Search

Community ecologists are active in describing species by their functional traits, quantifying the functional structure of plant and animal assemblages and inferring community assembly processes with null-model analyses of trait distribution and functional diversity indices. Intraspecific variation in traits and effects of spatial scale are potentially important in these analyses. Here, we introduce the R package cati (Community Assembly by Traits: Individuals and beyond) available on CRAN, for the analysis of community assembly with functional traits. cati builds on a recent approach to community assembly that explicitly incorporates individual differences in community assembly analyses and decomposes phenotypic variations across scales and organizational levels, based on three phenotypic variance ratios, termed the T-statistics. More generally, the cati package 1) calculates a variety of single-trait and multi-trait indices from interspecific and intraspecific trait measures; 2) it partitions functional trait variation among spatial and taxonomic levels; 3) it implements a palette of flexible null models for detecting non-random patterns of functional traits. These patterns can be used to draw inferences about hypotheses of community assembly such as environmental filtering and species interactions. The basic input for cati is a data frame in which columns are traits, rows are species or individuals, and entries are the measured trait values. The cati package can also incorporate a square distance matrix into analyses, which could include phylogenetic or genetic distances among individuals or species. Users select from a variety of functional trait metrics and analyze these relative to a null model that specifies trait distributions in a regional source pool. [ABSTRACT FROM AUTHOR]

Recent studies have shown that accounting for intraspecific trait variation ( ITV) may better address major questions in community ecology. However, a general picture of the relative extent of ITV compared to interspecific trait variation in plant communities is still missing. Here, we conducted a meta-analysis of the relative extent of ITV within and among plant communities worldwide, using a data set encompassing 629 communities (plots) and 36 functional traits. Overall, ITV accounted for 25% of the total trait variation within communities and 32% of the total trait variation among communities on average. The relative extent of ITV tended to be greater for whole-plant (e.g. plant height) vs. organ-level traits and for leaf chemical (e.g. leaf N and P concentration) vs. leaf morphological (e.g. leaf area and thickness) traits. The relative amount of ITV decreased with increasing species richness and spatial extent, but did not vary with plant growth form or climate. These results highlight global patterns in the relative importance of ITV in plant communities, providing practical guidelines for when researchers should include ITV in trait-based community and ecosystem studies. [ABSTRACT FROM AUTHOR]

In the Mediterranean region, patches of vegetation recovering from disturbance and transiently dominated by shrubs produce one of the world's most prized fungi, the black truffle ( T uber melanosporum). In these successional plant communities, we have fragmentary knowledge of the distribution of T . melanosporum in space among ectomycorrhizal ( ECM) host species and in time. Molecular identification of hosts (Restriction Fragment Length Polymorphism) and fungi (Internal Transcribed Spacer sequencing) and quantification of T . melanosporum mycelium (quantitative Polymerase Chain Reaction) were employed to evaluate the presence of T . melanosporum on four dominant ECM host species ( Q uercus ilex, Q uercus coccifera, A rbutus unedo, C istus albidus) and the extent to which their respective ECM communities shared fungal diversity, over the course of development of truffle grounds, from recent unproductive brûlés to senescent ones where production has stopped. We found that truffle grounds host rich communities in which multi-host fungal species dominate in frequency. When considering both ECM tips and soil mycelia, we documented a dynamic and spatially heterogeneous pattern of T . melanosporum distribution in soils and a presence of ECM tips restricted to Q . ilex roots. This study advances our knowledge of the ecology of T . melanosporum, and provides insight into the extent of ECM fungal sharing among plant species that dominate Mediterranean landscapes. [ABSTRACT FROM AUTHOR]

Information about the 33rd New Phytologist Symposium held in Zürich, Switzerland in May 2014 is presented. The event featured four important topics pertaining to ecology and the evolution of symbiosis among plants and mycorrhizal fungi. The symposium also highlighted ideas offered by professor Alicia Montesinos-Navarro on the ecological network theory that illustrates the interaction between mycorrhizal fungi and plants.