The Likelihood That an Animal Will Successfully Avoid a Predator's

question 37

Essay

The likelihood that an animal will successfully avoid a predator's attack should increase if the presence of the predator is detected. Animals are, of course, known to warn others of a predator's presence--the well-known prairie-dog warning call is an example. Some aquatic animals are known to send chemical signals. For example the crayfish and Iowa darter may excrete ammonium from their gills or possibly in their urine during periods of heightened metabolic activity. In an experiment to see if red-legged frogs (Rana aurora) may send or respond to chemical signals, specimens in Oregon were collected as embryos and raised in an aquarium. As tadpoles they were separated into two pairs of aquaria. The "upper tank" in each pair was connected to the "lower tank" to create a (very!) small river. A wooden heron model was placed in one of the upper tanks and moved around for 30 seconds to simulate a predator attack. Both the sender (upper tank) and receiver (lower tank) animals were monitored for added activity (increased movement) indicating antipredator behavior. (a) What is the explanatory variable (factor) for this experiment? (b) What is the response variable for this experiment? (c) During the course of the experiment the investigators were very careful with the wooden heron model not to come in contact with the glass of the aquaria or make noise in any other way. If they had been unsuccessful and their wooden heron made significant amounts of noise, how would that affect the interpretation of the results?

---

Definitions:

Trade Credit

An arrangement where a supplier allows a customer to purchase goods or services and pay for them at a later date.

Factoring

Factoring is a financial transaction where a business sells its accounts receivable to a third party at a discount in exchange for immediate cash.

Capital Investment Analysis

The process of evaluating the potential returns of an investment in fixed assets or long-term projects versus its costs.

Risk-Return Trade-Off

The principle that potential return rises with an increase in risk.