Evolution- “Change Over Time”. All of the changes that have occurred in living things since the beginning of life on Earth. Theories of Evolution. Darwin vs. Lamarck. Lamarck. Darwin. Jean-Baptiste LaMarck. French, Early 1800’s Theory of Inheritance of Acquired Characteristics
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All of the changes that have occurred in living things since the beginning of life on Earth
Theories of Evolution
Darwin vs. Lamarck
1. Principle of Use & Disuse:
“Survival of the Fittest”
An example of Adaptive Radiation
Using Darwin’s Theory, explain how all of these different species evolved.
“Seeing this gradation & diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends.”
What common ancestor do all of
These organisms share?
What common ancestor do the seed eating and cactus eating finches share?
What do each of the finch pictures on here represent?
are spit In two due to a geographic barrier. This can lead to reproductive isolation. How could this lead to speciation?
If members of a species live far away from each other, they will have a decreased chance of mating. This would create reduced gene flow, but not total isolation. Speciation would probably also require different selective pressures at the two ends.
Eventually, this could alter gene frequencies in groups at different ends of the range so much that they would not be able to mate if they were reunited…that’s speciation!
The process by which favorable heritable traits become more common in successive generations of a population of reproducing organisms, and unfavorable heritable traits become less common.
Consider, for example, a population of shellfish called limpets. The shell color of these limpets ranges from white, to tan, to dark brown. As adults, limpets live attached to rocks. On light-colored rocks, white-shelled limpets have an advantage because their bird predators cannot easily see them. On dark-colored rocks, dark-colored limpets have the advantage because they are camouflaged. On the other hand, birds easily see tan-colored limpets on either the light or dark backgrounds. These tan-colored limpets will be at a selection disadvantage and will most likely become extinct from the population. This type of natural selection is known as:
Consider a population of spiders in which the average size is a survival advantage. Predators in the area might easily see and capture spiders that are larger than average. However, small spiders may find it difficult to find food. Therefore, in this environment, average-sized spiders are more likely to survive. This type of natural selection is known as:
Imagine a population of woodpeckers pecking holes in trees to feed on the insects living under the bark. Suppose that a species of insect that lives deep in tree tissues invades the trees in a woodpecker population’s territory. Only woodpeckers with long beaks could feed on that insect. Therefore, the long-beaked woodpeckers in the population would have a selective advantage over woodpeckers with very short or average-sized beaks. This type of natural selection is known as:
MECHANISM OF EVOLUTION
Mechanisms of Evolution
Genetic Drift occurs when the frequency of alleles change
(NOT natural selection)
Newly Established Population
G H Hardy – British Mathematician
Wilhelm Weinberg – German Doctor
If we are evolving…
If we are not…
If a population is in genetic equilibrium and 30% of the individuals are homozygous recessive for the trait of color, what is the percentage of homozygous dominant individuals?
If a population is in genetic equilibrium and 41% of the individuals are homozygous recessive for the trait of color, what is the percentage of homozygous dominant individuals?
Using the example of the west nile mosquitoes that are sprayed with a pesticide, suppose one mosquito has a genetic mutation that allows the mosquito to survive. Which graph best represents the frequency of this gene over time?
You have determined the frequency of the dominant allele in a population. Over the next two generations, the frequency of this allele does not change. Which factors below must be true in order to maintain this equilibrium:
The frequency of a particular recessive allele in a population of chipmunks is .3 The frequency of the dominant allele in this same population is: