The article by Daniel H. Janzen discusses the concept of coevolution, defining it as an evolutionary change in one population's traits in response to another population's traits, followed by a reciprocal response. He criticizes common misuses of the term, such as assuming mutualistic congruence between species leads to coevolution, or that a parasite and its host are coevolved just because the parasite has evolved to circumvent the host's defenses. Janzen argues that many defense traits in plants may have evolved through coevolution with now-extinct animals, and that strongly coevolved systems often lead to ecological independence. He calls for a more precise use of the term "coevolution" to avoid confusion with other concepts like "interaction," "symbiosis," and "mutualism."The article by Daniel H. Janzen discusses the concept of coevolution, defining it as an evolutionary change in one population's traits in response to another population's traits, followed by a reciprocal response. He criticizes common misuses of the term, such as assuming mutualistic congruence between species leads to coevolution, or that a parasite and its host are coevolved just because the parasite has evolved to circumvent the host's defenses. Janzen argues that many defense traits in plants may have evolved through coevolution with now-extinct animals, and that strongly coevolved systems often lead to ecological independence. He calls for a more precise use of the term "coevolution" to avoid confusion with other concepts like "interaction," "symbiosis," and "mutualism."