Download Chapter 19--vertebrates

Chapter 13
How Populations Evolve
PowerPoint Lectures for
Campbell Biology: Concepts & Connections, Seventh Edition
Reece, Taylor, Simon, and Dickey
© 2012 Pearson Education, Inc.
Lecture by Edward J. Zalisko
THE EVOLUTION OF
POPULATIONS
(Sections 13.7-13.8)
© 2012 Pearson Education, Inc.
13.7 Evolution occurs within populations
 A population is
– a group of individuals of the same species and
– living in the same place at the same time.
 Populations may be isolated from one another
(with little interbreeding).
 Individuals within populations may interbreed.
 We can measure evolution as a change in
heritable traits in a population over generations.
© 2012 Pearson Education, Inc.
13.7 Evolution occurs within populations
 A gene pool is the total collection of genes in a
population at any one time.
 Microevolution is a change in the relative
frequencies of alleles in a gene pool over time.
© 2012 Pearson Education, Inc.
13.7 Evolution occurs within populations
 Population genetics studies how populations
change genetically over time.
© 2012 Pearson Education, Inc.
13.8 Mutation and sexual reproduction produce
the genetic variation that makes evolution
possible
 Organisms typically show individual variation.
 However, in The Origin of Species, Darwin could
not explain
– the cause of variation among individuals or
– how variations were passed from parents to offspring.
© 2012 Pearson Education, Inc.
Figure 13.8
13.8 Mutation and sexual reproduction produce
the genetic variation that makes evolution
possible
 Mutations are
– changes in the nucleotide sequence of DNA and
– the ultimate source of new alleles.
© 2012 Pearson Education, Inc.
13.8 Mutation and sexual reproduction produce
the genetic variation that makes evolution
possible
 On rare occasions, mutant alleles improve the
adaptation of an individual to its environment.
– This kind of effect is more likely when the environment is
changing such that mutations that were once
disadvantageous are favorable under new conditions.
– The evolution of DDT-resistant houseflies is such an
example.
© 2012 Pearson Education, Inc.
13.8 Mutation and sexual reproduction produce
the genetic variation that makes evolution
possible
 Chromosomal duplication is an important source of
genetic variation.
– If a gene is duplicated, the new copy can undergo
mutation without affecting the function of the original
copy.
– For example, an early ancestor of mammals had a
single gene for an olfactory receptor. That gene has
been duplicated many times, and mice now have 1,300
different olfactory receptor genes.
© 2012 Pearson Education, Inc.
13.8 Mutation and sexual reproduction produce
the genetic variation that makes evolution
possible
 Sexual reproduction shuffles alleles to produce
new combinations in three ways.
1. Homologous chromosomes sort independently as they
separate during anaphase I of meiosis.
2. During prophase I of meiosis, pairs of homologous
chromosomes cross over and exchange genes.
3. Further variation arises when sperm randomly unite with
eggs in fertilization.
© 2012 Pearson Education, Inc.
Chapter 14
The Origin of Species
PowerPoint Lectures for
Campbell Biology: Concepts & Connections, Seventh Edition
Reece, Taylor, Simon, and Dickey
© 2012 Pearson Education, Inc.
Lecture by Edward J. Zalisko
DEFINING SPECIES
(Sections 14.1-14.3)
© 2012 Pearson Education, Inc.
14.1 The origin of species is the source of
biological diversity
 Microevolution is the change in the gene pool of a
population from one generation to the next.
 Speciation is the process by which one species
splits into two or more species.
– Every time speciation occurs, the diversity of life
increases.
– The many millions of species on Earth have all arisen
from an ancestral life form that lived around 3.5 billion
years ago.
© 2012 Pearson Education, Inc.
14.2 There are several ways to define a species
 The word species is from the Latin for “kind” or
“appearance.”
 Although the basic idea of species as distinct lifeforms seems intuitive, devising a more formal
definition is not easy and raises questions.
– How similar are members of the same species?
– What keeps one species distinct from others?
© 2012 Pearson Education, Inc.
