Primeiro ensaio (opcional 10/03/2017)
The importance of one simple idea
Crick's (1958) central dogma was a plausible attempt to understand how the mechanisms of transmission and expression of genetic inheritance work. This dogma was as revolutionary as problematic; the fact that this hypothesis was introduced to the scientific community under the term “dogma” caused discomfort and several critics to its postulant, mainly for the contradiction between the true meaning of this word and the scientific method. By definition, a dogma is a belief that cannot and should not be questioned, for some the use of this term was too pretentious and for others outrageous. Crick himself would recognize years later that this was an unfortunate choice of word; to him “dogma” did not mean the same that for the rest of us and decided to use this term in order to avoid the overuse of the word “hypothesis” (which had been used some years before by him when describing his Sequential hypothesis). Furthermore, he also stated that he wanted to suggest that this new conjecture was more central and more powerful but, sadly, the use of the word dogma caused perhaps more problems than it was worth. To my mind, and leaving the semantics aside, this “dogma” accomplished its mission; in 1958 we knew nothing about the processes involved in the replication of the DNA and was precisely this risk and unsupported hypothesis that encouraged several teams of scientists to try to corroborate or refute it. Although over simplistic for some, Crick´s dogma represents the cornerstone and starting point of a long process of understanding the extraordinary machinery wrapped in DNA synthesis which is still ongoing.
Correção Ana Laura (17/03/17)
No início, apresenta bem o que será abordado ao longo do
Tem toda uma contextualização histórica a cerca do problema da palavra "dogma" usada por Crick, que está clara, mas poderia ser apenas um pouco mais objetiva, como por exemplo, estas duas partes "…the fact that this hypothesis was introduced to the scientific community under the term “dogma” caused discomfort and several critics to its postulant, mainly for the contradiction between the true meaning of this word and the scientific method." e "By definition, a dogma is a belief that cannot and should not be questioned, for some the use of this term was too pretentious and for others outrageous" poderiam ser unidas e sintetizadas por que falam basicamente a mesma coisa.
O que parece é que entre quase todo o ensaio e a última sentença há uma quebra de linearidade em relação ao assunto central do texto.
Ensaio 2 (17/03/2017)
When only good taxonomy matters
The taxonomy is suffering deep changes in different hierarchical levels, not only at genus level as species too. These changes are reflected in the disproportionate increase in both species and genera number. Most of the new genera and species (regardless the method used) have been described by researchers that cannot be called taxonomists sensu stricto. In this context, I would like to present one example of how a good taxonomist could present a robust and coherent taxonomic hypothesis. Fooden (1963) based on morphological characters and an extensive set of samples, proposed only two species of woolly monkeys (genus Lagothrix): L. lagothricha and L. flavicauda, the first with four subspecies. In a second revision and with limited sample and scarce phylogenetic evidence, these four subspecies were elevated to full species rank by Groves (2001). Nevertheless, after 50 years, new molecular evidence presented by Ruiz-García et al. (2014) and Di Fiore et al. (2015) corroborated Fooden’s (1963) original proposal. As a conclusion, regardless the methodology, the expertise and the good criteria of the taxonomist would reflect better taxonomic hypothesis.
Di Fiore A., P.B. Chaves, F.M. Cornejo, C.A. Schmitt, S. Shanee, L. Cortés-Ortiz, V. Fagundes, C. Roos and V. Pacheco. 2015. The rise and fall of a genus: Complete mtDNA genomes shed light on the phylogenetic position of yellow-tailed woolly monkeys, Lagothrix flavicauda, and on the evolutionary history of the family Atelidae (Primates: Platyrrhini). Molecular Phylogenetics and Evolution 82B: 495-510.
Fooden, J. 1963. A Revision of the Woolly Monkeys (Genus Lagothrix). Journal of Mammalogy (en inglés) 44 (2): 213-247.
Groves C. 2001. Primate taxonomy. Smithsonian Institution Scholarly Press, Washington DC.
