“Vertebrate Diversity /Phylogenetic Tree”
phylogenetic tree
 A phylogenetic tree or evolutionary tree is a branching diagram or
"tree" showing the inferred evolutionary relationships among
various biological species or other entities based upon similarities
and differences in their physical and/or genetic characteristics.
 The taxa joined together in the tree are implied to have
descended from a common ancestor.
 http://viwephotos.info/%E2%98%86%E2%98%86/phylogenetictree<<image
 . Trees are useful in fields of biology such as bioinformatics,
systematics and comparative phylogenetics.
Vertebrates
 Veryebrates- an animal of a large group distinguished by the
possession of a backbone or spinal column, including mammals,
birds, reptiles,
 General characteristics of vertebrates
 Vertebrates may be characterized by 12 general
derived characteristics. You should become very
familiar with these traits, and identify how they
are expressed in the vertebrates you will see in
lab.
1. Bilateral symmetry
2. Two pairs of jointed locomotor appendages, which can include fins
(pectoral and anal/dorsal fins, as well as the forelimbs and hindlimbs).
3. Outer covering of protective cellular skin, which can be modified into
special structures such as scales, hair and feathers
4. Metamerism found in skeletal, muscular and nervous system. This
was described in a previous lecture - structures can include ribs,
vertebrae, muscles and ganglia/peripheral nerves.
5. Well-developed coelom, or body cavity completely lined with
epithelium (cellular tissue), that may be divided into 2 to 4
compartments.
6. Well-developed internal skeleton of cartilage and bone, separated
into axial skeleton (skull, vertebrae, ribs, sternum) and appendicular
skeleton (girdles and appendages).
7. Highly developed brain enclosed by skull, and nerve cord enclosed by
vertebrae. This provides advanced neural structures that are highly
protected from damage.
8. Well-developed sense organs (eyes, ears, nostrils) located on the
head (cephalization).
9. Respiratory system, including either gills or lungs, and located closely
to the pharynx or throat.
10. Closed circulatory system with ventral heart and median dorsal
artery.
11. Genital and excretory systems closely related, utilizing common
ducts and pathways.
12. Digestive tracts with two major digestive glands (liver and pancreas)
that secrete into it.
 Grouping the vertebrate classes
1.
2.
3.
4.
5.
6.
7.
8.
 In the vertebrate classes, there are further ways
of subdividing the groups based on derived
characteristics. There are eight recognized
extant classes of vertebrates
Myxini– hagfishes
Cephalaspidomorpha– lampreys
Chondrichthyes - cartilagenous fishes
Osteichthyes - bony fishes
Amphibia - frogs, toads, salamanders, and caecilians
Reptilia - turtles, snakes, lizards, crocodilians
Aves – birds
Mammalia - mammals
Requirements in grouping Vertebrates
 Vertebrates can also be grouped based on their general
habitat requirements:
Pisces - collective term for all fishes; includes Myxini,
Cephalaspidomorpha, Chondrichthyes, Osteichthyes
Tetrapoda - collective term for the terrestrial vertebrates; they have
four feet unless some have been secondarily lost or converted to other
uses. Includes Amphibia, Reptilia, Aves, Mammalia
 Or based on their feeding habits:
Agnatha - jawless vertebrates, including Myxini and
Cephalaspidomorpha
Gnathostomes - vertebrates with jaws derived from the mandibular
arch, which may have (in primitive vertebrates) supported gills. Includes
Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, Mammalia
 Or based on their embryonic characteristics
Anamniotes - vertebrates that lack an amnion, or extraembryonic
membrane that surrounds the embryo and encases it in amniotic fluid.
Includes Myxini, Cephalaspidomorpha, Chondrichthyes, Osteichthyes,
Amphibia.
Amniotes - vertebrates that possess an amnion. Includes Reptilia, Aves,
Mammalia
http://www.youtube.com/watch?v=xwuhmMIIspo<<video
QUESTIONS:
1. What are three characteristic of vertebrates?
2. What are eight recognized extant classes of vertebrates?
3. What is a phylogenetic tree?
4. What is a vertebrate?
5. The taxa joined together in the tree are implied to have descended
from a common________.
a. reptiles
b. ancestors
c. insulin
d. cell membrane
ANSWERS:
1.
 Bilateral symmetry
 Two pairs of jointed locomotor appendages, which can
include fins (pectoral and anal/dorsal fins, as well as the
forelimbs and hindlimbs).
 Outer covering of protective cellular skin, which can be
modified into special structures such as scales, hair and
feathers
2. * Myxini – hagfishes
* Cephalaspidomorpha – lampreys
* Chondrichthyes - cartilagenous fishes
* Osteichthyes - bony fishes
* Amphibia - frogs, toads, salamanders, and caecilians
* Reptilia - turtles, snakes, lizards, crocodilians
* Aves – birds
* Mammalia – mammals
3. A phylogenetic tree or evolutionary tree is a branching diagram or
"tree" showing the inferred evolutionary relationships among various
biological species or other entities based upon similarities and
differences in their physical and/or genetic characteristics
4. A vertebrate is an animal of a large group distinguished by the
possession of a backbone or spinal column, including mammals, birds,
reptiles,
5. b. ancestors