These notes cover the second chapter of the course, including the lecture, readings, and essential discussions. Whether you missed a class, need to review for exams, or want a concise summary of complex topics, these notes are your go-to resource. They are ideal for students who want to save time ...
macroevolution: major changes in the history of life, usually evident in
the fossil record
1. origin of new species: generates biological diversity
2. origin of evolutionary novelty: any newly acquired structure of
property that permits the performance of a new function: ex: wings
on birds and big brains in humans
3. explosive diversification following evolutionary breakthrough:
thousands of plants species after the flower evolved
4. mass extinctions: explosion of mammals following dinosaur extinction
•the formation of new species, called speciation, occurs when 1 or more
new species branch from a parent species
a. nonbranching evolution can transform a population but does not create
new species
b. branching evolution splits a lineage into 2 or more species
biological species concept is one way to define species
•defines species as a population or group of populations whose members
can interbreed to produce fertile offspring
1. based on classification: observable and measurable physical traits
2. based on ecological niche: an ecological niche describes how an
organism or population responds to the distribution of resources and
competitors; in other words, how an organism makes a living
3. based on genetic history: should have identical genomes
the origin of species:
•what prevents biological species that are closely related from
interbreeding?
•for example what maintains the species boundary between the western
spotted skunk and the eastern skunk?
a. their geographic ranges overlap in the great plains region
b. they appear similar and yet cannot interbreed
•they are reproductive barriers that isolate the gene pools of species
-we classify the barriers as either prezygotic or postzygotic
•the barriers will block interbreeding before (pre-) or after (post-) the
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