Permanent versus Inducible Defenses

Defenses can be permanent (constitutive) or inducible. Phenotypic plasticity in defensive traits enables prey organisms to express a particular defense only if a reliable cue for a future attack is present. Thereby, the organisms can minimize costs affiliated with the formation or maintenance of a defense when predation risk is low. Inducible defenses are an appropriate mechanism to cope with the variable hazard of a frequently changing predator spectrum. In the animal kingdom, inducible defenses cover a taxonomic range from protozoans to vertebrates. The defensive traits range from behavior, morphology, and life-history adaptations to the activation of the specific immune system of vertebrates. Daphnia show the most prominent examples of morphological plasticity triggered by chemical cues, so-called kairo-mones, released by predatory invertebrates and fish. For example, elongated helmets, tail spines, or crests have been shown to reduce predator-caused mortality (Figure 2).

Several factors have been identified that favor the evolution of inducible as opposed to permanent defenses: (1) The attacker has to have a variable but sometimes relevant impact; (2) the defense must be effective within a relatively short time, so lag phases can be avoided; (3) a reliable cue has to indicate the danger; and (4) costs or tradeoffs have to outweigh the benefit of the defense during relevant periods of time.

Oplan Termites

Oplan Termites

You Might Start Missing Your Termites After Kickin'em Out. After All, They Have Been Your Roommates For Quite A While. Enraged With How The Termites Have Eaten Up Your Antique Furniture? Can't Wait To Have Them Exterminated Completely From The Face Of The Earth? Fret Not. We Will Tell You How To Get Rid Of Them From Your House At Least. If Not From The Face The Earth.

Get My Free Ebook


Post a comment