Chapter 27: Animal Diversity Flashcards
Example of a good clade
Birds
-all birds descended from common ancestor that was a bird
Grade
-level of morphological organization wherein a group of organisms share a number of characteristics but may not owe them to a common ancestor
Clade
- Complete branch of an evolutionary tree
- All members descended from a single common ancestor that is a member of the group.
Clade or Grade for Kingdom Animalia:
- All animals are heterotrophs
- heterotrophs obtain energy and organic molecules from other organisms, dead or alive
Grade
-many Protists are also ingestive heterotrophs
Examples of a good grade
- “Cactus” growth form
- Flight
- Endothermy
- Multicellularity
- “Tree” growth form
- Vertebrate “leglessness”
Clade or Grade for Kingdom Animalia:
-All animals are multicellular
Grade
-plants, fungi, protists, some prokaryotes have multicellularity
Clade or Grade for Kingdom Animalia:
-Animals held together by:
•Unique Extracellular matrix of collagen, proteoglycan, adhesive glycoprotein (fibronectin), and integrin
•Unique intercellular junctions
Clade
Clade or Grade for Kingdom Animalia:
-Animals typically show active movement
Grade
-many Protists and some prokaryotes are motile
Clade or Grade for Kingdom Animalia:
-Animals are species-rich and diverse form
Grade
Clade or Grade for Kingdom Animalia:
-Animals occupy all major habitats on earth
Grade
Clade or Grade for Kingdom Animalia:
-Most animals reproduce sexually
Grade
Clade or Grade for Kingdom Animalia:
-Most animals have a characteristic pattern of development.
Zygote->Cleavage->Blastula->Gastrula
-Unique Hox developmental genes
Clade
Clade or Grade for Kingdom Animalia:
- Animals cells are organized into tissues
- Muscle tissue and nervous tissue are unique
Clade
Synapomorphy characteristics for the Kingdom Animalia
• Unique Extracellular matrix of collagen, proteoglycan, adhesive glycoprotein (fibronectin), and integrin • Unique intercellular junctions • Development includes a blastula • Hox developmental genes • Muscle tissue and nervous tissue -sponges lack "true" tissues
Phylum Cnidaria
- Jellyfish
- Anemones
- Corals
- ~10,000 species
Phylum Porifera
• Sponges
• ~8000 species
- Phyla Calcarea and Silicea in text
Phylum Acoela
- “acoel flatworms”
- formerly within Platyhelminthes
- appear to be basal bilaterians
- ~400 species
Phylum Rotifera
- Rotifers or “wheel animals”
- Microscopic
- Mostly benthic and freshwater
- ~1800 species
Phylum Platyhelminthes
- “flatworms” (planarians, flukes, tapeworms)
- formerly included acoelomorph worms
- ~20,000 species
Phylum Mollusca
- Molluscs (snails, clams, octopuses, chitins, nudibranchs)
* ~100,000 living species
Phylum Annelida
- Segmented worms
- Mostly marine but includes earthworms and leeches
- ~12,000 species
Phylum Anthropoda
- Arthropods: millipedes, centipedes, spiders, scorpions, mites, ticks, crustaceans, insects
- > 1,000,000 species named, true number may be 30x
Phylum Nematoda
- Roundworms
- Found pretty much everywhere, doing anything
- ~20,000 species named, true number may be 100x
Phylum Echinodermata
- Echinoderms: sea stars, sea urchins, sand dollars, sea cucumbers, sea lilies
- Start out bilateral symmetrical but have radial symmetry as adults
- ~6,000 species
Phylum Chordata
- Subphylum Tunicata
• Urochordata: sea squirts and planktonic relatives
• ~2,200 species - Subphylum Cephalochordata
• Lancelets or amphioxus; fish-like, marine, burrowers
• ~30 species - Subphylum Craniata
• Vertebrates: lampreys, fish, amphibians, reptiles, birds, and mammals
• Hagfishes
• ~54,000 species
How old are animals?
