ED.05- HOMOLOGY AND COMPARATIVE BIOLOGY

homology

sir Richard Owen- the same structure under a variety of forms and function. similarity due to shared ancestry

analogy

different structures of similar forms and function. Darwin- convergence or similarity arising independently of ancestry

what's convergence

similar traits arising independently

how are homologous structures identified

topological patterns- The positional relationship between parts and some fixed 'landmark' points like the eye and nose openings.

vestigial structures

body part or trait that has lost its original function through evolution.

homology uses

taxic homology- define taxa. shoe evidence of species relatedness. transformational- evolutionary transformations in structures. mammal ear.

homology types

serial- repeated structures of similar identity. embryological, cellular, sequence- % similarity in base sequence,

orthology

functionally equivalent homologues ( unduplicated)

paralogy

functionally divergent or redundant homologue (involves gene duplication: analogous concept to serial homology) homologous but distinct from genes in different species (orthologs), allowing them to evolve new functions or retain similar ones.

Owen

Owen and his contemporaries believed these similarities existed because species were created according to a divine or abstract "Archetype" (a blueprint).