Transcript Animal Diversity PPT

LECTURE PRESENTATIONS
For CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
Chapter 32
An Overview of Animal Diversity
Lectures by
Erin Barley
Kathleen Fitzpatrick
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Overview: Welcome to Your Kingdom
• Scientists have identified 1.3 million living
species of animals
– How many more would you guess there are?
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Video: Coral Reef
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Figure 32.1
Which of these organisms are animals?
How do you define “animals”?
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How do you define “animals”?
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Eukaryotic
Multicellular
Heterotrophic…via ingestion
Have tissues, except for the basal taxon (sponges)
Have nervous and muscle tissue…usually
Motile…usually at least for a phase
Cells do not have walls, but instead are held together by
collagen (derived trait)
• Have blastula phase (usually) which undergoes
gastrulation forming tissue layers (two or three)
• Most animals, and only animals, have Hox genes that
regulate the development of body form
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Video: Sea Urchin Embryonic Development
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Figure 32.2-1
Zygote
Cleavage
Eight-cell
stage
Early embryonic
development in animals
Figure 32.2-2
Early embryonic
development in animals
Zygote
Cleavage
Blastocoel
Cleavage
Eight-cell
stage
Blastula
Cross section
of blastula
Figure 32.2-3
Early embryonic
development in animals
Zygote
Cleavage
Blastocoel
Cleavage
Eight-cell
stage
Blastula
Cross section
of blastula
Gastrulation
Blastocoel
Endoderm
Ectoderm
Archenteron
Cross section
of gastrula
Blastopore
• Many animals have at least one larval stage
– What are some examples?
– Do humans have a larval stage?
• A larva is sexually immature and morphologically
distinct from the adult; it eventually undergoes
metamorphosis
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Concept 32.2: The history of animals
spans more than half a billion years
• What % of animal species are extinct?
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Concept 32.2: The history of animals
spans more than half a billion years
• What % of animal species are extinct? 99%
• The common ancestor of living animals may have
lived between 675 and 800 million years ago
• This ancestor may have resembled modern
choanoflagellates, protists that are the closest
living relatives of animals
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Figure 32.3
Greatn Grandma
Individual
choanoflagellate
Choanoflagellates
OTHER
EUKARYOTES
Sponges
Animals
Other animals
Collar cell
(choanocyte)
Neoproterozoic Era (1 Billion–542 Million
Years Ago)
• Early members of the animal fossil record include
the Ediacaran biota, which dates from 565 to 550
million years ago
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Figure 32.4
1.5 cm
(a) Mawsonites spriggi
0.4 cm
(b) Spriggina floundersi
Paleozoic Era (542–251 Million Years
Ago)
• The Cambrian explosion (535 to 525 million
years ago) marks the earliest fossil appearance of
many major groups of living animals
• There are several hypotheses regarding the cause
of the Cambrian explosion and decline of
Ediacaran biota
– New predator-prey relationships
– A rise in atmospheric oxygen
– The evolution of the Hox gene complex
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Figure 32.5
• Animal diversity continued to increase through the
Paleozoic, but was punctuated by mass
extinctions
• Animals began to make an impact on land by 460
million years ago
– How can we tell this?
• Vertebrates made the transition to land around
360 million years ago
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Mesozoic Era (251–65.5 Million Years Ago)
• Coral reefs emerged, becoming important marine
ecological niches for other organisms
• The ancestors of plesiosaurs were reptiles that
returned to the water
• During the Mesozoic era, dinosaurs were the
dominant terrestrial vertebrates
• The first mammals emerged
• Flowering plants and insects diversified
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Cenozoic Era (65.5 Million Years Ago to
the Present)
• The beginning of the Cenozoic era followed mass
extinctions of both terrestrial and marine animals
• These extinctions included the large, nonflying
dinosaurs and the marine reptiles
• Mammals increased in size and exploited vacated
ecological niches
• The global climate cooled
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animals can have
diverse body
plans
How would radial symmetry
be advantageous?
(a) Radial symmetry:
What behavior and morphological
traits do bilateral animals have in common?