14.2 There are several ways to define a species
 The biological species concept defines a
species as
– a group of populations,
– whose members have the potential to interbreed in
nature, and
– produce fertile offspring.
– Therefore, members of a species are similar because
they reproduce with each other.
© 2012 Pearson Education, Inc.
14.2 There are several ways to define a species
 Reproductive isolation
– prevents members of different species from mating with
each other,
– prevents gene flow between species, and
– maintains separate species.
– Therefore, species are distinct from each other because
they do not share the same gene pool.
© 2012 Pearson Education, Inc.
Figure 14.2A
Figure 14.2B
14.2 There are several ways to define a species
 The biological species concept can be problematic.
– Some pairs of clearly distinct species occasionally
interbreed and produce hybrids.
– For example, grizzly bears and polar bears may interbreed and
produce hybrids called grolar bears.
– Melting sea ice may bring these two bear species together more
frequently and produce more hybrids in the wild.
– Reproductive isolation cannot usually be determined for
extinct organisms known only from fossils.
– Reproductive isolation does not apply to prokaryotes or
other organisms that reproduce only asexually.
– Therefore, alternate species concepts can be useful.
© 2012 Pearson Education, Inc.
Figure 14.2C
Grizzly bear
Polar bear
Hybrid “grolar” bear
14.2 There are several ways to define a species
 The morphological species concept
– classifies organisms based on observable physical traits
and
– can be applied to
– asexual organisms and
– fossils.
– However, there is some subjectivity in deciding which traits to
use.
© 2012 Pearson Education, Inc.
14.2 There are several ways to define a species
 The ecological species concept
– defines a species by its ecological role or niche and
– focuses on unique adaptations to particular roles in a
biological community.
– For example, two species may be similar in appearance
but distinguishable based on
– what they eat or
– where they live.
© 2012 Pearson Education, Inc.
14.2 There are several ways to define a species
 The phylogenetic species concept
– defines a species as the smallest group of individuals that
shares a common ancestor and thus
– forms one branch of the tree of life.
– Biologists trace the phylogenetic history of a species by
comparing its
– morphology or
– DNA.
– However, defining the amount of difference required to
distinguish separate species is a problem.
© 2012 Pearson Education, Inc.
14.3 Reproductive barriers keep species separate
 Reproductive barriers
– serve to isolate the gene pools of species and
– prevent interbreeding.
 Depending on whether they function before or after
zygotes form, reproductive barriers are categorized
as
– prezygotic or
– postzygotic.
© 2012 Pearson Education, Inc.
Figure 14.3A
Individuals of different species
Prezygotic Barriers
Habitat isolation
Temporal isolation
Behavioral isolation
Mechanical isolation
Gametic isolation
Fertilization
Postzygotic Barriers
Reduced hybrid viability
Reduced hybrid fertility
Hybrid breakdown
Viable, fertile offspring
14.3 Reproductive barriers keep species separate
 Five types of prezygotic barriers prevent mating or
fertilization between species.
1. In habitat isolation, two species live in the same general
area but not in the same kind of place.
2. In temporal isolation, two species breed at different times
(seasons, times of day, years).
© 2012 Pearson Education, Inc.
Figure 14.3B
Figure 14.3C
14.3 Reproductive barriers keep species separate
 Prezygotic Barriers, continued
3. In behavioral isolation, there is little or no mate
recognition between females and males of different
species.
4. In mechanical isolation, female and male sex organs are
not compatible.
5. In gametic isolation, female and male gametes are not
compatible.
© 2012 Pearson Education, Inc.
14.3 Reproductive barriers keep species separate
 Three types of postzygotic barriers operate after
hybrid zygotes have formed.
1. In reduced hybrid viability, most hybrid offspring do not
survive.
2. In reduced hybrid fertility, hybrid offspring are vigorous
but sterile.
3. In hybrid breakdown,
– the first-generation hybrids are viable and fertile but
– the offspring of the hybrids are feeble or sterile.
© 2012 Pearson Education, Inc.
