Transcript Document

THEORY OF
EVOLUTION
Chapter 16
Idea of Evolution
◦ Charles Darwin (1809-1882)
◦ English naturalist
◦ Took a trip around the world on a ship called H.M.S. Beagle
◦ Mostly fascinated with the Galapagos Islands
◦ Best known for his theory of evolution by natural selection
Darwin’s Journey
◦ Began in 1831
◦ Sailed on a ship called the H.M.S. Beagle
◦ Five year voyage sailing around the coast of South America
and Australia
Observations Aboard the Beagle
◦ Darwin collected 68 species of beetles
◦ Wrote about the different characteristics of habitats and
species that live there
◦ Species vary globally
◦ There are similar organisms around that world with similar ecological
habitats
◦ Ex: Rhea birds in S. America and ostriches in Africa
Observation Aboard the Beagle
◦ Species vary locally
◦ Related animals species often occupy different habitats
within a local area
◦ Ex: Tortoise shell shape among Galapagos Islands
Observation Aboard the Beagle
◦ Species vary over time
◦ Some fossils of extinct animals were similar to living
species
◦ Ex: Armadillo fossils compared to modern day armadillos
Darwin’s Findings
◦ Galapagos Islands
◦ Groups of animals vary from island to island
◦ Ex: tortoises and finches on each island resemble each other but differ in
the shape and function of their shells and beaks
◦ Darwin believed these unique animals all came from a common
ancestor and they changed/adapted to their environment
Idea of Evolution
◦ Evolution
◦ Development of new types of organisms over time
◦ Heritable change in the characteristics within a
population from one generation to the next
http://ed.ted.com/lessons/myths-and-misconceptions-about-evolution-alex-gendler
Ideas of Darwin’s Time
◦ Scientists thought all species were permanent and unchanging
◦ The Earth was believed to only be a few thousand (not
billions) of years old
◦ During Darwin’s time, new research was being done to figure
out the geology of the Earth
Ideas that Influenced Darwin
◦ James Hutton was a geologist in 1700’s
◦ Made connections between mountains, valleys, and layers of
rock
◦ Believed the Earth was older than thousands of years -- a time
so old for the human mind to image
◦ The Earth changes very slowly and some layers can accumulate
as the environment is changing
Ideas that Influenced Darwin
◦ Charles Lyell was a English geologist
that believed the Earth’s surface
continues to change
◦ He explained that past processes that
occurred are still occurring now
◦ Ex: Volcanoes erupted in the past and still today
◦ Published a great work called Principles of Geology in
1830 that built on the work of Hutton
◦ Darwin read this book while on his journey
around the world
Ideas that Influenced Darwin
◦ Jean-Baptiste Lamarck
◦ French naturalist that supported the idea that populations of
organisms change over time
Ideas that Influenced Darwin
◦ Proposed two hypotheses: Called Theory of Acquired Traits
◦ Organisms could change during their lifetime by using or not using selected
parts of the body
◦ Individuals could pass these acquired traits on to their offspring
◦ Ex: Giraffes could lengthen their neck by stretching over a period of
time to get the height they needed to eat and survive and then pass the
longer neck trait to their offspring
Ideas that Influenced Darwin
◦ Thomas Malthus was an English economist in the 1790s
◦ Reasoned that if the human population grew continuously, there would not be
enough resources for everyone
◦ His reasoning explained why plants and animals produced more a high amount
of offspring since a portion will not survive due to environmental factors
◦ Ex: Maple tree produces thousands of seeds each summer
◦ Ex: Oysters produce millions of eggs each year with the understanding that
only a fraction will survive
Darwin’s Ideas
◦ Around the same time Darwin and Wallace formed theory to explain
evolution
◦ Darwin was able to publish his book first called On the Origin of Species
in 1858
◦ Book explained how evolution occurs by means of natural selection
Free in iBooks!
