Download Evolution PPT Notes

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Evolution Notes
Important Definitions:
 Evolution:
 Process by which modern organisms have __________________ from ancient organisms
 ___________________________________
 Theory:
 A well ___________________ explanation of phenomena that have occurred in the
natural world
Charles Darwin (1809-1882)
 Father of ________________________
 Born in England in 1809
 After college, in 1831, he joined the crew of the _______________________________ and sailed
around the world for ______ years.
 This was one of the most important voyages in the history of ________________.
 During his travels, Darwin made numerous observations and collected evidence that led him to
propose a revolutionary hypothesis about the way life ________________________________.
Darwin’s Observations
 During his travels, Darwin saw great __________________.
 In a single day, he found 68 species of beetles and he wasn’t even looking for them!
 Darwin saw that only certain animals lived in certain places even when the
_________________________ were the same.
 While on his journey, Darwin collected many __________________ (preserved remains of
ancient organisms)
 Some fossils resembled _________________________ organisms, while others looked
completely ______________________.
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The Galapagos Islands
 Located 600 miles off the west coast of ______________________
 13 large islands, 6 small islands, and many other islets and rocks
 The islands all vary in ____________________ and ______________________
 Similar ____________________
 Varying amounts of __________________ (depends on height of island)
 Some islands were covered in plant and animal life, others had very few organisms
 Depends on rain and volcanic activity
 Darwin looked at tortoises and noticed that the tortoises on different _____________________
had different characteristics.
 He also looked at finches and collected many specimens and noticed that each had a different
shaped _______________________.
 The different shaped beaks came from different islands
 He concluded that the beak shape was a result of the available
_______________________ sources on each island.
Ideas that Shaped Darwin’s Thinking
 By the time Darwin when on his voyage, many discoveries had turned up important pieces of
evidence.
 The most important = The ______________________ – made scientists question their
beliefs and forced them to adjust their ideas
 During the 18th and 19th centuries, ___________________ was being studied in great detail
 Scientists gathered information suggesting that the Earth was very old and had changed
________________________ over time.
The Geologists
 ____________________ ____________________
 Proposed that layers of rocks form very slowly
 Some rocks are moved up by forces beneath the Earth’s surface, others are buried, and
others are pushed up from the sea floor to form ___________________ ranges.
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 Because of these things, Hutton proposed that the Earth had to be much older than a
_______________________________ years
 ____________________ ____________________
 Stated that one must explain past events in terms of ___________________ that they can
actually observe, since processes that shaped the Earth millions of years earlier continue
in the ________________________.
Lamarck’s Evolution Hypotheses
 He recognized that living things change over time and that all species were descended from
other species.
 Also realized that organisms were somehow ____________________ to their environments.
 Proposed 3 hypotheses:
1. ________________________________________ – organisms are continually changing
and acquiring features that help them live more successfully in their environments
i. Ex.
2. ___________________________ – organisms could alter the size or shape of particular
organisms by using their bodies in new ways
i. Ex.
ii. Ex.
3. ________________________________ – inheritance of a trait that your parents acquired
sometime in their life
i. Ex.
 Lamarck’s ideas are incorrect in several ways:
 He didn’t know how traits were _______________________.
 He did not know that an organism’s _________________________ has no effect on its
heritable characteristics.
 Though incorrect, Lamarck was one of the first to realize that organisms are adapted to the
_____________________________.
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On the Origin of Species
 In 1858, ____________________ __________________ wrote Darwin an essay that summarized
his own thoughts on evolution and ______________________________.
 This gave Darwin the courage to present his own work.
 In 1859, __________________________________ was published.
 Darwin’s book described two things:
 Mechanism for evolution = __________________________________
 Also explained the _____________________ behind his ideas
Inherited Variation and Artificial Selection
 Darwin knew that traits were passed from parent to offspring
 __________________ variation – differences that are passed from parent to offspring
 Even though Darwin didn’t know how heredity worked, he argued that variation did matter.
 He argued that humans used these variations to their advantage when it came to farming.
 Those cows that produced the most milk were used for mating; the cows that didn’t
produce much milk were ignored.
 __________________________ – nature provides the variation, and humans select those
variations they find useful
Evolution by Natural Selection
 ________________________________________ –
 Members of the same species compete regularly to obtain _____________________,
____________________________, and other necessities of life
 Darwin used _______________________ idea to help him.
