Fearful symmetry in aposematic plants

Abstract

Symmetry has been proposed to increase the efficiency of visual aposematic displays in animals, and I suggest that it may also be true for many aposematic spiny or poisonous plants. For instance, in the very spiny plant taxa cacti, Aloe sp., Agave sp. and Euphorbia sp., which have been proposed to be aposematic because of their colorful spine system, the shoots, and in cacti, the spiny fruits as well, are usually radially symmetric. Moreover, in the radial symmetric shoots of Agave and Aloe their individual spiny leaves are also bilaterally symmetric. Spiny or poisonous fruits of various other taxa, the symmetric spiny leaf rosettes and flowering spiny heads of many Near Eastern species of the Asteraceae and other taxa, and poisonous colorful flowers in taxa that were proposed to be aposematic are also symmetric. Thus, in plants, like in animals, symmetry seems to be commonly associated with visual aposematism and probably contributes to its effectiveness. Symmetry may stem from developmental constraints, or like in flowers, have other signaling functions. However, because of the better perception of symmetry by animals it may exploit inherited modes of animal sensing that probably result in paying more attention to symmetric shapes. All these possible alternatives do not negate the probable deterring role of symmetry in plant aposematism.

The spiny, thorny and prickly plants in the flora of Israel

“…As part of the study on the evolution of plant protection by spines and thorns conducted in our group (e.g. Lev‐Yadun, 2001, 2003a, b, 2006, 2009a, b, c, 2011; Lev‐Yadun & Ne'eman, 2004, 2006; Halpern et al ., 2007a, b, 2011; Ronel, Malkiel & Lev‐Yadun, 2007; Lev‐Yadun & Gould, 2008; Lev‐Yadun & Halpern, 2008; Lev‐Yadun, Ne'eman & Izhaki, 2009; Nassar & Lev‐Yadun, 2009; Ronel & Lev‐Yadun, 2009; Ronel et al ., 2009, 2010), we characterized the thorn/spine/prickle system in the whole native wild flora of Israel. To the best of our knowledge, a whole‐flora approach of this character (defence by sharp appendages) has never been carried out before.…”

Visual-, Olfactory-, and Nectar-Taste-Based Flower Aposematism

“…Toxic colorful flowers, which were one of the first plant organs proposed to be aposematic [28,100], are, like almost all flowers, typically symmetric. Thus, Lev-Yadun [123] suggested that, as is the case in various animals, visual aposematism in spiny and poisonous plants also seems to be commonly associated with symmetry, including that of flowers and inflorescences. For instance, the flowering spiny inflorescences of many Near Eastern species of the Asteraceae (Figure 5), as well as those of other spiny taxa [55,113] (Figure 6), are radially symmetric.…”

Vividly warm: The color saturation of logos on brands' customer sensitivity judgment

“…In nature, highly saturated colors are signals of danger or reward. For instance, poisonous creatures, like snakes and aposematic plants, often use their vivid, highly saturated colors as a warning to other creatures 21,22 . For some birds and reptiles, highly saturated body colors are a sign of aggression 23‐25 .…”