Download Darwin and Natural Selection Notes Galapagos Islands

Darwin and Natural Selection Notes
Galapagos Islands- islands off cost of South America and where Darwin recorded many
observations; refer to pages 418-422 for additional information.
Darwin observed differences and similarities among various species living on the mainland and
those living
 Tortoises
 Finches had different types of beaks _______________________________________________
 Darwin guessed that some of the birds from South America ___________________________
and changed over the years
These observations show
 ______________________________________________________________________________

______________________________________________________________________________
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Patterns in species suggested species had changed over time and had given rise to
______________________________________________________________________________
Darwin concluded
 Each species has _______________________________________________________________


Darwin called this ______________________________________________________________
or Evolution: the slow, gradual change in a species population over time
Common Descent with Modification
o Darwin proposed that organisms descended from _____________________________
o
o
o
o
o
Idea that organism change with time, _______________________________________
Caused evolution of new species
Takes place over long periods of time
Natural Selection can be observed as changes in body structure, ecological niches or
habitats
Species today look different than their ancestors
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Theory of Natural Selection: Survival of the Fittest
 Mechanism by which Darwin proposed evolution took place
 Darwin published his theory in the book ___________________________________________
Natural Selection
 Driving force for evolution
 During the struggle for resources, _________________________________________________
 Idea that at least some of the differences between individuals, which impact their survival
and fertility, ___________________________________________________________________

Five Basic Components of Natural Selection, page 420
1. ________________________________________________________________________
2. ________________________________________________________________________
3. ________________________________________________________________________
o
Organisms compete for
o Food
o Water
o Shelter
o Space
o Mates
4. ________________________________________________________________________
o
o
o
Fitness is the ability of an individual to survive and reproduce in its specific
environment. Fitness is a result of adaptations
Some organisms are more suited to their environment as a result of
variations in the species
Individuals that are fit to their environment survive and leave more
offspring than those who aren’t
5. _______________________________________________________________________
o
o
o
Living species today are descended with modifications from common ancestral
species that lived in the past
Characteristics of fit individuals increase in a population over time.
Over time, genes for less favored characteristics will be eliminated from the gene
pool
Adaptations and Extinction
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

An ______________________ is any inherited characteristic (a genetic variation) that can
increase an organism’s chance of survival.
An organism does not change because of need or desire to survive. The organism either
already has the variation that enables it to survive or it dies
_________________________ occurs when an entire population of a species can not adapt to
environmental changes
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