Figure 14.3G
Horse
Donkey
Mule
Chapter 19
The Evolution of Vertebrate
Diversity
PowerPoint Lectures for
Campbell Biology: Concepts & Connections, Seventh Edition
Reece, Taylor, Simon, and Dickey
© 2012 Pearson Education, Inc.
Lecture by Edward J. Zalisko
Introduction
 The duck-billed platypus is a strange animal and
hard to classify. It has
– a furry body,
– bill and webbed feet that look like a duck, and
– mammary glands that produce milk for its young.
– In addition, it lays eggs!
© 2012 Pearson Education, Inc.
Figure 19.0_1
Chapter 19: Big Ideas
Vertebrate Evolution and
Diversity
Hominin Evolution
Primate Diversity
Figure 19.0_2
VERTEBRATE EVOLUTION
AND DIVERSITY
© 2012 Pearson Education, Inc.
19.1 Derived characters define the major clades of
chordates
 Biologists have developed a phylogenetic tree of
chordate groups using
– anatomical,
– molecular, and
– fossil evidence.
 Figure 19.1
– illustrates a current view of the major clades of
chordates and
– lists some of the derived characters that define the
clades.
© 2012 Pearson Education, Inc.
Figure 19.1
Ancestral
chordate
Chordates
Tunicates
Lancelets
Brain
Head
Vertebral column
Jawed vertebrates
Sharks,
rays
Ray-finned
fishes
Jaws
Lobe-fins
Lungs or lung derivatives
Lobed fins
Amniotic egg
Mammals
Milk
Amniotes
Reptiles
Legs
Tetrapods
Amphibians
Vertebrates
Lampreys
Craniates
Hagfishes
19.2 Hagfishes and lampreys lack hinged jaws
 Hagfishes and lampreys
– are craniates,
– have a notochord, but
– lack hinged jaws and paired fins.
 Lampreys but not hagfishes have rudimentary
vertebral structures. Thus,
– lampreys are vertebrates but
– hagfishes are not vertebrates.
© 2012 Pearson Education, Inc.
19.2 Hagfishes and lampreys lack hinged jaws
 Hagfishes are deep-sea scavengers that produce
slime as an antipredator defense.
 Lamprey adults are parasites that penetrate the
sides of fishes with their rasping tongues.
 Larval lampreys
– resemble lancelets and
– are suspension feeders that live in freshwater streams,
where they feed, buried in sediment.
© 2012 Pearson Education, Inc.
Figure 19.2A
Slime glands
Figure 19.2B
19.3 Jawed vertebrates with gills and paired fins
include sharks, ray-finned fishes, and lobefinned fishes
 Jawed vertebrates
– appeared in the fossil record about 470 million years ago
and
– quickly diversified using their paired fins and tail to chase
a wide variety of prey.
 Jaws may have evolved by modifications of skeletal
supports of the anterior pharyngeal (gill) slits.
 The remaining gill slits remained as sites of gas
exchange.
© 2012 Pearson Education, Inc.
Figure 19.3A
Gill Skeletal
rods Skull
slits
Mouth
Hinged jaw
19.3 Jawed vertebrates with gills and paired fins
include sharks, ray-finned fishes, and lobefinned fishes
 Three lineages of jawed fishes with gills and paired
fins are commonly called fishes:
1. chondrichthyans—sharks and rays,
2. ray-finned fishes—tuna, trout, and goldfish, and
3. lobe-finned fishes—coelacanths and lungfishes.
© 2012 Pearson Education, Inc.
19.3 Jawed vertebrates with gills and paired fins
include sharks, ray-finned fishes, and lobefinned fishes
 Chondrichthyans have
– a flexible skeleton made of cartilage,
– electrosensors on their heads, and
– a lateral line system that helps them locate prey.
– Most sharks are fast-swimming predators, with sharp
vision and a keen sense of smell.
– Most rays are adapted for life on the bottom, with
dorsoventrally flattened bodies and eyes on the top of
their heads.
