Vertebrate Zoology: Chapter 1
The diversity, Classification and Evolution of vertebrates
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
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
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
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
DIVERSITY Parental Care
Some babies self sufficient: precocial young (fish and amphibians)
Others require extended periods of parental care (humans)
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
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
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
Osteichthyes Bony fishes; very diverse Bone skeleton Numerous vertebrae Dermal scales on skin, skin has
mucus glands Jaws are present Divided into major groups
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
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
AMPHIBIANS: Salamanders, Frogs and Caecillians Aquatic larval form (e.g tadpoles) Terrestrial adult form Bare skin, lack scales, hair, or
feathers Three orders
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
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
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
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
BIRDS: AVES Lineage of dinosaurs Characterized by flight, and
feathered wings. > 9000 species Very active during the day, great
vocals!!
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
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
Phylogeny The evolutionary relationships
among organisms, patterns of lineage branching produced by the true evolutionary history of the organisms being considered
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
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
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)
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
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
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
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
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.
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
Other cladistics terminology Paraphyletic
Groups that do not contain the common ancestor