Problem 13 - Campbell Biology

Question

Synthesis/Evaluation WRITE ABOUT A THEME: INTERACTIONS In Batesian mimicry, a palatable species gains protection by mimicking an unpalatable one. Imagine that individuals of a palatable, brightly colored fly species are blown to three remote islands. The first island has no predators of that species; the second has predators but no similarly colored, unpalatable species; and the third has both predators and a similarly colored, unpalatable species. In a short essay (100-150 words), predict what might happen to the coloration of the palatable species on each island through time if coloration is a genetically controlled trait. Explain your predictions.

Step-by-Step Solution

Answer

Island 1: Reduced bright coloration. Island 2: Reduced bright coloration. Island 3: Maintained or enhanced bright coloration.

Step 1: Understanding Batesian Mimicry

Batesian mimicry occurs when a harmless species evolves to imitate the warning signals of a harmful species to deter predators. This concept is crucial for predicting evolutionary outcomes based on environmental factors.

Step 2: Scenario Analysis - Island with No Predators

On the first island with no predators, there is no selective pressure for the palatable flies to retain their bright coloration. Over time, the fly population might show a reduction in bright coloration as there's no survival advantage to maintaining it.

Step 3: Scenario Analysis - Island with Predators but No Unpalatable Species

On the second island with predators but no unpalatable species, the bright coloration might render the flies more visible to predators. This visibility without the benefit of mimicry protection could lead to a decrease in the bright coloration trait, as predators will eat more of the brightly colored flies.

Step 4: Scenario Analysis - Island with Predators and Unpalatable Species

On the third island with both predators and a similarly colored unpalatable species, the bright coloration provides a mimicry advantage. Flies that maintain their bright coloration may be less likely to be predated upon, retaining and possibly even enhancing this coloration trait over time.

Step 5: Summary Prediction

Summarize the expected evolutionary outcomes: (1) first island: reduction in bright coloration; (2) second island: reduction in bright coloration; (3) third island: maintenance or enhancement of bright coloration due to mimicry advantages.

Key Concepts

evolutionary biology

Evolutionary biology is the study of how species change over time through genetic variations and natural selection. Species evolve to adapt to their environment to improve their survival and reproduction rates. These adaptations can involve changes in behavior, physiology, and appearance. Batesian mimicry is one excellent example of how species can evolve. A palatable species evolves to mimic an unpalatable species to avoid being eaten by predators. This provides survival advantages in environments where predators learn to avoid harmful species based on their appearance. Understanding the mechanisms of evolutionary biology helps us predict how organisms might adapt to changes in their environment.

predator-prey interactions

Predator-prey interactions are a fundamental aspect of ecological communities. These dynamics affect the population size, distribution, and evolution of both predators and prey. When a prey species evolves traits that reduce the likelihood of being eaten, such as Batesian mimicry, this alters predator behavior. For example, if a palatable fly mimics a toxic one, predators will avoid it. If predators are present but no toxic species exist, the mimicry may fail, leading to higher predation rates. Understanding these interactions helps explain the evolutionary changes in species over time.

genetic traits

Genetic traits are characteristics passed from parents to offspring through genes. These traits determine appearance, behavior, and physiology. In the context of Batesian mimicry, the bright coloration of the fly species is a genetic trait. If this trait offers a survival advantage by mimicking a toxic species, it becomes more prevalent through natural selection. On the island scenarios, we predict specific changes based on genetic traits: On the first island with no predators, there's no pressure to maintain bright coloration, leading to a possible reduction in this trait. On the second island, bright coloration may make flies more visible to predators, reducing the trait over time. The third island where predators and toxic species coexist offers protection for brightly colored flies, enhancing the trait. This illustrates how environmental factors and predator-prey dynamics can drive the prevalence of genetic traits in populations over time.