ukázat omezení vztáhnout sebraná data k tomu, co je o předmětu již známo Diskuse je svým způsobem dialogem s úvodem práce spekulovat

Transcription

1 ? DISKUSE?

2 Tomáš Herben Je skoro nejdůležitější částí práce. Její smysl je dvojí: (i) ukázat omezení, za nichž byla získána data v práci (v čem by daný pokus mohl být lepší, a v čem naopak předčí pokusy publikované dříve; jak moc vadí, že třeba jsou jen z malého území, či několika málo let, nebo že ve skleníku při pokusu bylo možná trochu horko, a to nejen badateli), a (ii) vztáhnout sebraná data k tomu, co je o předmětu již známo, porovnat je s navazujícími údaji v literatuře a tak vlastně ukázat, jaký význam má to podivné, co se objevilo. V ní autor ukazuje, že nejen nějaká data sebral, ale cosi si o nich myslí a dokáže je vztáhnout k tomu o předmětu již známému. Nešvar je samozřejmě lineární řazení analogických výsledků jiných autorů bez komentáře a srovnání; takovou informaci každý dokáže vytáhnout z dobré databáze. Diskuse může být rozmanitým způsobem členěna; DP typicky mívá dílčí diskusi metodiky a výsledků, kde se probírají hlavně omezení a případně nedostatky a výhody zvoleného sběru dat (zejména pokud má práce několik spolu volně souvisejících částí), a celkovou diskusi, která naopak dává jednotlivá dílčí zjištění jednotlivých částí práce dohromady a činí interpretaci sebraných dat, a srovnává je se známými fakty. Diskuse je svým způsobem dialogem s úvodem práce: měla by se vrátit ke všem hlavním otázkám a kontextům v úvodu položeným a ukázat, jak se mění ve světle zjištěných faktů a jak zjištěná fakta na ony otázky odpovídají. Diskuse je take částí, kde si autor může (ba přímo má) dovolit o předmětu spekulovat, naznačit, jaký další postup při jeho zkoumání se mohl volit, co širšího mohou výsledky naznačovat a podobně. Je to svým způsobem nejvolnější část práce.

3 The purpose of the Discussion is to state your interpretations and opinions, explain the implications of your findings, and make suggestions for future research. Its main function is to answer the questions posed in the Introduction, explain how the results support the answers and, how the answers fit in with existing knowledge on the topic. The Discussion is considered the heart of the paper and usually requires several writing attempts. 1. Organize the Discussion from the specific to the general: your findings to the literature, to theory, to practice. 2. Begin by re-stating the hypothesis you were testing and answering the questions posed in the introduction. Support the answers with the results. 3. Describe the patterns, principles, and relationships shown by each major finding/result and put them in perspective. The sequencing of providing this information is important; first state the answer, then the relevant results, then cite the work of others. 4. Discuss and evaluate conflicting explanations of the results. 5. Identify potential limitations and weaknesses 6. Summarize the principal implications of the findings, regardless of statistical significance. 7. Provide recommendations (no more than two) for further research. 8. Explain how the results and conclusions of this study are important and how they influence our knowledge or understanding of the problem being examined.

4 Most important, always write the discussion for the reader; the discussion is not a forum for you to impress others with your knowledge of the subject. You should be trying to convince the reader of the merits of the study results. No one has thought as long and as hard about your study as you have. As the person who conceived, designed, and conducted the study, the meaning of the results and their importance seem obvious to you. However, they might not be so clear for the person reading your paper for the first time. One of the purposes of the discussion is to explain the meaning of the findings and why they are important, without appearing arrogant, condescending, or patronizing. How to Write an Effective Discussion Do not use the discussion section to criticize other studies. Although you should contrast your findings to other published studies, this should be done professionally. Do not use the discussion to attack other investigators. The discussion should begin with a statement of the major findings of the study. This should be the very first paragraph in the discussion.

5 Discussion and verbiage The Discussion is harder to define than other sections. Thus, it is usually the hardest section to write. Many paper are rejected by journal editors because of a faulty Discussion, even though the data of the paper might be both valid and interesting. Many, if not most, Discussion sections are too long and verbose.

6 Components of the discussion - 1 Try to present the principles, relationship, and generalization shown by the Results. And bear in mind, in a good Discussion, you discuss---you do not recapitulate---the Results. Show how your results and interpretations agree (or contrast) with previously published work.

7 Factual Relationships In simple terms, the primary purpose of the Discussion is to show the relationships among observed facts.

8 Significance of the paper The Discussion should end with a short summary or conclusion regarding the significance of the work. Anderson and Thistle (1947) said it: Finally, good writing, like good music, has a fitting climax. Many a paper loses much of its effect because the clear stream of the discussion ends in a swampy delta. In other words of T. S. Eliot, Many scientific paper end Not with a bang but a whimper

9 Defining scientific truth Exhibit your little piece of mirror, or shine a spotlight on one area of the truth. The simplest statements evoke the most wisdom; verbose language and fancy technical words are used to convey shallow thought.