 Malthus reasoned that if the human population continued to _____________
unchecked, sooner or later there would be insufficient ____________________
for everyone.
 Darwin applied this to all _________________________.
 In this struggle, the predators that are faster or have a particular way of hunting will catch
more prey. Those prey that are faster, better camouflaged, or better protected can
better avoid being caught.
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 ______________________________________
 ___________________ – the ability of an individual to survive and reproduce in its
specific environment
 Central to Darwin’s idea of natural selection
 ___________________ – any inherited characteristic that increases an organism’s chance
for survival
 Successful adaptations enable organisms to become better suited to their
environment and thus better able to ________________ and _________________.
 Survival of the fittest (aka _______________________________) – individuals that are
better suited to their environment survive and reproduce more successfully
 ________________ selects for those that are best ____________________
 Only certain individuals of a population reproduce
 Over time, natural selection results in changes in the inherited characteristics of a
population. These changes increase a species ________________ in its environment.
 Example – __________________________ and the Peppered Moths
 ___________________________________________
 Darwin proposed that over long periods, natural selection produces organisms that have
different structures, establish different niches, or occupy different habitats.
 This results in species looking different from __________________.
 Each living species has descended, with slight ____________________, from other
species over time.
 ________________________________ – all species (living and extinct) were derived from
a common ancestor
 This is shown by the “Tree of Life”
Evidence for Evolution
 ________________________________
 Darwin saw fossils as a record of the history of ______________
 Compared fossils from newer rock layers to older rock layers to see how life has changed
over time
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 ___________________________________________
 Different species of animals that are found in similar environments will evolve to have
_________________________ features
 ____________________________________________
 These are structures that have different mature forms but develop from the same
embryonic tissues
 Same _______________, different __________________
 Ex = _____________________________________
 _____________________________________________
 Structures similar in appears and function but have different origins and different internal
structures
 Different __________________, same _________________
 Ex = ______________________________
 Ex = ______________________________
 _______________________________
 Structure that serves no useful purpose or function
 Ex = _________________________
 __________________________________
 Embryos are similar at early stages, but become more different as time goes by
Summary of Darwin’s Theory
 Individual organisms differ, and some of this variation is ________________________.
 Organisms produce more offspring than can ________________________, and many that do
survive do not ______________________.
 Because more organisms are produced than can survive, they compete for limited
_________________________.
 Each organism has advantages and disadvantages in the _________________________________.
Individuals best suited to their environment survive and ____________________________ most
successfully. These organisms pass their heritable traits to their offspring. Other individuals die
or leave fewer offspring. This process of natural selection causes species to change over time.
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 Species alive today are _______________________________________ from ancestral species
that lived in the distant past. This process, by which diverse species evolved from common
ancestors, unites all organisms on Earth into a single ____________________________.
Genes and Variation
 Darwin’s theory of evolution by natural selection explained how life on Earth changed, or
__________________, over many generations.
 What Darwin did not know was how genes were passed down through each ________________.
 In genetic terms, evolution is any change in the relative frequency of _____________________ in
a population.
 ___________________________ – the number of times an allele occurs in a population
compared to the number of times other alleles for the same gene occur
 Ex = 20 individuals are TT, 30 are Tt, and 25 are tt
 Frequency of T = _________
 Frequency of t = _________
 There are two main sources of genetic variation
 _________________ – any changes in a sequence of DNA
 Are all mutations bad???
 ___________________________________________
 If a dog is born with a thicker coat in a cold snowy environment, that mutation
would be _____________________.
 However, if that same dog is born with a thick coat in the desert, that mutation
would be _______________.
 ____________________ – occurs during gamete formation
 It can produce _________________ of different gene combinations
Speciation
 ____________________ is the formation of new species from existing species.
 For one species to evolve into a new species, a separation of ____________________ must occur.
 As new species evolve, populations become reproductively isolated from one another. This can
happen in three ways:
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 _______________________ Isolation – occurs when populations have different courtship
and reproductive behaviors.
 _______________________ Isolation – occurs when geographic barriers separate
populations
 _______________________ Isolation – occurs when populations reproduce at different
times
 There are 3 requirements for speciation to take place:
 _____________________________________
 _____________________________________
 A gene pool consists of all genes found in a population
 ____________________________________