Ruiz-García M., M. Pinedo-Castro and J. M. Shostell. 2014. How many genera and species of woolly monkeys (Atelidae, Platyrrhine, Primates) are there? The first molecular analysis of Lagothrix flavicauda, an endemic Peruvian primate species. Molecular Phylogenetics and Evolution 79: 179-198.
Correção ensaio (17/03/2017)
Eu achei seu texto muito bom, principalmente pelo fato de desenvolver uma opinião pessoal, bem sustentada num caso concreto e focada na discussão da aula. Esse é o dever ser de um ensaio.
Segundo o exposto pelo Daniel na aula (eu não vou repetir), más se complementar:
- A voz passiva, exemplo: … were elevated…
- Poderia ter deixado mais ampla a ideia original, como proposito do seu ensaio. A ideia original eu entendo como a conclusão, mas deveria aparecer na sua frase tópico, no começo do texto. Assim seja uma tão lapidaria quanto: Most of the new genera and species (regardless the method used) have been described by researchers that cannot be called taxonomists sensu stricto. (Isso precisa ter um apoio maior que um único caso só, que é mais uma opinião sobre o caso exposto, eu acho, pelo menos.)
Obrigada pelas suas correções!
Ensaio 3 (24/03/2017)
Darwin and his natural selection idea
Darwin´s (1856) concept of natural selection was a revolutionary idea for most of scientists at his time. Since the publication of the first edition of “On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life”, Darwin stated that he was sure that there were several factors, unknown by him, of speciation. Darwin also declared that natural selection alone would not explain by itself the vast diversity of plants and animals. Perhaps, based on misunderstandings or lack of knowledge, several scientists distorted Darwin’s idea proclaiming natural selection as the unique force of speciation. Kimura (1969) corrected and expanded the vision of the processes involved in evolution. The most important Kimura’s statement was that most of the evolutionary processes are explained by Genetic drift and not by natural selection. This idea changed profoundly our vision of evolution. Furthermore, Kimura’s (1969) agrees with Darwin’s predictive (and perhaps ignored) ideas.
Comments (Caio Gueratto):
My observations regarding the text are expressed below:
Lack of reference in the first sentence. Who says Charles Darwin`s concept was a revolutionary idea?
Lack of reference here as well: " Perhaps, based on misunderstandings or lack of knowledge, several scientists distorted Darwin’s idea proclaiming natural selection as the unique force of speciation." Which scientists?
"The most important Kimura’s statement was that most of the evolutionary processes are explained by Genetic drift and not by natural selection.". It is in passive voice and there is a grammatical issue here. Suggestion of change: kimura's most important statement was that Genetic drift explains most of the evolutionary process instead of natural selection).
Some sentences have breaks and inversions that make them more difficult to undestand than when they are not broken. An example: "…Darwin stated that he was sure that there were several factors, unknown by him, of speciation".
"This idea changed profoundly our vision of evolution." In which way? Expand a little bit more your ideas.
"Furthermore, Kimura’s (1969) agrees with Darwin’s predictive (and perhaps ignored) ideas." Which ones and how does Kimura agree? Expand a little bit more your ideas.
Ensaio 4 (31/03/2017)
Effective population size and its relation with taxonomy
The number of mammal species has rapidly increased in the last two decade. In particular, primate species are the target of a taxonomic inflation (Mace 2004). Every year new species (and genera) of primates are described. Some of these species are the result of arbitrary elevation of subspecies to the full species rank and others of molecular phylogenies that have become more common in these days. In the latter case, the main criterion for splitting species is the time of divergence between taxa. As pointed out in class, this criterion can be (and it is) used for organisms as bacteria and virus in which the Effective population size (Ne) may be calculated. I do not recall any case when the Ne had been calculated for primates. Therefore, the practice of splitting primate species (and even genera) under this criterion is harmful for taxonomy because creates a great ambiguity. For some authors 70% of divergence between two taxa should be enough for others do not. We must understand that genomics are a good complement for other methods but should not be taken as the holy grail of current taxonomy.