Introduction to Animal Evolution

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Nutrient cycling is strongly regulated by
vegetation. When plants are not present,
nutrients are lost from the system.
Fig. 54.21
pages 1213-1214
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Ohio reservoir
Gizzard shad
Ecologists are recognizing the need of
understanding how landscapes (comprise different
ecosystems) and food webs interact.
Bioscience 2005
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Ecosystem. All the organisms living in a
community AND the abiotic factors with which they
interact.
Ecosystem Dynamics 1- Energy flow Primary
production gross and net aquatic
(light and nutrients). terrestrial
(climate and nutrients). Secondary
production gross and net production
and trophic efficiencies biomass and number
pyramids green world hypothesis. 2-
Matter (chemical) cycling Biogeochemical
model. Water, carbon, nitrogen. Role
of decomposers. Vegetation regulation.
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SOME questions from February 24th
1- Is the final cumulative? Can we have some
sort of study guide?
2- What happens to the rest of the light energy
if only 1 is used?
3- How would omnivores be classified in consumer
nomenclature?
4- If organic and inorganic materials are only
recycled, where are they from?
5- Is there any way to artificially produce
photosynthesis to limit CO2?
6- If we need 2,000 calories per day and maybe
half go out as feces, does that mean that we use
only 10 calories for growth per day?
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World population 'to rise by 40'
The world's population continues to grow but at a slower pace. The world's population is expected to rise from the current 6.5 billion to 9.1 billion by 2050, the UN says.
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Introduction to Animal Evolution
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What is an animal?

• How would you know?
• What are the challenges that all animals must
  deal with?

• Are there some fundamental similarities in the
  ways that animals solve these problems (similar
  adaptations) ?

Major Themes --gt
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Growth Development

• form and function are related
• Compare the means of support for animal and
  plant bodies.
• differentiation and specialization into tissues
• tissues, organs, and organ systems
• body plan, size, and symmetry
• How is it possible that cells of the same animal
  can have a different structure and function?
• reproduction
• sexual and asexual
• developmental stages

What is significant about the fact that larval
forms are sexually immature?
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Sensing and Responding to the Environment

• sensory systems
• Describe what is meant by environment in this
  context. Provide some examples of conditions that
  are monitored.
• motor systems (locomotion)
• What special tissue(s) enable this kind of
  movement?
• feeding and digestive functions
• Describe some examples of how body structure
  is related to feeding style.

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Internal Regulation

• energy balance
• What factors may influence an animals energy
  budget?
• transport
• water
• nutrients and wastes
• gas exchange
• How do animals cope with abiotic stresses?
• intercellular communication
• local
• long distance

Provide one example of each type of intercellular
communication.
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Proposed evolution of the animals
Fig 28.8
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Early embryonic development can help organize the
diversity of animal life
What type of cell division occurs during
cleavage?
When does the body form take on a tube within a
tube appearance?
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Patterns in Animal Evolution

• Simple to more complex body form
• Hypothesized colonial flagellated protist
  ancestor
• Cell aggregates, to a gastrula-like (or
  tissue-grade) protoanimal to

Fig. 32.3
Which stages demonstrate cell differentiation?
morphogenesis?
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The Parazoa - Phylum Porifera
pore-bearers
Describe at least two functions of
amoebocytes. How would you describe the feeding
strategy?

• No gastrulation occurs during development no
  true tissues
• If sponges have no muscle or nerve tissues, how
  do they accomplish movement of water into the
  spongocoel?

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Patterns in Animal Evolution (continued)

• tissues organized into organs and organ systems
  (a tube w/in a tube body plan, with 3 embryonic
  germ layers)

Discuss the concept of stem cells in the
context of animal embryology.
Mesoderm (although, not in all animals)
Fig. 32.1 Characteristics of the body plan
(anatomy) and embryonic development are key to
understanding the relationships between different
animal groups.
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Patterns in Animal Evolution (continued)

• Bodies with no symmetry to bodies with symmetry
• Branch Radiata
• 2 germ layers ectoderm endoderm
• Branch Bilateria
• 3 germ layers
• Which body form demonstrates cephalization?
• Describe at least one example of an animal with a
  high degree of cephalization. What other
  characteristics are associated with
  cephalization?

Fig. 32.5
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Patterns in Animal Evolution (continued)
Fig. 32.6
What do the colored layers represent?

• Bodies with no body cavity (e.g. flatworms)
• to bodies with a false body cavity
• (e.g. rotifers and round worms)
• to bodies with a true body cavity

pseudocoelom
coelom
What normally fills the pseudocoelom?
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Coelomates
Fig. 32.7

• Differences include
• Cleavage
• Fate of blastopore
• Process of coelom formation

Name one organism representative of the animal
groups listed at the top of the figure.
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How is structure related to function at major
stages in the life cycle of a sea star? What can
early embryonic development tell us about
phylogentic relationships in animals? What is
metamorphosis, and how is it different from
morphogenesis?
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Traditional Animal Phylogentic Tree
Which animals have a body cavity? What are the
possible functions of a body cavity in animals?
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Animal Phylogeny Modern

• Based on sequences in ribosomal RNA (molecular
  systematics)
• Acoelomate flatworms lost their coelom
• Coelom development happened early
• Combine phyla with lophophore and trocophore
  larvae
• Combine phyla that molt (ecdysis)

Fig 32.8
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X
X
X
X
X
X
Tissues allow for different cells to take
different roles cnidocytes, unique in the
animal kingdom, and extracellular digestion by
gastrodermis allow food larger than individual
cells.
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Plylum Cnidaria cnidarians

• extracellular digestion by gastrodermis allows
  food larger than individual cells
• Radial symmetry - detect and respond to stimuli
  from any direction
• Muscles and simple nerve net

Fig 33.6
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Polyp vs. medusa

• 2 cell layers
• Skin
• Gastro-vascular cavity lining
• 2 body forms
• polyp
• medusa
• Hydra eating
• Swimming jelly fish

Fig 33.4
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Phylum Platyhelminthes flat worms

• Bilateral symmetry with some cephalization
  gastrovascular cavity
• A thin body between dorsal and ventral surfaces
• NO coelom (acoelomate)
• Flatworms, trematodes, tapeworms

Fig 33.12
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Phylum Nemertea - ribbon worms

• Actually acoelomate, but some similarities to the
  protostomes
• Complete digestive tract closed circulatory
  system

What are the advantages of a complete digestive
tract? of a closed circulatory system?
Photo from http//www.seaslugforum.net/factsheet.
cfm?basenemertea
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Phylum mollusca mollusks

• Over 150,000 spp mostly marine
• Soft body protected in most by a hard shell made
  of calcium carbonate

Bivalves clams, etc.
Gastropods snails, slugs
Fig 33.20
Fig 33.18
Polyplacophora chitons
Cephalopods squid, etc.
Fig 33.17
Fig 33.22b
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Mollusk anatomy

• Important consumers
• Filter feeders
• Grazers
• Carnivores
• 3 Main body parts
• Foot
• movement
• Viscera mass
• internal organs
• Mantle
• secretes shell gas exchange

Most use a strap like rasping organ called a
radula to scrape food cephalopods have a beak