Scientists observed that marine bryozoan fossils lack intermediate forms. This evidence supports which hypotheses? Check all that apply.
_____ Evolution occurs in spurts, alternating with long periods of little change.
_____ Evolution proceeds steadily, with gradual, incremental change in a given evolutionary line.
_____ There is variability in the rate of evolution.
_____ Evolution proceeds at a constant rate that is the same for all organisms.
Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
Gather Content
· What do you already know about punctuated equilibrium?
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
__X__ Evolution occurs in spurts, alternating with long periods of little change.
_____ Evolution proceeds steadily, with gradual, incremental change in a given evolutionary line.
__X__ There is variability in the rate of evolution.
_____ Evolution proceeds at a constant rate that is the same for all organisms.
Clarify Question
· What is the key concept addressed by the question?
o This question addresses punctuated equilibrium.
· What type of thinking is required?
o This question is asking you to analyze the information given, using logic, to dissect the problem and determine the answer.
Gather Content
· What do you already know about punctuated equilibrium?
o The punctuated equilibrium hypothesis argues that species have long periods of little or no evolutionary change (termed stasis), punctuated by quick bursts of evolutionary change.
o When natural selection is strong, evolutionary change can occur rapidly, so the “punctuated” part of the theory is not controversial. A more difficult question involves the long periods of stasis (the equilibrium): Why would species exist for thousands, or even millions, of years without changing?
o Most researchers now believe that a combination of stabilizing and oscillating selection is responsible for stasis. If the environment does not change over long periods of time, or if environmental changes oscillate back and forth, then stasis may occur for long periods.
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
o Does the lack of intermediate fossils suggest that evolution proceeds steadily? No, because then you would expect to see the gradual change reflected in the fossil record.
o Does the lack of intermediate fossils suggest that evolution proceeds at a constant rate that is the same for all organisms? No, because you would expect to see intermediate fossils represented.
o Does the lack of intermediate fossils suggest that there is variability in the rate of evolution? Yes. Infrequent, rapid change means that intermediate forms may not become fossilized.
o Does the lack of intermediate fossils suggest that evolution occurs in spurts, alternating with long periods of little change? Yes. This can explain why intermediate forms were not well-represented in the fossil record.
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
o The question required you to analyze the information given, using logic, to dissect the problem and determine the answer.
o Did you recognize that a lack of intermediate fossils suggests that change happens quickly, in keeping with the punctuated equilibrium model?
You might also like to view...
Multiple independent experiments have demonstrated that phytochrome helps trigger seasonal change responses in the plant such as changing color and loosening of leaves. Plants have the ability adapt to seasonal changes in their surroundings. This statement is an example of:
A. a hypothesis B. deductive reasoning C. a theory D. an experiment E. inductive reasoning
The dinoflagellate Pfisteria is an important protist. Which of the following statements DOES NOT describe its attributes?
A. It causes nervous disorders in humans. B. It uses toxins to attack fish which it then consumes. C. It lies dormant on the bottom until stimulated by chemicals from fish. D. It is a major cause of food poisoning in humans. E. Its toxins damage fish skin thereby increasing exposure to the pathogen.
When crossing-over occurs, _______________ genes usually stay together.
A. sex-linked B. multi-allelic C. linked D. pleiotropic
Which food components help your body build muscle mass?
What will be an ideal response?