1. Phylogenetics, Background Info (continued) and Craniates

2. Discussion of article
Next article
Additional Reading
Schedule Changes
Lecture material

3. Cladistic Classification / Phylogenetic systematics
The science of evolutionary grouping based on shared derived characteristics
The naming of organisms based on these groups
Plesiomorphy:
Synapomorphy:
Autapomorphy:
Monophyly:
Paraphyly:
Polyphyly:

4. M N A B C
Cladogram
Branch
Node
Internode
Root
OTU
Ingroup
Outgroup
Autapomorphy
Plesiomorphy
Synapomorphy
spizit

5. The five synapomorphies of the Chordates
In combination:
Notochord
Hydroskeleton
Liquid-filled cells encased in a fibrous CT sheath
Allows for lateral undulation
Dorsal-hollow CNS (cf. paired structures of annelids and arthropods)
Post-anal tail
Extension of the body caudal to the anus
Increases the length of the body associated with locomotion

6. Endostyle Pharyngeal slits
Longitudinal groove in the floor of the pharynx
Lined with glandular cells
Bind iodine in matrix (homologous to thyroid gland)
Transports food to esophagus
Pharyngeal slits
Filter feeding
Respiratory

7. Characteristics and Phylogenetic Relationships of Chordates
Tunicates
2000 species
Mostly Ascidians (sessile adults)
Hermaphroditic
In larvae – locomotion
Notochord absorbed in the adult
Tubular nerve cord
Ependyma only
Integrates locomotion
Retained to some degree in adult
Eyespot, balancing organ
Cerebral vesicle becomes a ganglion in adult

8. Tunicate Adult

9. Tunicate larvae
Cf. vertebrate

10. Cephalochordates 45 species, mostly Branchiostomata (Amphioxus)
World-wide distribution
Motile
Short, post-anal tails
Distinct anterior end
Not well developed head
Notochord extends entire length of body
Dioeceous

14. The Parade of the Craniates
50,000 known living species
Plus extinctions since 500 MYA
Mostly marine
Hagfish + Vertebrata
Clearly exhibit all 5 chordate synapomorphies
Some only in the embryonic stages
Thyroid gland in all craniate adults
Paired, cephalized sensory organs
Nose, lateral eyes, ears
Major organ systems

15. “Cephalized”
Why the concentration of
paired sensory organs here?

18. Major synapomorphies of the Craniates
Developmental
Neural crest
Neurogenic placodes
Nervous System
Above
Braincase (skeletal)
Complex sense organs
Cranial nerves
Tripartite brain
Endocrine system is complex
Gut
Muscularization
Regionalization
Differentiated organs
Cardiovascular
Gills
Heart
Hemoglobin