Lecture 6: Feedback Loops

Question 1

what is a feedback loop

Answer 1

outputs of a system feed back into the system, as inputs and prompt new outputs

Question 2

negative vs positive feedback

Answer 2

negative feedback:
- outputs mitigate the response
- “your house is too warm, shut off the heater”
positive feedback:
- outputs increase the response
- platelets stick together to clot injuries

Question 3

ecology vs evolutionary biology

Answer 3

ecology: study of interaction between organisms and environment
evolutionary biology: study of the evolutionary processes that produced diversity of life on Earth

Question 4

ecology & evolutionary biology are related in that:

Answer 4

they’re a feedback loop; ecological change affects how organisms survive, which leads to evolutionary change and so on

Question 5

The process of adapting to a particular environment

Answer 5

1. members of the same species vary in traits (phenotype)
2. certain traits which increase survival and reproduction in members leave more offspring
3. traits must be heritable

Question 6

including what decides which traits are beneficial

Answer 6

• the environment decides
• abiotic and biotic factors in the environment place selective pressure on organisms

Question 7

phenotypic plasticity

Answer 7

• changes in morphology, physiology, or behavior **based on the environment **
• can’t be transmitted to offspring
• doesn’t lead to evolutionary change

Question 8

adaptation

Answer 8

• changes in morphology, physiology, or behavior that are genetically determined
• are transmitted to offspring
• leads to evolutionary change

Question 9

The clausen, Keck and Hiesey experiment: initial observations, hypotheses, tests

Answer 9

Initial: - climatic forms of plants, some tall, some short in the Sierra Nevada and Plateau

Hypotheses:
1. phenotypic plasticity vs adaptation
2. can you change low-land forms into alpines by transferring them into the alpine environment
3. morphological vs physiological characters

Experiment:
1. established 3 gardens in varying California altitude + climate
2. **cloned **representatives of different climatic races
3. differences in morphology and physiology

Question 10

experiment final observation

Answer 10

climatic races that were high in the alpines couldn’t grow at sea level