Evidence of Evolution
Mechanisms of Evolution
Darwin's Theories
Key Terms
Random
100
What type of structure is shown here? What do they tell us about evolution?
Analogous Structures (same function, different structure). Tell us that the organisms were exposed to similar environmental pressures.
100
How does migration (gene flow) contribute to evolution?
It introduces new genes/alleles into a population
100
The variety of organisms and their variations in an ecosystem
Biodiversity
100
Webbed feet of a duck to help swim, special muscles in sloths toes that allow it to hang for long amounts of time, and elephants tusks that allow them to protect themselves are all examples of what?
Adaptation
100
How would you define a species?
A group of individuals that interbreed and produce viable, fertile offspring
200
A structure that no longer serves a purpose but is still present in the organism
Vestigial Structures
200
How do mutations contribute to natural selection?
The DNA change creates new alleles that may be beneficial or more suitable for an environment. Thus allowing that organism or population to survive in the environment.
200
What did Darwin mean by Survival of the Fittest?
Individuals with favorable traits will endure limiting factors & gain resources and will be more likely to survive. Those organisms that survive are more likely to mate and reproduce thus passing on their traits.
200
Evolution is any change in the ___________ over time.
gene pool
200
Head for cover
300
What structures are shown here?
Homologous structures (same structure, different function)
300
What is it called when a small group of individuals remains after a chance event such as a forest fire?
genetic drift
300
What is 'descent with modification'?
The principle that each new species has descended with genetic changes from other species over time. Today's species look different from the ancestor species.
300
What is speciation?
The creation of two or more species from an original ancestor population
300
A species of organisms can no longer mate because their anatomy doesn't fit and they mate at different times of year. What is this mechanism of evolution?
Reproductive isolation
400
Homologous structures tell us that organisms may have...
shared a common ancestor at some point
400
The Grand Canyon caused the separation of a population of squirrels, eventually resulting in two different squirrel species after many generations of not being able to mate. What mechanism of evolution is this?
Geographic Isolation
400
How are Natural Selection and Fitness related?
Organisms and populations accumulate adaptations as they seek to survive in their environment. The adaptations lead to increased fitness because species are able to survive in their environment and reproduce to pass on those adaptations to their offspring. Eventually the gene pool has changed because of the adaptations and passing on of traits to offspring.
400
What is microevolution?
evolutionary change within a species or small group of organisms, especially over a short period of time.
400
Try to understand
500
What does genetic sequencing tell us about evolution?
organisms that are more closely related have more similar genes and share a larger percentage of genes
500
How are Natural Selection and Genetic Drift different?
Natural Selection is when an organism adapts and becomes better suited to their environment over time allowing them to survive and pass on their genes. Genetic drift is a chance event that causes the gene pool to change in a population because only a small number of organisms and genes remain.
500
How would Darwin explain the different beak sizes of the Galapagos Finches that he observed and studied?
Darwin would say that the finches beak shape and size were dependent upon the food availability in their environment. Over time, Natural selection caused finches to have different beak sizes and shapes because of the resource availability. If finches had beaks that helped them better eat hard seeds that were large, that species was more prominent on that island.
500
Which would be considered more fit? Why?
A great white shark that produces 1-2 offspring at a time.
A seahorse that produces hundreds of offspring at a time.
A seahorse that produces hundreds of offspring at a time. Fitness refers to reproduction rates and has nothing to do with the fastest, largest, or strongest organism
500
Explain the Peppered Moth phenomena in terms of Natural Selection.
Before the industrial revolution, peppered moths were generally white with black/gray spots. There was a small percentage of black peppered moths. As the industrial revolution began, the tree bark began to change from white to black. This caused the white peppered moths to stand out to prey, and die off. Eventually you see a shift and there are more black peppered moths because they are able to blend in with the bark and evade predators. Natural selection has favored the black peppered moths in this case and allowed them to survive to reproduce more than the white ones.