• Oldest unambiguous fossil animals:
- ~550 million years ago
• Molecular estimate:
- older, maybe 700 million to 1 billion years
• Compare with
- Age of Earth: 4.6 billion years
- 1st Prokaryotes: 3.5-3.9 billion years ago
- 1st Eukaryotes: 2.1 billion years ago
Cambrian Explosion
- Relatively brief time in geologic history when many present-day phyla of animals first appeared in the fossil record
- This burst of evolutionary change occurred about 535-525 million years ago and saw emergence of first large, hard-bodied animals
Four keys of the animal body plan
- Evolution of tissues
- Evolution of bilateral symmetry
- Evolution of a body cavity
- Evolution of deuterostome development
Evolution of tissues
• Tissue is group of similar cells organized into a structural and functional unit (and isolated from other tissues by a membranous layer)
• Sponges lack “true” tissues
- May have epidermis (pinacoderm)
- Closer to unicellular level of organization
• Cell types remain totipotent (ability to differentiate into other cell types)
- Sometimes called “Parazoa”
• Other animals have well-developed tissues (“Eumetazoa”)
Evolution of bilateral symmetry
• Asymmetry
- Lacking definite symmetry
- Characteristic of many sponges
• Radial symmetry
- Symmetry about a radius or diameter (starfish)
- Characteristic of Cnidaria and adult echinoderms
• Bilateral symmetry
- Right and left halves that are mirror images (humans)
- Have top and bottom (dorsal & ventral), front and back (anterior & posterior), and left and right
- “Bilateria”
Bilateria
• 3 germ layers
- Basic tissue layers in early embryo which develop into organs and tissues
- Endoderm, mesoderm, & ectoderm
- “Triploblastic”
- Radiata (Cnidaria & Ctenophora) are diploblastic
- Sponges have only 1 “germ layer”
• Cephalization
- Evolution of definite head and brain area
- Associated with greater levels of activity and greater coordination of that activity
- Sense organs and brain are located at anterior end
Evolution of a body cavity (coelom)
• Coelom
- fluid- or air-filled space between digestive tract and outer body wall
• Advantages
- Gut can be longer, and can move independently of body wall (e.g., peristalsis)
- Allows space into which structures can expand (e.g., eggs in ovary)
- Provides a simple circulatory system, if fluid filled
- Provides a storage space for waste products, from which they me be discharged to outside via excretory ducts
- Provides a hydrostatic organ, if fluid filled
Types of body cavities
• Acoelomate
- No body cavity
• Blastocoelomate(“Pseudocoelomate”)
- Cavity is between mesoderm and endoderm (e.g., Nematoda and Rotifera)
- Old name bad: not “false”, just different
• Coelomate
- Cavity is fully enclosed within mesoderm (e.g., mollusks, arthropods, echinoderms, & chordates)
- Reduced in some and placed with “hemocoel or haemocel”
• Cavity is expansion of circulatory system
Acoelomate
- No body cavity
- Space between the gut and the body wall is filled with a more or less solid mass of mesodermal tissue
- E.g., Platyhelminthes, Acoela
Blastocoelemate
- Fluid-filled cavity between the gut and the mesoderm of the body
- Developmental remnant of bastocoel
- E.g., Nematoda & Rotifera, others
Coelomate (Eucoelomate)
- Fluid-filled cavity fully enclosed by mesoderm
- Characteristic of “higher” Bilateria
- E.g., Annelids, Molluscs, Arthropods..
