BIOLOGY 1M03 Lecture Notes - Lecture 6: Natural Experiment, Rifampicin, Allele FrequencyPremium
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BIOLOGY 1M03 - Lecture 6 - Evolution by Natural Selection (Continued)
Expansion on Homologies:
● Developmental homology is known as similarities in embryonic traits.
○ An example of this type of homology is the gill pouches found during
embryonic development in chicks, humans, and cats.
● Structural homology refers to similarities in adult morphologies (appearances of
○ An example of this type of homology is the common structural plan found
in the bones of the limbs in vertebrates (animals with a backbone).
● Many traits are similar in species because of the theory of having a common
ancestor. If species were created independently of one another, these similarities
might not have occurred.
● The homology of structural homology is assessed on the basis of three critea:
Evidence for Evolution:
● The prediction that species are not static, but dynamic is supported by the
○ Most species have gone extinct
○ Fossil (extinct) species frequently resemble living species found in the
○ Transitional features document change in traits through time
○ Vestigial traits are common
○ The characteristics of populations can be observed changing today
● The prediction that species are related, not independent, is supported by the
○ Closely related species often live in the same geographic area.
○ Homologous traits are common and are recognized at three levels:
■ Genetic (gene structure and the genetic code)
■ Developmental (embryonic structures and processes)
■ Structural (morphological traits in adults)
○ The formation of new species from pre-existing species can be observed
Evolution’s Internal Consistency - The Importance of Independent Data Sets:
● The most powerful evidence for any scientific theory, including evolution by
natural selection, is called internal consistency. This term refers to observation
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