10 Příkladová studie...

11 Příkladová studie... Results Analysis of molecular diversity A total of 32 strains were isolated from the polar regions, including 26 Arctic and 6 Antarctic strains. The overall diversity was relatively low in comparison to the genetic diversity identified in the temperate zone (Rindi et al. 2011; Škaloud and Rindi 2013; Ryšánek et al. 2015). In general, our molecular investigations revealed the presence of 8 genotypes belonging to four distinct Klebsormidium lineages (Fig. 1), identified as clades B, E1, E2 and E4 sensu Rindi et al. (2011). The great majority of strains (77%) were inferred within clade B... Population differentiation of the superclade B strains To evaluate the intercontinental dispersal capabilities of the polar Klebsormidium strains, we conducted a population-level investigation of all available strains belonging to superclade B, including 21 Arctic, 4 Antarctic, and 26 temperate strains. Two highly variable, plastidencoded spacers were used, including the 691 bp long spacer atpe-trnm, and the 698 bp long spacer ndhk-ndhc. Analyses of DNA variation in both sequenced spacers showed...

12 Příkladová studie... Discussion Diversity and abundance In our study we found very low genetic diversity of the genus Klebsormidium in Polar Regions, by molecular analysis of 31 strains we observed only 8 genotypes in two superclades B and E, which include clade E1, E2, and E4 according Rindi et al. (2011). In this study Rindi et al. (2011) analysed 75 Klebsormidium strains contain also Interfilum and observed seven main superclades (A-G), which included sixteen well-supported clades. In comparison with this study we found very low diversity which is known today mainly from temperate zone. In contrast to temperate zone the genetic diversity Population structure of clade B and distribution Most of the strains from Polar Regions used in study were in superclade B and members of this superclade are found around the world, but mainly from temperate zone where had cosmopolitan distribution. Consequently we evaluated population structure of this superclade to determine whether the difference between strains from polar regions and North Temperate Zone. For this purpose we used spacers between genes in chloroplast DNA, which are also used for population studies in high plants (Doorduin et al. 2011, Hollingsworth et al. 2011). Both molecular markers show that there is...

13 Discussion Příkladová studie... Diversity and abundance In our study we found very low genetic diversity of the genus Klebsormidium in Polar Regions, by molecular analysis of 31 strains we observed only 8 genotypes in two superclades B and E, which include clade E1, E2, and E4 according Rindi et al. (2011). In this study Rindi et al. (2011) analysed 75 Klebsormidium strains contain also Interfilum and observed seven main superclades (A-G), which included sixteen well-supported clades. In comparison with this study we found very low diversity which is known today mainly from temperate zone. In contrast to temperate zone the genetic diversity Diversity and abundance in polar regions The genus Klebsormidium is one of the most abundant micro-autotrophs in various terrestrial and aerophytic habitats (citace). In fact, species of this genus are regularly listed as among the most abundant organisms found during diversity assessments of various habitat types worldwide (e.g., citace). Indeed, the recently published investigation of the Klebsormidium phylogeographic structure revealed its ubiquitous distribution on a global scale (Ryšánek et al. 2015). All the above-mentioned studies thus imply the high global dispersal and comparable diversity estimates of the genus Klebsormidium through the various regions. However, our investigation of newly isolated Klebsormidium strains revealed a conspicuously low genetic diversity in the polar regions as compared to the recently published DNA-based diversity assessments. Based on the molecular investigations...

14 Discussion Příkladová studie... Population structure of clade B and distribution Most of the strains from Polar Regions used in study were in superclade B and members of this superclade are found around the world, but mainly from temperate zone where had cosmopolitan distribution. Consequently we evaluated population structure of this superclade to determine whether the difference between strains from polar regions and North Temperate Zone. For this purpose we used spacers between genes in chloroplast DNA, which are also used for population studies in high plants (Doorduin et al. 2011, Hollingsworth et al. 2011). Both molecular markers show that there is... Understanding the dispersal capacities Considering its cosmopolitan distribution and predominance in the polar regions, superclade B represents an ideal model for testing the dispersal capabilities of microorganisms on a global scale. To differentiate the particular populations, we sequenced highly variable spacers between the chloroplast genes, a method frequently used in population structure assessment of higher plants (Doorduin et al. 2011; Hollingsworth et al. 2011). The most common haplotypes were shared across the arctic and temperate regions, indicating intensive gene flow and global dispersal. Seemingly, the intensive gene flow at a global scale may prevent adaptation of populations to the local environment (Kawecki and Ebert 2004; Whitaker 2006). However, our knowledge about local adaptation mechanisms of protists is severely limited and needs further investigations (Weisse 2008; Weisse et al. 2011; Rengefors et al. 2015).