© 2012 Pearson Education, Inc.
Figure 19.3B
Gill openings
Figure 19.3C
19.3 Jawed vertebrates with gills and paired fins
include sharks, ray-finned fishes, and lobefinned fishes
 Ray-finned fishes have
– an internal skeleton reinforced with a hard matrix of
calcium phosphate,
– flattened scales covered with mucus,
– an operculum that covers a chamber of gills, and
– a buoyant swim bladder (derived from an ancestral
lung).
 With more than 27,000 species, ray-finned fishes
are the most diverse group of vertebrates.
© 2012 Pearson Education, Inc.
Figure 19.3D
Bony skeleton
Dorsal fin
Gills
Operculum
Pectoral fin
Anal fin
Heart
A rainbow trout,
a ray-fin
Swim bladder
Pelvic fin
Figure 19.3E
A seahorse
A balloon fish
A flounder
19.3 Jawed vertebrates with gills and paired fins
include sharks, ray-finned fishes, and lobefinned fishes
 Lobe-fins have muscular pelvic and pectoral fins
that are supported by rod-shaped bones.
 Today, three lineages of lobe-fins survive:
1. coelacanths, living deep in the oceans, were once
thought to be extinct,
2. lungfishes, which can gulp air into lungs, inhabit
stagnant waters in the Southern Hemisphere, and
3. tetrapods, adapted to life on land, include terrestrial
vertebrates.
© 2012 Pearson Education, Inc.
Figure 19.3F
19.4 EVOLUTION CONNECTION: New fossil
discoveries are filling in the gaps of tetrapod
evolution
 During the late Devonian, a line of lobe-finned
fishes gave rise to tetrapods, jawed vertebrates
with limbs and feet that can support weight on land.
 Adapting to life on land was a key event in
vertebrate history.
 All subsequent groups are descendants of these
early land-dwellers.
© 2012 Pearson Education, Inc.
19.4 EVOLUTION CONNECTION: New fossil
discoveries are filling in the gaps of tetrapod
evolution
 Like plants, vertebrates faced obstacles on land in
regard to
– gas exchange,
– water conservation,
– structural support,
– a means of locomotion,
– adapting sensory organs that worked well in water but
not on land, and
– reproduction.
© 2012 Pearson Education, Inc.
19.5 Amphibians are tetrapods—vertebrates with
two pairs of limbs
 Amphibians
– include salamanders, frogs, and caecilians,
– use their moist skins to supplement their lungs for gas
exchange,
– often have poison glands in their skins,
– usually return to standing water to reproduce,
– undergo metamorphosis from a larval stage to the adult
form, and
– were the first tetrapods able to move on land.
© 2012 Pearson Education, Inc.
Figure 19.5C
Figure 19.5D-E
19.6 Reptiles are amniotes—tetrapods with a
terrestrially adapted egg
 Reptiles (including birds) and mammals are
amniotes.
 The major derived character of this clade is an
amniotic egg with four internal membranes.
1. The amnion is a fluid-filled sac surrounding the embryo.
2. The yolk sac contains a rich store of nutrients for the
developing embryo.
3. The allantois also helps dispose of metabolic waste.
4. The chorion (and allantois) enable the embryo to obtain
oxygen from the air and dispose of carbon dioxide.
© 2012 Pearson Education, Inc.
19.6 Reptiles are amniotes—tetrapods with a
terrestrially adapted egg
 Reptiles
– include lizards, snakes, turtles, crocodilians, birds, and
extinct dinosaurs,
– have a skin covered with scales and waterproofed with
keratin,
– obtain most of their oxygen using lungs, and
– are ectothermic, absorbing external heat rather than
generating much of their own.
© 2012 Pearson Education, Inc.
Figure 19.6A
Figure 19.6B
Embryo
Amniotic
cavity with
amniotic fluid
Allantois
Chorion
Amnion
Yolk
(nutrients)
Yolk sac
Shell
Albumen
Figure 19.6C
19.7 Birds are feathered reptiles with adaptations
for flight
 Most birds can fly, and nearly every part of their
bodies reflects adaptations that enhance flight.
