NEW TRENDS IN TAXONOMY.pptx

1) CHEMOTAXONOMY
2) SEROTAXONOMY
3) CYTOTAXONOMY

1. Newer Trends In Systematics RISHAD K A I MSc APPLIED ZOOLOGY Department of Zoology University of Calicut

2. 1) CHEMOTAXONOMY 2) SEROTAXONOMY 3) CYTOTAXONOMY 4) NUMERICAL TAXONOMY 5) CLADISTICS 6) MOLECULAR SYSTEMATICS

3. SEROTAXONOMY # Also known as Immunotaxonomy # Basic Principle : Organisms which are closely related would have similar proteins #Serology- Study of serum and other body fluids

4. # Use immunological principles / techniques in systematics # Comparing immunological differences between various species # Help in working out phylogenetic relationship among various species through comparison of their proteins

5. EXPERIMENT 1) Collect human serum 2) Inject human serum in to rabbit Rabbit produces antibodies against human serum

6. 3) Collect rabbit serum containing antibodies 4) Antibodies containing serum of rabbit mixed with human serum Rabbit serum with antibodies + Human serum = Formation of precipitate ( CASE A )

7. 5) Rabbit serum containing antibodies mixed with Chimpanzee serum Precipitate almost as much as in Case A

8. 6) Rabbit serum containing antibodies mixed with Baboon serum Approximately half as much precipitate as case A

9. 7) Rabbit serum containing antibodies mixed with Dog serum No precipitate

10. The degree of precipitation of antigen-antibody reaction indicates the degree of relationship # Complete absence of precipitate indicates wide difference in the relationship of the organisms

11. ‘Homologous' or ‘Reference reaction‘ The precipitation is total when it is between the antibodies and specific antigen that originally stimulated their formation. This total antigen-antibody reaction is called 'homologous' or 'reference reaction'. {EXPT No : 4&5}

12. ‘Heterologous' or 'cross reaction‘ When the precipitation occurs but to a lesser extent i.e., the antigen is chemically different from but related to the original one which stimulated the antibody production then such a reaction is said to be a ‘Heterologous' or 'cross reaction‘ {EXPT No : 6&7}

13. The more closely related animals are to one another, the greater will be the similarity in their chemical makeup and consequently also in any antigen derived from them. This is the 'Law of Proportionality' on which immunotaxonomy or serotaxonomy is based.

14. From a practical taxonomic point of view, what is important is that the more amino acid replacements that occur in proteins as two taxa diverge, the fewer antigenic determinants (Epitope) they will have in common. Epitope : Specific piece of the antigen to which an antibody binds

15. The comparative precipitate reaction in immunotaxonomy of animals are usually studied by the techniques like immunoelectrophoresis # The antigen used for stimulating antibody production may be egg proteins, serum proteins, eye lens proteins etc

16. CYTOTAXONOMY Also known as Chromosomal Taxonomy/Karyological approach in taxonomy # Deals with all the aspects of taxonomy at a cellular level. #This includes, the structural, genetical and biochemical aspects and is used to compare genetic affinity between organisms

17. #The basic principle of Cytotaxonomy is that closely related species share a more similar karyotype than less related ones   # Chromosome numbers and nuclear DNA content are among the most reliable and practical characters for cytotaxonomical analyses

18. The interpretation, characterization and identification of a cell's complete chromosome set is referred to as karyotyping and is the first stage in the process of using chromosomal characters for systematics.

19. Karyotypic information effectively forms an independent data set for phylogenetic analysis and has probably been most useful in the investigation of groups of closely related and morphologically similar organisms

20. Difficulties in Karyotyping? For many organisms karyotyping is relatively easy if an appropriate protocol is followed, however, in some groups the presence of large numbers of small chromosomes or of generally very small cells can make this a more complicated process. For example, most birds have a small number of normal sized chromosomes but also have a large number of micro-chromosomes which may be extremely difficult to count.

21. # Karyotypes within interbreeding populations of a species are usually remarkably constant. # The degree of variation in chromosome No between closely related species is subject to great variation. # In some groups even closely related species can be widely dissimilar in their chromosome No E.g. : Ant genus Myrmecia in which n (Haploid chromosome No) ranges from 1 to 42

22. # In some cases related ones have almost same chromosome No. E.g. : Lepidoptera(Butterflies& Moths) and the Trichoptera (Caddis flies),which diverged from one another at least 65 million year ago, the commonest chromosome number is approximately the same (n = 30 or 31).

23. # Chromosome No alone is typically a poor indicator of phylogeny # In order to use chromosome No more meaningfully, It is necessary to able to identify individual chromosomes and analyze the following features(The main criteria used in cytotaxonomy) 1)Identify polytene chromosomes 2) Analyze the differences in the densities of Euchromatin and heterochromatin 3) Differences in the relative amounts of A-T & C-G 4) Calculate Intra chromosomal asymmetry index (Ai) (Zarco, 1986) 5) Chiasma frequency 6) Chromosome banding 7)Number and size of satellites and secondary constrictions

24. In some cases no morphological difference can be found between individuals with widely different chromosome numbers (e.g. the bedstraw, Galium aparine includes individuals with 2n = 22, 44, 66 and 88).

