Intra-specific trait variation remains hidden in the environment

It has been a longstanding goal for plant scientists to elucidate the adaptation of plant functional traits. One common approach is to explore trait variation along environmental gradients, which are assumed to be indicative of evolutionary processes shaping traits and species distributions. To achieve this goal, many high-profile studies focus on comparing species (i.e. inter-specific) mean trait values over continental or global scales (e.g. Wright et al., 2017). However, this approach assumes that trait variation within species (i.e. intra-specific) is negligible and aligned with global patterns. Yet, it has been shown that intra-specific trait variation across environments may differ substantially compared to inter-specific patterns (e.g. Kichenin et al., 2013; Mclean et al., 2014). In this issue of New Phytologist, Anderegg et al. (2021; pp. 1375–1387) reveal intra-specific trait variation can be much greater than interspecific trait variation across shared climate gradients.