Autoavaliação
Em relação ao meu desenvolvimento durante o curso, considero que alcancei todos os objetivos estabelecidos. Identifiquei minhas deficiências conceituais (durante as primeras aulas, particularmente entendendo os mecanismos de replicação, transcrição e tradução) e investi mais tempo do que o programado no curso para melhorar e participar ativamente das discussões em sala de aula. Além disso, considero que compreendi os conceitos e métodos relacionados à evolução molecular abordados no curso, o que me proporcionou uma direção mais clara para o meu projeto, aproveitando as diretrizes introdutórias oferecidas pelo curso.
Em relação às minhas fraquezas, poderia melhorar a otimização e o planejamento do meu plano de estudos.
Considero que minha nota é 9,8.
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Comentários Dan
TExto excelente, com ponto de vista pessoal que traz enorme riqueza ao conteúdo sendo discutido. Eu considero que trazer os aspectos de diversidade social/economica são bastante importantes.
Existem alguns probleminhas com palavras em inglês que não significam exatamente o que a gent epensa que significa, exemplos:
"concretized" - melhor seria algo como "corroborated"
"pretends" - aqui sera "assumes"
De amnaeira geral, argumento muito bem construído, um texto maduro que possivelmente mereça publicação.
Nota - 9.8
**ENSAIO FINAL
Biology Education: Moving Beyond the Natural Selection Paradigm**
Darwin’s theory of Evolution by means of natural selection is one of the most relevant paradigms in biology. The theory proposes the transformation of species over time through natural selection, a mechanism that favors those organisms better adapted to environmental conditions. Thus, adaptation can be understood as the final result that leads a lineage to evolve. This theory is strongly supported by multiple pieces of evidence and due to that, it permeates evolutionary thinking (King & Jukes, 1969).
Evolution was, for a long time, assumed to be the result of selective pressures. The postulates of Darwin’s theory lacked evidence regarding the mechanism to explain descent with modification. The genetic basis to support the theory was understood later with the acceptance of Mendel’s laws (Koonin, 2009). Consequently, the theory as a whole was adopted as the Modern Synthesis and was concretized based on genetic laws. Currently, the development of genetics and the underlying evolution mechanisms occurring at the molecular level are better understood. As a result, the paradigm previously established, supposing natural selection as the unique mechanism of evolution, was broken (Kimura, 1968; King & Jukes, 1969).
The development of evolutionary biology supports with evidence that natural selection is not the single mechanism involved in evolution. Kimura (1968) proposed the Neutral Theory, demonstrating genetic drift as a stochastic mechanism of evolution. Hence, genetic drift configures the genetic structure of populations because selectively neutral mutations appear at higher rates and they are plausible to be fixed rapidly in finite populations (Kimura, 1968). Nevertheless, the conception of the new synthesis, also called Neo-Darwinian theory, pretends that positive natural selection, acting on mutations, is the main evolutionary mechanism regulating allelic frequencies within populations (Kimura, 1991).
The pervasiveness of natural selection in evolutionary thinking reflects the rejection of evidence supporting new revolutionary theories. The traditional thought is focused on explaining classical theories and providing an overview of general discussions given during the construction of new concepts and lines of thought. Consequently, evolution education programs are subject to focusing the curriculums following the same thinking structure, as explained above.
During my formation as a biologist at the Universidad del Atlántico in Colombia, I was directed toward the same teaching structure. The curricular content for the course of evolution was mostly concentrated on teaching Darwin's postulates to explain general evolutionary patterns. The unit's contents encompass a wide range of topics in an introductory course on Evolution (Table 1). Nevertheless, discussions formulated were normally directed around natural selection. Consequently, students are biased to understand whatever pattern showing evolutionary change as a result of adaptive selection.
Table 1. Curriculum Content of the Evolution Course at the Universidad del Atlántico.
I was able to compare my current knowledge of evolution as a postgraduate student with my own argumentation from 2015 when I took my first course in evolution as an undergraduate student. One of our activities was to use a simulator of natural selection, changing the selection strength and mutation rate to observe the behavior of a population in terms of phenotypes across several generations. I got the results shown in Figure 1 using a slow mutation rate (0.2) and no selection strength (0). My interpretation was adaptationist, as I stated: 'Phenotypic frequencies change across generations, but only phenotypes 3 and 4 remain present, probably due to the survival of the fittest.' Clearly, I overlooked the fact that selection was not occurring, and I did not clearly understand what the variation in frequencies along generations meant. I did not consider that they were changing randomly along generations, and other processes could better explain the pattern I was seeing.
