Vertebrate Zoology: Chapter 1

1. Vertebrate Zoology: Chapter 1 The diversity, Classification and Evolution of vertebrates

2. Diversity • Numerous & diverse • More than 50, 000 species • Range in size from small fishes (0.5 g) to full mature whales (>100 000 kg) • Habitats vary • Deep oceans to top of the highest mountains

3. DIVERSITY • Feeding Behavior • Obtain energy from food they eat • Complex and vary extensively • Carnivores eat other animals and catch they prey in various ways • Some search for prey • Some wait in hiding for their prey • Some pursue their prey at high speeds • Some swallow prey while it is still alive and struggling to kill itself • Snakes inject toxins that paralyze the prey • All cats kill prey with a distinctive bite on the neck

4. DIVERSITY • Herbivores eat plant materials • Developed some specializations • Well sculptured teeth • Digestive tracts with special places for bacteria that digest some of the plant materials e.g. cellulose

5. DIVERSITY • Reproduction: necessary for survival and continuity • Great diversity WRT mating and courtship • In general males court females • Females care for the young • Male female roles reversed for some animals • Modes of reproduction vary from egg laying to live births

6. DIVERSITY • Parental Care • Some babies self sufficient: precocial young (fish and amphibians) • Others require extended periods of parental care (humans)

7. DIVERSITY: Types of Vertebrates • Hagfishes (Myxinoidea) • Long and slender & pinkish • produce large quantities of sticky slime • Almost blind • Jawless (Agnatha) • No trace of vertebrae (backbone) • Marine and parasitic, also scavenge

8. DIVERSITY: Types of Vertebrates • Lampreys (Petromyzontoidea): • Jawless • Both marine and freshwater • Round mouth • Rudimenatry vertebrae • Scaleless fishes • Slimy, no internal hard tissue • Larva is called ammocoetes

9. Chondrichthyes: Sharks, rays and ratfishes • All classified as chondrichthyes (Chondro= cartilage, ichthyes = fish • All lack true bone, have a cartilage skeleton • Only teeth and vertebrae are sometimes calcified • Jawed fish • Some sharks are small <=15 cm, others are large. Largest is 10m • Rays live on bottom of water bodies and tend to have flat bodies • Broad fins used for swimming • Ratfishes are long with slender tails

10. Osteichthyes • Bony fishes; very diverse • Bone skeleton • Numerous vertebrae • Dermal scales on skin, skin has mucus glands • Jaws are present • Divided into major groups

11. Osteichthyes • Lobe Finned fishes (fleshy finned) • Also called sarcopterygians • Only eight species • Ray Finned Fishes • Fins appear like webs of skin supported by bony or horny spines • More than 20 000 species, dominant aquatic vertebrates (from deep seas to freshwater streams and ponds) • Major source of food for people

12. Osteichthyes • 2 groups of Actinopterygians: • The chondrostei • Bichis, sturgeons, paddlefishes • Sturgeons are the source of carvia • Paddlefish have a paddle-like snout and found in Mississippi river • Neopterygians • More modern • Include the teleostei group with more than 20 000 species • Familiar teleosts are trout, bass, salmon, panfish, sole swordfish, salmon and tuna

13. AMPHIBIANS: Salamanders, Frogs and Caecillians • Aquatic larval form (e.g tadpoles) • Terrestrial adult form • Bare skin, lack scales, hair, or feathers • Three orders

14. AMPHIBIANS: Salamanders, Frogs and Caecillians • Salamanders/Urodela • Elongated animals, terrestrial, usually with four legs; Have tails as adults • Frogs (Anurans): Frogs, toads, treefrogs • Short bodies, no tails as adults; Large heads • Large hind legs (walking, jumping, climbing) • Caecilians • are an order of legless amphibian. • most have no tail, also called rubber eels • Burrowing animals

15. Turtles • Turtles are easily distinguished by the presence of a shell which encloses the animal in a bony case. • Turtles inhabit a variety of terrestrial and aquatic environments, from the open ocean to the arid deserts. • Shoulders and hips are inside the ribs • Unique animals

