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PowerPoint Lectures for
Biology: Concepts & Connections, Sixth Edition
Campbell, Reece, Taylor, Simon, and Dickey
Chapter 19 The Evolution of Vertebrate
Diversity
Lecture by Joan Sharp
The duck-billed platypus is a strange animal and hard to classify
– It has a furry body, bill, and webbed feet, and it lays eggs
– It has mammary glands that produce milk for its young
– The platypus bill is not similar to that of a duck, but instead is a sensory organ for locating food underwater
– A large portion of the platypus brain is devoted to processing sensory information from its bill
The duck-billed platypus is a monotreme, a small group of egg-laying mammals
Introduction: What Am I?
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VERTEBRATE EVOLUTION AND DIVERSITY
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A phylogenetic tree for chordates is based on a sequence of derived characters
19.1 Derived characters define the major clades of chordates
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Ancestralchordate
Brain
Head
Vertebral column
Jaws
Lungs or lung derivatives
Lobed fins
Legs
Amniotic egg
Milk
Mammals
Reptiles
Amphibians
Lobe-fins
Ray-finned fishes
Sharks, rays
Lampreys
Hagfishes
Lancelets
TunicatesC
ran
iate
s
Am
nio
tes
Hagfishes and lampreys are craniates but lack hinged jaws and paired fins
– In hagfishes, the notochord is the body’s main support in the adult
– Lampreys have a supportive notochord but also have rudimentary vertebral structures, making them vertebrates
19.2 Hagfishes and lampreys lack hinged jaws
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Hagfishes are deep-sea scavengers that produce slime as an antipredator defense
Lampreys are parasites that penetrate the sides of fishes with their rasping tongues
– Larval lampreys resemble lancelets
– They are suspension feeders that live in freshwater streams, where they feed buried in sediment
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19.2 Hagfishes and lampreys lack hinged jaws
Slimeglands
Slimeglands
Novel vertebrate features arose 470 million years ago
– Paired fins and tail
– Hinged jaws
Where did jaws come from?
– They arose as modifications of skeletal supports of the anterior pharyngeal gill slits (originally used for trapping suspended food particles)
– The remaining gill slits remained as sites of gas exchange
19.3 Jawed vertebrates with gills and paired fins include sharks, ray-finned fishes, and lobe-finned fishes
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Gillslits
Skeletalrods
Skull
Mouth
Hinged jaw
There are three lineages of jawed fishes
– Class Chondrichthyes includes sharks and rays
– Ray-finned fishes and lobe-fins have lungs (or lung derivatives)
– Lobe-finned fishes have muscular fins supported by stout bones
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19.3 Jawed vertebrates with gills and paired fins include sharks, ray-finned fishes, and lobe-finned fishes
Chondrichthyans
– Sharks and rays have a flexible skeleton made of cartilage
– Most sharks are fast-swimming predators, with sharp vision and a keen sense of smell
– Electrosensors on their heads and a lateral line system aid them in locating prey
– Most rays are adapted for life on the bottom, with dorsoventrally flattened bodies and eyes on the top of their heads
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19.3 Jawed vertebrates with gills and paired fins include sharks, ray-finned fishes, and lobe-finned fishes
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19.3 Jawed vertebrates with gills and paired fins include sharks, ray-finned fishes, and lobe-finned fishes
Video: Seahorse Camouflage
Video: Coral Reef
Video: Clownfish and Anemone
Video: Manta Ray
Video: Shark Eating a Seal
Gillopenings
Ray-finned fishes have
– Internal skeleton reinforced with a hard matrix of CaPO3
– Flattened scales covered with mucus
– Operculum to move water over the gills
– Buoyant swim bladder (derived from an ancestral lung)
The diverse group of ray-finned fishes includes 27,000 species
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19.3 Jawed vertebrates with gills and paired fins include sharks, ray-finned fishes, and lobe-finned fishes
GillsBony skeleton Dorsal fin
Anal fin
Swim bladderPelvic finHeartPectoral fin
Operculum
Rainbow trout,a ray-fin
GillsBony skeleton Dorsal fin
Anal fin
Swim bladderPelvic finHeart
Pectoral fin
Operculum
Rainbow trout,a ray-fin
Lobe-fins
– Lobe-fins have muscular pelvic and pectoral fins, supported by rod-shaped bones
– Three lineages of lobe-fins survive
– Coelacanths
– Lungfishes
– Tetrapods
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19.3 Jawed vertebrates with gills and paired fins include sharks, ray-finned fishes, and lobe-finned fishes
