Unripe red fruits may be aposematic

Abstract

leaves, [28][29][30][31] and these color changes were proposed to serve physiological functions (see refs. 32 and 33), anti herbivory functions (see refs. 29, 34 and 35) or both (see refs. 36-38). Color changes also characterize old aposematic spines, thorns and prickles of many taxa that lose their conspicuousness when the organ they protect matures and needs less defense. 39Aposematic coloration, a well-known phenomenon in animals (e.g., see refs. 40-42), has recently been shown to be common also in thorny plants and in plants that mimic them 39,[42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57] as well as in certain poisonous plants, some of which proposed to be aposematic earlier. 13,14,[36][37][38]46,47,51,[58][59][60][61][62][63][64][65][66][67] In animals, aposematic coloration is usually red, orange, yellow, black and white or combinations of these, which protect unpalatable, dangerous or poisonous prey species. [40][41][42] The similarity between aposematic colors in poisonous insects and ripe fruits has already been demonstrated, 68,69 but their aposematic role in fruits was not considered by Herrera 68 and was not found to operate in artificial fruit-like objects introduced to domestic chicks. 69 Several types of defensive aposematic coloration have been proposed to occur in fruits that repel large herbivores: (1) brightly colored poisonous fruits; 13,14,60,65 (2) pods of several wild annual legumes (Lathyrus ochrus, Pisum humile, P. elatius and Vicia peregrina) have conspicuous reddish spots arranged along them that appear to mimic aposematic lepidopteran caterpillars and may repel various herbivores; 37,46,47,70 (3) colorful (yellow, red, purple or various combinations of these) aposematic thorn-like unripe soft fruits in several wild Erodium species and in Sinapis alba growing in Israel. 44 Here we report that conspicuous red but unripe fruit of several plant species are poisonous or unpalatable. We propose that in such cases fruit color may contribute to the general attraction of frugivores to the plant but at the same time serve as an aposematic IntroductionAdvertisement is an important aspect of plant-animal relationships because it attracts pollinators to flowers 1-4 and seed-dispersing frugivores to ripe fruit. [5][6][7][8][9][10] Fruit color is the typical visual signal that plants use to communicate with frugivores, 5,6,8,[11][12][13][14] although other plant parts (branches of the raceme, panicle or leaves) may also contribute to this signaling system. 5,7 Multicolored fruit displays, where fruits first change their color from green to a conspicuous color when they have reached full size but are still unripe and later to a second conspicuous color upon ripening, have been studied in plants of several ecosystems. 7,8,11,[15][16][17][18][19][20][21] Some studies indicated that bicolored fruit displays enhance seed dispersal 7,11,[15][16][17][18][19][21][22][23] but other studies did not. 11,15,16,19,23 Thus, it seems that promotion of dispersal can only partly explain multicolo...

Why do many galls have conspicuous colors? A new hypothesis

“…Advertisement of chemically-defended galls may reduce predation by mammalian herbivores, avian insectivores and frugivores and various arthropods. Frugivorous vertebrates (birds and mammals) are often attracted or deterred by fruit coloration which is stage dependent (ripe and unripe) (Snow and Snow 1988;Schaefer and Schmidt 2004;Hill 2006;Lev-Yadun et al 2009). Colorful galls may therefore attract frugivores as ripe fruits.…”

Fearful symmetry in aposematic plants

“…26,27 (2) Similarly, putative aposematic toxic fruits 28,29 and spiny unripe red fruits that were also proposed to be aposematic 29 constraints, or in flowers and fruit with other signaling systems for gene dispersal, as well as with perceptual exploitation of animal sensing sensu Schaefer and Ruxton, 31 because animals probably pay more attention to symmetric shapes. 25,26 There is an obvious need for experimental testing of the role of symmetry in visual plant aposematism.…”

Pflanzliche Sekundärstoffe: Ethnobotanische Überlegungen zu ihrer Bedeutung für die menschliche Ernährung und die Medizin - Teil 1: Grundlagen der pflanzlichen Sekundärstoffe

“…In allen Klimazonen einschliesslich der Tropen sind Schwarz und Rot die häufigsten Farben reifer Früchte. Ähnlich wie im Tierreich gibt es unter Pflanzen eine blosse Vortäuschung einer Wehrhaftigkeit durch die Präsentation einer aposematischen Färbung (Phänomen der Mimikry) [14,15]. …”