Changes Over Time - Coach Jones
Transcript of Changes Over Time - Coach Jones
Changes Over Time
EVOLUTION
Charles DarwinThe Father of Evolution
History
• Darwin’s World (1809 - 1875)• Height of the British colonial period.• Beginning of the Industrial
Revolution.• New Ideas:
– Taxonomy of Carolus Linnaeus– Lyell’s “Principles of Geology”
Carolus Linnaeus (1707 – 1778)
Believed in the “Fixity of Species”
Binomial System of Nomenclature
Charles Lyell
• Father of Geology
Charles Lyell’s view of the process of formation of sedimentary rock
• Suggests that sedimentary rock is very old – therefore the species that are represented in this rock must also be old.
• Most fossils are found in sedimentary rock.
• Older fossils will be found below younger fossils.
Charles DarwinAt the age of 22, he joined a 5 year expedition aboard the HMS Beagle to map the coast of South America
The voyage of the Beagle
1. Members of a population have heritable variations.(Inheritance of traits)
Charles Darwin’s Theory of Evolution:
2. In a population, more individuals are produced than the environment can support. They compete for food and shelter. (overpopulation- struggle for survival).
3. Some individuals have adaptive characteristics that enable them to survive and reproduce better than other individuals (survival of the fittest).
4. An increasing number of individuals in succeeding generations have these adaptive characteristics (natural selection)
Darwin described his theory in the form of a long essay which he called
“On the Origin of Species”.
Publication of “On The Origin of Species” in 1859
Charles Darwin
At age 50 (1859) At age 65 (1874)
Charles Darwin
Before publication After publication
• Through his observations made in the Galapagos Islands, Charles Darwin formulated a theory of how species change over time, called natural selection.
• Natural selection is governed by the principles of genetics.
• The change in the frequency of a gene in a given population leads to a change in a population and may result in the emergence of a new species.
• Natural selection operates on populations over many generations.
Evolution
• A change in successive generations of organisms, due to random mutation and changes in the organisms’ surroundings
• Evolution takes place through a set of processes that include: – mutation,
– adaptation,
– natural selection,
– extinction.
Mutation
• Genetic mutations and variety produced by sexual reproduction allow for diversity within a given population.
• Many factors can cause a change in a gene over time.
Mutation• Mutations are
important in how populations change over time because they result in genetic changes to the gene pool.
• Mutations are inheritable changes because a mutation is a change in the DNA code
Mutation- a change in the DNAA mutation may
result in a:
1. favorable change or adaptation in genetic information that improves a species’ ability to exist in its environment
2. an unfavorable change that does not improve a species’ ability to exist in its environment.
Mutation- a change in the DNA
3. in a change in the genetic information that neither harms nor helps the species.
Mutation- a change in the DNA
Adaptation
• Adaptations are structures, functions, or behaviors that enable a species to survive.
Adaptation• Depending on the rate of
adaptation, the rate of reproduction, and the environmental factors present, structural adaptations may take millions of years to develop.
Natural Selection
• the survival and reproduction of the individuals in a population that exhibit the traits that best enable them to survive in their environment.
• The Survival of the Fittest
Natural Selection
• Populations produce more offspring than the environment can support.
Natural Selection• The unequal ability
of individuals to survive and reproduce leads to the gradual change in a population, generation after generation over many generations.
Natural Selection
• Organisms with certain genetic variations will be favored to survive and pass their variations on to the next generation.
• These five canine species evolved from a common ancestor through natural selection
African wild
dog
CoyoteFox WolfJackal
Thousands to
millions of years
of natural selection
Ancestral
canine
When humans choose organisms with specific characteristics as breeding
stock, they are performing the role of the environment
• This is called “artificial selection”
Example of artificial selection in plants: five vegetables derived from wild mustard
Artificial Selection in Animals: Dog Breeding
German
shepherd
Yorkshire terrier English springer
spaniel
Mini-dachshund Golden retriever
Hundreds to
thousands of years
of breeding
(artificial selection)
Ancestral dog
The evolution of insecticide resistance is an example of natural selection in action
Chromosome with gene
conferring resistance
to insecticide
Additional
applications of the
same insecticide will
be less effective, and
the frequency of
resistant insects in
the population
will grow
Survivor
Insecticide
application
Fossil Record
• Although there is not a complete record of ancient life for the past 3.5 billion years, a great deal of modern knowledge about the history of life comes from the fossil record.
• The study of fossils provides strong evidence for evolution.
Hominid skulls Petrified Trees
Ammonite casts Fossilized organic matter in a leaf
Scorpion in amber “Ice Man”
Distribution of species
• Most marsupials live in Australia
• This supports the theory of continental drift.
Distribution of species
Geographic isolation can lead to speciation
Species• Organisms that
can breed and produce FERTILE offspring.
Adaptive Radiation• where species all
deriving from a common ancestor have over time successfully adapted to their environment via natural selection
Homologous Structures• Body parts in different organisms
that have similar bones and similar arrangements of muscles, blood vessels, and nerves and undergo similar embryological development, but do not necessarily serve the same function; e.g., the flipper of a whale and the forelimb of a horse.
Homologous Structures
Human Cat Whale Bat