Zoo 2 Chapt 2
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This document discusses key anatomical and evolutionary concepts including homology, analogy, homoplasy, apomorphy, plesiomorphy, synapomorphy, and symplesiomorphy. It provides examples of hair being a synapomorphy of therians and an autapomorphy of mammals. Additionally, it notes that the carnassial pair formed from the 4th upper premolar and 1st lower molar is a synapomorphy of cats and dogs that indicates their close relationship.
Zoo 2 Chapt 2
- 1. Chapter 2 Anatomical and Evolutionary Concepts
- 2. Anatomical and Evolutionary Concepts Discussion on Similarities: Homology Analogy Homoplasy
- 3. Homology homology was probably first popularized by Huxley in 1863 to argue for human evolution. Refers to features of two or more organisms sharing common ancestry.
- 4. Analogy
- 5. Apomorphy: A derived or specialised character. mor Plesiomorphy: An ancestral or primitive character. more Synapomorphy: An apomorphy (derived or specialised character) shared by two or more groups which originated in their last common ancestor. more Symplesiomorphy: A character shared by a number of groups, but inherited from ancestors older than the last common ancesto
- 6. Within this taxon set, hair is a shared derived character (synapomorphy) of therians that indicates a close relationship of marsupial and placental mammals.
- 7. Within this taxon set, hair is a unique character (autapomorphy) of mammals
- 8. The Carnassial Pair as a synapomorphy of Cats & Dogs The diagram indicates that a particular character state (presence of a carnassial pair formed from the 4th upper premolar and the 1st lower molar) occurs Cats and Dogs. Eutherian insectivores (such as shrews) and marsupials (such as kangaroos) retain the ancestral, unspecialized form of the molariform teeth.
- 9. Symplesiomorphy The possession of a character state that is primitive (plesiomorphic) and shared between two or more taxa. Shared possession of a symplesiomorph character state is not evidence that the taxa in question are related.