Handout #12

Eukaryota is the other main branch of evolution
Alveolates have sacs beneath the plasma
membrane and include dinoflagellates,
apicomplexans, and ciliates
Apex
Red blood cell
TEM 26,000!
– Dinoflagellates are unicellular algae
– Apicomplexans are parasites
• Plasmodium, which causes malaria (300 million per
year with 2 million deaths
Amoebozoans have pseudopodia and include amoebas and slime
molds
Amoebas move and feed by means of pseudopodia
A plasmodial slime mold is a multinucleate plasmodium
Cellular slime molds have unicellular and multicellular stages
45!
–
–
–
15!
Amoeboid cells
LM 1,000!
Slug-like aggregate
Reproductive
structure
Red algae and green algae are the closest
relatives of land plants
– Red algae contribute to coral reefs
– Green algae may be unicellular, colonial, or multicellular
Chlamydomonas
LM 80 !
LM 1,200 !
Volvox colonies
Red algae and green algae are the closest relatives of land plants
–
–
–
Red algae contribute to coral reefs
Green algae may be unicellular, colonial, or multicellular
The life cycles of many algae involve the alternation of haploid
gametophyte and diploid sporophyte generations
Mitosis
Male
gametophyte
Spores
Gametes
Mitosis
Meiosis
Female
gametophyte
Fusion of
gametes
Sporophyte
Zygote
Mitosis
Eukaryotic evolution
Key
Haploid (n)
Diploid (2n)
Animal development
• May include a blastula, gastrula, and larval stage
Key
Haploid (n)
Sperm
Diploid (2n)
2
1
Meiosis
Adult
8
Egg
Zygote
(fertilized egg)
3
Eight-cell stage
Metamorphosis
4
Blastula
(cross section)
Digestive tract
Ectoderm
Larva
7
Endoderm
Internal sac
Animal diversity
6
Future
Later gastrula mesoderm
(cross section)
5
Early gastrula
(cross section)
Animals can be characterized by basic features of their “body
plan”
– Animal body plans
• May vary in symmetry
Top
Dorsal surface
Anterior
end
Posterior
end
Ventral surface
Figure 18.3A
Bottom
Animal diversity
Development of
Animal diversity
Different types of body cavities
Tissue-filled region
(from mesoderm)
Body covering
(from ectoderm)
Digestive tract
(from endoderm)
Body covering
(from ectoderm)
Muscle layer
(from mesoderm)
Digestive tract
(from endoderm)
Pseudocoelom
Body covering
(from ectoderm)
Coelom
Tissue layer
lining coelom
and suspending
internal organs
(from mesoderm)
Digestive tract
(from endoderm)
Flatworms are the simplest bilateral animals
– Flatworms
• Are bilateral animals with no body cavity
– A planarian has a gastrovascular cavity
• And a simple nervous system
– Flukes and tapeworms
• Are parasitic flatworms with complex life cycles
Colorized SEM 80!
Units with
reproductive
structures
Hooks
Sucker
Scolex
(anterior
end)
Tapeworms
Cattle, pigs, fish
Nematodes have a pseudocoelom and a complete digestive
tract
– Nematodes, phylum Nematoda
• Have a pseudocoelom and a complete digestive tract
• Are covered by a protective cuticle
Hook worms
Animal diversity
Diverse molluscs are variations on a common body plan
– All molluscs have a muscular foot and a mantle
•
Which may secrete a shell that encloses the visceral mass
•
Feed with a rasping radula
– Many mollusks
Visceral mass
Coelom
Heart
Kidney
Mantle
Mantle
cavity
Reproductive
organs
Digestive
tract
Shell
Figure 18.9B, C
Radula
Anus
Gill
Digestive tract
Radula
Mouth
Mouth
Foot
Figure 18.9A
Nerve
cords
Figure 18.9D
•Cephalopods
– Cephalopods are adapted to be agile predators
• And include squids and octopuses
Figure 18.9E, F
Animal diversity
Annelids are segmented worms
– The segmented bodies of phylum Annelida
• Give them added mobility for swimming and burrowing
– Earthworms and leaches
• Have a closed circulatory system
Anus
Circular
muscle
Epidermis
Segment wall
(partition
between
segments)
Segment
wall
Longitudinal
muscle
Dorsal
vessel
Mucus-secreting
organ
Figurer 18.10D
Bristles
Dorsal Coelom
vessel
Brain
Excretory
organ
Intestine
Excretory
organ
Digestive
tract
Nerve cord
Bristles
Ventral vessel
Segment
wall
Blood vessels
Mouth
Giant
Australian
earthworm
Nerve cord
Pumping segmental vessels
Arthropods are segmented animals with jointed appendages
and an exoskeleton
– The diversity and success of arthropods
• Are largely related to their segmentation, exoskeleton, and
jointed appendages
Cephalothorax Abdomen
Antennae
(sensory
reception)
Thorax
Head
Figure 18.11D
Head
Antenna
Thorax
Abdomen
Swimming
appendages
Forewing
Eye
Hindwing
Figure 18.11A
Walking legs
Mouthparts (feeding)
Pincer (defense)
Colorized SEM 900!
