Question

1. construct an explanation that could account for the change in the number and color of male guppy spots over time. your explanation should include a cause, mechanism and effect. use evidence from the experiment and reasoning to support your explanation.

explanation
cause
strong predator introduced to environment
mechanism
natural selection, guppies with large number of blue and/or iridescent spots targeted by predator
effect
guppies with few blue/iridescen spots survive ar reproduce mor often leading t increase in thi genotypes
evidence
describe specific evidence from dr. endlers experiment that helps support your explanation.
reasoning
describe a chain of reasoning that connects the evidence described to your explanation.

Explanation:

• Evidence: In Dr. Endler's experiment, when guppies were in environments with strong predators (like Crenicichla alta), there was a noticeable change in the guppy population. Guppies in such high - predation environments had fewer and less - conspicuous spots compared to guppies in low - predation environments. This shows that the presence of predators (the cause) led to a change in the guppy phenotype.
• Reasoning: The strong predator (cause) acts as a selective pressure. Through natural selection (mechanism), guppies with more blue/iridescent spots (which may be more visible to predators) are more likely to be eaten. Guppies with fewer spots are more likely to survive (effect). The evidence from Dr. Endler's experiment, where the predator - mediated change in spot number and color was observed, directly supports this chain of reasoning. The experiment provides a real - world example of how a change in the environment (introduction of a strong predator) leads to a change in a population trait (spot number and color in guppies) via the mechanism of natural selection.

Answer:

• Evidence: In Dr. Endler's experiments, when guppies were placed in pools with strong predators (such as Crenicichla alta), over time, the guppy populations in those pools had fewer blue and iridescent spots compared to guppy populations in pools with weak predators or no predators.
• Reasoning: The introduction of a strong predator (cause) creates a selective environment. Guppies with more blue/iridescent spots are more easily detected by the predator. Through natural selection (mechanism), these more - spotted guppies are eaten more frequently. Guppies with fewer spots are more likely to survive, reproduce, and pass on their genes (effect). The evidence from Dr. Endler’s experiment, which shows the predator - induced change in spot characteristics, directly links the cause (predator introduction), mechanism (natural selection), and effect (change in guppy spot number and color) as described.