BIOL 1000 Lecture Notes - Lecture 16: Metaphase, Microevolution, Genetic Drift
2 Jul 2018
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7/2/18
BIOL 1000-HOW POPULATIONS EVOLVE
13.1 DARVIN PROPOSED NATURAL SELECTION AS THE MECHANISM OF EVO-
LUTION:
•Artificial Selection:
I. Darwin’s greatest contribution to biology was his explanation of how life evolves.
II. Insights into how incremental change occurs could be seen in examples of artificial se-
lection.
III. Darwin reasoned that if artificial selection can bring about so much change in a relatively
short period of time, then natural selection could modify species considerably over hundreds or
thousands of generations.
IV. Humans select individuals with desired traits over generations.
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7/2/18
V. Selective Breeding that modifies species.
13.2 SCIENTISTS CAN OBSERVE NATURAL SELECTION IN ACTION:
•Biologists have documented evolutionary change in thousands of scientific studies.
•An example of natural selection in action is the evolution of pesticide resistance in hun-
dreds of insect species. This example leads to 2 main points about natural selection:
I. Natural Selection is more of an editing process than a creative mechanism
VI. It is contingent on time and place, favouring those heritable traits in a varying population
that fit the current, local environment.
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7/2/18
13.3 MUTATION AND SEXUAL REPRODUCTION PRODUCE THE GENETIC VARIA-
TION THAT MAKES EVOLUTION POSSIBLE:
•Mutations are the ultimate source of the genetic variation that serves as raw material for
evolution.
•Organisms that reproduce sexually, most of the genetic variation in a population results
from the unique combination of allies that each individual inherits.
•Fresh assortments of existing alleles arise every generation from 3 random components of
sexual reproduction:
A. Crossing over.
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Document Summary
13. 1 darvin proposed natural selection as the mechanism of evo- Darwin"s greatest contribution to biology was his explanation of how life evolves. Insights into how incremental change occurs could be seen in examples of artificial se- Darwin reasoned that if artificial selection can bring about so much change in a relatively short period of time, then natural selection could modify species considerably over hundreds or thousands of generations. Humans select individuals with desired traits over generations. 13. 2 scientists can observe natural selection in action: Biologists have documented evolutionary change in thousands of scientific studies. An example of natural selection in action is the evolution of pesticide resistance in hun- dreds of insect species. This example leads to 2 main points about natural selection: Natural selection is more of an editing process than a creative mechanism. It is contingent on time and place, favouring those heritable traits in a varying population that fit the current, local environment.
