01 Taxonomy with symbiosis v24

Taxonomy Overview

Definition of Taxonomy

  • Taxonomy: The science of naming organisms and classifying them into groups called taxa (singular: taxon).

Hierarchal Classification

  • Species: Basic unit of classification (e.g., Felis catus for domestic cat).

  • Genus: A group of species that are closely related (e.g., Felis).

  • Family: A group of genera (e.g., Felidae).

  • Order: Grouping families (e.g., Carnivora).

Diversity of Organisms

Estimated Diversity

  • Estimates of living organisms on Earth vary:

    • Older estimates: 3 to 100 million.

    • New estimates (2011): Approximately 8.7 million (± 1.3 million).

      • Breakdown: 6.5 million species on land and 2.2 million in oceans.

      • Studies suggest that 86% of land species and 91% of ocean species are yet to be discovered.

Role of Microscopes in Taxonomy

  • The invention of the microscope expanded taxonomy by increasing the number of organisms discovered, resulting in more organisms to classify.

Understanding Species

What is a Species?

  • Definition: A group whose members can freely breed within themselves (biological species concept).

  • Plural of species: species; singular: species.

Species Interactions

Interactions Overview

  • Various interactions that species may have, including:

    • Food Supply

    • Protection

    • Transportation

    • Reproduction

    • Hygiene

    • Digestion

Symbiotic Relationships

Types of Symbiotic Relationships

  • Mutualism (+/+): Both organisms benefit (e.g., E. coli in human intestine).

  • Commensalism (+/0): One benefits, the other is unaffected (e.g., barnacles on whales).

  • Parasitism (+/-): One benefits at the expense of the other (e.g., malaria).

Ectosymbiosis vs. Endosymbiosis

  • Ectosymbiosis: One organism lives on the surface of another (e.g., barnacles on whales).

  • Endosymbiosis: One organism lives within the tissues of another (e.g., E. coli in humans).

Historical Perspectives on Taxonomy

Ancient Western Thought

  • Classification based on human-centered views (e.g., Aristotle's categorization by habitat).

Carl Linnaeus (1707-1778)

  • The father of modern taxonomy, developed binomial nomenclature to classify organisms using Latin names.

Taxonomic Classification System

Traditional Ranks

  • Taxonomic hierarchy includes:

    • Domain

    • Kingdom

    • Phylum

    • Class

    • Order

    • Family

    • Genus

    • Species

  • Mnemonic device: "Do Kings Play Cards On Fine Green Satin?"

Example Taxonomic Grouping for Humans

  • Domain: Eukarya

  • Kingdom: Animalia

  • Phylum: Chordata

  • Class: Mammalia

  • Order: Primates

  • Family: Hominidae

  • Genus: Homo

  • Species: sapiens

Binomial Nomenclature

Definition and Format

  • A two-word system for naming organisms: Genus + Species.

  • Genus name is capitalized; species name is lowercase (e.g., Homo sapiens).

Importance of Binomial Nomenclature

  • Advantages include:

    1. Universal scientific communication.

    2. Unique name for each organism.

    3. Reflects relationships between organisms.

Dichotomous Key

Definition and Usage

  • Dichotomous Key: A tool used for classifying organisms by making a series of choices based on characteristics.

  • Conditions for a sound key:

    1. Two mutually exclusive choices for each step.

    2. Unique endpoints for individual organisms.

Representation

  • Can be presented in written or diagrammatic forms (e.g., flow charts).

Homologous Structures

Analysis of Structures

  • Similar structures indicating a common ancestor (e.g., Human arm, Dog foreleg, Seal flipper).