Artificial Selection
◦ Darwin studied animal breeders
◦ Farmers would select to breed only trees with the largest
fruit, or the cows that produce the most milk
◦ Darwin called this process artificial selection
◦ Nature provides the variations, and humans select hose they
find to be useful and allow them to breed and pass on traits
to offspring
http://www.youtube.com/watch?v=AJNK3FwtZFg
Evolution by Natural Selection
◦ Mechanism from descent with
modification
◦ 1. Struggle for Existence
◦ 2. Variation and Adaptation
◦ Traits vary within a species and their
environment called adaptations
◦ Organisms produce more
offspring than can survive
◦ These adaptations help increase ability
to survive
◦ Ex: dogs give birth to a litter of
puppies, while only a majority
survive
◦ Ex: Mimicry with coral snake and
scarlet snake
Natural Selection (cont’d)
◦ 3. Survival of the Fittest
◦ Organisms best adapted for an
environment will survive best and
reproduce
◦ The ability for an organism to
reproduce and pass on adaptations
◦ Ex: camouflage to help hide from
predators
http://www.youtube.com/watch?v=t-LTWFnGmeg
◦ 4. Natural Selection
◦ Process by which organisms with
variations most suited to their local
environment survive and leave more
offspring
◦ Organisms choose their mate based on
desired traits
◦ Ex: beetles that are not eaten because of
their color, will reproduce
Common Descent
◦ Idea that every species must have descended by reproduction from pre-existing
species that arrange over time
◦ Ex: finch beaks at Galapagos
◦ All species – living and extinct – are descended from ancient common ancestors
Transitional Species
◦ Organisms with features that are between hypothesized
ancestors
http://ed.ted.com/lessons/myths-and-misconceptions-about-evolution-alex-gendler
Age of the Earth & Fossils
◦ Noted that fossils of
extinct animals
resembled living species
◦ Relative Age
◦ Age compared to other
fossils in order of old to
young
◦ Absolute Age
◦ Using radioactive dating
to get actual number age
Age of the Earth and Fossils
◦ Age of the Earth
◦ Geologists are certain based on
evidence via radioactive dating to
indicate the Earth is about 4.5 billion
years old
◦ Fossils
◦ Remains of an organism that died long
ago
◦ Many fossils form a series that can trace
back to an ancient extinct ancestor
◦ Superposition
◦ Idea that strata form in layers where the
layers closest to the top are the younger
than below
Anatomy and Embryology
◦ Anatomy: study of the body
◦ Embryology: study of development
◦ Homologous structures
◦ Anatomical structures that originated
from the same common ancestor
◦ Ex: bones in arms of humans,
penguins, alligator and bat
◦ Related structure but function may differ
Anatomy and Embryology
◦ Analogous Structures
◦ When structures have similar
function, but did not develop
the same way
◦ Ex: wings of bat vs. bird
◦ Vestigial Structures
◦ Organs that no longer serve a
function in an organism
◦ Ex: human tail bone, appendix
Anatomy and Embryology
◦ Embryology
◦ Similar patterns of
embryological
development provide
further evidence that
organisms have
descended from a
common ancestor
◦ Many animals look
similar during
development and
produce homologous
tissue
Genetics and Molecular Biology
◦ At the molecular level, the genetic code and homologous
molecules provide evidence of common descent
Phylogeny
◦ Relationships among groups
of organisms
◦ Can make a “tree” of animals
evolved
◦ Trunk of the tree would
represent species that are closely
related
◦ Branches represent a separate
population or lineage
Evolution in Action
◦ Biologists tested the hypothesis by comparing DNA from
the various species
◦ DNA evidence supported hypothesis 2 that each lizard evolved
independently on each island
◦ Convergent Evolution
◦ Process by which different species
evolve similar traits
◦ Ex: twig-dwelling species came from
different ancestors but evolved similar
adaptations to their environment
Divergence & Radiation
◦ Divergence evolution
◦ Process by which the descendants of a single ancestor
diversify into species that each fit different parts of the
environment
◦ Ex: All breeds of dog share a common ancestor with wolves
Divergence & Radiation
◦ Adaptive Radiation
◦ Pattern of diversity when a new population in a new environment
undergoes divergent evolution
Coevolution
◦ Evolution is on-going and many species may evolve together
◦ Coevolution
◦ When two or more species have evolved adaptations to each other’s
influence
◦ Ex:
◦ Predator/Prey Interactions
◦ Introduction of new species
◦ Creating antibiotics