Exploring Evolutionary Patterns: Anatomy, Function, and Systems Approach

1. What’s it all about? Try to understand broad patterns of evolution by comparing the anatomy of different species (why things are like they are). Functional anatomy – generally form and function are linked both at the organism level and the cellular level (but is there more than one way of doing something) And there is more than one use to which something can be put (feathers as insulators became used for flying)

2. Systems approach • emphasises comparisons at several different levels • anatomy • cell structure • gene organisation Different systems – integumentary, skeletal, muscular, nervous, endocrine, digestive, respiratory, circulatory, excretory, reproductive

4. Cellular level – specialised in the same way for particular functions Rbc – no nucleus except camels and Dalmatians

5. Gene level - we have the same patterning genes as fish, amphioxus and flies – Hox genes

6. Functional anatomy & development Ontogeny recapitulates phylogeny? Or at least evolutionary change works through changes in development • 1. Differential growth – kangaroos • Heterochrony = changes in timing • paedamorphosis = retention of embryonic characteristics by adults • peramorphosis = development of new shapes beyond the adult form

8. Axolotl (Ambystoma mexicanum)

10. Systematics = naming, classifying, relationships between organisms • still a subject of intense debate • still finding new species • Phylogenies = relationships

11. most recently evolved Phylogenetic classification Node = hypothetical common ancestor of two or more species. Relative timings root Phylogeny branch Note : this is a hypothesis and constantly changes according to new discoveries node

12. Monophyletic group = taxon that includes hypothetical common ancestor and all of its descendents X + +

13. Scientific naming genus specific name Homosapiens italicised

14. How do you do this? No use Specific similarities = synapomorphies Character similarities = parsimony

16. Amniotic egg Hair Warm blooded Feathers 0 1 1 1 1 1 1 1 0 0 0 0 0 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 0 0 0 Frogs Turtles Snakes & lizards Crocodilians Birds Monotremes (platypus) Marsupials Eutherians (rest of mammals)

17. Endothermy evolved convergently Same for viviparity, also in lepidosaurs

18. Homoplasy = independent evolution of a function

19. But from the point of view of the limb they are all homologous

20. Earth = 4.6 billion yrs old Multicellular organisms = 1 billion yrs Animals with hard skeletons marks phanerozoic eon (visible animals) Age of mammals + bony fishes Age of reptiles tetrapods Age of fishes craniates molluscs, arthropods, echinoderms

21. N.B. continental drift!!!!

22. So must link phylogenetic history to historical biogeography 2 tribes of actinopterygian fishes – shallow dwelling – but now deep oceans separate areas of fossils

23. But - what was the world like in early Cretaceous?

24. Anatomical terminology