Question

Daphnia from lakes with large fish predator populations show which of the following?

1) A large degree of phenotypic plasticity for negative phototaxis in the presence or absence of fish-occupied water
2) No phenotypic plasticity relating to phototaxis in the presence or absence of fish-occupied water
3) Extremely strong inducible positive phototaxis in the presence of fish-occupied water
4) Minimal phototaxis in the presence or absence of fish-occupied water

Answer 1

Daphnia from lakes with large predator fish populations exhibit significant phenotypic plasticity, showing negative phototaxis to enhance their survival in the presence of predators.

Step-by-step explanation:

Daphnia from lakes with large fish predator populations show a large degree of phenotypic plasticity for negative phototaxis in the presence or absence of fish-occupied water. Phenotypic plasticity is the ability of an organism to change its phenotype in response to changes in the environment. In this case, the Daphnia are likely to exhibit a change in behavior, such as avoiding light (negative phototaxis), to reduce the risk of being seen and eaten by predators. This adaptive behavior shows how species can adjust their physical and behavioral traits to increase their chances of survival in different environmental conditions. The study of stickleback fish suggests that environmental changes and species interactions can have significant impacts on ecosystems, indicating that such behavioral adaptations in Daphnia can be essential for maintaining their populations in environments with predatory threats.

Answer 2

Daphnia in lakes with large predator fish populations show a large degree of phenotypic plasticity for negative phototaxis, which helps them avoid predation. This is an example of an adaptive behavioral response to the presence of predator cues in their environment.

Step-by-step explanation:

Daphnia, also known as water fleas, demonstrate significant phenotypic plasticity in relation to phototaxis when exposed to environments with varying predator populations. Specifically, when Daphnia detect chemical cues from fish-occupied water, indicating the presence of predators, they exhibit a negative phototaxis, which means they move away from light. This behavior is likely adaptive as it helps them avoid being seen and eaten by predators that hunt by sight.

Therefore, the correct option among the provided choices for Daphnia in lakes with large fish predator populations is: 1) A large degree of phenotypic plasticity for negative phototaxis in the presence or absence of fish-occupied water.

Research, including studies by Davidson et al. (2011) on invasive species, suggests that organisms often display higher levels of phenotypic plasticity in new environments as an adaptive strategy. The reciprocal effects of the environment and population evolution are important factors in simulation models that aim to predict ecosystem dynamics. When threatened by predators, such as in John Endler's studies on guppies, organisms may adapt their behavior or physical traits to enhance their chances of survival, as by guppies developing drab colors to avoid predator detection. When environmental factors like pollution disrupt these adaptive traits, species may face new challenges for survival, such as difficulties in mate recognition due to coloration being less distinguishable.