Chapter 36: Comparing Vertebrates Section 1: Evolution of the Vertebrates.
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Transcript of Chapter 36: Comparing Vertebrates Section 1: Evolution of the Vertebrates.
![Page 1: Chapter 36: Comparing Vertebrates Section 1: Evolution of the Vertebrates.](https://reader036.fdocuments.net/reader036/viewer/2022082611/56649e305503460f94b20398/html5/thumbnails/1.jpg)
Chapter 36: Comparing Vertebrates
Section 1: Evolution of the Vertebrates
![Page 2: Chapter 36: Comparing Vertebrates Section 1: Evolution of the Vertebrates.](https://reader036.fdocuments.net/reader036/viewer/2022082611/56649e305503460f94b20398/html5/thumbnails/2.jpg)
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
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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
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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
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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
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Trends in Vertebrate Evolution
Convergent evolution is just the opposite Adaptive radiations among different
organisms produce species that are similar in appearance and behavior
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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
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Chapter 36: Comparing Vertebrates
Section 2: Form and Function in Vertebrates
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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
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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
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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
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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
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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
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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
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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
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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
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Reproduction
Almost all vertebrates reproduce sexually In some vertebrates fertilization is external In other fertilization occurs inside the body of
the female
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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