BIO 2135 Lecture Notes - Lecture 1: Pinacoderm, Autapomorphy, Choanocyte

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15 Feb 2016
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January 22, 2016 – Porifera
(Podcast for this section)
Apomorphies
- derived characters within a group
Plesiomorphies
- primitive characters within a group
Synapomorphies
- derived characters shared between groups
Symplesiomorphies
- shared primitive characters that are shared between groups
Autapomorphies
- shared derived characters that de$ne a taxon
- molluscs have a radula, but nothing else does – the radula is a autapomorphy
of the molluscs – it de$nes them
Using collagen and arising from choanocytes is an autapomorphy of animals as a
whole, but not of protists. Autapomorphies become plesiomorphies when you
subdivide the group.
Monophyletic
Polyphyletic
Paraphyletic
- a group shares a common ancestor with other organisms you haven’t placed
in the group
Animalia autapomorphies
- multicellular eukaryotes
- ingestive heterotrophs
- cells with di+erent functions
- choanocytes
- collagen as an adhesive
* These become symplesiomorphies for every subdivision of kingdom Animalia as
they are no longer the de$ning features of the organisms.
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