Figure 1. Result of the natural selection simulator used during the evolution course in the year 2015. Mutation rate: 0.2 and selection strength: 0.
The fact that most discussions carried out during the course were around morphological examples could be the reason for the bias in my interpretation. The focus of the teacher’s discourse was generally on morphologic traits, probably for practical effects or due to Darwin’s evolutionary theory being constructed based on morphologic evidence. Furthermore, evolutive processes at the molecular scale received less attention during the course, being mostly directed to present the relevance of the discovery of genetic mechanisms to explain those proposals of Darwin's theory. Population genetics is, in my opinion, superficially explained, and the remaining forces implied in evolutionary processes are not well understood.
Selectively neutral traits are implicitly harder to explain because of their non-adaptive nature. In fact, Darwin (1859) recognized some variations not subject to natural selection, since they appear as neither deleterious nor favorable. Darwin (1859) considered these traits as bewildering because they were not fixed by natural selection. However, the main rejection of the Neutral Theory is based on the argument that almost no mutation is neutral (King & Jukes, 1969). Genetic drift was early suggested as a random mechanism leading to the fixation of changes during evolution (Koonin, 2009). Even though when chance was not supported with empirical evidence at the beginning, currently there is enough evidence to change the way in which evolution is taught (see Kimura, 1991).
Shortcomings in understanding molecular evolution and assimilating the role of selectively neutral mutations are not related to the lack of teaching of molecular biology. In my opinion, there exists a general misinterpretation of novel concepts that involve a higher level of complexity, resulting in them being hardly incorporated into introductory courses on evolution. An example in this context is the macroevolution hypothesis proposed by Kimura (1990), which was explained in terms of phenotype (Kimura, 1991). This hypothesis is also called 'the four-stage scenario' and states: A population is liberated from preexisting selective barriers; neutral mutations arise with relaxed selection pressure; potential selection occurs on some neutrally accumulated mutants (at the phenotypic level), turning out to be useful in a new environment; finally, intergroup competition occurs, and individual selection leads to adaptive evolution resulting in a radically different taxonomic group. Under a precarious understanding of neutral theory, probably all the underlying processes involved in evolution could be summarized in a classic adaptationist scenario. Both Neutral theory and Darwin’s theory should be considered as complementary to understanding evolution as a result of multiple processes involving molecular, genetic, and morphologic levels.
On the other hand, the social context where courses are provided could explain the monopoly of adaptationist thought, being this a classic current. The Universidad del Atlántico is located in Barranquilla, Colombia. It was the first university to found a biology program in the Colombian Caribbean region, being established since 1989. It was created in response to the local requirements in aquaculture and zooculture and was linked to the faculty of basic sciences. The main purpose for the creation of a biology program in the Caribbean region was focused on resolving local issues involving economic development. Then, the education level expected would be highly influenced by the market.
In contrast, other biology teaching institutions, such as the Instituto de Biociências in Brazil, specifically the zoology department, were established a longer time ago, in 1934, and it was created as part of a course on Natural History of the Faculty of Philosophy of the University of São Paulo. It is clearly different the purpose of this program since the beginning, which was to understand the natural world. These different approaches lead to having a different meaning for education, with a deeper understanding of sciences. The timeframe within which educational programs can be enhanced and more effectively tailored to current knowledge is also a significant factor in determining the maturity of the knowledge being transmitted.
References
Darwin,C. (1859) On the Origin of Species. Murray, London
Kimura,M. (1968) Evolutionary rate at the molecular level. Nature, 217, 624–626.
King JL, Jukes TH. (1969). Non-Darwinian Evolution. Science 164:788-97.
Kimura, M. (1990) in Population Biology of Genes and Molecules, eds. Takahata, N. & Crow, J. F. (Baifukan, Tokyo), pp. 1-16.
Kimura,M. (1991) Recent development of the neutral theory viewed from the Wrightian tradition of theoretical population genetics. Proc. Natl Acad. Sci. USA, 88, 5969–5973.
Koonin, E. (2009) Darwinian evolution in the light of genomics. Nucleic Acids Research, 37, No. 4: 1011-1034.
Websites:
https://www.ib.usp.br/zoologia/info/historico.html
https://www.uniatlantico.edu.co/pregrado/facultad-de-ciencias-basicas/biologia/generalidades/