The role of functional traits and individual variation in the co‐occurrence of Ficus species

Abstract

The processes that structure assemblages of species in hyper-diverse genera, such as Ficus (Moraceae), are not well understood. Functional diversity of co-occurring species can reveal evidence for assembly processes; however, intraspecific variation may weaken species-level patterns. We studied whether functional and phylogenetic diversity of Ficus species indicated the effects of spatial variation in filters associated with topography or niche partitioning related to resource use and biotic interactions. We also asked whether individual trait patterns supported species-level patterns. We studied six traits (leaf area, succulence, specific leaf area [SLA], maximum diameter breast high [dbh], fruit size, and latex exudation) for 22 Ficus species and 335 individuals > or = 10 cm dbh on a 20-ha forest plot in China. We found that higher elevation was correlated to changes in mean and reduced diversity of five traits, possibly due to frequent disturbances at higher elevations that favored fast-growing, poorly defended species with high SLA. Maximum dbh showed phylogenetic conservatism but high diversity among co-occurring species, suggesting adult stature is an important axis of within-quadrat niche partitioning. At the individual level, trait patterns were qualitatively consistent but were stronger than species-level patterns, especially for the leaf traits with the greatest intraspecific variation (SLA and succulence). Individual-level SLA exhibited the strongest evidence for both traits among and within-quadrat niche partitioning and indicated elevational filtering. Local niche partitioning and elevational filtering likely play an important role in maintaining species and functional diversity in the most speciose genus at our study site. Our results highlight the importance of individual variation, as it may reveal otherwise obscured niche effects.

Ontogenetic shifts in trait‐mediated mechanisms of plant community assembly

“…We also found positive relationships between survival and wood density across size classes, likely because higher wood density confers greater resistance to damage (Kitajima 1994, Chave et al 2009) or because high wood density is broadly associated with a conservative, slow life history with high survival (Wright et al 2010, Reich 2014. Future research efforts that collect trait data on individuals of different sizes that occupy different environments will help shed additional light on this question (Iida et al 2014, Lasky et al 2014c.…”

The evolution and ecology of individual specializations amongst a group of dietary generalists.

“…Specialization, coexistence, and the loss of ecological opportunity: Individual specializations (IS) can decrease the interaction strength among competing species (Lichstein et al 2007;Bolnick et al 2011;Lasky et al 2014). When individuals use a smaller subset of the population's dietary resources, the number of individuals from each species that overlap in resource use will be reduced Lasky et al 2014).…”

“…When individuals use a smaller subset of the population's dietary resources, the number of individuals from each species that overlap in resource use will be reduced Lasky et al 2014). As a result, the resources may not become limiting.…”

“…As a result, the resources may not become limiting. Individual specializations can therefore promote species coexistence and increase the number of species present in a community (Lichstein et al 2007;Lasky et al 2014). The greater number of species in a community will decrease available ecological opportunity that could have been used for the niche expansion needed to develop more distinct polymorphisms.…”

“…in natural populations (Lichstein et al 2007;Bolnick et al 2011;Lasky et al 2014). In the former example, the competitive effects of each heterospecific competitor, cut-throat trout and prickly sculpin, may have different effects on the foraging behavior of threespined sticklebacks.…”