Milkweed plants contain cardiac glycosides, substances that are toxic to many sp
ID: 50013 • Letter: M
Question
Milkweed plants contain cardiac glycosides, substances that are toxic to many species. However, the caterpillars of the monarch butterfly have evolved to feed on milkweed, and are thus able to tolerate the toxins and even sequester them for protection from predators. Milkweed also produces a sticky substance called latex, which can entrap and kill small monarch caterpillars. It has recently been discovered that monarch caterpillars often nibble through a leaf's petiole (attachment point) before feeding on the leaf - this cuts off the supply of latex to the leaf. If you could travel far into the future, what development do you think you would be most likely to find in the milkweed/monarch interaction?
Monarchs have evolved to tolerate ingestion of latex and no longer chew through leaf petioles prior to feeding
Milkweed plants have evolved to have tougher petioles; most monarchs are unable to chew through them prior to feeding on leaves.
Monarch have switched from feeding on milkweed to feeding on oak leaves.
Milkweed plants have stopped producing cardiac glycosides, allowing other species besides monarchs to feed on them.
Explanation / Answer
Milkweed plants have evolved to have tougher petioles; most monarchs are unable to chew through them prior to feeding on leaves.
Explanation:
Because the caterpillar has evolved to cope up with the strategy of milkweed, the next option for the milkweed is to develop a better strategy to avoid infestation by caterpillar. Therefore, it would develop tougher petioles.