Putting plant resistance traits on the map: a test of the idea that plants are better defended at lower latitudes

Abstract

Summary• It has long been believed that plant species from the tropics have higher levels of traits associated with resistance to herbivores than do species from higher latitudes. A meta-analysis recently showed that the published literature does not support this theory. However, the idea has never been tested using data gathered with consistent methods from a wide range of latitudes.• We quantified the relationship between latitude and a broad range of chemical and physical traits across 301 species from 75 sites world-wide.• Six putative resistance traits, including tannins, the concentration of lipids (an indicator of oils, waxes and resins), and leaf toughness were greater in highlatitude species. Six traits, including cyanide production and the presence of spines, were unrelated to latitude. Only ash content (an indicator of inorganic substances such as calcium oxalates and phytoliths) and the properties of species with delayed greening were higher in the tropics.• Our results do not support the hypothesis that tropical plants have higher levels of resistance traits than do plants from higher latitudes. If anything, plants have higher resistance toward the poles. The greater resistance traits of high-latitude species might be explained by the greater cost of losing a given amount of leaf tissue in low-productivity environments.

On the factors that promote the diversity of herbivorous insects and plants in tropical forests

“…have found no consistent relationship between latitude and either the amount of herbivory on plants or the degree of resistance in plants (43,44).…”

What does the geography of parthenogenesis teach us about sex?

“…This was firmly thought to be the case for a long time, until recent meta-analyses over large geographic scales yielded conflicting results ( [113], versus [114,115]). However, some authors argue that such broadscale studies will miss the relevant patterns occurring within species [116], as, for instance, the latitudinal gradient in plant -enemy interactions documented in the dandelion, a textbook example of geographic parthenogenesis [4].…”

Untargeted metabolic profiling reveals geography as the strongest predictor of metabolic phenotypes of a cosmopolitan weed

“…Geographic factors, including distance, isolation, latitudinal, and longitudinal gradients, have previously been shown to be important in explaining intraspecific variation in targeted metabolites for vascular plants, reflecting possible adaptations to local conditions (Davey, Burrell, Woodward, & Quick, 2008; Moles et al., 2011; Züst et al., 2012). In performing networking analysis on untargeted metabolomic data, the current work also demonstrates unique patterns of co‐occurrence, such that many of the metabolite features co‐occur in plants sampled within the same geographic region.…”