Taxonomy(Introduction,levels of taxonomy, scientific naming, nomenclatural types, taxonomic categories, biological species concept, modes of speciation, rankless system of phylogenetic systematics).pptx

This PPT includes,
Introduction
Levels of taxonomy
Nomenclature
Scientific naming
Nomenclature types
Classification
Taxonomic categories
Biological species concept
Morphological species concept
Evolutionary species concept
Modes of speciation
Rankless system of phylogenetic systematics

1. Taxonomy Introduction Levels of taxonomy Nomenclature Scientific naming Nomenclature types Classification Taxonomic categories Biological species concept Morphological species concept Evolutionary species concept Modes of speciation Rankless system of phylogenetic systematics

2. Introduction Taxonomy (Arrangement by the rules) Branch of biology that deals with, Identification (placement of a new organism into a previously described group) Nomenclature (the naming of organisms) Classification (ordering or organisms into groups- can be phenetic or phylogenetic) of organisms Systematics Process of organizing taxonomic information about organisms into a logical classification that provides the framework for all comparative studies Scientific study of biological diversity and its evolutionary history Systematics + taxonomy= systematic biology

3. Aristotle (Greek Philosopher) 1 st classification of organisms-2000 Years ago Classification of organisms as Plants and Animals Carolus Linnaeus ( Swedish Naturalist) Modern biological classification- 18 th century Simple system of classification Classification+ Naming Hierarchy concept (A ranking system)

4. Who is going to give name to us ? We are tiny creatures. will they name us ? We are separate green groups. We provide food to you all. We need to be named first !! We are aerial creatures. We are different from you guys. We should be named unique

5. Formal naming of particular organism according to some standard system Organisms = must have only one scientific name (many vernacular names are observed based on the regions) Criteria for scientific naming of Plants, Algae and Fungi are based on Rules and Recommendations of International Code of Nomenclature (ICN) Formerly called ICBN- International Code of Botanical Nomenclature Similarly ICZN for naming of animals- International Code of Zoological Nomenclature Nomenclature You are invited to our naming ceremony It has been arranged by ICZN Hello everyone !!! ICBN are naming us. You are all invited to our naming ceremony !!

6. The Madrid code is the 2025 Edition of the International Code of Nomenclature for Algae, Fungi and Plants (ICNafp) which sets the rules for the scientific naming of these organisms It is based on decisions from the 20 th International Botanical Congress Held in Madrid in July 2024 It is the successor to the Shenzhen Code Includes changes like provisions for rejecting new names considered derogatory to groups of people.

7. Scientific naming Scientific names of species= Binomials (2 names) Carolus Linnaeus- Father of Modern Taxonomy Proposed system of binomial nomenclature (or binary nomenclature) According to binomial nomenclature, 1 st name- Genus Name (Generic Name) 2 nd name- Species name/ Specific epithet (Specific name – term only used in Zoology) Genus name- starts with CAPITAL LETTER Specific epithet- starts with small letter Names of Binomial- italicized / underlined (indicates their Latin Origin) Mangifera indica Scientific name of Mango = Binomial Genus name Specific epithet

8. Nomenclature types Scientific names must be associated with some physical entity- known as nomenclatural type/ simple type One particular specimen of an organism to which the scientific name of that organism is formally attached Types are usually physical specimens that are kept in a museum/ herbarium research collection, but it may also be an illustration Holotype Neotype Syntype Paratype Lectotype Topotype Epitype

9. Classification Arrangement of taxa into some type of order Purpose : To provide a system for cataloguing and expressing relationships between taxa Not a single step process but involves hierarchy of steps in which each step represents a category termed Rank Rarely the term taxonomic category is used instead of rank Taxon is defined as group of organisms typically treated at a given rank

10. Biological species concept Ernst Mayr (1942) Explains why members of species resemble one another and differ from other species Species- groups of actually / potentially interbreeding natural populations, which are reproductively isolated from other such groups These populations are reproductively isolated means- members of species do not interbreed with members of other species Recognition of biological species: Interbreeding among populations of same species Reproductive isolation between populations of different species If two populations- capable of exchanging genes freely either under natural/ artificial condition- said to be conspecific (belong to same species) If two populations- not capable of exchanging genes freely and reproductively isolated –are specifically distinct

