Distance decay 2.0 – a global synthesis of taxonomic and functional turnover in ecological communities

Abstract

Understanding the variation in community composition and species abundances, i.e., β-diversity, is at the heart of community ecology. A common approach to examine β-diversity is to evaluate directional turnover in community composition by measuring the decay in the similarity among pairs of communities along spatial or environmental distances. We provide the first global synthesis of taxonomic and functional distance decay along spatial and environmental distance by analysing 149 datasets comprising different types of organisms and environments. We modelled an exponential distance decay for each dataset using generalized linear models and extracted r2 and slope to analyse the strength and the rate of the decay. We studied whether taxonomic or functional similarity has stronger decay across the spatial and environmental distances. We also unveiled the factors driving the rate of decay across the datasets, including latitude, spatial extent, realm, and organismal features. Taxonomic distance decay was stronger along spatial and environmental distances compared with functional distance decay. The rate of taxonomic spatial distance decay was the fastest in the datasets from mid-latitudes while the rate of functional decay increased with latitude. Overall, datasets covering larger spatial extents showed a lower rate of decay along spatial distances but a higher rate of decay along environmental distances. Marine ecosystems had the slowest rate of decay. This synthesis is an important step towards a more holistic understanding of patterns and drivers of taxonomic and functional β-diversity.

Seed banks alter metacommunity diversity: The interactive effects of competition, dispersal and dormancy

“…Stabilising competition is often detected in plant communities (Adler et al, 2018), suggesting our local stabilisation model may provide insight into the roles of seed banks for spatial diversity patterns. For example, terrestrial plant communities tend to exhibit high beta‐diversity relative to other systems (Graco‐Roza et al, 2021), matching model predictions for low to moderate dispersal and moderate survival in the seed bank. Plant systems have been shown to experience dispersal limitation (Myers & Harms, 2009; Tilman, 1997), and separately beta‐diversity has been shown to be high for organisms with seed dispersal (Soininen et al, 2007).…”

Concepts and applications in functional diversity

“…functional richness along gradients of thermal seasonality (latitude) (Graco-Roza et al, 2021;Lamanna et al, 2014;Schumm et al, 2019), glacier cover (L. E. Brown et al, 2018), or urbanization (Buchholz, Gathof, Grossmann, Kowarik, & Fischer, 2020;Sol et al, 2020).…”

“…These include questions such as what ecological processes and ecosystem services we lose if a species goes extinct or a community change (Cadotte et al, 2011;Cooke et al, 2019), the filtering effect of a given habitat on species traits (Martínez et al, 2021;Micó et al, 2020), and how does the functionality of a community vary through seasons (Rocha et al, 2012). At a broader, macroecological scale, many studies have explored variations in functional richness along gradients of thermal seasonality (latitude; Graco-Roza et al, 2021;Lamanna et al, 2014;Schumm et al, 2019), glacier cover (Brown et al, 2018) or urbanisation (Buchholz et al, 2020;Sol et al, 2020). Mapping the richness of traits can also serve to identify areas of conservation priority based on criteria beyond species richness (Brum et al, 2017;Strecker et al, 2011).…”

A protocol for reproducible functional diversity analyses

“…Note that most approaches to study functional diversity can also integrate intraspecific variation in community-level calculations, including functional dendrograms (Cianciaruso et al, 2009, Cardoso et al, 2015, weighted sums of trait probability distributions across organizational levels (Carmona et al, 2016(Carmona et al, , 2019, or the union of species-level functional hypervolumes (Mammola & Cardoso, 2020;Graco-Roza et al,…”