25. where bi and Bi are the lengths of the shortest and longest arms of the n chromosomes in the karyotype. This index is framed so as to be close to zero if all the chromosomes are metacentric and near one if all are telocentric.

26. some are dominated by metacentrics others have high proportions of acrocentrics and/or telocentrics .Such differences are often apparent even between quite closely related taxa such as species within a genus or genera within a tribe.

27. CHEMOTAXONOMY # Also known as Biochemical systematics / Biochemical approach in taxonomy

28. Used increasingly in the systematics of animals, both for identification of organisms as well as for working out interrelationships between them . # sometimes it becomes impossible to distinguish between similar organisms ,In such cases identification may be possible by comparing the chemical substances of the organisms.

29. The compounds studied in most of the cases are proteins, amino acids and peptides. As a result biochemical studies in the taxonomy are often referred to as 'protein taxonomy' .

30. Biochemical studies ,such as enzymology,pheromology,histochemisty,etc are very important in taxonomy # These studies are least influenced by environmental factors. proteins are more closely controlled by genes and less subjected to natural selection than the anatomical features. #Biochemical taxonomy mainly involves the comparison and contrasting of the biomolecules of different kinds of organisms to reveal their genetic similarity or divergence

31. Nitrogenous Excretory Products Ammonia -characteristics of aquatic life form urea -land and water dwellers uric acid-terrestrial life forms A frog, in its tadpole stage excretes ammonia just like a fish. When it turns into an adult frog and moves to land, it excretes urea instead of ammonia. Thus an aquatic ancestry to land animal is established.

32. A chick on up to its fifth day of development excretes  ammonia ; from its 5th to 9th day ,  urea ; and thereafter, uric acid. # Based on these findings, Baldwin sought a biochemical recapitulation in the development of vertebrates with reference to nitrogenous excretory products.

33. End products of digestion Irrespective of the type of animal, the end products of protein, carbohydrates and fats are amino acids, simple sugars, and fatty acids respectively. It can thus be comfortably concluded that the similarity of the end products is due to common ancestry.

34. Digestive enzymes   Proteins are always digested by a particular type of enzymes like pepsin, trypsin, etc., in all animals from a single celled amoeba to a human being. The complexity in the composition of these enzymes increases from lower to higher organisms but are fundamentally the same. Likewise, carbohydrates are always digested by amylase, and fats by lipase.

35. CHEMOTAXONOMY IN PLANTS It is widely used in cases of plants. Chemotaxonomy is considered to be a better way of differentiation of plants and also understand the relationships between plants The plants can be linked on the basis of primary and secondary metabolites.

36. Examples of chemotaxonomy are: 1) Volatile oils are found in the family Umbelliferae and family Rutaceae. 2) Tropane alkaloids are found in the family Solanaceae. 3) Steroidal alkaloids occur in the family Buxaceae. 4) Diterpenoids are found in the family Euphorbiaceae. 5) Cardiac glycosides are found in the family Asclepiadaceae and family Apocynaceae.

37. Gram staining & Chemotaxonomy method of staining used to classify bacterial species into two large groups:  Gram-positive bacteria and Gram-negative bacteria # Gram staining differentiates bacteria by the chemical and physical properties of their cell walls. # Gram-positive cells have a thick layer of peptidoglycan in the cell wall that retains the primary stain, crystal violet. # Gram-negative cells have a thinner peptidoglycan layer that allows the crystal violet to wash out .They are stained pink or red by the counterstain commonly safranin

38. NUMERICAL TAXONOMY - Also called Numerical phenetics OR simply phenetics - Based on the assessment of the similarities and differences of organisms using mathematical procedures

39. # Since numerical taxonomy is mainly based on the principles propounded by Adanson (1727-1806) it is often called Neo-Adansonian principle. # Various other terms such as ' Taxonometrics ', ' Taxonometry ', ' Taximetry ' and ' Taxemetrics ' are also used for numerical taxonomy. + Also called Mathematical Taxonomy

40. - Phenetics is the classification of organisms based entirely on observed phenotypic similarities and differences, without considering whether the similarities are due to evolutionary relation and common ancestry # Not reflect evolutionary descent (Drawback)

41. + Phenetics takes into account as many comparable characters as possible, and then applies complex computer techniques to determine which groups are most alike and which ones are most different from each other + All characters have equal weightage in assessing the overall degree of similarity

42. Operational taxonomic units (OTUs)

43. # The use of computers in numerical taxonomy has made it possible to compare a large number of characters from many organisms with relative ease. After comparisons of the organisms they are grouped according to overall similarity or dissimilarity and wherever necessary presented graphically.