Module 1

• Morphology 


  study of parts or forms of organisms and relationships
• Carl von Linne


  proposed a naming system for plants and animals called Linnaean taxonomy
• Philosophie Zoologie 3 arguments

  1. Fact
  2. course
  3. Mechanism
• Inheritance of acquired characteristics

  • multiple origins of life
  • forms become more complex over time
  • assumes that changes arise due to need and are inheritable
• Charles Robert Darwin

  • proposed the conditions for and mechanism of evolutionary change
• Descent with modification


  species possessing traits with the most favorable for survival
• Alfred Russell Wallace

  • independently and coincidentally arrived at the same notion of natural selection as Darwin
• Descent with modification

  • single origin of life or common ancestry
• Natural Selection

  • useful variations for survival will be preserved and passed on to offspring
• Variations exist in populations
• Georges Cuvier

  • Immutability of structure
  • brought attention to the function of parts
• Archetype

  • biological blueprint
  • basis of organismal structure
• Thomas Henry Huxley

  • differential plan between skull and vertebrae
• Homology

  • features sharing common ancestry
• Serial Homology


  repeating structures (ex: gill arches, vertebrae)
• Analogy


  features with similar function
• Homoplasy 


  features that look alike
• The relationship between the beaks of parrotfish and Philippine trogon: HOMOPLASY

  
• Homology and Analogy

  • common ancestry with similar function
• Homology and Homoplasy

  • common ancestry with similar appearance
• Analogy and Homoplasy

  • similar function and appearance, but no common ancestry
• Radial symmetry

  • laid out from a central axis
  • planes passing through center divide the animal into equal or mirrored halves
• Segmentation

  • repeating or duplicating sections of a structure
• Segmentation in vertebrates is heteronomous (repeating parts becomes unlike each other)
• Phylogeny


  the course of evolution charted by a species or a group of species, depicted using a dendrogram.
• Plesiomorphic 


  ancestral or primitive trails possessed by ancestor
• Symplesiomorphic


  shared ancestral traits
• Apomorphic 


  derived or advanced trait possessed by descendants
• Synapomorphic 


  shared derived traits
• Autapomorphic 


  derived trait unique to a descendant lineage
• Polyphyletic 


  the group contains taxa without a common ancestor

  
• Paraphyletic


  group contains some but not all descendants of a common ancestor

  
• Monophyletic 


  group contains all descendants of a common ancestor

  
• 5 Key Structures of Chordates

  1. Notochord
  2. Pharyngeal slits
  3. Endostyle
  4. Dorsal hollow nerve cord
  5. Post-anal tail
• Coelom 


  fluid-filled internal body cavity
• Notochord


  slender rod; develops from mesoderm
• Notochord


  dorsal to coelom; parallel to the central nervous system
• Notochord 


  core of cells and fluid encased in sheath of fibrous connective tissue
• Notochord has elastic rod-like properties

  • allows for lateral flexing
  • cannot collapse axially
• Pharyngeal slit 


  arose in hemichordata