During the late Devonian, a line of lobe-fin fishes gave rise to tetrapods, jawed vertebrates with limbs and feet
19.4 New fossil discoveries are filling in the gaps of tetrapod evolution
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Devonian Carboniferous
Ray-finned fish
Coelocanth
Lungfish
Eusthenopteron
Pandericthys
Tiktaalik
Acanthostega
Ichthyostega
Tetrapod with no gills,
limbs better-adapted
for bearing weight
Modern
amphibians
Reptiles (including birds) and mammalsTime known
to exist
420 400 380 360 340 320 300 280 260 0
Millions of years ago
Devonian Carboniferous
Ray-finned fish
Coelocanth
Lungfish
Time knownto exist
420 400 380 360 340 320 300 280 260 0
Millions of years ago
Devonian Carboniferous
Time knownto exist
Eusthenopteron
Pandericthys
Tiktaalik
Acanthostega
Ichthyostega
Tetrapod with no gills,limbs better-adapted
for bearing weight
420 400 380 360 340 320 300 280 260 0
Millions of years ago
Devonian Carboniferous
420 400 380 360 340 320 300 280 260 0
Millions of years ago
Modern
amphibians
Reptiles (including birds) and mammalsTime knownto exist
Bonessupportinggills
Tetrapodlimbskeleton
Amphibians were the first tetrapods able to move on land
– Most amphibians have tadpole larvae
This group includes frogs, salamanders, and caecilians
– Salamanders walk on land with a side-to-side bending
– Frogs hop with powerful hind legs
– Caecilians are blind and legless, burrowing in moist tropical soil
19.5 Amphibians are tetrapods—vertebrates with two pairs of limbs
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Reptiles (including birds) and mammals are amniotes
– The major derived character of this clade is an amniotic egg with an amnion, a private pond in which the embryo develops
Amniotic reptiles include lizards, snakes, turtles, crocodilians, and birds
– Terrestrial adaptations of reptiles include scales, waterproofed with keratin
– Nonbird reptiles are ectothermic, but regulate their temperature by basking or seeking shade
19.6 Reptiles are amniotes—tetrapods with a terrestrially adapted egg
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19.6 Reptiles are amniotes—tetrapods with a terrestrially adapted egg
Video: Galápagos Tortoise
Video: Galápagos Marine Iguana
Video: Snake Ritual Wrestling
Birds evolved from a lineage of small, two-legged dinosaurs called theropods
– Archaeopteryx is the oldest bird (150 million years old), with feathered wings
– It resembled a small bipedal dinosaur, with teeth, wing claws, and a long tail with many vertebrae
Living birds evolved from a lineage of birds that survived the Cretaceous extinctions
19.7 Birds are feathered reptiles with adaptations for flight
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Video: Soaring Hawk Video: Swans Taking Flight
Video: Flapping Geese
Wing claw(like dinosaur)
Feathers
Teeth(like dinosaur)
Long tail withmany vertebrae(like dinosaur)
Birds are reptiles with feathered wings, endothermic metabolism, and a number of adaptations for flight
– Loss of teeth
– Tail supported by only a few small vertebrae
– Feathers with hollow shafts
– Strong but light honeycombed bones
Flight is very costly, and birds are endotherms with a high rate of metabolism
Birds have relatively large brains and display complex behaviors
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19.7 Birds are feathered reptiles with adaptations for flight
Mammals are endothermic amniotes with hair, which insulates their bodies, and mammary glands, which produce milk
– Mammalians generally have larger relative brain size than other vertebrates and a relatively long period of parental care
19.8 Mammals are amniotes that have hair and produce milk
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The first true mammals arose 200 million years ago as small, nocturnal insectivores
– Marsupials diverged from eutherians (placental mammals) 180 million years ago
– They underwent an adaptive radiation following the Cretaceous extinction, giving rise to large terrestrial carnivores and herbivores, bats, and aquatic whales and porpoises
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19.8 Mammals are amniotes that have hair and produce milk
Monotremes are egg-laying mammals
– Living monotremes include the duck-billed platypus
Unlike monotremes, the embryos of marsupials and eutherians are nurtured by a placenta within the uterus
– The placenta allows nutrients from the mother’s blood to diffuse into the embryo’s blood
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19.8 Mammals are amniotes that have hair and produce milk
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19.8 Mammals are amniotes that have hair and produce milk
