Final answer:
Chromatophores in fish can change color based on environmental factors, aiding in camouflage or signaling. Pollution clouding water could affect female fish's ability to select male partners of their species, possibly interrupting the speciation process or changing selection criteria. To test the hypothesis of coloration as defense, an experiment can compare predation rates of a mimic species with and without the presence of the model species.
Step-by-step explanation:
An example of chromatophores exhibiting extrinsic controls in fish can be seen in environmental changes influencing color pattern changes. For instance, when fish experience a background color change in their habitat, stress, or encounter predators, the nervous system and hormonal signals can lead to color change by expanding or contracting chromatophores. This is a form of adaptive camouflage or signaling.
In the scenario described, with sympatric speciation leading to two species of fish with distinct male coloration used for mating, the onset of pollution creating a cloudy lake could hinder the female fish's ability to discern male coloration. This could result in reduced mating success rate within the species, potential mating mistakes between the species, or a shift in the selection process toward other cues, such as behavior or pheromones.
To test the hypothesis that coloration is an adaptation to defend against predation and an example of Batesian mimicry, an experimental design could involve the following steps:
- Introduce both the species that is presumed to be the mimic and the species that is modeled into a controlled environment.
- Observe the reaction of predators when encountering both species separately and together.
- Compare predation rates of the mimic species in the presence and absence of the model species.