Speciation Time Scales exam Flashcards
Speciation Time Scales exam
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Speciation
The process by which one population splits into two distinct species. Microevolution
Evolutionary changes within a species or small group of organisms, especially over a short period. Macroevolution
Major evolutionary changes that occur over long periods, often resulting in the formation of new species. Gradual Evolution
A model of evolution which suggests slow, constant changes over time, leading to numerous intermediate forms. Punctuated Equilibrium
A model of evolution which posits long periods of stasis interrupted by rapid changes, resulting in fewer intermediate forms. What does gradual evolution predict about the fossil record?
It predicts that the fossil record should contain many intermediate forms showing a smooth transition from one species to another. What does punctuated equilibrium predict about the fossil record?
It predicts that the fossil record will show fewer intermediate forms, with species appearing to jump from one form to another. Stabilizing Selection
A type of natural selection that favors the average individuals in a population and reduces variation. Directional Selection
A type of natural selection that favors one extreme phenotype over the mean or other extreme. Intermediate Forms
Fossils or organisms that show the transitional states between an ancestral form and that of its descendants. What is the role of stabilizing selection in punctuated equilibrium?
It maintains long periods of stasis with little to no evolutionary change. What is the role of directional selection in punctuated equilibrium?
It drives rapid evolutionary changes during short periods of time. How does gradual evolution view the rate of evolutionary change?
As slow and relatively constant over time. How does punctuated equilibrium view the rate of evolutionary change?
As occurring in rapid bursts, separated by long periods of stasis. What is an example of gradual evolution in the fossil record?
The smooth transition from terrestrial ancestors to modern whales. What is an example of punctuated equilibrium in the fossil record?
Species appearing to jump from one form to another with few intermediate forms. How long are the periods of rapid change in punctuated equilibrium?
Tens of thousands to a hundred thousand years. Why are intermediate forms less common in the fossil record according to punctuated equilibrium?
Because the rapid changes occur over relatively short periods, leaving fewer specimens to be preserved. What connects microevolution and macroevolution?
Speciation. What does the term 'stasis' refer to in punctuated equilibrium?
Long periods of little to no evolutionary change. What is the significance of intermediate forms in gradual evolution?
They provide evidence of slow, continuous evolutionary change. What is the significance of rapid changes in punctuated equilibrium?
They explain the sudden appearance of new species in the fossil record. How does punctuated equilibrium explain the lack of intermediate forms?
Intermediate forms existed but were not around long enough to be commonly preserved in the fossil record. What is the main difference between gradual evolution and punctuated equilibrium?
Gradual evolution involves slow, constant change, while punctuated equilibrium involves long periods of stasis interrupted by rapid change. What is the impact of stabilizing selection on biodiversity?
It reduces variation and maintains the status quo within a population. What is the impact of directional selection on biodiversity?
It increases variation by favoring one extreme phenotype, leading to rapid evolutionary change. How do gradual evolution and punctuated equilibrium contribute to our understanding of speciation?
They provide different models to explain how species adapt and evolve over time.
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