Question

Recall the experiment discussed in class about guppy color patterns (spots) measured in populations exposed to varying risks of predation. From this experiment, concluded that: Guppy color pattern did not affect the risk of predation. Predators were more likely to catch and eat brightly-colored guppies. Predators were less likely to catch and eat brightly-colored guppies. Brightly-colored guppies were more likely to outcompete drab-colored guppies.

Answer 1

John Endler's research on Trinidad guppies showed a correlation between guppy coloration and predation risk, which suggested a significant genetic variability and a trade-off between attractiveness to mates and survival against predators. His experiment demonstrated how the guppies adapted to different environmental pressures, evident in their coloration changes.

Step-by-step explanation:

Understanding Guppy Color Patterns and Predation Risk

In 1980, John Endler's experiment focused on natural selection among Trinidad guppies, revealed a dynamic relationship between guppy coloration and predation. Endler hypothesized that guppy populations exposed to less predation would exhibit brighter colors due to sexual selection, as female guppies showed a preference for more vividly colored males. In contrast, in environments with higher predation, male guppies were more drab-colored to enhance camouflage and survival. Endler's field experiment introduced guppies from an area with predators to an environment without predators and observed a transition in their coloration towards brightness over several generations, supporting the hypothesis.

These findings show that there was significant genetic variability within the guppy population, as the expression of coloration could change given different environmental pressures. The trade-off between bright colors attracting females and the risk of predation by being more visible is a classic example of an evolutionary balance between sexual selection and natural survival. If brightly colored fish from low predation areas were moved back to high predation areas, it's likely that they would suffer higher predation rates compared to their drab counterparts, potentially shifting the population's coloration back to less conspicuous colors over time.

Lastly, if the preference of female guppies shifted from coloration to size, one might expect that over time, larger guppies would be favored in terms of reproductive success, potentially leading to an increase in average size within the population. This would represent a change in selective pressure, influencing the guppies’ phenotypic traits favored by natural selection.