bis2c: lecture 27: having a diploblast
TRANSCRIPT
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Lecture 27: Having a Diploblast
BIS 002C Biodiversity & the Tree of Life
Spring 2016
Prof. Jonathan Eisen
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Where we are going and where we have been…
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•Previous lecture: •26: Animals and Sponges
•Current Lecture: •27: Diploblasts
•Next Lecture: •28: Triploblasts
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Animal Diversity Topics
• Major Groups
• Diversity within Groups
• Key Features of Groups !Body Plans, Forms and Symmetry !Reproduction and Life Cycles !Mobility !Feeding
• Examples
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Key Topics
• Monoblasts vs. diploblasts vs. triploblasts
• Ctenophore features
• Placozoan features
• Cnidarian features
• Cnidarian examples !Coral !Box jellies
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Where we are …
!5Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Fila
ster
ea
Icht
hyos
pore
a
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Animal Diversity
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Animal Diversity
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Diploblasts
Triploblasts
Monoblasts
!8Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
In the diplontic life cycle, the organism is diploid and the gametes are the only haploid stage.
HAPLOID (n)
DIPLOID (2n)Zygote (2n)
Mature organism (2n)
Gametes Male (n) Female (n)
FertilizationMeiosis
Animal Life Cycle
Animal Life Cycle
!9Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
HAPLOID (n)
DIPLOID (2n) Zygote (2n)
Mature organism (2n)
Gametes Male (n) Female (n)
FertilizationMeiosis
Monoblasts (1)
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2
1
Animal Life Cycle
!9Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
HAPLOID (n)
DIPLOID (2n) Zygote (2n)
Mature organism (2n)
Gametes Male (n) Female (n)
FertilizationMeiosis
Diploblasts (2)
3
2
1
Animal Life Cycle
!9Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
HAPLOID (n)
DIPLOID (2n) Zygote (2n)
Mature organism (2n)
Gametes Male (n) Female (n)
FertilizationMeiosis
Triploblasts (3)
3
2
1
In the diplontic life cycle, the organism is diploid and the gametes are the only haploid stage.
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Diploblasts
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Ctenophores: Comb Jellies
!11Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016 12
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Ctenophores: Comb Jellies
Ctenophores: Comb Jellies
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• ~ 100 species, all marine, some in very deep environments. • Radial symmetry, diploblastic • The two cell layers are separated by a gelatinous mesoglea. • Ctenes: comb like rows of cilia (for swimming & feeding) • Very similar in outward appearance to cnidarians. • Sticky, but not stinging, cells; called ‘lasso’ cells. • 1 mm to 1.5 m in size
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Placozoans
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Chapter 31 Opener Did Placozoans Diverge at the Root of the Animal Tree?
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Figure 31.17 Placozoan Simplicity
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Figure 31.17 Placozoan Simplicity
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• Small (2-3mm), diploblastic*, benthic, marine animals. • 1 described species, asymmetrical • No tissues, few specialized cells. • Feed by phagocytosis • Motile larvae •Their relative ‘absence’ of morphological features may be secondarily derived.
Cnidarians
!22Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Cnidarians: Some Key Features
• ~ 11,000 species
• Most are marine (salt water), a few aquatic (fresh water)
• Features !Gastrovascular cavity !Cnidae; specialized collection of cells (prey
capture, defense) !Muscle fibers and nerve nets for movement !Two stage adult life cycle !Specialized nematocysts !Many species have microbial symbionts
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Anthozoans: Sea anemones & sea pens
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Anthozoans: Corals
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Scyphozoan (Jellyfish) and Hydrozoan
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Cnidaria: Cubozoa (box jellies)
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The Life Cycle of Most Cnidarians Has Two Stages
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• Planula: free swimming larvae
• Polyp: sessile. Produces medusa by budding
• Medusa stage: free-swimming; produce gametes.
!30Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Feature I: Nematocysts Are Potent Weapons
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Tentacles have specialized cells with organelles called nematocysts (a form of cnidae) that inject toxins into prey organisms.
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Cnidarian Example I: Corals
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Anthozoans: Corals
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Anthozoans: Corals
• Colonial.
• Polyps secrete matrix of organic molecules on which they deposit calcium carbonate, which forms a skeleton.
• Living polyps form a layer on top of a growing mass of skeletal remains, which forms coral reefs and islands.
• Many grow in clear, nutrient-poor tropical waters.
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Coral Symbiosis with Dinoflagellates
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Corals contain symbiotic dinoflagellates (algae) called zooxanthellae
Clicker
What are dinoflagellates?
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Clicker
What are dinoflagellates?
A. Eukaryotes in the Alveolate lineage
B. Eukaryotes in the Plantae lineage
C. A type of cyanobacteria
D. Small dinosaurs
E. The sister group to animals
!40Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2014
•Most are marine and are important photoautotrophic primary producers
•Mixture of pigments give them a golden brown color.
•Have two flagella, one in an equatorial groove, the other in a longitudinal groove.
Alveolates: Dinoflagellates
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Certium tenue
Coral symbiont
Clicker
What is the minimum number of symbiotic events in the history of the Dinoflagellate chloroplast?
A. 0
B. 1
C. 2
D. 3
E. 4
!42Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Clicker
What is the minimum number of symbiotic events in the history of the Dinoflagellate chloroplast?
A. 0
B. 1
C. 2
D. 3
E. 4
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2014
N M
N M
C
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Secondary Endosymbiosis
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2014
Dinoflagellate Kryptoperidinium foliaceum
http://onlinelibrary.wiley.com/doi/10.1111/j.1550-7408.2007.00245.x/full45
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2014
N M
Tertiary Endosymbiosis
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N MN M
C
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2014
N M
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N MN M
C
Host
Symbiont
After a tertiary symbiosis
Cnidarians: Major Groups
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Anthozoa Hydrozoa Scyphozoa Cubozoa
• ~ 11,000 species
• Most are marine (salt water), a few aquatic (fresh water)
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2014
Quaternary?
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NM
N M
N MN M
C
Host
Symbiont
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2014
Symbiodinium in coral polyp (Porites porites)
50https://microbewiki.kenyon.edu/index.php/File:Hosttissuesection.png
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Classes of symbiosis
Organism
Class of symbiosis A B
Mutualism + +
Commensalism + 0
Parasitism + -
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Classes of symbiosis
Organism
Class of symbiosis A B
Mutualism + +
Commensalism + 0
Parasitism + -
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Cnidaria Example II: Cubozoa - Box Jellies
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Cnidaria: Cubozoa
!56Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• Also called box jellies or sea wasps. • Sting is very toxic, may cause death in humans. • Some species with well-developed eyes.
Lecture 26: Cnidaria, Ctenophora
• Previous lecture: ! Bis2B !
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Another Cnidarian Symbiosis
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Some anemones form mutualisms with clownfish; why do they not get stung?
They have a protective coating that prevents the nematocysts from firing.
!59Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016