Early scientists proposed ideas about evolution Evolution is the biological change process by which descendants come to differ from their ancestors A species is a group of organisms that can reproduce and have fertile offspring ID: 912625
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Slide1
Chapter 10
Principles of Evolution
Slide2Early scientists proposed ideas about evolution.
Evolution is the biological change process by which descendants come to differ from their ancestors.
A species is a group of organisms that can reproduce and have fertile offspring.
Slide3There were many important naturalists in the 18th century.
Linnaeus
: classification system from kingdom to species
Buffon
: species shared ancestors rather than arising separately
E. Darwin
: more-complex forms developed from less-complex forms
Lamarck
: environmental change leads to use or disuse of a structure
Slide4The age of the Earth was a key issue in the early debates over evolution
Common view was that Earth was created about 6000 years ago and the Earth nor its species have changed
Theories of geologic change set the stage for Darwin’s theory.
Slide5There were three theories of geologic change.
catastrophism
gradualism
uniformitarianism
Slide6The theory of
catastrophism
states that
natural disasters such as floods and volcanic eruptions have happened often during Earth’s history.Shaped landforms and caused species to become extinct
Slide7James Hutton proposed that changes in landforms were the result of slow changes over a long period of time – principal of
gradualism
Slide8Uniformitarianism is the prevailing theory of geologic change.(Lyell)
The geologic processes that shape Erath are uniform through time
Slide9Darwin’s observations
Slide10Charles Darwin the Naturalist
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Slide11Charles Darwin and his
Voyage on the Beagle
Born Feb. 12, 1809
Joined Crew of HMS Beagle, 1831
Naturalist5 Year Voyage around worldAvid Collector of Flora & FaunaAstounded By Variety of Life
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Slide1212
A reconstruction of the HMS Beagle sailing off Patagonia.
Slide13Darwin Left England in 1831
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Darwin returned 5 years later in 1836
Slide14HMS Beagle’s Voyage
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Slide15The Galapagos Islands
Volcanic islands off the coast of South America
Very different climates
Island species varied from mainland species & from island-to-island species
Animals On Islands UniqueTortoisesIguanasFinches
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Slide16Darwin observed differences among island species.
Variation is a difference in a physical trait.
Galápagos tortoises that live in areas with tall plants have long necks and legs.
Galápagos finches that live in areas with hard-shelled nuts have strong beaks.
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Slide18The Finches
Finches on the islands resembled a mainland finch
More types of finches appeared on the islands where the available food was different (seeds, nuts, berries, insects…)
Finches had different types of beaks adapted to their type of food gathering
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Slide1919
Slide20An
adaptation
is a feature that allow an organism to better survive in its environment.
Species are able to adapt to their environment.
Adaptations can lead to genetic change in a population.
Slide21Darwin found fossils of extinct animals that resemble modern animals.
Darwin found fossil shells high up in the Andes mountains.
Darwin observed fossil and geologic evidence supporting an ancient Earth.
Slide22He saw land move from underwater to above sea level due to an earthquake.
Darwin extended his observations to the evolution of organisms.
Slide23Theory of Natural Selection
Slide24KEY CONCEPT
Darwin proposed natural selection as a mechanism for evolution.
Slide25Several key insights led to Darwin’s idea for natural selection.
Darwin noticed a lot of variation in domesticated plants and animals.
Artificial selection is the process by which humans select traits through breeding.
neck feathers
crop
tail feathers
Slide26Natural selection is a mechanism by which individuals that have inherited beneficial adaptations produce more offspring on average than do other individuals.
Heritability is the ability of a trait to be passed down.
There is a struggle for survival due to overpopulation and limited resources.
Darwin proposed that adaptations arose over many generations.
Slide27There are four main principles to the theory of natural selection.
variation
Natural selection explains how evolution can occur.
Fitness is the measure of survival ability and ability to produce more offspring.
overproduction
adaptation
descent with modification
VARIATION
OVERPRODUCTION
ADAPTATION
DESCENT with
MODIFICATION
Slide28Natural selection can act only on traits that already exist.
Structures take on new functions in addition to their original function.
Natural selection acts on existing variation.
wrist bone
five digits
Slide29Evidence for Evolution
Slide30KEY CONCEPT
Evidence of common ancestry among species comes from many sources.
Slide31Evidence for evolution in Darwin’s time came from several sources.
Fossils provide evidence of evolution.
Fossils in older layers are more primitive than those in the upper layers.
Slide32The study of geography provides evidence of evolution.
island species most closely resemble nearest mainland species
populations can show variation from one island to another
Slide33Embryology provides evidence of evolution.
Larva
Adult
barnacle
Adult crab
identical larvae, different adult body forms
similar embryos, diverse organisms
Slide34The study of anatomy provides evidence of evolution.
Human hand
Bat
wing
Mole
foot
Homologous structures are similar in structure but different in function.
Homologous structures are evidence of a common ancestor.
Slide35Human hand
Bat wing
Mole foot
Fly wing
Analogous structures are not evidence of a common ancestor.
The study of anatomy provides evidence of evolution.
Analogous structures have a similar function.
Slide36Vestigial structures are remnants of organs or structures that had a function in an early ancestor.
Ostrich wings are examples of vestigial structures.
Structural patterns are clues to the history of a species.
Slide37Evolutionary Biology Today
Slide38Fossils provide a record of evolution.
Paleontology is the study of fossils or extinct organisms.
Slide39Paleontology provides evidence to support evolution.
Slide40Molecular and genetic evidence support fossil and anatomical evidence.
Two closely-related organisms will have similar DNA sequences.
Slide41Pseudogenes are sequences providing evidence of evolution.
no longer function
carried along with functional DNA
can be clues to a common ancestor
Slide42Hox genes indicate a very distant common ancestor.
control the development of specific structures
found in many organisms
Protein comparisons, or molecular fingerprinting reveals similarities among cell types of different organisms.
Slide43Scientist from any fields contribute to the understanding of evolution.
The basic principles of evolution are used in many scientific fields.
Evolution unites all fields of biology.