– The forelimbs have been remodeled as feather-covered
wings that act as airfoils.
– Large flight muscles anchored to a central ridge along
the breastbone provide power.
– Many features help reduce weight for flight:
– Present-day birds lack teeth.
– The tail is supported by only a few small vertebrae.
– Feathers have hollow shafts.
– Their bones have a honeycombed structure that makes them
strong but light.
© 2012 Pearson Education, Inc.
19.7 Birds are feathered reptiles with adaptations
for flight
 Flight is very costly, and present-day birds have a
high rate of metabolism.
 Unlike other living reptiles, birds are endothermic,
using heat generated by metabolism to maintain a
warm, steady body temperature.
 Birds have relatively large brains and display
complex behaviors. They have
– acute senses,
– fine muscle control, and
– excellent eyesight.
© 2012 Pearson Education, Inc.
Figure 19.7A
Figure 19.7B
19.7 Birds are feathered reptiles with adaptations
for flight
 Birds evolved from a lineage of small, two-legged
dinosaurs called theropods.
– Archaeopteryx is the oldest, most primitive known 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.
© 2012 Pearson Education, Inc.
Figure 19.7C
Teeth
(like dinosaur)
Wing claw (like dinosaur)
Long tail with
many vertebrae
(like dinosaur)
Feathers
19.8 Mammals are amniotes that have hair and
produce milk
 Mammals are endothermic amniotes with
– hair, which insulates their bodies, and
– mammary glands, which produce milk.
 Mammals have efficient respiratory and circulatory
systems that support their high rate of metabolism.
 Mammalian teeth are differentiated for many kinds
of diets.
© 2012 Pearson Education, Inc.
19.8 Mammals are amniotes that have hair and
produce milk
 Monotremes are egg-laying mammals. Living
monotremes include
– the duck-billed platypus and
– echidnas.
 Unlike monotremes, the embryos of marsupials and
eutherians are nurtured by a placenta, in which
nutrients from the mother’s blood diffuse into the
embryo’s blood.
© 2012 Pearson Education, Inc.
Figure 19.8A
19.8 Mammals are amniotes that have hair and
produce milk
 Marsupials have a brief gestation and give birth to
tiny, embryonic offspring that complete development
while attached to the mother’s nipples.
 Eutherians are mammals that bear fully developed
live young. They are commonly called placental
mammals because their placentas are more
complex than those of marsupials.
© 2012 Pearson Education, Inc.
Figure 19.8B
Figure 19.8C
19.8 Mammals are amniotes that have hair and
produce milk
 The first true mammals arose 200 million years ago
and were probably small, nocturnal insectivores.
– Monotremes are the oldest lineage of mammals.
– Marsupials diverged from eutherians (placental mammals)
about 180 million years ago.
– Mammals underwent an adaptive radiation following the
Cretaceous extinction of dinosaurs, giving rise to large
terrestrial carnivores and herbivores, bats, and aquatic
whales and porpoises.
© 2012 Pearson Education, Inc.
PRIMATE DIVERSITY
© 2012 Pearson Education, Inc.
19.9 The human story begins with our primate
heritage
 The mammalian order Primates includes the lemurs,
tarsiers, monkeys, and apes.
– Primates probably arose as small arboreal mammals
before 65 million years ago, when dinosaurs still
dominated the planet.
 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.
© 2012 Pearson Education, Inc.
Figure 19.9A
19.9 The human story begins with our primate
heritage
 A phylogenetic tree shows that all primates are
divided into three groups:
1. lemurs, lorises, and pottos,
2. tarsiers,
3. anthropoids, including monkeys and apes with a fully
opposable thumb, in which the tip of all four fingers
can touch the thumb.
© 2012 Pearson Education, Inc.
