1. Chapter 36: Comparing Vertebrates
Section 1: Evolution of the Vertebrates

2. Evolution of the Vertebrates
Ever since the first vertebrates appeared more than 500 million years ago, they have been evolving
Have developed many new and unusual features
Sharper claws
Longer hair
Amniotic egg
Paired front and rear limbs

3. The Vertebrate Family Tree
Most scientists agree that:
Amphibians evolved from lobe-finned fish ancestors
Reptiles evolved from amphibian ancestors
Birds and mammals evolved from reptile ancestors

4. Trends in Vertebrate Evolution
Two general trends appear repeatedly during the course of vertebrate evolution
If closely related evolutionary lines are subjected to different forces of natural selection, they tend to become more dissimilar as they evolve
If evolutionary lines encounter extremely similar forces of natural selection, they tend to become more similar to one another as they evolve

5. Trends in Vertebrate Evolution
As different vertebrate groups evolved, they utilized the same basic sets of body parts for many uses
The pattern of evolution known as adaptive radiation is also known as divergent evolution
One species gives rise to many species that appear different externally but are similar internally

6. Trends in Vertebrate Evolution
Convergent evolution is just the opposite
Adaptive radiations among different organisms produce species that are similar in appearance and behavior

7. Body Temperature Control
Many chemical reactions work better at certain temperatures
When the body temperature is too low, animals slow down and become immobile
When the body temperature is too high, body systems are stressed and fail to function properly
Many techniques of temperature control have appeared in vertebrates
Incorporate three important features
A source of heat for the body
A way to conserve that heat
A method of eliminating excess heat when necessary

8. Chapter 36: Comparing Vertebrates
Section 2: Form and Function in Vertebrates

9. Form and Function in Vertebrates
Vertebrates perform the essential functions of life with a variety of body structures
Evolutionary processes have modified certain basic structures over time
As you move through the vertebrate classes from fishes to mammals, organ systems tend to become increasingly complex

10. Movement
All vertebrates except jawless fishes have a vertebral column (backbone) made of numerous individual bones called vertebrae
Connected to one another by tough ligaments that allow the vertebral column to bend to a certain extent
Two pairs of limbs are attached to this basic supporting structure by sets of bones called limb girdles
Most of the bones in the body can be made to move through the contraction of muscles that are attached to the bones

11. Movement Fish and snakes
Main body muscles are arranged into blocks that are positioned on either side of the vertebral column
Contract in waves, one after another
Make the body bend rapidly back and forth
Amphibians, reptiles, birds, and mammals
The position of the limbs relative to the body shifts toward the center
The movement of the vertebral column when the animal runs changes from a side-to-side motion to an up-and-down motion

12. Feeding The heads of vertebrates show many adaptations for feeding
The organs of the digestive systems of vertebrates are equally well adapted for different feeding habits
Carnivores
Short digestive tracts with special enzymes that break down meat
Herbivores
Long intestines and stomachs with bacteria that break down cellulose

13. Respiration Aquatic vertebrates Use gills for respiration
As water passes over the gill filaments, oxygen diffuses into the blood in the capillaries and carbon dioxide diffuses from the blood into the water
Terrestrial vertebrates
Use lungs to breathe
When the animals inhale, oxygen-rich air enters the lungs
When the animals exhale, carbon dioxide-rich air is expelled

14. Internal Transport Fishes and larval amphibians
Single-loop circulatory system
Blood travels from the heart to the gills to the body and back to the heart
Two chambered heart
Vertebrates with lungs
Double-loop circulatory system
Heart and lungs
Heart and body

15. Excretion
Excretory systems eliminate nitrogenous wastes and regulate the amount of water in the body
Most vertebrates rely on kidneys for excretion
Nitrogenous wastes are first produced in the form of ammonia
Aquatic amphibians and fish
Ammonia diffuses from the gills into the surrounding water
Mammals, terrestrial amphibians, and cartilaginous fishes
Ammonia is changed into urea
Reptiles and birds
Ammonia is changed into uric acid

16. Response All vertebrates display a high degree of cephalization
The size and complexity of the cerebrum and cerebellum increase as you move through the vertebrate classes from fish to mammals

17. Reproduction Almost all vertebrates reproduce sexually
In some vertebrates fertilization is external
In other fertilization occurs inside the body of the female

18. Reproduction Vertebrates show three different modes of development
Oviparous
Eggs develop outside the mother’s body
Ovoviviparous
Eggs develop inside the mother’s body but the embryos receive the nutrients they need from the yolk that surrounds them, not from the mother directly
Viviparous
Developing embryos obtain nutrients directly from the mother’s body