Clinal versus disruptive latitudinal variation in fruit traits of a South American mistletoe

AMICO GUILLERMO C.; AGUSTINA DI VIRGILIO; GUILLERMO SCHMEDA-HIRSCHMANN; MARCELO AIZEN A.

OECOLOGIA

SPRINGER

Lugar: Berlin; Año: 2022

0029-8549

Fruit traits have historically been interpreted as plant adaptations to their seed dispersers. On the other hand, diferent environmental factors, which vary spatially and temporally, can shape fruit-trait variation. The mistletoe Tristerix corymbosus has a latitudinal distribution along the South American Pacifc rim that encompasses two diferent biomes, the matorral of central Chile and the temperate forest that extends south of the matorral. This mistletoe shows contrasting fruiting phenology (spring vs summer), fruit color (yellow vs green), and seed dispersers (birds vs marsupial) in these two biomes. We characterized geographic variation of morphological and nutritional fruit traits of T. corymbosus to evaluate which macroecological factor, biome or latitude, better explains spatial variation in these variables. For each of 22 populations, we obtained envi-ronmental data (temperature, precipitation, and canopy cover), measured fruit and seed morphology traits (size, shape, and weight), and pulp moisture and nutritional content (fber, protein, fat, carbohydrates, ash, and caloric content). Patterns of variation for each variable were described by ftting and comparing fve diferent simple models varying in slope, intercept or both. Fruit morphology showed a clear biome-related disruptive pattern, seed morphological traits were unrelated to either biome or latitude, whereas nutritional variables showed diverse patterns. Diferent environmental factors seem to afect fruit development and phenology, determining the observed fruit characteristics, with seed dispersers playing a minor role in shaping these patterns. More generally, the contrasting plant-seed disperser associations we addressed can be interpreted as the outcome of an ecological-ftting rather than of a coevolutionary process.