SYSTEMATICS

• Biosystematics


  The study and classification of living things for the determination of evolutionary relationships; the science of classifying organisms
• Taxonomy


  The theory and practice of identifying, naming, and classifying organisms
• Stages/levels/periods of taxonomy


  • Alpha taxonomy
  • Beta taxonomy
  • Gamma taxonomy
• Alpha taxonomy


  Identifying and characterizing species based on gross morphological features
• Beta taxonomy


  Arranging species in a hierarchical system of classification
• Gamma taxonomy


  Studying intraspecific differences and evolutionary history
• Alpha diversity


  Biodiversity in a specific area, ecosystem or community, typically expressed by species richness
• Beta diversity


  Comparison of species diversity between ecosystems, the rate of change in species composition across habitats
• Gamma diversity


  The net species richness across a larger region, the overall diversity of various ecosystems in an area
• Linnaeus introduced the binomial nomenclature system for naming organisms
• Aristotle founded the classification of living things, using functional, binary, and empirical features
• Theophrastus studied the classification of ivy based on growth form and leaf/fruit characteristics
• Belon compared the skeletons of humans and birds, an early example of comparative anatomy
• Linnaeus developed a hierarchical classification system with seven levels: Empire, Kingdom, Class, Order, Genus, Species, Variety
• Linnaeus' "sexual system" of plant classification based on floral parts was controversial but influential
• The contemporary standard hierarchy includes seven levels: Kingdom, Phylum, Class, Order, Family, Genus, and Species
• Floral parts were even analogized to the foreskin and labia
• Nomenclature for many fungal, plant, and other eukaryote groups is founded on the Species Plantarum (Linnaeus, 1753), and that for animals the 10th Edition of Systema Naturae (Linnaeus, 1758)
• Hierarchy of the taxonomic system

  • Imperium (Empire)
  • Regnum (Kingdom)
  • Classis (Class)
  • Ordo (Order)
  • Genus
  • Species
  • Varietas (Variety)
• The contemporary standard hierarchy includes seven levels: Kingdom, Phylum, Class, Order, Family, Genus, and Species, although other levels are often created as needed to describe diversity conveniently
• Georges Louis Leclerc, Comte de Buffon

  Began his scientific career in mathematics and probability theory, appointed director of the Jardin du Roi (later Jardin des Plantes), making it into a research center
• Buffon is best known for the encyclopedic and massive Histoire naturelle, générale et particulière (1749–1788)
• Buffon's beliefs


  • Taxa are arbitrary, hence there could be no preferred classification
  • Species were real (due to the moule intérieur—a concept at the foundation of comparative biology)
  • Species could "improve" or "degenerate" into others, changing in response to their environment
  • Mammalian species of tropical old and new world, though living in similar environments, share not one taxon
• Jean-Baptiste Lamarck


  • Believed classifications were entirely artificial, but still useful (especially if dichotomous)
  • Proposed the theory of Transmutation - where species are immutable, but creatures may move through one species to another based on a motivating force to perfection and complexity, as well as the familiar "use and dis-use"
• Georges Cuvier


  • Divided animal life into four "embranchements": Vertebrata, Articulata, Mollusca, and Radiata
  • Believed species were immutable but could go extinct, with new species only appearing to be new, and were really migrants not seen before
  • Established the process of extinction as fact
• Étienne Geoffroy Saint-Hilaire


  • Believed there were ideal types in nature and that species might transform among these immutable forms
  • Believed environmental conditions motivated change, mediated during the development of the organism
  • Believed in a fundamental unity of form for all animals (both living and extinct), with homologous structures performing similar tasks
• Johann Wolfgang von Goethe

  • Coined the term "Morphology" to signify the entirety of an organism's form through development to adult
  • Applied these ideas to the comparative morphology and development of plants, creating morphological ideals to which all plants ascribed
• Lorenz Oken


  • A leader in the "Naturphilosophie" and an ideal morphologist, sought general laws to describe the diversity in nature through the identification of ideal forms
  • Created five groups of animals based on his perception of sense organs
• Richard Owen


  Defined homology and analogy, derived the general archetype for vertebrates based on the serial homology of vertebral elements
• Charles Darwin


  • Brought the causative theory of evolution to generate and explain the hierarchical distribution of biological variation
  • Thought in terms of evolutionary "trees", but felt classifications were more than just evolutionary trees
• Darwin transformed Owen's archetype into an ancestor, and cladistics further transformed the ancestor into a median
• Ernst Haeckel


  • Presented the situation in a graphical form, including both genealogical relationships, degrees of modification, and Aristotle's Scala Naturae
  • Coined the word "Phylogeny" to describe the scheme of genealogical relationships
  • Believed paleontology, development, and morphology were the primary ways to discover phylogeny
• August Schleicher constructed linguistic trees as Darwin had biological, and thought there were better linguistic fossils than biological
• Contributions of Systematics to Other Fields of Biology

  • Patterned Diversity
  • Applied Biology (Epidemiology, Biological Control, Wildlife Management, Determination of Sequential Events, Environmental Problems, Soil Fertility, Introduction of Commercially Important Species)
• Biosystematics, taxonomy, and classification are related but distinct concepts in systematic biology.
• How species should be defined in a particular group of organisms gives rise to practical and theoretical problems that are referred to as the species problem
• The scientific work of deciding how to define species has been called microtaxonomy
• Speciation


  The evolutionary process by which biological populations evolve to become distinct species
• Charles Darwin was the first to describe the role of natural selection in speciation in his book 'The Origin of Species' (1859)
• Geographic modes of speciation

  • Allopatric
  • Peripatric
  • Parapatric
  • Sympatric