BIO 3220 COMPARATIVE VERTEBRATE ANATOMY Thank you to McGraw-Hill and Dr. Anil Rao (MSCD) for use of PowerPoint illustrations
Dec 18, 2015
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