Mouthparts
A scorpion (about 8 cm long)
Figure 18.11B, C
A black widow spider (about
1 cm wide)
A dust mite (about 420
!m long)
Animal diversity
Echinoderms have spiny skin, an endoskeleton, and a water
vascular system for movement
– Echinoderms, phylum Echinodermata
• Includes organisms such as sea stars and sea urchins
• Are radially symmetrical as adults
Tube foot
Tube foot
Spine
Animal diversity
Our own phylum, Chordata, is distinguished by four features
– Chordates, phylum Chordata have
• A dorsal hollow nerve cord
• A stiff notochord
• Pharyngeal slits
• A muscular post-anal tail
– The simplest chordates are tunicates and lancelets
• Marine invertebrates that use their
pharyngeal slits for suspension feeding
Excurrent
siphon
Dorsal, hollow
nerve cord
Post-anal tail
Head
Pharyngeal
slits
Mouth
Muscle
segments
Notochord
Adult
(about 3 cm high)
Figure 18.14A, B
Notochord
Mouth
Pharynx
Pharyngeal
slits
Digestive tract
Water exit
Larva
Segmental
Anus
muscles
– Most chordates are vertebrates
• With a head and a backbone made of
vertebrae
Dorsal,
hollow
nerve cord
Post-anal
tail
Lampreys are vertebrates that lack hinged jaws
– Lampreys lack hinged jaws and paired fins
Figure 18.16A
– Most vertebrates have hinged jaws
• Which may have evolved from skeletal
supports of the gill slits
Jawed vertebrates with gills and paired fins include sharks,
ray-finned fishes, and lobe-fins
– Three lineages of jawed vertebrates with gills and
paired fins
• Are commonly called fishes
sharks and rays
• Have a flexible skeleton made of cartilage
Figure 18.17A
Animal diversity
Ray-finned Fishes
– The ray-finned fishes have
• A skeleton reinforced with a hard matrix of calcium
phosphate
• Operculi that move water over the gills
• A buoyant swim
bladder
Bony skeleton
Dorsal fin
Gills
Operculum
Pectoral fin
Heart
Anal fin
Swim bladder
Pelvic fin
Rainbow trout,
a ray-fin
Figure 18.17B
Lobe-fins
– The lobe-fin fishes
• Have muscular fins supported by bones
Figure 18.17C
Amphibians were the first vertebrates with two pairs of limbs
– Amphibians
• Were the first tetrapods with limbs allowing
movement on land
• Most amphibian embryos and larvae still must
develop in water
• Include frogs, toads, and salamanders
Figure 18.18B–D
Reptiles are amniotes—tetrapods with a terrestrially adapted
egg
– Terrestrial adaptations of reptiles include
• Waterproof scales
• A shelled, amniotic egg
– Living reptiles other than birds
• Are ectothermic
Figure 18.19A, B
Mammals are amniotes that have hair and produce milk
– Mammals are endothermic amniotes with
• Hair, which insulates their bodies
• Mammary glands, which produce milk
– Monotremes lay eggs
Figure 18.21A
Mammals are amniotes that have hair and produce milk
– Mammals are endothermic amniotes with
• Hair, which insulates their bodies
• Mammary glands, which produce milk
– Monotremes lay eggs
– The embryos of marsupials and eutherians are nurtured
by the placenta within the uterus
Animal diversity
Origin of Humans
?
Woodland ape to Homo erectus to Homo sapians
Woodland ape to Homo erectus to Homo sapians
Paranthropus
robustus
0
0.5
Millions of years ago
4.5
5.0
5.5
6.0
6.5
7.0
Homo
neanderthalensis
Australopithecus
afarensis
3.0 Australopithecus
anamensis
3.5
4.0
Homo
sapiens
Australopithecus
africanus
1.5
2.5
?
Paranthropus
boisei
1.0
2.0
Homo
ergaster
Kenyanthropus
platyops
Ardipithecus
ramidus
Orrorin tugenensis
Sahelanthropus
tchadensis
Homo
habilis
Homo
erectus
Homo habilis to Homo sapians
Woodland ape to Homo erectus to Homo sapians
Homo erectus takes a journey
Australopithicus afarensis: The story of Lucy
•Australopithicus afarensis lived from approximately 4 to
2.7 million years ago along the northern Rift valley of east
Africa, and perhaps even earlier
•Aproximately 300 individuals have been found
•Walked upright with longer arms
•Lived in social groups but no evidence of tool use or fire
Australopthicus africanus, or "Southern Ape of Africa."
•This speciman of a child, often called the "Taung Baby,”
• 3 to 2 million years ago
• Some of the permanent teeth are not yet descended, suggesting an
age of about 8 years at the time of death.
•An imprint of the brain case is preserved in limestone, and the
foramen magnum, the opening in the skull through which the spinal
cord attaches to the brain, indicates that this creature walked upright
like human beings
Australopithicus robustus: A contemporary of early human species
•These australopithicines (ape species) are small brained (about 400 cc)
compared to human species contemporaneous with them, and they are not
regarded as ancestral to human beings,.