Video: Galápagos Sea Lion
Video: Bat Pollinating Agave Plant
Video: Bat Licking Nectar
Video: Wolves Agonistic Behavior
Marsupials have a brief gestation
– They give birth to tiny, embryonic offspring
– The offspring complete development attached to the mother’s nipples, usually inside a pouch or marsupium
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19.8 Mammals are amniotes that have hair and produce milk
Eutherians bear fully developed live young
– They are commonly called placental mammals, because their placentas are more complex than those of marsupials
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19.8 Mammals are amniotes that have hair and produce milk
PRIMATE DIVERSITY
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The mammalian order Primates includes the lemurs, tarsiers, monkeys, and apes
– Primates arose as small arboreal mammals before 65 million years ago
Many primate characters are arboreal adaptations
– Shoulder and hip joints allow climbing and brachiation
– Grasping hands and feet are highly mobile and flexible
– Sensitive hands and feet aid in manipulation
– A short snout and forward-pointing eyes enhance depth perception
19.9 The human story begins with our primate heritage
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A phylogenetic tree shows that all primates are divided into three groups
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19.9 The human story begins with our primate heritage
Lemurs, lorises,
and pottos
Tarsiers
New World monkeys
Old World monkeys
Gibbons
Orangutans
Gorillas
Chimpanzees
Humans
0
Millions of years ago
102030405060
Ancestral
primate
An
thro
po
ids
Ho
min
oid
s (a
pe
s)
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19.9 The human story begins with our primate heritage
The lorises, lemurs, and pottos make up one group of primates
– 32 living species of lemur are found only in Madagascar
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19.9 The human story begins with our primate heritage
The tarsiers form a second group of primates
– These small, nocturnal tree-dwellers have flat faces and large eyes
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19.9 The human story begins with our primate heritage
The anthropoid group includes monkeys, apes, and humans
– Anthropoids have large relative brain size
– They rely more on eyesight and less on olfaction than other mammals
– Anthropoids have fully opposable thumbs
Hominoids (apes) include gibbons, orangutans, gorillas, chimpanzees (and bonobos), and humans
– Nonhuman apes have a smaller geographic range than monkeys
– Nonhuman apes live only in Africa and Southeast Asia, in tropical rain forests
Apes have relatively large brain size and flexible behavior
Gorillas, chimpanzees, and humans have a high degree of social organization
19.10 Hominoids include humans and four other groups of apes
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Gibbons are the only fully arboreal apes
– They are monogamous
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19.10 Hominoids include humans and four other groups of apes
Video: Chimp Cracking Nut
Video: Chimp Agonistic Behavior
Video: Gibbons Brachiating
Orangutans are shy and solitary and live in rain-forest trees and the forest floor
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19.10 Hominoids include humans and four other groups of apes
Gorillas, the largest of the apes, are fully terrestrial
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19.10 Hominoids include humans and four other groups of apes
Chimpanzees make and use tools
Humans and chimpanzees diverged from a common ancestor between 5 and 7 million years ago
– They share 99% of their genes
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19.10 Hominoids include humans and four other groups of apes
HOMINID EVOLUTION
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The oldest possible hominid yet discovered, Sakelanthropus tchadensis, lived about 7 to 6 million years ago
The fossil record suggests that hominid diversity increased dramatically between 4 to 2 million years ago
19.11 The hominid branch of the primate tree is only a few million years old
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Australopithecus
anamensis
Australopithecus
afarensis
Australopithecus
africanus
Paranthropus
boisei
Paranthropus
robustus
Homo
ergaster?
Homo
sapiens
Homo
neanderthalensis
Homo
erectus
Homo
habilisKenyanthropus
platyops
Ardipithecus
ramidus
Sahelanthropus
tchadensis
Orrorin tugenensis
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.5
5.5
5.0
4.0
6.0
7.0
6.5
Bipedalism arose 4 million years ago in the first australopiths
– A large brain evolved later
What is the evidence for this?
