Ch. 16-17 Flashcards
What did people believe that species where?
Perfect and unchangeable
Evolutionary theory
A scientific explanation to account for the diversity of life
James Hutton
Discovered that the earth changed because of the weather
Published “Principles of Geology”. Influenced Darwin
Charles Lyell
“Principle of Population” said human population will grow faster than the space and food supplies needed to sustain it
Thomas Malthus
Recognized that living things have changed over time and that organisms adapted to their environments
Jean-Baptiste Lamarck
What 3 things did Lamarck state in his theory?
- Tendency toward perfection
- Use and disuse
- Inheritance of acquired traits
Tendency toward perfection
Organisms are continually acquiring features to help them live successfully
Use and disuse
Organisms could alter themselves physically by using their bodies in new ways(fly—>arms into wings)
Inheritance of acquired traits
Acquired characteristics could be inherited(work out to get big muscles=your children will have big muscles)
Why was Lamarck wrong?
- Realized organisms are adapted to their environments
- An organism’s behavior has no effect in inheritable characteristics
- No evidence that organisms try to become more perfect
What did Darwin observe in the Galápagos Islands?
- Many plants and animals were well suited for their environment
- He noticed where these species lived, and where they didn’t
- Looked at fossils
What formed the basis for early evolutionary ideas?
Fossils
Who was the first scientist to publish using fossil evidence?
Charles Darwin
Gene Pool
All the genes, including all the different alleles for each gene, that are present in a population
Allelic frequency
The number of times an allele occurs in a gene pool, compared to the total number of alleles in that pool for the same gene
Natural selection
Explanation for how evolution occurs in nature
What are organisms with favorable variations able to do?
Survive, reproduce, and pass on their variations to the next generation
Why does each generation have a large amount of offspring?
The more that they have the more they are likely to survive
Why does Natural selection occur?
- Overproduction
- Genetic variation (individuals will be slightly different from each other)
- Survival struggle (competition for resources)
- Successful reproduction
Natural variation
A variation in the expression of their traits
What does natural variation often take the form as?
A curve
When do most individuals express the phenotype on the curve?
At the peak of the curve
Why are there fewer individuals at the ends of the curves?
Their phenotype doesn’t give them as good a chance than those at the peak
What is the favorable phenotype determined by?
The environment
Fitness
The ability of an individual to survive and reproduce in a specific environment
Survival of the fittest
States that individuals with characteristics that are not well suited to their environment will either die more often or leave few offspring
Adaptation
Any variation that aids an organisms chances of survival in its environment
What are some examples of adaptations?
- Camouflage
- Thorns
- Color
Speciation
Process by which new species are generated
When does speciation occur?
When populations of a single species are reproductively isolated from each other
Do we need speciation?
Yes
What are the different ways groups of the same species can be reproductively isolated from each other?
- Continental drift
- Mountain uplifting
- Changes in sea level
- Changes in climate
- Island formation
What 2 things cause speciation?
- Selective pressures
2. Reproductive isolation
Selective pressures
Some traits that are fit in one environment, but might not be in another
What happens during selective pressure?
Genes can no longer transfer between diverged populations and the allergic frequency in the 2nd population will begin to change
Homologous structure
Structure that is similar in arrangement, inn functions, or in both and was inherited from a common ancestor
Vestigal structure
A structure in a present day organism that no longer serves its original purpose (appendix)
Where are fossils formed?
Sedimentary rock
How are fossils formed?
- Quickly covered with sediment
- U disturbed
- Bones replaced with minerals from rock
- Weathering and erosion uncover them
By examining where fossils are located and the changes, what can we learn?
How species evolved over time
Transitional fossils
Fossils that show the intermediate stage between current species and their ancestors
Are transitional fossils direct descendants?
No
Allele Frequency
The percentage of any specific allele in the population(how often the allele shows up)
Do allele frequencies change?
YES
What has to change in order for an allele frequency to change?
The genotype
What would happen if there were significant changes in the gene pool of a population?
Evolution of a new species over time
Genetic drift
An alteration of allergic frequencies by chance events
Genetic equilibrium
The frequency of alleles remains the same over many generations (no evolution)
Bottleneck effect
A change in allele frequency following a dramatic reduction in the size of a population (ex. Disease)
What can the bottleneck effect do?
Reduce a population genetic diversity
Founder effect
A few individuals colonize a new habitat
What 5 things did Hardy-Weinberg predict would disturb genetic equilibrium?
- Non random mating
- Small population
- Immigration
- Emigration
- Mutations
- Natural selection
Adaptive radiation
Species that derived from a common ancestor that have successfully adapted to their environment by natural selection
Divergent evolution
Species that were similar to ancestral species become more and more distinct
Convergent evolution
Occurs when distantly related organisms evolve similar traits
Evolution
Change over time
