in japan, native honeybees have evolved an effective defense strategy against giant Japanese hornets. imported European honeybees, however, are unable to defend themselves. explain this in terms of coevolution?
In order to explain the phenomenon in terms of coevolution, we first need to understand the concept itself. Coevolution refers to a reciprocal evolutionary change between two or more species interacting with each other over a long period of time. It occurs when the adaptations in one species influence the selective pressures on another species, leading to a continuous cycle of evolutionary change.
In the case of native Japanese honeybees (Apis cerana japonica) and giant Japanese hornets (Vespa mandarinia japonica), they have been engaged in a coevolutionary arms race for thousands of years. Japanese honeybees have developed a unique defense strategy to counter the hornets' attacks, known as "heat balling."
When hornets enter a honeybee hive, Japanese honeybees quickly respond by forming a tight cluster around the intruders. By vibrating their flight muscles, the honeybees generate heat, rapidly raising the temperature within the cluster. This increase in temperature is tolerable for honeybees, but it becomes lethal for giant hornets since they can't tolerate high temperatures. The heat balling defense effectively cooks the hornet to death, protecting the honeybee colony.
Now, let's consider the European honeybees (Apis mellifera), which have been introduced to Japan in recent centuries. Unlike native Japanese honeybees, European honeybees have not coevolved with giant Japanese hornets. As a result, they have not developed the heat balling defense mechanism to counter these predators.
This discrepancy in defense strategies can be explained by the differences in historical interactions between the respective species and the evolutionary pressures they have faced. Native Japanese honeybees and giant Japanese hornets have been engaged in an arms race, with the hornets exerting selection pressure on the honeybees to develop effective countermeasures. Over generations, the honeybees that exhibited better defense mechanisms against hornets were more likely to survive and pass on their traits, leading to the coevolution of the two species.
Conversely, European honeybees have not faced the same selection pressures from giant Japanese hornets throughout their evolutionary history. Therefore, they lack the specific adaptations required to defend themselves effectively.
In conclusion, the different defense capabilities between native Japanese honeybees and European honeybees in Japan can be explained by coevolution. Native honeybees have developed a specialized defense strategy, the heat balling technique, due to their long-term evolutionary arms race with giant Japanese hornets. European honeybees, having not coevolved with these hornets, lack this defense mechanism.