Arthropod Wing Movement Mimicry

Abstract

Adaptive active plant organ movement has attracted considerable scientific attention since Darwin’s time (Darwin 1881). The best known examples are growth towards the light (Darwin 1881), repositioning of trunks and branches of trees in relation to the vector of gravity (Timell 1986; Groover 2016), sun tracking (Koller 2011), prey-driven movements, i.e., of Dionaea (Simons 1992) and movements during self-seed-dispersal (autochory) (Koller 2011; Abraham and Elbaum 2013). Quick anti-herbivory plant movements are best known in Mimosa pudica and several other related taxa that down-fold their leaflets to reduce visibility and accesibility when mechanically disturbed (Simons 1992), and Braam (2005) proposed that the quick Mimosa leaflet movement may also deter herbivores. Leaflets of Schrankia micropylla down-fold when touched, and by doing this expose their thorns (Eisner 1981), a character later proposed to be a type of visual aposematism (Lev-Yadun 2009a). In the herb Cardamine scutata, the very fast silique bursting expels and even kills chewing caterpillars, thus defending its seeds (Yano 1997). In addition, Yamazaki (2011), in a broad and intriguing theoretical treatment of potentially defensive plant movements, advocated the hypothesis of considering the possible roles of passive leaf movement induced by wind and rain as a common anti-herbivory defense. The hypothesis of this mode of passive defensive leaf movement was tested experimentally and was strongly supported (Warren 2015; Leonard et al. 2016). Interestingly, all plant taxa expressing quick active leaf or leaflet movements (Dionaea, Mimosa pudica, Schrankia micropylla and Desmodium motorium) are found in warm parts of the globe, probably because high temperatures allow quick movements in plants, a group that is usually and even mostly ectothermal.