Mimicry

Abstract

In its most general form mimicry refers to phenotypes of an organism that are adaptively modified to resemble living or nonliving components of its environments. Phenotype mimicry can be used in a number of different ways, most notably, to protect individuals against predators and other enemies. Such protective mimicry includes masquerade (copying an inanimate object in the environment), Batesian mimicry (an edible prey copies a defended prey) and Müllerian mimicry (shared warning signals between defended prey species). Phenotype mimicry may also be used aggressively, where for example, a predaceous mimic uses mimicry to hide from or to lure victims. In sexual mimicry (e.g. females look like males or vice versa), phenotype mimicry may be used to remove costs of sexual selection. In song mimicry, mimicry may be used to attract mates, to deter predation or facilitate grouping. Although mimicry is used in very diverse ways in nature, there may be similarities in the evolutionary ecology of mimetic phenotypes. A key point is that if the fitness of individual mimics increases with the number of mimics in a habitat then we may expect monomorphisms in the phenotypes; but if fitness declines as abundance increases we may anticipate the opposite. Key Concepts: Mimicry refers to phenotypes of an organism that are adaptively modified to resemble living or nonliving components of their environments. The most extensively studied forms of mimicry are those used to protect prey from predators (especially mimetic resemblance of the colour patterns of a warningly coloured animal: Batesian and Müllerian mimicries). In masquerade edible prey mimics inanimate objects in their environment (twigs and stones) to prevent predators noticing and attacking them. Nature has found many different uses for phenotype mimicry in addition to avoidance of predation (e.g. aggressive use by predators to enable predation; by nectarless flowers to attract pollinators and by sexual mimicry and vocal mimicry). Though mimicry is used in various ways there may be some common evolutionary issues; for example, how phenotype mimicry can evolve when the intermediate forms are less fit than both the original ancestral and the perfectly mimetic trait. The benefits to a mimic are likely to change with the local abundance of the mimetic phenotype in a locality. Sometimes mimics benefit when there are many present (and we expect monomorphism in mimicry). Often mimics lose benefits as the mimetic phenotype increases in abundance (in which case diversification of mimetic phenotypes may be expected). When mimicry harms another organism we may expect counteractive measures in the form of adaptive change within an organism's lifetime (by learning) or by adaptive change across generations (coevolution).