Close Notes: Species Change over Time:
________________- occur following a _____________ drastic change in the environment
If organisms don’t ____________ quickly enough to survive, they die
The extinction of a species can affect an __________ ecosystem
- __________ that relied on the ___________ species for food may die
- Species that once ___________ for food with the extinct species may thrive
Extinction is a ____________ part of evolution
Scientist s estimate that about __________ of all species that ever lived on Earth have become __________
On average a species will ___________ on Earth 2 to ______ million years
- Natural Events that cause Extinctions: ____________, rainfall, volcanic eruption, __________, flooding or drought, ________land masses or seas, a __________ in food supply, a new _________ or __________
- ________ million years ago species living in the ocean and on land became extinct because ________ _________ moved together which ________ the _________ of Earth
- ______million years ago _________ disappeared on Earth
- ___________Theory- at the rock layer between the Cretaceous and Tertiary periods evidence of an asteroid can be found
Human Threats for extinction:
Reduce human encroachment –land management
Non - native species introduced to new locations
Contaminated land, air, water
Land use management
Species taken for food, energy, medicine
Ozone depletion, greenhouse effect
Reduce demand, laws
Answer the following questions from the video. Isn’t Evolution just a Theory?
- What is a theory?
- What is an inference?
- What was Charles Darwin’s theory?
Charles Darwin (1809-1882) Sailed around the world 1831-1836
What did __________ Travels reveal?
- The ____________ of living species was far ___________than anyone had previously known!!
- These observations led him to develop the _________ of ____________!!
- Based in part his evolutionary theory on observations of _________ species on the Galapagos Islands.
- ___________ species of finch had developed ___________ beak _________for the types of food that was available on the different islands
- Suggested that the ___________ species of finch had __________ from the original species in response to ___________ environmental conditions
How did tortoises and birds differ among the islands of the Galapagos?
- Each _________ had its ________ type of tortoises and birds that were clearly _________ from other islands
- ____________ provides variations, ___________ select variations that are useful.
Natural Selection and Species Fitness:
- Over time, _________ selection results in changes in the ___________ characteristics of a population.
- These changes _________ a species fitness (survival rate)
- The traits that help an organism survive in a particular environment are “____________” in natural selection
Summary of Darwin’s Theory
Theory of Natural Selection
- Darwin knew from personal experience that dog breeders can produce new species over time by selective breeding techniques. Breeding dogs with desired traits produces a new breed of dog. This process is called artificial selection.
- He thought this process might be ______________ occurring in nature and termed it natural selection
Key Principles of Natural Selection
- ___________________ - most organisms produce more offspring than can survive
- _______________ - visual differences among individuals result from differences in genetic material this process of changing base pairs in the DNA is called a mutation.
________________ - A trait that improves an organism’s chance for survival and reproduction.
_______________- The individuals that have the adaptation increase in numbers and are able to adapt to the environment over the individuals who do not have the adaptation
Evidence of Evolution
Evolution and Speciation
- ________ ________ – Common group of _______ genes present in a population.
- ____________ genetic info. of _________ members
- Allele frequency is # of times alleles occur
Variation in Populations:
2 processes can lead to this:
- ___________ -change in DNA sequence
- ________ __________ – from sexual reproduction
Evolution of populations: Occurs when there is a __________ in relative frequency of alleles
Speciation: The Formation of a _______ Species
- As new species evolve, ___________ become reproductively isolated.
- _________________ ___________ – members of 2 populations cannot interbreed and produce fertile offspring.
Speciation in Darwin’s Finches:
- Speciation of the Galapagos Finches occurred by:
- Geographic Isolation which led to – Reproductive isolation and
- Changes in the new population’s gene pool due to __________________.