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Anatomical and Molecular Homologies
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Evidence of Evolution
Similar to Vestigial
Much like vestigial structures, an example of molecular homology can be seen in the shaping of organs in two different organisms; such as the stomach in a cow and in a human. Both have the same molecular purpose, but different ways of approach.
Through Homologies
Molecular Homology
similarity in the sequence of a protein or nucleic acid between organisms of the same or different species
Types
Morphological (Anatomical)
Ontogenetic (Embryological)
Cellular (Molecular)
Homology
"Common Ancestor"
"If humans evolved from monkeys, why are there still monkeys?"
Characteristics cont.
homo
= relation
logical
= equivalent
A key factor that drives molecular homology is homologous recombination, in which nucleotide sequences are exchanged between two molecules of DNA
For example, baboons have tails therefore exhibiting a primitive trait. Apes do not, expressing a derived trait. But both come from a common ancestor.
a relationship defined between structures or DNA derived from a common ancestor
Characteristics
Primitive or symplesiomorphy: trait that is unchanged from original ancestor
ex: All vertebrates have a bony tail posterior to the anus
Derived or synapomorphy: trait that is modified from original ancestor
ex: No external tail in humans.
Anatomical Homology
Morphological and physiological similarities between different species of plants and animals
Embryological Homology
EvoDevo
similarities in embryonic development of two or more species
Vestigiality
Vestigial traits or adaptations are traits that have been favored by natural selection
ex: tonsils, appendix