Introduction to Plant Systematics

Introduction to Plant Systematics

• The Earth is populated by a vast array of organisms, exhibiting diverse structures, habits, habitats, feeding mechanisms, and physiological traits.
• Biodiversity encompasses all the types of biological forms on Earth.
• Biodiversity is studied through science, and its definitions in this field overlap. This encompasses species, genetic, and ecosystem diversity.

Types of Biodiversity

• Species diversity refers to the total number of different species within a community.
• Genetic diversity refers to the total number of different genotypes (genetic variations) within a population of a community.
• Ecosystem diversity refers to the variety of variations that exist in diverse ecosystems. These are identified based on geographical regions.

Importance of Biodiversity

• Biodiversity provides resources for food, shelter, and livelihoods.
• Biodiversity protects from natural disasters and pandemics.
• Understanding biodiversity enriches our art, literature, and other cultural endeavors.
• Biodiversity fuels our curiosity to explore vast expanses.
• An estimated 1.8 million species have been identified, with over 750,000 insects, 47,000 vertebrate animals, and 250,000 flowering plants among them.
• Many species remain unknown.
• A high percentage of species that once existed are now extinct.

Why Study Systematics?

• Systematics is the branch of biology that studies the diversity and evolutionary relationships of organisms. This encompasses comparative anatomy, biochemistry, physiology, and ecology.
• Systematics also covers the classification of living organisms.
• Classification, broadly speaking, groups objects or information based on their similarities
• Biological classification groups living organisms into easily identified groups or categories based on observable characteristics.
• Systematics helps organise diversity for easier identification and study.
• Systematics reveals relationships among living groups.
• Systematics identifies evolutionary trends and biological evolution.
• Systematics aids in interpreting the fossil record.

Taxonomy and Systematics

• Taxonomy is used for naming and classifying organisms based on their characteristics and evolutionary history.
• Early systems, such as Aristotle's classification system categorized all living things into two large categories, plants and animals.
• Problems with these systems arose as classifying organisms based on their environment rather than internal traits led to issues such as grouping unrelated organisms together and classifying similar organisms into disparate groups.
• Later systems utilized internal anatomy. For example the work of Ray introduced the concept of species.
• A Two-Kingdom system of classification was proposed to categorize life on Earth. This system included plant and animal categories
• Later, the Three-Kingdom, the Five-Kingdom and the Six-Kingdom system expanded.
• Carl Woese proposed a three domain system for classification which was based on ribosomal RNA. This included the Kingdoms Bacteria, Archaea, and Eukarya

Viruses

• Viruses have features of both living and nonliving things.
• Viruses do not meet definitions for life or being an organism.
• Viruses are ultramicroscopic entities, smaller than most prokaryotes.
• Viruses reproduce by infecting cells
• Viruses have different shapes (helicase, round, complex).