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

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Presentation on theme: "Vertebrate Zoology: Chapter 1 The diversity, Classification and Evolution of vertebrates."— Presentation transcript:

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


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