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Welcome to CVA

Fall 2004

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Introduction

• Syllabus• Schedule

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Comparative Vertebrate Anatomy

• What is it?– Vertebrate Descriptive Morphology– Vertebrate Functional Morphology

• Ontogenetic change• Phylogenetic change

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It incorporates:

• Genetics– mechanisms of heredity– effects on variation– control of development

• Embryology (study of development)• Molecular Biology• Biochem

Physiology: form and function at many levels

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• Paleontology– Historical record of past anatomy– How many species have existed on Earth?– How many are extinct?

• Ecology– Interactions between species and their

environment

• Physics? (Handout)

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Area of coverage

• Kingdom Animalia– Phylum Chordata

• Subphylum Urochordata (=Tunicata)– Sea squirts, larvaceans, thaliaceans

• Subphylum Cephalochordata– Amphioxus (lancelet)

• Subphylum Craniata (=Vertebrata of Haeckel)

– Hagfish (Mixini)– Vertebrata

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Proto

stom

e

Inve

rtebr

ates

Crinoid

s, Sea

stars

, etc

Ptero

bran

chia

Enter

opne

usta

(Aco

rn w

orm

s)

Tunica

tes

(Tun

icata

)

Amph

ioxus

(Cep

haloc

hord

ata)

Crania

tes

Deuterostomata

Pharyngotremata

ChordataHemichordataEchinodermata

Somitichordata

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• Protostome inverts• Deuterostome inverts

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Hemichordata (incertae sedis)(=Enteropneusta)

Pterobranch

Acorn Worm

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Acorn worm (Sarcoglossa)

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Pharyngeal (“gill”) slits

• Opening from the gill chamber

– Can include associated tissues

• P. pouch – outpocketing of the gut

• P. arch – tissues lying between P. slits

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Urochordata (=Tunicata)Corella parallelograma

Notochord – cordlike skeleton of the back

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Ascidian tunicate

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P. Chordata, Sp. Cephalochordata

Amphioxus

Somites – rectangular shaped pairs of mesoderm on sides of notochord – gives rise to axial skeleton, muscles

and dermis

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Sp. Craniata

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Some Concept Review

• Ideas of Darwin and Wallace

• Evolutionary Developmental Concepts

– Ontogeny: the history of an individual from initiation of cell division to death

– Phylogeny: the evolutionary history of independent lineages or species

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“Ontogeny recapitulates phylogeny”

• Ernst Haeckel (1834-1919)

• German anatomist

• Embryonic stages of an animal reflect its evolutionary history

1874

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• Better explained by:– Von Baer’s “Law”

(1828): General (primitive) features develop earlier in ontogeny than do special features (derived) that distinguish groups

– Biogenetic “Law”: features that develop earliest in ontogeny are the oldest phylogenetically and features developing later in ontogeny are of more recent phylogenetic origin

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A few notes on Patterns and Process in Evolution

• Homology:

• Analogy:

• Homoplasy:

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Cladistic Classification / Phylogenetic systematics

• The science of evolutionary grouping based on shared derived characteristics

• The naming of organisms based on these groups

– Plesiomorphy:– Synapomorphy:– Autapomorphy:– Monophyly:– Paraphyly:– Polyphyly:

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A B CNM

CladogramBranchNodeInternodeRootOTUIngroupOutgroupAutapomorphyPlesiomorphySynapomorphy

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Next Time…

• Characters that define the Vertebrates

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