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Lecture 6

BIOL 215 Lecture Notes - Lecture 6: Homeobox, Taphonomy, Molecular Clock

Course Code
BIOL 215
Neil Price

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Adaptive Radiations
-Process by which organisms adapt rapidly over a short period of time
-Opens up new niches that these organisms can fill
-A response to an opportunity due to conditions such as: key adaptation that opens up
new ecological and evolutionary possibilities, competitive advantage, fill previously
unavailable niches, specialization (for example, by feeding on different things the
niche gets split up)
A clade will have several branches due to adaptive radiation. The organism will exploit
parts of the environment that was never used before allowing rapid adaptation.
Adaptive radiation events usually follow mass extinction.
Chicxulub Impact Crater—End Cretaceous Mass Extinction
-Created a lot of debris and affected primary producers and therefore ruining the food
chain. This caused a mass extinction.
-Iridium abundance in clay played a part in the extinction (due to crater).
Extinction List
-All ammonites
-All non-bird dinosaurs
-All pterosaurs
-All marine animals
This allowed new organisms to replace them.
Fossil remains of first eukaryotic multicellular organisms showed they were very small.
3 lineages of organisms that are found in Ediacaran fossils.
Lack many characteristics we see in many organism now. Labelled as osmotrophs.
Relationship to Cambrian animals is uncertain because of the lack of similarities.
Rangeomorphs occupy different levels
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