Move over, Sherlock Holmes. There is a new master of disguise—and it’s a plant! Camouflage and mimicry are usually reserved for the animal realm. The hawk moth caterpillar scares away predators by resembling a snake. Myrmarachne jumping spiders imitate ants as they creep up on unsuspecting insects—fangs ready. Fewer examples of mimicry—or crypsis—are known for plants. But as in some mistletoe species in Australia, all of these imposters copy only one other species. That’s not the case with the woody vine Boquila trifoliolata, which transforms its leaves to copy a variety of host trees. Native to Chile and Argentina, B. trifoliolata is the first plant shown to imitate several hosts. It is a rare quality—known as a mimetic polymorphism—that was previously observed only in butterflies, according to this study, published today in Current Biology. When the vine climbs onto a tree’s branches, its versatile leaves (inset) can change their size, shape, color, orientation, and even the vein patterns to match the surrounding foliage (middle panel; the red arrow points to the vine, while the blue arrow indicates the host plant). If the vine crosses over to a second tree, it changes, even if the new host leaves are 10 times bigger with a contrasting shape (right panel). The deceit serves as a defense against plant-eating herbivores like weevils and leaf beetles, according the researchers. They compared the charlatan leaves hanging on branches with the leaves on vines still crawling on the forest floor in search of a tree or scaling leafless trunks. Herbivory was 33% and 100% worse for the vines on the ground and on tree trunks, respectively. It is unclear how B. trifoliolata vines discern the identity of individual trees and shape-shift accordingly. The vines could read cues hidden in odors, or chemicals secreted by trees or microbes may transport gene-activating signals between the fraud and the host, the researchers say.
Figure 1. Leaf Mimicry in the Climbing Plant Boquila trifoliolata Pictures of the twining vine B. trifoliolata co-occurring with woody species in the temperate rainforest of southern Chile, where leaf mimicry in terms of size, color, and/or shape is evident. White arrows point to the vine (V) and to the host tree (T). Leaf length of the tree species is shown in parentheses ; this may help to estimate leaf size variation in the vine. (A) Myrceugenia planipes (3.5–8 cm). (B) Rhaphithamnus spinosus (1–2 cm). (C) Eucryphia cordifolia (5–7 cm). Notably smaller leaves of B. trifoliolata appear to the left of the focus leaf. (D) Mitraria coccinea (a woody vine; 1.5–3.5 cm). Both here and in (F), the serrated leaf margin of the model cannot be mimicked, but the vine shows one or two indents. (E) Aextoxicon punctatum (5–9 cm). (F) Aristotelia chilensis (3–8 cm). (G) Rhaphithamnus spinosus (1–2 cm). (H) Luma apiculata (1–2.5 cm). The inset shows more clearly how B. trifoliolata has a spiny tip, like the supporting treelet and unlike all the other pictures (and the botanical description) of this vine. See also Figure S1 for pictures showing different leaves of the same individual of B. trifoliolata mimicking different host trees.
source: by Nsikan Akpan via sciencemag.org and whyevolutionistrue.wordpress.com