Figure 19.9B
Lemurs, lorises,
and pottos
Ancestral
primate
Tarsiers
Orangutans
Gorillas
Chimpanzees
Humans
60
50
30
40
Millions of years ago
20
10
0
Apes
Gibbons
Anthropoids
Old World monkeys
Monkeys
New World monkeys
19.9 The human story begins with our primate
heritage
 Monkeys do not constitute a monophyletic group.
– Old World monkeys (Africa and Asia)
– probably evolved first,
– lack a prehensile tail, and
– have nostrils that open downward.
– New World monkeys have
– a prehensile tail and
– nostrils that are wide open and farther apart.
© 2012 Pearson Education, Inc.
Figure 19.9C
Figure 19.9D
Figure 19.9E
A golden lion
tamarin
(note nostrils that
open to the side)
A black spider
monkey (note
prehensile tail)
Figure 19.9F
19.10 Humans and four other groups of apes are
classified as anthropoids
 In addition to monkeys, the anthropoid group
includes apes: gibbons, orangutans, gorillas,
chimpanzees (and bonobos), and humans.
 Apes
– lack a tail and
– have relatively long arms and short legs,
– have relatively larger brains with respect to size, and
– more flexible behavior.
© 2012 Pearson Education, Inc.
19.10 Humans and four other groups of apes are
classified as anthropoids
 Gorillas, chimpanzees, and humans have a high
degree of social organization.
 Nonhuman apes
– live only in Africa and Southeast Asia, in tropical rain
forests and
– have a smaller geographic range than monkeys.
© 2012 Pearson Education, Inc.
Figure 19.10
A gibbon
An orangutan
A chimpanzee
A gorilla and offspring
19.10 Humans and four other groups of apes are
classified as anthropoids
 Gibbons are
– monogamous and
– the only fully arboreal apes.
© 2012 Pearson Education, Inc.
Figure 19.10_2
A gibbon
19.10 Humans and four other groups of apes are
classified as anthropoids
 Orangutans are
– shy,
– solitary, and
– live in rain-forest trees and the forest floor.
© 2012 Pearson Education, Inc.
Figure 19.10_3
An orangutan
19.10 Humans and four other groups of apes are
classified as anthropoids
 Gorillas are
– the largest of the apes and
– fully terrestrial.
© 2012 Pearson Education, Inc.
Figure 19.10_4
A gorilla and offspring
19.10 Humans and four other groups of apes are
classified as anthropoids
 Chimpanzees make and use tools.
 Humans and chimpanzees
– are closely related,
– share 99% of their genes, and
– diverged from a common ancestor between 5 and 7
million years ago.
© 2012 Pearson Education, Inc.
Figure 19.10_1
A chimpanzee
HOMININ EVOLUTION
© 2012 Pearson Education, Inc.
19.11 The hominin branch of the primate tree
includes species that coexisted
 Paleoanthropology is the study of human origins
and evolution, the brief history since the divergence
of human and chimpanzee lineages.
 Paleoanthropologists have unearthed
– about 20 species of extinct hominins, species that are
more closely related to humans than to chimpanzees, and
– thousands of hominin fossils.
 Figure 19.11 presents some of the known hominins.
© 2012 Pearson Education, Inc.
Figure 19.11
0
Paranthropus
robustus
0.5
1.5
Millions of years ago
2.5
3.0
5.5
Australopithecus
anamensis
(fragments)
Homo
erectus
Homo
habilis
Kenyanthropus
platyops
Ardipithecus
ramidus
6.0
6.5
7.0
Homo
neanderthalensis
Australopithecus
afarensis
4.5
5.0
Homo
sapiens
Australopithecus
africanus
3.5
4.0
?
Paranthropus
boisei
1.0
2.0
Homo
ergaster
Sahelanthropus
tchadensis
19.12 Australopiths were bipedal and had small
brains
 Unlike chimpanzees, humans
– walk upright and
– have larger brains.
 Bipedalism arose millions of years before larger
brain size. Evidence of bipedalism includes
– 3.6-million-year-old upright-walking hominin footprints
and
– fossil skeletons.
© 2012 Pearson Education, Inc.
