Lecture 07 Outline Chapter 26

Lecture 07 Outline Chapter 26 - Bio II Lecture notes:...

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Bio II Lecture notes: copyright: Dr. Will Crampton UCF Slide 1 (revision) Phylogenies based on derived characters (synapomorphies). Dot – evolution of new character Slide 2: (revision) Synapomorphies are “ Homologous” traits Homology – similarity due to shared ancestry. Homologous structures have the same evolutionary origin Slide 3: (revision) Homologous trait vs. Analogous trait (a.k.a. ‘homoplastic’ trait) Slide 4: (revision) Synapomorphies define a monophyletic group: contains ancestor and all descendents: Slide 5: (revision) Summary: Synapomorphic trait = homologous trait i.e. traits shared due to common ancestry Homoplasic trait = analogous trait i.e. traits shared, but not due to common ancestry … usually evolve by CONVERGENT EVOLUTION Slide 6: (revision): Synapomorphies – - Morphological - Molecular Slide 7: (revision) What are phylogenies based on? 1
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- morphological synapomorphies (for fossil and living organisms) - molecular synapomorphies (for living organisms only) Slides 8-10: See Fig. 26.11 pp. 543 Contrasting SYNAPOMORPHY (shared + derived) with PLESIOMORPHIC (ancestral) traits example: PHLUM CHORDATA = ANIMALS THAT POSSESS A NOTOCHORD ETC. Outgroup- taxon outside a closely related group – the Lancelet. Ingroup – the rest of the group, whose interrelationships we wish to reconstruct Character: vertebral column: State in the OUTGROUP is absent. The ancestral condition is ABSENT. Series of nested groups: each defined by a SHARED AND DERIVED CHARACTER. synapomorphies for vertebrae: vertebral column; for gnathostomes: hinged jaws. for tetrapods: 4 walking legs
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Lecture 07 Outline Chapter 26 - Bio II Lecture notes:...

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