11. Two species: Morphologically similar Difficult to distinguish But are nevertheless reproductively isolated Source: Peter Stiling (2012), Ecology- global insights and investigations, Mc GrawHill Publications, Page no. 51 When two organisms breed within a species, Their genes pass into their offsprings As process is repeated= genes of different organisms are constantly shuffled around the species gene pool The shared gene pool gives the species its identity By contrast- genes are not transferred to other species Different species therefore take on different appearance Sibling species (Cryptic species )

12. Advantages of this concept: It is objective, same criterion used for all groups of plants It has scientific basis as the populations showing reproductive isolation do not intermix and morphological differences are maintained even if the species grow in same area Concept – Based on analysis of features and does not need experience to put in into practice Source: https://www.researchgate.net/figure/The-flowers-of-Dendrobium-species-photographed-at-the-medicinal-and-ornamental-plant_fig1_248076912 Image showing various Dendrobium species

13. Morphological species concept Also called Typological concept Was primarily followed by early taxonomists like, Carolus Linnaeus based on the work of Plato and Aristotle Useful for general taxonomic purposes especially in the field and herbarium (identification of plants) Concept is very widely applied and most species have been recognized using this concept Used in easily observing morphological and geographical features of populations Can be applied for cryptic form as well Greater majority of species recognized through this concept corresponds to those established after experimental confirmation Drawbacks : Highly subjective and different sets of characters are used in different group of plants Requires much experience to practice Concept does not take into account the genetic relationship between plants

14. Source: Raven Johnson, Biology, 10 th Edition, Page no. 460, 468 Image showing ExampleS for Morphological species concept

15. Evolutionary species concept George Gaylord Simpson(1961) Megalitsch (1954), Wiley (1978) An evolutionary species is a single lineage of ancestor-descendant populations which maintains its identity from other such lineages and which has its own evolutionary tendencies and historical fate Lineage- single series of demes (populations) that share common history of descent, not shared by other demes Identity of species- based on recognition systems In sexually reproducing species, system- include recognition because of phenotypic, behavioral and biochemical differences In asexual species, phenotypic and genotypic differences maintain identity of species

16. Source: https://en.wikipedia.org/wiki/Evolution_of_the_horse#/media/File:Horseevolution.svg Example-1 fossil record of horse lineage (Equus)

17. Source: https://www.researchgate.net/figure/A-rooted-phylogenetic-tree-of-Bacteria-computed-from-representative-proteins As_fig5_7815051 Example-2 Rooted Phylogenetic tree of bacteria

18. Source: Raven Johnson, Biology, 10 th Edition, Page no. 656 Example-3 Cladogram showing morphological data for group of 7 vertebrates

19. Source: https://humanorigins.si.edu/evidence/genetics Example-4 Lineage of Humans

20. Grant (1981) recognized micro species Micro species: populations of predominantly uniparental plant groups which are themselves uniform and are slightly differentiated morphologically from one another Micro species v/s cryptic species: Morphologically similar but cytologically/ physiologically different Stace (1989)- used semi-cryptic species Ex. Micro species: Erophila verna (single biotype/ groups of similar biotypes, some of which are marked by one or two characters Clonal micro species: reproducing by vegetative propagation Ex. Phragmites Agamospermous micro species: reproducing by agamospermy. Ex. Rosa canica Autogamous micro species: predominantly Autogamous, chromosomally homozygous. Ex. Erophila Erophila verna Phragmites Rosa canica

21. Source: https://www.vc77botany.org/erophila-verna-common-whitlowgrass

22. Biological species concept (Ernst Mayr, 1942) Species are groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups Evolutionary species concept George Gaylord Simpson(1961) A species is a single lineage (an ancestor- descendent sequence) of populations or organisms that maintains an identity separate from other such lineages and which has its own evolutionary tendencies and historical fate Morphological species concept Carolus Linnaeus based on the work of Plato and Aristotle Defines species as a group of organisms that share a common set of observable physical characteristics or morphological traits

23. Generalized model of Process of speciation Stage I- The onset of speciation Gene flow interrupted between 2 populations of the same species Absence of gene flow = 2 populations become genetically differentiated, adapt to different local conditions or to different ways of life (also caused by Reproductive isolation mechanisms especially Post zygotic reproductive isolation) Stage II-Completion of Reproductive isolations 2 outcomes are possible: A single gene pool comes about, because the loss of fitness in the hybrids is not very great ( through ecological competition) 2 species ultimately arise, because natural selection favors the development of reproductive isolation Source: Francisco J Ayala, James W Valentine, The Benjamin Cummings Publishing company, Evolving- The theory and processes of organic evolution, Page no.204-206