•Their huge teeth and skulls, often with prominent dorsal crests to which large
jaw muscles attached, show that they specialized in eating tough plant material.
They were apparently vegetarians, while our ancestors evolved as omnivores
with a taste for meat.
•2 million to 1 million years ago
Homo habilis: The first human species
•Existed from approximately 2.2 to 1.6 million years ago in east Africa.
•Exhibit a clear trend toward larger brain size.
•H. habilis brains are about 30% larger than those of A. africanus.
•Males were much larger than females, as shown by the two skulls at far right. The
male is pictured on the left. Sexual dimorphism in early Hominid species expressed
itself in significant size differences.
•Likely used tools
Homo erectus: The first large-brained humans
•Homo erectus lived from approximately 2 million to around 400,000
years ago.
•Homo erectus is a large brained species, with adult brains ranging from
900 to 1200 cc. This size range means that the larger brained individuals
of this species exhibit a fifty-percent increase in brain size over the older
Homo habilis.
•a teen-age boy, 12 or 13, who lived 1.65 million years ago
Homo erectus: Tool use and adaptation to the environment
•Homo erectus was an accomplished tool maker and tool user;
•hand-axes
•Wooden tools and weapon.
•The first species to use and control fire about 1 to l.5 million years ago
Homo erectus: Developmental trends
1.5 million years in age, is on the left, and the most recent, approximately .5 million years old,
Homo sapiens: Earliest forms of our own species
300,000 to 400,000 years ago
Homo sapiens: Earliest forms of our own species
Archaic Homo Sapiens Sites:
400,000 - 200,000 BCE
Archaic Homo Sapiens Sites in Europe:
300,000 - 200,000 BCE
Homo sapiens neandertalensis: reconsideration of human origins
Homo sapiens neandertalensis: reconsideration of human origins
•a robust human species occupying Europe and western Asia from
approximately 135,000 to 30,000 years ago.
•Neanderthal remains appear primitive and crude
•Their arm and leg bones were approximately twice as thick as ours
•Otherwise, their bodies are strikingly modern.
•Their average brain capacity (1400-1500 cc) actually exceeds that
of modern humans
•The speech areas of the Neanderthal brain are not as developed as
ours and the forebrain is smaller.
•The Neanderthal were the first humans to live in Ice Age conditions
•Simple tool kit did not change much
Homo sapiens neandertalensis: reconsideration of human origins
•a robust human species occupying Europe and western Asia from
approximately 135,000 to 30,000 years ago.
•Neanderthal remains appear primitive and crude
•Their arm and leg bones were approximately twice as thick as ours
•Otherwise, their bodies are strikingly modern.
•Their average brain capacity (1400-1500 cc) actually exceeds that
of modern humans
•The speech areas of the Neanderthal brain are not as developed as
ours and the forebrain is smaller.
•The Neanderthal were the first humans to live in Ice Age conditions
•Simple tool kit did not change much
Homo sapiens neandertalensis: culture
•Burial rituals
•Maintained individuals with crippling diseases
•Disappeared after “modern humans arrived in Europe
Homo sapiens sapiens: The Symbol User
Skull size, tools, and distinctive features
•Our human species moved to Europe approximately 35,000 years
ago.
•Their average brain capacity actually similar that of modern humans
•The speech areas are developed
•Tool kit evolves
Homo sapiens sapiens: The Symbol User
Skull size, tools, and distinctive features
•Tool kit evolves
•Burial rituals
•Culture
Homo sapiens sapiens: The Symbol User
Skull size, tools, and distinctive features
•Tool kit evolves
•Burial rituals
•Culture
Homo sapiens sapiens: The Symbol User
Skull size, tools, and distinctive features
•Tool kit evolves
•Burial rituals
•Culture
The Physical Characteristics of Humans
Brain Size
•400cc
•1200cc
•1400cc
•a big brain is not an obvious evolutionary
advantage
•requires an inordinate amount of care and
feeding
The Physical Characteristics of Humans
Erect Posture and Bi-Pedalism
•Skull position
•S shaped spine
•Hips
•feet
•An ancient development
The Physical Characteristics of Humans
Human Skin as a Heat Diffusion Device
•Running releases a great deal of heat
The Physical Characteristics of Humans
Hands
•Placement of our thumb
The Physical Characteristics of Humans
The Human Face and Eyes
•Communication
•Depth perception
•Speech
•Color vision
•Teeth and jaws
The Physical Characteristics of Humans
Sexual Dimorphism
The Physical Characteristics of Humans
Neoteny
Woodland ape to Homo erectus to Homo sapians
Paranthropus
robustus
0
0.5
Millions of years ago
4.5
5.0
5.5
6.0
6.5
7.0
Homo
neanderthalensis
Australopithecus
afarensis
3.0 Australopithecus
anamensis
3.5
4.0
Homo
sapiens
Australopithecus
africanus
1.5
2.5
?
Paranthropus
boisei
1.0
2.0
Homo
ergaster
Kenyanthropus
platyops
Ardipithecus
ramidus
Orrorin tugenensis
Sahelanthropus
tchadensis
Homo
habilis
Homo
erectus