Skip to main content
UploadLanguage (EN)Support
BusinessMobileSocial MediaMarketingTechnologyArt & PhotosCareerDesignEducationPresentations & Public SpeakingGovernment & NonprofitHealthcareInternetLawLeadership & ManagementAutomotiveEngineeringSoftwareRecruiting & HRRetailSalesServicesScienceSmall Business & EntrepreneurshipFoodEnvironmentEconomy & FinanceData & AnalyticsInvestor RelationsSportsSpiritualNews & PoliticsTravelSelf ImprovementReal EstateEntertainment & HumorHealth & MedicineDevices & HardwareLifestyle
Zeeshan Hanjra, profile picture
Uploaded byZeeshan Hanjra
PPTX, PDF60,506 views

Taxonomic evidences

This document discusses various types of taxonomic evidence that can be used to classify organisms, including morphology, anatomy, palynology, embryology, cytology, phytochemistry, ultrastructure, and genome analysis. It provides examples of specific morphological, anatomical, and other characteristics that taxonomists examine for each type of evidence. The document emphasizes that integrating data from multiple sources provides the strongest basis for classification and determining phylogenetic relationships between taxa.

Science◦
Downloaded 179 times
Taxonomic Evidences Zeeshan Hanjra 15211506-050 Bs Botany University Of Gujrat
Contents: • Introduction • Morphology in Relation to Taxonomy • Anatomy in Relation to Taxonomy • Palynology in Relation to Taxonomy • Embryology in Relation to Taxonomy • Cytology in Relation to Taxonomy • Phytochemistry in Relation to Taxonomy • Ultra Structure in Relation to Taxonomy • Genome Analysis and Nucleic Acid Hybridization in Relation to Taxonomy
Introduction: “Taxonomic characters are the taxonomic attributes that can be used to provide the evidence from which relationships (the phylogeny) between taxa are inferred” We will discuss taxonomic evidences in relation to 1. Morphology (deals with the external characters) 2. Anatomy (The study of the structure of organisms and their parts) 3. Palynology (The study of plant pollen, spores)
4. Embryology (The study of embryo) 5. Cytology (The study of structure and function of cells) 6. Phytochemistry (The study of phytochemicals, which are chemicals derived from plants) 7. Ultra Structure (The architecture of cells and biomaterials that is visible at higher magnification) 8. Genome Analysis and Nucleic Acid Hybridization (Identification, measurement, arrangement of genomic features)
1. Morphology in Relation to Taxonomy: • It mainly deals with the external characters of the plant such as Habit, Root structure, Stem structure, Stem habit, Bud structure, Leaf structure, Inflorescence type, Flower type, Perianth structure, Androecium type, Stamen character,Gynoecial type, Carpel structure, Ovule type, Fruit type, and Seed type. • It provided the basic language for plant characterization, classification and identification etc. • Morphological data is useful in taxonomic studies.
2. Anatomy in Relation to Taxonomy • The evidences come from wood cell type, size and shape, Wood cell wall sculpture, pattern, Stealer pattern, Vascular bundle type, Xylem type, wood type and ray type, Ground tissue type, Epidermal type, Mesophyll type, Scleried type, Stomatal type, Trichrome type, crystal type, Nodal type, Venation type, Petiole vasculation type, Periderm origin, Phloem cell type, Specialized cell type. • The application of anatomical data to phylogenetic problem is of great value in elucidating taxonomic relationships.
3. Palynology in Relation to Taxonomy: • Basic evidentiary characters are Pollen unit type, Pollen grain polarity, Pollen grain shape, Pollen grain symmetry, Pollen grains nuclear state, Pollen wall architecture, Exine stratification, Exine structure, Exine sculpture, Aperture type, Aperture number, Aperture position, Aperture shape, and Aperture structure. • In Magnoliidae the pollen is nucleate. • In Caryophyllidae the pollen is trinucleate.
• In Ericaceae the pollen is in tetrads. • In Asclepiadaceae pollen remain in Pollinia. • In Taraxaccurn the pollen wall is echinate. • In Quercus the pollen wall is scabrate Cont.