16. Tuatara, Lizards, Snakes • Skins is covered with scales • Tuatara • Small nearly extinct order of very unusual lizard-like reptiles know as the beaked reptiles. Have unique features such as a third eyelid. • All living species found in New Zealand • Lizards: > 4000 species • Snakes: > 2700 species

17. Alligators and Crocodiles • Semi aquatic predators, same lineage as dinosaurs • Long snouts with numerous teeth • Skins contains bones (osteoderms) beneath the scales • Care for their young

18. BIRDS: AVES • Lineage of dinosaurs • Characterized by flight, and feathered wings. • > 9000 species • Very active during the day, great vocals!!

19. Mammals • >4500 species • Mostly eutherians (placental animals): show placentation and long gestation • Marsupials, placentation to a small extend, very short gestation. Give birth to very immature young that would then grow in the external pouch (kangaroo) • Marsupials are mostly in Australia( Kangaroos, Koalas, and wombarts) • Some marsupials hatch young from eggs instead: the platypus and the echidnas from australia

20. Vertebrate Classification: terms • Books classifies vertebrate from an evolutionary standpoint • Phylogenetics: used to classify vertebrates • This is a field of biology that deals with relationships between organisms. It includes the discovery of these relationships and the study of the causes behind this pattern

21. Phylogeny • The evolutionary relationships among organisms, patterns of lineage branching produced by the true evolutionary history of the organisms being considered

22. Cladistics • Phylogenies are proposed thru a process called cladistics or phylogenetic systematics • It attempts to produce a hypothesis about the evolutionary sequences of events that led to a group of organisms • Each group of organisms is called a clade • Its makes use of shared derived characters

23. Clade • Phylogenetic lineage originating from a common ancestor • It is a group of organisms which include the most recent common ancestor of all its organisms and all the descendents of that common and recent ancestor • Comes from the Greek word Clado meaning twig or branch

24. Derived Character • Modified version of the primitive condition of that character. Thus the character has changed from its ancestral condition • Presence of hair is a primitive character state of all mammals, whereas the hairlessness of whales is a derived state for one subclade within mammals • Also called apomorphy (apo = away from, morph = form)

25. Shared Derived Character • A character derived from the ancestral conditions and is shared among several taxa that all descended from a common ancestor that first exhibited the derived character. • E.g. foot bones(tarsals, carpals, digits) of terrestrial vertebrates: Bones not seen in ancestral pattern seen in lobe finned fishes. • Also called synapomorphy (syn = together) • Apomorphy: means derived character

26. Primitive Character • All called Plesiomorphy • Inherited characters seen in ancestors of a clade. Not derived • Original condition of that character within the clade under consideration • Presence of hair is a primitive character • Hairlessness is a derived state for one subclade of mammals -whales

27. Shared Primitive Character • A character that is the same as the ancestral condition and is shared among several taxa • These carry no information WRT phylogeny of the organisms under study • All called sympleisomorphy

28. Cladograms • Hypothesised phylogenies from cladistics: Cladograms are diagrams showing animal branches during evolution • It’s a hypothesis about a group of animals • Subject to change as more data is available or re-evaluated • Cladograms are not truths

29. Cladograms • Evlutionary relationship between humans and great apes • Some cladograms show humans as the sister taxon to the chimpanzees • Others show show gorilla as the sister taxon • Thus a cladogram is a hypothesis that like any other hypothesis or theory in science is subject to change as more data are accumulated • See figure 1.2: study the cladogram and understand the data.

30. Other cladistics terminology • Taxa: Groups of organisms of same species or different species • Clades: groups of organisms in a cladogram • Monophyletic groups. Groups of organisms which contain the common ancestor plus all descendents (e.g. mammalia is a monophyletic group (clade) as it contains all living and extinct mammals plus the ancestor of all mammals

31. Other cladistics terminology • Paraphyletic • Groups that do not contain the common ancestor