Download Invertebrates 1

Bi 212: Lecture 1
Kingdom Animalia:
Overview and Phylogeny
Lecture outline
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Course overview
Overview: Diversity lectures
What is an animal?
Introduction to major phyla in
Kingdom Animalia
5. Overview: Evolutionary history and
phylogeny (Kingdom Animalia)
1. Course overview
 See syllabus
 Sign up for PLTL if interested
 You must register!
 Sign up for specific session
2. Overview: Diversity Lectures
 Phylogeny/Evolutionary relationships
 Ancestral vs. derived characters
 Body plan (anatomy and physiology)
 How animal meets its basic needs
 Relationship of structure and function
 Selected aspects of life-history and
ecology
3. What is an animal?
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Eukaryotic
Multicellular
Heterotrophic
No cell wall
Hox genes
Share characteristics of early
development
Hox genes
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Defined: Homeotic (regulatory)
gene containing the highly
conserved “homeobox” sequence of
180 nucleotides
Hox genes are found only in animals
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Similar homeobox sequence found in more
distantly related organisms, but not within
homeotic genes
Involved in regulation of body plan,
development of limbs, etc…
 Nearly identical
hox genes regulate
development in
similar body
regions for very
distantly related
organisms
Shaking the Tree, Readings from
Nature in the History of Life,
edited by Henry Gee, University
of Chicago Press.
Early development: animals
Phylum Porifera: sponges
Phylum Cnidaria:
Have Cnidocytes
Phylum Ctenophora:
The comb jellies
Phylum Platyhelminthes:
The flatworms
Phylum Nematoda:
The roundworms
Phylum Annelida:
The segmented worms
Phylum Mollusca:
The “soft-bodied” animals
Phylum Arthropoda:
Jointed appendages
Phylum Echinodermata:
Spiny-skinned
Phylum Chordata:
Animals with notochords
5. Phylogenetic overview
 Hypothesized to be
monophyletic
 Evolved from
choanoflagellate
 “Kingdom” Protista
 Based on molecular
evidence as well as
similarity to sponges
(Phylum Porifera)
 Modern choanoflagellate
(aquatic)
Animal evolution
 Note rapid increase in early Cambrian
Kevin Peterson
Dartmouth
Hypotheses for Cambrian
“explosion”
 Evolution of Hox gene complex
 What role would this play?
 Coevolution of predators and prey
 What does this mean?
 Atmospheric oxygen had increased
sufficiently
 Why would this matter?
 Are these hypotheses mutually exclusive?
Phylogeny based on morphology & development
Scott Freeman BIOLOGICAL SCIENCE, Second Edition © 2005 Pearson Prentice Hall, Inc.
Phylogeny based on molecular data
Scott Freeman BIOLOGICAL SCIENCE, Second Edition © 2005 Pearson Prentice Hall, Inc.