Pod and seed defensive coloration (camouflage and mimicry) in the genus Pisum

Abstract

The small genusPisumis composed of two annual species,P.fulvumand the domesticated peaP.sativum. The domesticated pea has two main wild-type taxa:P.elatiusandP.humile. Members of the genusPisumare not well defended from herbivory by high levels of toxins like the seeds of many other legume species. We studied the color patterns in the pods and seeds of these three wild taxa (P.fulvum,P.elatiusandP.humile) in order to examine their potential for defensive coloration (camouflage and Batesian mimicry). All three taxa are polymorphic concerning pod and seed coloration. The mature pods of many individuals ofP.humileandP.elatiusmimic aposematic caterpillars, but some are plain green. The pods of some individuals ofP.elatiushave a zigzag or straight red marking along them that resembles the conspicuous dorsal markings of the local common venomous viper, potentially mimicking it. The pods of many individuals ofP.fulvumhave dark blotches that when compared to such patterns in animals, potentially function as camouflage. The seeds of all three species are camouflaged by either: (1) color matching with that of soil (especiallyP.fulvumandP.elatius), (2) disruptive coloration (especiallyP.humile), (3) variability in seed-coat color that may undermine the use of search images by visually oriented granivores that look for cryptic seeds (all taxa). The mature pods ofP.fulvumare also defended in many inflorescences by degenerated flowers that develop into sharp thorns. It seems that this species is still in the process of evolving this mechanical defense as the response to millennia of strong grazing pressure.

Partly transparent young legume pods: Do they mimic caterpillars for defense and simultaneously enable better photosynthesis?

“…It is interesting that while the young partly transparent pods of Lathyrus ochrus, Pisum elatius and P. humile seem to mimic caterpillars because they are partly transparent (e.g., Fig. 1), when these pods are more mature and no longer transparent, they mimic aposematic caterpillars by expressing a line of very conspicuous red spots (see 24,25 ; and Fig. 3).…”

“…A detailed analysis of defensive pod and seed coloration in the 3 Mediterranean Pisum species showed that many individuals of 2 of them (Pisum elatius and P. humile) visually mimic aposematic caterpillars. 25 Interestingly, aposematic caterpillar mimicry is also performed by nestlings of the Amazonian birds Laniocera hypopyrra and Laniisoma elegans in order to reduce predation. 26,27 Caterpillar mimicry as defense from herbivory is part of a larger phenomenon of visual, e.g., 24,25,[28][29][30][31][32] and chemical 33 animal mimicry as defense from herbivory.…”

“…Some weeks later, the plants will simultaneously have pods that mimic aposematic caterpillars. 24,25 Toward the end of the season, only pods that mimic aposematic caterpillars are found on the plants. Since real aposematic caterpillars are found in the fields where these plants grow, e.g., Figure 10 in 24 , such aposematic caterpillars seem to be the models for the mimicry.…”

Red/purple leaf margin coloration: Potential ecological and physiological functions

“…Aposematism has been proposed to operate in poisonous seeds (Cook et al, 1971;Wiens, 1978;Harborne, 1982), flowers (Hinton, 1973;LevYadun, 2009), fruits (Hill, 2006;Lev-Yadun, 2009), leaves (LevYadun and Gould, 2007Archetti, 2009a;Archetti et al, 2009), and thorny plants (Lev-Yadun, 2001, 2003a,b, 2006aNe'eman, 2004, 2006;Rubino and McCarthy, 2004;Ruxton et al, 2004;Speed and Ruxton, 2005;Halpern et al, 2007a, b;Gould, 2007, 2009;Lev-Yadun and Halpern, 2008). Other types of defensive coloration include mimicry of butterfly eggs (Shapiro, 1981a,b;Williams and Gilbert, 1981), mimicry of dead leaves (Stone, 1979), mimicry of ants, aphids, poisonous caterpillars (Lev-Yadun and Inbar, 2002), of spider webs (Yamazaki and Lev-Yadun, 2015), of thorns (Lev-Yadun, 2003a), of leaf-mining insects (Smith, 1986;Soltau et al, 2009), delayed greening to diminish (and probably also signal) nutritive value (Kursar and Coley, 1992), undermining of herbivorous insect camouflage Lev-Yadun, 2006aLevYadun andGould, 2007, 2009), variegation and coloration as camouflage (Wiens, 1978;Givnish, 1990;Lev-Yadun, 2006b;Fadzly et al, 2009;Niu et al, 2014;Aviezer and Lev-Yadun, 2015), and variegation that someho...…”

Plants Are Not Sitting Ducks Waiting for Herbivores to Eat Them

“…I was painfully wounded by such spring actions numerous times during field work and fully appreciate their nasty reaction. Plants also use camouflage, [38][39][40][41][42][43][44][45] and pathogenic bacteria that they insert into the tissues of herbivores, 46 they undermine the camouflage of herbivorous insects, 47 and also use strong windinduced leaf movements to get rid of herbivores, 48,49 all of these in order to defend themselves from herbivory. Plants have many other types of mechanical defenses 30,50,51 including even anisotropic arrangement of structural defenses that can lead invertebrate herbivores away from the plants.…”