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CHAPTER 14 DIRECTED READING “The Green Mountain”
A PLAGUE OF FROGS
(See Key Below)
Answer the following questions in the space provided. (4 points each)
1. What was the focus of Johnson’s work?
2. Describe the statistics Johnson found in these ponds.
3. Why did Johnson narrow his search to only 4 ponds?
4. What factors made Johnson’s experiment more “real” or widely accepted than previous experiments?
5. Explain the difference between mechanically disturbing the limb and by some sort of chemical signal.
6. What are the two categories of deformities according to Stan Sessions?
2.
7. Who is Dan Sutherland and what was his opinion on the Johnson’s results?
8. If the parasite theory was found to be the sole cause, would it have an effect on humans? Why or why not?
9. What does the phrase snail-parasite-frog complex mean?
10.Why do scientists not believe parasites are the sole cause?
11.What is a variable phonology?
12.What did the discovery of Ribeiroia at the deformities sites in Minnesota result in?
13.What did Johnson find at “Danube”?
14.According to Martin Ouellet’s report, what were some biotic and abiotic factors involved?
15.What was Martin Ouellet’s frustration at this point in the study?
16.What did the radiographs show?
17.Why was spongiform bone a contraindication of parasitism?
18.Why was it not enough to say parasites cause deformities?
19.What do biologists refer to as “recruitment”?
20.Explain the concept of carrying capacity.
21.What is the reproductive strategy of frogs according to Dave Hoppe?
22.What is a lunker?
23.What is Aeromonas hydrophilia and what effect did it have on the leopard frog population?
24.Why was A. hydrophila able to infect the frogs when it had not been able to in the past?
25.What is Alan Pounds known for? Explain his work.
KEY
CHAPTER 14 DIRECTED READING “The Green Mountain”
A PLAGUE OF FROGS
Answer the following questions in the space provided. (4 points each)
1. What was the focus of Johnson’s work?
4 of the 35 ponds he studied in Santa Clara County with frog & salamander deformities. (Page 263)
2. Describe the statistics Johnson found in these ponds.
He studied 15,000 amphibians and found that between 25-45% of the frogs were affected. Extra limbs accounted for over 50% of the deformities found. (Page 263)
3. Why did Johnson narrow his search to only 4 ponds?
There were the only ones that were home to a species of snail that harbored Riberoia. (P. 264)
4. What factors made Johnson’s experiment more “real” or widely accepted than previous experiments?
Infection rates were “realistic”, parasites infect “at will”, parasites were the same that were associated with the deformities, test organism was the same as the one in the wild, rates of deformities in the
lab matched those in the field. (Page 264)
5. Explain the difference between mechanically disturbing the limb and by some sort of chemical signal.
Mechanical disruption caused a positional confrontation among cells that were resolved via intercalation. Chemical signals “reset” the positional values of the cells in the limb. (I.e. parasites could not rule
out chemicals and vice versa) (Page 265-266)
6. What are the two categories of deformities according to Stan Sessions?
a. Frogs that exhibited a range of abnormalities caused by parasites.
b. Frogs that exhibited solely missing or partial limbs. (Page 266)
7. Who is Dan Sutherland and what was his opinion on the Johnson’s results?
He is a parapsychologist from the University of Wisconsin, La Crosse. He was certain the deformed frogs he found were NOT infected with trematode cysts. (Page 266)
8. If the parasite theory was found to be the sole cause, would it have an effect on humans? Why or why not?
Answers will vary. The parasites at this point only affect amphibians. Loss of a species in the environment for aesthetic reasons. (Page 267)
9. What does the phrase snail-parasite-frog complex mean?
The life cycle of Ribeiroiaas the causation of the deformities. (Page 267)
10.Why do scientists not believe parasites are the sole cause?
Because they found some deformed frogs that did not contain the parasites. (Page 268)
11.What is a variable phonology?
An annual life cycle. (Page 270)
12.What did the discovery of Ribeiroia at the deformities sites in Minnesota result in?
A new set of questions. (Page 270)
13.What did Johnson find at “Danube”?
Deformed frogs that did not have Ribeiroia, but the host snail was in the pond. (Page 271)
14.According to Martin Ouellet’s report, what were some biotic and abiotic factors involved?
Abnormal regeneration after injury, agricultural pesticides, chemical composition of water, presence of fish, disease, high tadpole densities, extreme temperatures, hereditary mechanisms, nutritional deficiencies,
parasites, radiation, UV light, viruses, metals and other chemical contaminants. (Page 271)
15.What was Martin Ouellet’s frustration at this point in the study?
He did not find the same results in his control studies. Therefore, the correlation between cause and effect was eliminated. (Page 272)
16.What did the radiographs show?
There were spongiform bone morphologies in some locations but not others. This showed that different causes were at work. (Page 273)
17.Why was spongiform bone a contraindication of parasitism?
None of the parasite-infected frogs had spongiform bone. (Page 273)
18.Why was it not enough to say parasites cause deformities?
That is not the whole story; it is a true statement, but there is more to it. (Page 275)
19.What do biologists refer to as “recruitment”?
An addition to the breeding pool. (Page 276)
20.Explain the concept of carrying capacity.
The number of organisms of a given species that can successfully exist in a fixed habitat. (Page 276)
21.What is the reproductive strategy of frogs according to Dave Hoppe?
One pair of frogs gives rise to thousands of offspring. Almost all of them die, but some of them survive to eventually reproduce. (Page 276)
22.What is a lunker?
An adult leopard frog whose snout-to-vent length exceeds 100 millimeters. (Page 277)
23.What is Aeromonas hydrophilia and what effect did it have on the leopard frog population?
It is an aquatic bacterium that caused septicemia (blood poisoning), therefore decreasing the population. (Page 277)
24.Why was A. hydrophila able to infect the frogs when it had not been able to in the past?
The frogs were losing their natural resistance to this common pathogen as a result of a “marked decline in the quality of life”. (Page 277)
25.What is Alan Pounds known for? Explain his work.
He solved the mysterious disappearance of the Golden Toad. He was the person who started the global warming theory. (Page 284-285)
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