Protostome-Deuterostome differences
- Cleavage
- Source of mesoderm & formation of coelom
- Fate of blastopore
- Fate of embryonic cells
Protostome or Deuterostome:
- Spiral Cleavage
Protostome
Protostome or Deuterostome:
- Radial Cleavage
Deuterostome
Protostome or Deuterostome:
- Mesoderm comes from lip of blastopore
- Coelom forms as split within mesoderm (schizocoely)
Protostome
Protostome or Deuterostome:
- Mesoderm comes from an “out pocketing” of the wall of the early guy (archenteron)
- Coelom forms as the pocket “pinches off” (enterocoely)
Deuterostome
Protostome or Deuterostome:
- Blastopore develops into the mouth
Protostomes ( “first” & “mouth”)
Protostome or Deuterostome:
- Blastopore develops into the anus
Deuterostomes ( “second” & “mouth”)
Protostome or Deuterostome:
- Determinate (mosaic) development
- Blastomeres lose totipotency with first cleavage division
Protostomes
Protostome or Deuterostome:
- Indeterminate (regulative) development
- First few cleavage divisions yield totipotent daughter cells ( e.g.,monozygotic twins, triplets, …)
Deuterostomes
“Old” view of animal phylogeny
Based on morphology and embryology
“New” view of animal phylogeny
Based on genetic sequence data
Similarities or difference between “old” & “new” views of animal phylogeny:
• Animals are a natural group
- monophyletic, a clade
Similarity
Similarities or difference between “old” & “new” views of animal phylogeny:
• Sponges are basal animal
Similarity
Similarities or difference between “old” & “new” views of animal phylogeny:
• There is a large clade, Eumetazoa
- have true tissues
- all but sponges & few others
- basal Eumetazoa typically diploblastic, with radial symmetry
Similarity
Similarities or difference between “old” & “new” views of animal phylogeny:
• Most animal belong to clade Bilateria
- triploblastic & bilaterally symmetry
- “Cambrian explosion” was explosion of this clade
Similarity
Similarities or difference between “old” & “new” views of animal phylogeny:
• Deuterostomia is a clade
- including Chordates & Echinoderms
Similarity
Similarities or difference between “old” & “new” views of animal phylogeny:
• “Protostimes” consist of two major clades:
- Ecdysozoa
- Lophotrochozoa
Difference - old view
Look at pictures and diagrams throughout the slides
Review last few slides
Strong support for hypothesis that animals are derived from _______
Choanoflagellates
The most diverse Phyla is _______
Arthropoda
Ecdysozoa
• Consists of Phyla: - Nematoda - Arthropoda • Characterized by: - SHEDDING - Bilateral symmetry - Triploblastic
Lophotrochozoa
Consists of Phyla: - Platyhelminthes - Rotifera - Mollusca - Annelida Characterized by: - Early lophophore feeding OR trochophore larva stage - Bilateral symmetry - Triploblastic
Platyhelminthes and Acoela are _________ (acoelomate/blastocoleomate/eucoelomate)
Acoelomate
Nematoda and Rotifers are _________ (acoelomate/blastocoleomate/eucoelomate)
Blastocoleomate
Review the slides on Clades, Grades, & Taxa
Good luck
Porifera (sponges) are ______ (asymmetric/radial symmetric/bilaterial symmetric)
Asymmetric
Cnidaria (jellyfish, hydra) are ______ (asymmetric/radial symmetric/bilaterial symmetric)
Radial symmetric
A clade is a __________ (synapomophy/symplesiomorphy)
Synapomophy
Monophyletic taxon
– A set of species that includes the most recent common ancestor of the set, and all of the species descended from that common ancestor.
– A complete branch of an evolutionary tree (a clade).
– E.g., mammals
Paraphyletic taxon
– A set of species that includes the most recent common ancestor of the set, and some but not all of the species descended from that common ancestor.
– An incomplete branch of an evolutionary tree
– Examples on slides
Polyphyletic taxon
– A set of species that does not includes the most recent
common ancestor of the set.
– Parts of two different branches of an evolutionary tree.
A set of species that includes the most recent common ancestor of the set, and SOME BUT NOT ALL of the species descended from that common ancestor?
Paraphyletic taxon
A set of species that includes the most recent common ancestor of the set, and ALL of the species descended from that common ancestor?
Monophyletic taxon
A set of species that does not include the most recent
common ancestor of the set?
Polyphyletic taxon
True or False: Monophyletic taxon are an incomplete branch of an evolutionary tree (a clade)
False, Monophyletic taxon are an COMPLETE branch of an evolutionary tree (a clade)
True or False: Polyphyletic taxon are an incomplete branch of an evolutionary tree
False, Paraphyletic taxon are an incomplete branch of an evolutionary tree
Flipperoidea is an example of a ______ taxon
Polyphyletic taxon
Synapomorphy
- Shared, DERIVED character similarity
- Help identify monophyletic taxa (clades)
Symplesiomorphy
- Shared, ANCESTRAL similarity
- Likely lead to paraphyletic taxa
Echinoderms have __________ symmetry in their adult life.
Radial
