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?

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Definitions:

Minimum Cost

The least possible expenditure required to achieve a particular objective or the production of goods and services.

Transportation Problem

A type of optimization problem in operations research that involves finding the most cost-effective way to distribute products from several suppliers to multiple consumers.

Supply

The total amount of a product or service available for purchase at any given time.

Demand

The desire and ability of consumers to purchase goods or services at a given price.