In the given paragraphs, the author has interpreted and analyzed the primary source of knowledge and on the basis of that concluded his writings and hypotheses. It belongs to a review article (Guides.library.utoronto.ca).
“The Ctenophora-sister trees are an artefact.”
The provided literature piece belongs to an article review that presented the original information of phylogenetically linked lineages and controversies raised by their connections.
In the last paragraph, the author discussed the possible error that would have occurred during the phylogenetic analysis which resulted in the novel hypothesis of Porifera sister tree. This newly proposed theory had been very controversial. Citing others works such as “Pisani et al.” author provided a support from literature to his earlier sentence. The author connected this paragraph to the previous sections very well. In the last paragraphs, the links of Porifera and Ctenophore are suggested closer while it was physically hard to believe because Cnetophora is more close to other animals due to their developed physiological features. In the present paragraph, the author has described the reason for that misunderstanding and provided the evidence of new research conducted by others to support his argument.
The sentences of last paragraphs are interrelated discussing the available data in the literature on the topic. The more authentic relevance was the discussion of a reanalysis of 23,000 genes of various species to reconsider the given hypothesis. Author has explained the whole concept in only three sentences, where each sentence has its significance. The author concluded the paragraph with saying Cnetophora sister trees as an artifact that summarizes the whole piece of literature in one line.
Works Cited
Guides.library.utoronto.ca,. "Primary, Secondary, Tertiary - BIO153: Diversity Of Organisms –
Research Guides At University Of Toronto". N.p., 2016. Web. 19 Feb. 2016.
Telford, Maximilian J., Leonid L. Moroz, and Kenneth M. Halanych. "Evolution: A sisterly
dispute." Nature 529.7586 (2016): 286-287.
