Just how big is intraspecific trait variation in basidiomycete wood fungal fruit bodies?

Abstract

As the use of functional trait approaches is growing in fungal ecology, there is a corresponding need to understand trait variation. Much of trait theory and statistical techniques are built on the assumption that interspecific variation is larger than intraspecific variation. This allows for the use of mean trait values for species, which the vast majority of trait studies adopt. We examined the size of intra-vs. inter-specific variation in two deadwood fungal fruit body traits: size and density. Both coefficients of variation (CV) and Trait Probability Density analyses were used to quantify trait variation. We found that intraspecific variation in fruit body density was more than twice as variable as interspecific variation and fruit body size was hugely variable (CVs averaged 190%), although interspecific variation was larger. Further, there was a very high degree of overlap in the trait space of species, indicating that there is little niche partitioning at the species level. These findings show that intraspecific variation is highly important and should be accounted for when using trait approaches to understand fungal ecology. More data on variation of other fungal traits is also desperately needed to ascertain if the high level of variation found here is typical for fungi. While the need to measure individuals does reduce the ability to generalise at the species level, it does not negate the usefulness of fungal trait measurements. There are two reasons for this: first, the ecology of most fungal species remains poorly known and trait measurements address this gap; and secondly, if trait overlap between species more generally as much as we found here, then individual measurements may be more helpful than species identity for untangling fungal community dynamics.

Wood-inhabiting fungal responses to forest naturalness vary among morpho-groups

“…Certain fruitbody morphologies have also been speculated to be adaptations to harsh environmental conditions, such as freezing, desiccation or excess moisture, which could lead to differences in group-specific responses 29 , 30 . Even though there is a vast variation in the morphology of wood inhabiting fungal fruitbodies 31 , compared to other groups such as animals and plants, very little is still known about how morphological traits modulate the responses of species to environmental variation 32 , 33 .…”

Extending the CWM approach to intraspecific trait variation: how to deal with overly optimistic standard tests?

“…For other taxa, the extent of ITV remains less well understood, however (e.g. Gaudard et al 2019 for ants, Behm and Kiers 2014 for arbuscular mycorrhizal fungi, or Dawson and Jönsson 2020 for basidiomycetes). Consequently, researchers are now actively advocating the inclusion of ITV in most community ecological trait research, including in trait-environment relationship tests (Albert et al 2011).…”

Integrating intraspecific trait variability in functional diversity: an overview of methods and a guide for ecologists

“…Previous literature should be scrutinized when deciding whether 543 including ITV is relevant. Some taxonomic groups, such as invertebrates, have shown low levels 544 of ITV (1-6% of intraspecific trait variance; [63,86], whereas others, such as fungi, have shown 545 large ITV (more than twice as variable as interspecific variation; [96]). In turn, some traits can be 546 highly variable within a given taxonomic group (e.g., body mass CV in birds = 593%; [51]), while 547 others can be much less variable (tail length CV in birds = 71%; [115].…”