– Evidence from fossil trackways
– Evidence from hominid fossils
19.12 Upright posture evolved long before an enlarged brain
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Ancientfootprints
Homo sapiens has a brain size of around 1350 cc, triple that of australopiths
Homo habilis (2.4 million years ago) had a brain size of 500–800 cc
– Their fossils are found with stone tools
Homo ergaster (1.9–1.6 million years ago) had a brain size ranging from 850–1,100 cc
– Their fossils associated with more sophisticated stone tools
– Their long, slender legs were adapted for long-distance walking
19.13 Larger brains mark the evolution of Homo
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Homo erectus, with a brain volume of around 1,000 cc, was the first hominid to leave Africa
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19.13 Larger brains mark the evolution of Homo
Neanderthals lived in Europe until 30,000–40,000 years ago and were sympatric with our Cro-Magnon ancestors
– Neanderthals were muscular and robust, with a brain that was similar in size but distinct in shape to the human brain
– Neanderthals had large noses, heavy brows and cheekbones, and hunting tools made of stone and wood
19.14 Neanderthals and our human ancestors diverged half a million years ago
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Did Neanderthals interbreed with Cro-Magnons?
– A 1997 analysis of mtDNA isolated from Neanderthal bones suggests that they were a distinct species from modern humans
– The last common ancestor to humans and Neanderthals lived 500,000 years ago
– There is a current project to sequence Neanderthal DNA
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19.14 Neanderthals and our human ancestors diverged half a million years ago
Approximate rangeof Neanderthals
35,000 years ago
30,000–35,000 years ago
30,000 years ago
Key
Europe
Africa
Neander Valley
Original discovery
Atlantic Ocean
Black Sea
Mediterranean Sea
Analysis of mtDNA and Y chromosomes suggest that
– All living humans inherited their mtDNA from a woman who lived 160,000–200,000 years ago
– All living humans diverged from a common African ancestor
19.15 From origins in Africa, Homo sapiens spread around the world
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Our species emerged from Africa in one or more waves, migrating to Asia 50–60,000 years ago and then to Europe, Southeast Asia, and Australia
The capacity for creativity and symbolic thought may have triggered human evolution
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19.15 From origins in Africa, Homo sapiens spread around the world
NorthAmerica
SouthAmerica
Australia
Asia
Europe
Africa
100,000 BP
40,000 BP
50–60,000 BP
>40,000 BP(50–60,000?)
15–35,000 BP
Language is a uniquely human trait that permits the creation of human cultures
– Humans can use language in abstract ways
Linguistic ability has been linked to the human version of the FOXP2 gene
– FOXP2 (found in many vocalizing animals) codes for a transcription factor that controls the expression of many genes
– The human form of FOXP2 arose within the last 100,000 years
19.16 A genetic difference helped humans start speaking
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Human skin color varies geographically, likely as a result of natural selection
Natural selection may have balanced
– Skin’s ability to block UV radiation, which degrades folate, and
– Skin’s ability to absorb UV radiation in order to synthesize vitamin D
– Folate is vital for fetal development and spermatogenesis
– Vitamin D is essential for proper bone development (especially in pregnant women and small children)
19.17 EVOLUTION CONNECTION: Human skin color reflects adaptations to varying amounts of sunlight
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Introduced species are threatening Australia’s native animals
– The catlike quoll is a marsupial predator, endemic to Australia
– Quolls are dying because they feed on introduced poisonous cane toads
– Australia has moved some threatened species to uninhabited offshore islands that lack invasive species
19.18 CONNECTION: Humans threaten animal diversity by introducing non-native species
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Ancestralchordate
a.
b.
c.
d.
e.
f.
g.
h.
i.
Mammals
Reptiles
Amphibians
Lobe-fins
Ray-finned fishes
Sharks, rays
Lampreys
Hagfishes
Lancelets
Tunicates
1. Describe the key derived traits of chordates and chordate taxa
2. Describe the characteristics of the following vertebrate groups: hagfishes, lampreys, chondrichthyans, ray-finned fishes, lobe-finned fishes, amphibians, reptiles, birds, and mammals
3. Describe the transitional forms of animals from fish to amphibian
You should now be able to
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4. Distinguish between monotremes, marsupials, and placental mammals; note an example of each
5. Compare the three main groups of primates; list their characteristics and describe their evolutionary relationships
6. Distinguish between hominoids, hominids, australopiths, and members of the genus Homo
7. Describe the evidence that suggests when upright posture first evolved in humans
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You should now be able to
8. Describe the evolution of larger brain size in hominids
9. Describe the relationship between Neanderthals, Cro-Magnons, and modern humans
10. Explain how the FOXP2 gene may have influenced human evolution
11. Explain why skin color is not a reliable indicator of phylogenetic relationships
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You should now be able to