(b) Bilateral symmetry:
• Two-sided symmetry is called bilateral symmetry
• Bilaterally symmetrical animals have
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A dorsal (top) side and a ventral (bottom) side
A right and left side
Anterior (head) and posterior (tail) ends
Cephalization, the development of a head
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Tissues
• Animal body plans also vary according to the
organization of the animal’s tissues
– Tissues are collections of specialized cells isolated from
other tissues by membranous layers
– Sponges and a few other groups lack true tissues
• During development, three germ layers give rise to
the tissues and organs of the animal embryo
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1. Ectoderm is the germ layer covering the
embryo’s surface
2. Endoderm is the innermost germ layer and lines
the developing digestive tube, called the
archenteron
• Diploblastic animals have ectoderm and
endoderm
– These include cnidarians and comb jellies
• Triploblastic animals also have an intervening
mesoderm (#3) layer; these include all bilaterians
– These include flatworms, arthropods, vertebrates,
and others
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Body Cavities
• Most triploblastic animals possess a body cavity
• A true body cavity is called a coelom and is
derived from mesoderm
• Coelomates are animals that possess a true
coelom
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Figure 32.8
(a) Coelomate
Coelom
Digestive tract
(from endoderm)
Body covering
(from ectoderm)
Tissue layer
lining coelom
and suspending
internal organs
(from mesoderm)
(b) Pseudocoelomate
Body covering
(from ectoderm)
Pseudocoelom
Digestive tract
(from endoderm)
Muscle layer
(from
mesoderm)
(c) Acoelomate
Body covering
(from ectoderm) Tissuefilled region
(from
mesoderm)
Wall of digestive cavity
(from endoderm)
• Coelomates and pseudocoelomates belong to the
same grade
– A grade is a group whose members share key
biological features
– A grade is not necessarily a clade, an ancestor and all
of its descendants
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Protostome and Deuterostome Development
• Based on early development, many animals can be
categorized as having protostome development or
deuterostome development
– What are the roots of prototstome and deuterostome that give away
their meanings?
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Figure 32.9
Protostome development
(examples: molluscs,
annelids)
(a) Cleavage
Deuterostome development
(examples: echinoderms,
chordates)
Eight-cell stage
Eight-cell stage
Spiral and determinate
Radial and indeterminate
(b) Coelom formation
Coelom
Archenteron
Coelom
Mesoderm
Blastopore
Blastopore
Solid masses of mesoderm
split and form coelom.
(c) Fate of the
blastopore
Mesoderm
Folds of archenteron
form coelom.
Anus
Mouth
Digestive tube
Key
Ectoderm
Mesoderm
Endoderm
Mouth
Mouth develops from blastopore.
Anus
Anus develops from blastopore.
Cleavage
• In protostome development, cleavage is spiral
and determinate
• In deuterostome development, cleavage is radial
and indeterminate
– With indeterminate cleavage, each cell in the early
stages of cleavage retains the capacity to develop into a
complete embryo
– Indeterminate cleavage makes possible identical twins,
and embryonic stem cells
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Animal phylogeny
based on morphology
Cnidaria
Eumetazoa
Metazoa
ANCESTRAL
COLONIAL
FLAGELLATE
Porifera
Ctenophora
Protostomia
Bilateria
Deuterostomia
Ectoprocta
Brachiopoda
Echinodermata
Chordata
Platyhelminthes
Rotifera
Mollusca
Annelida
Arthropoda
Nematoda
Porifera
Ctenophora
Eumetazoa
ANCESTRAL
COLONIAL
FLAGELLATE
Metazoa
Animal phylogeny
based on molecular
systematics
Cnidaria
Acoela
Bilateria
Chordata
Platyhelminthes
Lophotrochozoa Ecdysozoa
Deuterostomia
Echinodermata
Rotifera
Ectoprocta
Brachiopoda
Mollusca
Annelida
Nematoda
Arthropoda
Points of Agreement
1. All animals share a common ancestor
2. Sponges are basal animals
3. Eumetazoa is a clade of animals
(eumetazoans) with true tissues
4. Most animal phyla belong to the clade Bilateria,
and are called bilaterians
5. Chordates and some other phyla belong to the
clade Deuterostomia
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Progress in Resolving Bilaterian
Relationships (we will cover in chapter 33)
• The morphology-based tree divides bilaterians into
two clades: deuterostomes and protostomes
• In contrast, recent molecular studies indicate three
bilaterian clades: Deuterostomia, Ecdysozoa, and
Lophotrochozoa
• Ecdysozoans shed their exoskeletons through a
process called ecdysis
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Figure 32.12
• Some lophotrochozoans have a feeding
structure called a lophophore
• Others go through a distinct developmental stage
called the trochophore larva
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Figure 32.13
Lophophore
Apical tuft
of cilia
Mouth
Anus
(a) Lophophore feeding
structures of an ectoproct
(b) Structure of a trochophore
larva
Future Directions in Animal Systematics
• Phylogenetic studies based on larger databases
will likely provide further insights into animal
evolutionary history
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Figure 32.UN02
535–525 mya:
Cambrian explosion
565 mya:
Ediacaran biota
365 mya:
Early land
animals
Origin and
diversification
of dinosaurs
Diversification
of mammals
Era
Paleozoic
Neoproterozoic
1,000
542
251
Millions of years ago (mya)
Mesozoic
Cenozoic
65.5
0
Figure 32.UN03
Common ancestor
of all animals
Metazoa
Porifera
(basal animals)
Eumetazoa
Ctenophora
Cnidaria
Acoela (basal
bilaterians)
Deuterostomia
Bilateral
symmetry
Three germ
layers
Lophotrochozoa
Ecdysozoa
Bilateria (most animals)
True
tissues
Homework: process ch 33 by completing the
following table
Phylum
Porifera
Cnidaria
Ctenophores
Platylhiminthes
Rotifera
Lophophorates
Mollusca
Annelida
Nematoda
Arthropoda
Echinodermata
Chordata
Key
Characteristics
Examples
1-2 pictures