24. Source: Peter Stiling (2012), Ecology- global insights and investigations, Mc GrawHill Publications, Page no. 54

25. Flies used the Hawthorn fruits to reproduce and to lay their eggs Introduction of apple trees provided more nutritious food source for developing maggots as well as an escape from parasitic wasps Shift of host plant Difference between the two types of fruits, Maturation timing Allowed for the evolution of isolation mechanisms and subsequent divergence of the two subspecies Source: https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/rhagoletis-pomonella Ex. Divergence of Rhagoletis pomonella (the maggot fly)

26. Source: https://evolution.berkeley.edu/modes-of-speciation/parapatric-speciation/ Divergence of Sweet vernal grass ( Anthoxanthum odoratum ) near mines

27. Allopatric Parapatric Sympatric Original population Initial step of speciation Evolution of reproductive isolation New distinct species after equilibrium of new ranges In isolation In adjacent niche Within the population Barrier formation New niche entered Genetic polymorphism

28. Rankless system of phylogenetic systematics An approach of classifying organisms based solely on their phylogenetic relationship, without assigning traditional Linnaean ranks (Eg. Kingdom, phylum, class, order, family, genus and species) Need of Rankless system: To accurately represent evolutionary relationships To provide a more nuanced understanding of biodiversity To improve the stability and consistency of classification

29. Clade based classification: (Rankless system ) Organism are grouped into clades, which are monophyletic groups containing a common ancestor and all its descendent Relationships are represented by phylogenetic trees, which illustrate the branching patterns of evolutionary history A Clade is a group of organism related by descent, and this approach to constructing a phylogeny is called Cladistics Cladistics- phylogeny (that is, builds family trees) according to similarities derived from a common ancestor, so called derived characters A derived character that is unique to a particular Clade is called- synapomorphy Key to the approach is being able to identify morphological, physiological or behavioral traits that differ among the organism being studied and can be attributed to a common ancestor By examining the distribution of these traits among the organism, it is possible to construct a Cladogram Source: Raven Johnson, Biology, 10 th Edition, Page no. 654

30. Source: Raven Johnson, Biology, 10 th Edition, Page no. 656 Components Cladogram: Proposed ancestors- indicated at the nodes between branches Lengths of branches- indicates evolutionary time Extinct groups- having shorter branches

31. Cladogram Phylogenetic tree Diagram showing the relationships among organism based on shared characteristics (synapomorphies) Diagram representing the evolutionary history or organism, including the relationships and timing of divergences Focuses on g rouping organisms based on shared derived traits Focuses on reconstructing the actual evolutionary history, including branch lengths and timing Branch lengths typically not proportional to time or genetic distance Branch length proportional to time or genetic distance Illustrates the order of branching and relationships among organism Provides information on the evolutionary relationships, timing and rates of evolution https://www.khanacademy.org/science/biology/her/tree-of-life/a/phylogenetic-trees https://en.wikipedia.org/wiki/Cladogram

32. Applications in Rankless system of phylogenetic systematics To reconstruct phylogenetic relationships- Cladograms help identify clades and reconstruct the evolutionary history of organism To identify monophyletic groups- Cladograms aid in recognizing monophyletic groups, which are essential for Rankless classification Testing hypothesis- Cladograms can be used to test hypotheses about evolutionary relationships and character evolution Phylogenetic analysis- Cladistics provides a framework for analyzing phylogenetic data and reconstructing evolutionary relationships Cladistic classification- Cladistics enables the development of Rankless classification based on phylogenetic relationships Comparative biology- Cladistics informs comparative studies in biology, such as comparative anatomy, embryology and genomics

33. Advantages Limitations More accurate representation Traditional ranks may be familiar and useful for communications than Rankless system Allows for easier updates and revisions as new data becomes available Can be more complex, nuanced, making it challenging to convey relationships to non-experts Avoids ambiguity and inconsistencies associated with traditional ranks Requires developing new methods and tools for classifying and comparing organism Ensures that classifications are consistent with phylogenetic relationships Without traditional ranks, some researchers may find difficulty in Rankless system Provides consistent framework for discussing evolutionary relationships Rankless systems can create challenges for naming and referencing clades Advantages and limitation of Rankless system