Download Evolution

Name________________________________Date____________Per_____
Darwin: Natural Selection & Evolution
Charles Darwin
 1831 – set sail for ____ years on HMS _________ as a
_______________
 22 year old English ____________ student
 Questioned the belief that organisms never _____________
Natural Selection
 In 1859, Darwin offered an explanation – evolution occurs by
________________
 He published his idea in The Origin of ___________
Darwin’s Observations
 Diversity – each area of the world has very _______________
______________
 __________ - preserved remains of an _______________ that lived in
the __________. The fossils Darwin saw looked ____________ than
organisms living at that time.
 Characteristics of _____________ Islands organisms – organisms were
different from ___________ elsewhere and from _____________ on
other Galapagos Islands
Adaptations
 Adaptation - __________ that helps an organism ____________ &
reproduce
 Examples: the finches’ beaks; the iguanas’ ____________; poison &
_______ taste; bright colors of ___________; animal coloring
Evolution
 Darwin studied his observations for _______ years after returning to
__________
 Reasoned that organisms arriving on Galapagos faced conditions
_____________ from on the _____________ of South America
 He hypothesized the species ___________ changed over many
______________ & became better __________ to the new conditions
 This gradual change is called _______________
 However Darwin could __________ explain how the changes happened
Natural Selection
 In 1859, Darwin offered an explanation – evolution occurs by
________________
 He published his idea in The Origin of ___________
Natural Selection
 Natural selection – process by which individuals that are better
___________ to their environment are more likely to __________ &
_____________ than other members of the same species
 Factors that affect natural selection
o Overproduction – produce more ______________ than can
___________
o Variation – any __________ between individuals of the same species
o Competition – members of a species will _____________ for
__________
Organisms with a ___________ variation will ___________ & reproduce.
Poor variations will _________ out. Over a long time, natural selection will
lead to ____________.
Reasons for Species Variation (speciation):
Climate: example is snowshoe rabbit
Geographic Isolation: example is Kaibab squirrel and Abert squirrel
Interaction Between Species:
 Mutualism – relationship in which _________ species ___________
 Commensalism – relationship in which _____ species benefits and the
other is neither ___________ nor ____________
 Parasitism – 1 organism lives in or on another organism and ________ it
Genetic Mutation: - chromosomal changes
 Darwin knew that changes happened, but ______________________.
 At the same time, Mendel was explaining how change happens
______________________.