4. Embryology in Relation to Taxonomy: • Embryology is the study of the successive stages of sporognesis, gametogenesis and the growth and development of embryo. • Basic evidences are another loculi number, arrangement, Anther wall formation and endothecium type, Archesporial cell number, Aril presence, Embryo sac development type, Embryo and Embryogeny type, Endosperm type, Integument number and structural type, Ovule orientation type and position, Tapetal type, Perisperm presence, Nucleolus character, and Haustorium formation type.
• Embryological evidences are important at higher category level e.g., in conjunction with other types of evidences in confirming the systematic position of taxa. Cont.
5. Cytology in Relation to Taxonomy: • Cytology is the study of the morphology and physiology of cells. • Normally anatomists deal with shapes, size, wall structure, pattern, etc. but cytologists deal with the internal organelles of the cell and detailed structure of cell wall. • Some evidential characters are chromosome number, structure, Chromosome meiotic behavior, Ploidy level and type, and Chromosome aberration etc.
• Cytological evidences is used for distinguishing taxa. • To determine the origin of groups and to understand the evolutionary history of related taxa particularly those at the intraspecific and specific levels cytotaxonomy is a part of experimental taxonomy. • Such studies are helpful in determining the categories of genus, species etc. generally in cases of controversy. Cont.
6. Phytochemistry in Relation to Taxonomy: • Chemo Taxonomy: The science of chemical taxonomy is based on classification of Plants on the basis of their chemical constituents related with the molecular characteristics. • Chemotaxonomy includes: i. Investigation of pattern of the compounds existing in plants. ii. Investigation pattern of the compounds in plant parts likes bark, wood, eaves, roots etc.
Cont. • Basic characters as evidence come from: Flavonoids,Terpenoids,Carotenoids,Polysaccharides,Alkaloids,Aminoacids, Fattyacids,Aromatic compounds, and C3-C4 photosynthesis etc. • Popularity of Phytochemistry is due to: i. Development of rapid analytical techniques. ii. Belief that data from many sources should be employed for classification.
7. Ultra Structure in Relation to Taxonomy: • Electron microscopic studies also play an important role in taxonomy Heywood and Dakhshini (1971) demonstrated the use of Electron microscopy in Taxonomy. • Important characters used in classification are as follows: 1. Sieve-tube plastids: Behnke et.al. studied more than 1500 species belonging to 380 families (1977, 1981) for sieve tube plastids and found 3 types of plastids depending upon accumulation of starch and protein(S-type, So-type, P- type).
2. Dilated cisternae (DC): • Iverson and Flood (1970) found Dilate cisternae (DC) in Capparales. • DC in the endoplasmic reticulum were reported by Bonnet and Newcomb (1965) in the root cells of Raphanus sativus. • Favali and Gerola (1968) reported DC in phloem parenchyma of foliar veins in Brassica chinensis. Jorgensem (1977) found them is Capparis sieve elements in evolutionary origin. Cont.
8. Genome Analysis and Nucleic Acid Hybridization in Relation to Taxonomy: • Genome Analysis and Nucleic Acid Hybridization contain identification, measurement, arrangement of genomic features. • Genome analysis has a very crucial role in understanding genomic relationships among species and is important to systematists, evolutionists, molecular biologists etc.
Genomic relationship among diploid species: Genomic relationship among diploid species is determined as: i. Crossing affinity: Interspecific crosses involving parental species with similar genus usually set normal pods and seeds while crosses between dissimilar species, seeds are commonly abortive. Some hybrids do not set seeds. Sometimes the crossing is successful in one direction and is genotype dependent. ii. Chromosome pairing: In inter specific hybrids the degree of chromosome pairing facilitates the analysis, of phylogenetic relationships among species; providing information about ancestral types.
The DNA based molecular markers are applied in various aspects of taxonomy to analyze: i. Genetic identity. ii. Genetic relatedness among populations, geographic populations and species. iii. Pedigree. iv. Differentiation among isolated species. v. Phylogenetic structure at various micro and macro levels.
Taxonomic evidences