Figure 19.12A
Figure 19.12B
19.13 Larger brains mark the evolution of Homo
 Australopiths had such small brains (400–450 cc)
that they were too small to be members of Homo.
 Homo habilis (2.4–1.6 million years ago) had a brain
size of 510–690 cc. Their fossils are found with
stone tools.
 Homo ergaster (1.9–1.6 million years ago) had a
brain size ranging from 750 to 850 cc. Their
– fossils are found with more sophisticated stone tools and
– long, slender legs were adapted for long-distance
walking.
 Homo sapiens has a brain size of around 1,300 cc.
© 2012 Pearson Education, Inc.
Figure 19.13A
1,500
Homo neanderthalensis
Homo
sapiens
Mean brain volume (cm3)
1,300
1,100
Homo erectus
900
Homo ergaster
700
500
300
0
20
Homo
habilis
Paranthropus boisei
Chimpanzee
Australopithecus
afarensis
40
60
80
100
Mean body mass (kg)
Gorilla
120
19.13 Larger brains mark the evolution of Homo
 Homo erectus
– had a brain volume of around 940 cc and
– was the first hominin to leave Africa.
 The oldest known fossils of hominins outside of
Africa are about 1.8 million years old.
© 2012 Pearson Education, Inc.
19.13 Larger brains mark the evolution of Homo
 Homo neanderthalensis, commonly called
Neanderthals
– lived in Europe from about 350,000 to 28,000 years ago
when they went extinct,
– had brains as large as modern humans, and
– hunted big game with tools made of stone and wood.
© 2012 Pearson Education, Inc.
Figure 19.13B
Key
30,000 years ago
30,00035,000 years ago
35,000 years ago
Atlantic Ocean
Original discovery
(Neander Valley)
Approximate range
of Neanderthals
Europe
Asia
Black Sea
Mediterranean Sea
Africa
19.13 Larger brains mark the evolution of Homo
 How are Neanderthals related to modern humans?
– An analysis of mtDNA isolated from Neanderthal bones
suggests that they were a distinct species from modern
humans.
– The last common ancestor between humans and
Neanderthals lived about 500,000 years ago.
© 2012 Pearson Education, Inc.
19.14 From origins in Africa, Homo sapiens
spread around the world
 Analysis of mtDNA and Y chromosomes suggests
that all living humans
– inherited their mtDNA from a woman who lived
160,000–200,000 years ago and
– diverged from a common African ancestor.
© 2012 Pearson Education, Inc.
19.14 From origins in Africa, Homo sapiens
spread around the world
 Our species emerged from Africa in one or more
waves, migrating to Asia 50,000–60,000 years ago
and then to Europe, Southeast Asia, and Australia.
 The capacity for creativity and symbolic thought
may have spurred human evolution.
© 2012 Pearson Education, Inc.
Figure 19.14
15,00035,000 BP
Europe
40,000 BP
North
America
Asia
50,00060,000 BP
Africa
100,000 BP
South
America
40,000 BP
(50,00060,000?)
Australia
19.15 Who were the “hobbits”?
 Fossils of small hominins named Homo floresiensis
that were found in Indonesia are controversial. The
2004 discovery of the nearly complete skeleton
was of a hominin that
– was about 1 meter tall,
– had a chimp-sized brain, and
– had a skull that displayed some humanlike traits.
 Scientists are trying to determine their relationship
to other hominins.
© 2012 Pearson Education, Inc.
Figure 19.15
19.17 CONNECTION: Our knowledge of animal
diversity is far from complete
 Thousands of new species of organisms are
discovered each year.
 Over half of newly discovered species are insects.
 The pace of discovery has recently increased due to
– better access to remote areas and
– new mapping technologies.
© 2012 Pearson Education, Inc.
Figure 19.UN03
Tunicates
Lancelets
Ancestral
chordate
Hagfishes
a.
Lampreys
b.
Sharks, rays
c.
Ray-finned fishes
d.
Lobe-fins
e.
Amphibians
f.
Reptiles
g.
Mammals
h.
i.