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A Plague of Frogs--Study Questions
Directed Reading Chapter 11
(See Key Below)
Answer the following questions in the space provided. (3 points each)
- Most of the reports of deformed frogs came from the northern part of the country. What did this suggest?
- What are Stan Sessions’ two contentions about the cause of the deformations?
- Why was the predator factor not considered a main cause of the deformities?
- Describe Mike Lannoo’s work at Okobuji.
- Give 2 reasons Lannoo discredited the predator theory.
- What is the common name for Ambystoma tigrinum?
- What was David Merrell’s contribution to the investigation?
- Explain the significance of the journal article “Natural Selection in a Leopard Frog Population”.
- Why did Hoppe and the Mottls study the preserved frog collection at the University of Minnesota?
- Why did Judy Helgen put a ban on disseminating information about the investigation?
- How many frogs from the CWB were deformed on this outing? What breed of frog were they?
- What type of deformity would an LR CUT frog have
- What % of frogs were deformed in the 3rd season at CWB? How does that compare to the 2nd season?
- Why was Dennis Bock unhappy with the state and federal agencies?
- What was the designated control site for CWB?
- Explain why it is important to have a control site for CWB.
- Describe the breeding adaptations that frogs in Minnesota exhibit.
- Why did the declining numbers of frogs at CWB concern Hoppe?
- Why did Hoppe take such extreme measures to return all collected frogs to CWB?
- Explain the significance of Hoppe’s “eggs in a cage” experiment.Identify Andy Blaustein. (Where did he get his education, etc.)
- What is the scientific name for Cascade frogs? Western toads?
- What is the usual mortality rate of Western toads?
- What did Blaustein think might be the cause of the deformities after his experiments?
- Why did he think that was the cause?
- Explain the function of photolyase.
- What is the difficulty is calculating UV penetration changes?
- What was Blaustein’s basic conclusion about ecological interactions?
- What types of damage did UV cause in frogs?
- Why was Saprolegnia ferax able to infect frogs now and not in the past?
- Why might some species in the pond have a robust photolyase response while others do not?
- What did Blaustein find in Hyla regilla?
- Explain Blaustein’s view on the parasite causation theory.
KEY (3 POINTS EACH)
A Plague of Frogs
Directed Reading Chapter 11
1. Most of the reports of deformed frogs came from the northern part of the country. What did this suggest?
That there is a geographic factor involved in the deformities. (Page 186)
2. What are Stan Sessions’ two contentions about the cause of the deformations?
Parasites might block limb development in certain instances, but that predation was the primary cause of missing legs. (Page 18186-187)
3. Why was the predator factor not considered a main cause of the deformities?
Predators are found everywhere, even where they were no deformities. So the deformities should be more common if caused by the predators (Page 187)
4. Describe Mike Lannoo’s work at Okobuji.
He did a catalog survey of the wetlands studying all the living creatures. (Page 187)
5. Give 2 reasons Lannoo discredited the predator theory.
Larger predators are after the whole frog, not just a leg. Smaller predators lacked the “shearing action” needed. (Page 188)
6. What is the common name for Ambystoma tigrinum?
Tiger salamanders (Page 188)
7. What was David Merrell’s contribution to the investigation?
He had preserved a large collection of leopard frogs and done field studies on them in the past. (Page 190)
8. Explain the significance of the journal article “Natural Selection in a Leopard Frog Population”.
It showed the deformations were not a new phenomenon. (Page 190)
9. Why did Hoppe and the Mottls study the preserved frog collection at the University of Minnesota?
To get a baseline. (Page 192)
10. Why did Judy Helgen put a ban on disseminating information about the investigation?
She was afraid the landowners would back out of their agreements to let the agency conduct studies on their land. (Page 193)
11. How many frogs from the CWB were deformed on this outing? What breed of frog were they?
157 out of 202; Juvenile mink frogs (Page 197)
12. What type of deformity would an LR CUT frog have?
Cutaneous fusion of the left rear leg. (Page 197)
13. What % of frogs were deformed in the 3rd season at CWB? How does that compare to the 2nd season?
75%, 50% (Page 198)
14. Why was Dennis Bock unhappy with the state and federal agencies?
Lack of thorough water testing at CWB. (Page 198)
15. What was the designated control site for CWB?
Butternut Lake (Page 199)
16. Explain why it is important to have a control site for CWB.
To validate the data collected at CWB. (Page 199)
17. Describe the breeding adaptations that frogs in Minnesota exhibit.
Leopard frogs, wood frogs, chorus frogs & spring peepers: early breeders, tolerate cold water. Mink & green frogs: breed later in warm water. (Page 199)
18. Why did the declining numbers of frogs at CWB concern Hoppe?
They were all dying out and also becoming more difficult to research them. (Page 201)
19. Why did Hoppe take such extreme measures to return all collected frogs to CWB?
To try and preserve the population. (Page 202)
20. Explain the significance of Hoppe’s “eggs in a cage” experiment.
Something in the water in CWB was causing the deformities.
The sole cause could not be predators. (Page 202)
21. Identify Andy Blaustein. (Where did he get his education, etc.)?
College-Long Island; Grad school University of Nevada and UC of Santa Barbara Animal Behavior scientist (Page 202)
22. What is the scientific name for Cascade frogs? Western toads?
Rana cascade Bufo boreas (Page 202)
23. What is the usual mortality rate of Western toads?
Less than 10% (Page 203)
24. What did Blaustein think might be the cause of the deformities after his experiments?
UV radiation (Page 203)
25. Why did he think that was the cause?
In the lab, with the same water, they hatched normally. (Page 203)
26. Explain the function of photolyase?
It is the enzyme that promotes repair in UV-damaged DNA. (Page 203)
27. What is the difficulty is calculating UV penetration changes?
They are constantly changing. (Page 203)
28. What was Blaustein’s basic conclusion about ecological interactions?
“Things are never as simple as you think they are or might wish them to be.” (Page 204)
29. What types of damage did UV cause in frogs?
Egg death, retinal eye damage, skin lesions, minor digit deformities, spinal curvatures, abdominal edema, and immune suppression. (Page 204)
30.. Why was Saprolegnia ferax able to infect frogs now and not in the past?
The frogs had weakened immune systems due to UV damage. (Page 204)
31. Why might some species in the pond have a robust photolyase response while others do not?
There could be several factors, including the human caused depletion of the ozone layer. (Page 204)
32. What did Blaustein find in Hyla regilla?
Extra hind legs caused by trematode cysts. (Page 205)
33. Explain Blaustein’s view on the parasite causation theory.He thinks they are involved, but not solely. (Page 205)
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