Adaptive radiation and extinction

Define what an adaptive radiation is

when organisms are able to enter a new niche & rapid increase of diversity

Define background extinction

the base level of extinction that is always occurring due to selective pressure

Define mass extinction and know the cutoffs for determining a mass extinction event

when a massive amount of biological lineages go extinct

Know one example of an adaptive radiation event

Darwin’s finches are an example of adaptive radiation, where one ancestral species diversified into many new species adapted to different environments.

Know the two causes of adaptive radiation and be able to describe them

Ecological opportunity: many niches are free at one time & a single organism moves into all of them

Morphological: a novel trait or mutation opens new areas for an organism to expand into

Be able to contrast life in the Ediacaran period and Cambrian period

Edicarian fossils: soft bodies, no limbs, similar to jellyfish

Cambrian: hard structures, shells

Know some of the features that first occurred during/after the Cambrian explosion

hard shell organisms became existent & organisms could move from being producers to consumers

Be able to describe proposed theories of why the Cambrian explosion occurred

1) the spontaneous evolution of more complex body plans allowed for additional niche usage

2) photosynthesis increased the atmospheric levels & dissolved oxygen

Know the importance of the HOX gene complex

lead to more complex body shape

Be able to describe the relationship between mass extinction and adaptive radiation

Mass extinction clears the ecological stage, and adaptive radiation is the burst of evolution that follows

Mass extinctions are caused by temporary catastrophic events

Identify possible causes of the end Permian extinction

increase CO2, sudden climate change, & sea level drop

Know the end Permian extinction was the largest ever mass extinction

Identify the proposed causes of the end cretaceous extinction

Chicxulub meteor & volcanic activity

The end cretaceous extinction was the most recent mass extinction

Be able to describe a hypothesis of why the dinosaurs went extinct during the end cretaceous extinction

because they were mesotherms they were too big and metabolism was too fast

Know the difference between mesotherms, endotherms, and ectotherms 

Meso: temp. Fluctuates with environment

Endo: warm blooded

Ecto: cold blooded