BIO 3220

COMPARATIVE VERTEBRATE ANATOMY

Thank you to McGraw-Hill and Dr. Anil Rao (MSCD) for use of PowerPoint illustrations

Basic Definitions

AnatomyMorphology

Phylogeny – Evolutionary History

PaleontologyFunctional AdaptationComparative MorphologyEmbryology

Homology

Shared common ancestrySame embryonic precursor

Analogy

Shared functionInsect wings & bird wingsGills & lungs

Homoplasy/Homoplastic Organs

Shared anatomyGenerally, not homologousE.g. Insect wings vs. leaf

Key Points

Homology

Analogy

Homoplasy

Form vs. Function

Function, then form– Darwin’s Theory of Natural Selection– Adaptation

Form, then function– Preadaptation

Evolution

Random chance mutations, coupled with geographic isolation leads to…

Change in gene frequency in a population

Divergent Evolution

RelatedPresent species evolved from common

ancestor

Convergent Evolution

Not closely relatedDissimilar features evolved to become

similar features

Parallel Evolution

Related & IsolatedCorresponding features undergo equivalent

changes in isolated environments

Organic Evolution

Present day species are descendants of previous species

Changes that have taken place in plants & animals over time

Vestigial Structures

Phylogenetic remnantBetter developed in ancestorE.g. pelvic girdle in python

Key Point

Can you think of a vestigial structure in humans?

Rudimentary Structure

More developed in descendantE.g. neck, ear

Ontogeny

An individual’s life historyFertilization to deathInfluenced by environment as well as

geneticsStructures earliest to develop are likely the

oldest phylogenetically

Heterochrony

Paedogenesis– Gonads develop quicikly

Paedomorphosis– Immature features of ancestor become features

of future SPECIESNeoteny

– Immature features are retained as an adult in the INDIVIDUAL

paedomorphosis