Aim
The number of studies investigating the nestedness and turnover components of beta diversity has increased substantially, but our general understanding of the drivers of turnover and nestedness remains elusive. Here, we examined the effects of species traits, spatial extent, latitude and ecosystem type on the nestedness and turnover components of beta diversity.

Location
Global.

Time period
1968–2017.

Major taxa studied
From bacteria to mammals.

Methods
From the 99 studies that partition total beta diversity into its turnover and nestedness components, we assembled 269 and 259 data points for the pairwise and multiple site beta-diversity metrics, respectively. Our data covered a broad variation in species dispersal type, body size and trophic position. The data were from freshwater, marine and terrestrial realms, and encompassed geographical areas from the tropics to near polar regions. We used linear modelling as a meta-regression tool to analyse the data.

Results
Pairwise turnover, multiple site turnover and total beta diversity all decreased significantly with latitude. In contrast, multiple site nestedness showed a positive relationship with latitude. Beta-diversity components did not generally differ among the realms. The turnover component and total beta diversity increased with spatial extent, whereas nestedness was scale invariant for pairwise metrics. Multiple site beta-diversity components did not vary with spatial extent. Surprisingly, passively dispersed organisms had lower turnover and total beta diversity than flying organisms. Body size showed a relatively weak relationship with beta diversity but had important interactions with trophic position, thus also affecting beta diversity via interactive effects. Producers had significantly higher average pairwise turnover and total beta diversity than carnivores.

Main conclusions
The present results provide evidence that species turnover, being consistently the larger component of total beta diversity, and nestedness are related to the latitude of the study area and intrinsic organismal features. We showed that two beta-diversity components had generally opposing patterns with regard to latitude. We highlight that beta-diversity partition may give additional insights into the underlying causes of spatial variability in biotic communities compared with total beta diversity alone.

/pdf/a-meta-analysis-of-nestedness-and-turnover-components-of-52n5f8at3l.pdf

A meta-analysis of nestedness and turnover components of beta diversity across organisms and ecosystems

Biodiversity includes multiscalar and multitemporal structures and processes, with different levels of functional organization, from genetic to ecosystemic levels. One of the mostly used methods to infer biodiversity is based on taxonomic approaches and community ecology theories. However, gathering extensive data in the field is difficult due to logistic problems, overall when aiming at modelling biodiversity changes in space and time, which assumes statistically sound sampling schemes. In this view, airborne or satellite remote sensing allow to gather information over wide areas in a reasonable time. Most of the biodiversity maps obtained from remote sensing have been based on the inference of species richness by regression analysis. On the contrary, estimating compositional turnover (beta-diversity) might add crucial information related to relative abundance of different species instead of just richness. Presently, few studies have addressed the measurement of species compositional turnover from space. Extending on previous work, in this manuscript we propose novel techniques to measure beta-diversity from airborne or satellite remote sensing, mainly based on: i) multivariate statistical analysis, ii) the spectral species concept, iii) self-organizing feature maps, iv) multi- dimensional distance matrices, and the v) Rao's Q diversity. Each of these measures allow to solve one or several issues related to turnover measurement. This manuscript is the first methodological example encompassing (and enhancing) most of the available methods for estimating beta-diversity from remotely sensed imagery and potentially relate them to species diversity in the field.

/pdf/measuring-b-diversity-by-remote-sensing-a-challenge-for-yw6njxpeaf.pdf

Measuring β-diversity by remote sensing: A challenge for biodiversity monitoring

World distribution, diversity and endemism of aquatic macrophytes

Unlike in land plants, photosynthesis in many aquatic plants relies on bicarbonate in addition to carbon dioxide (CO2) to compensate for the low diffusivity and potential depletion of CO2 in water. Concentrations of bicarbonate and CO2 vary greatly with catchment geology. In this study, we investigate whether there is a link between these concentrations and the frequency of freshwater plants possessing the bicarbonate use trait. We show, globally, that the frequency of plant species with this trait increases with bicarbonate concentration. Regionally, however, the frequency of bicarbonate use is reduced at sites where the CO2 concentration is substantially above the air equilibrium, consistent with this trait being an adaptation to carbon limitation. Future anthropogenic changes of bicarbonate and CO2 concentrations may alter the species compositions of freshwater plant communities.

/pdf/catchment-properties-and-the-photosynthetic-trait-1momgqegbo.pdf

Catchment properties and the photosynthetic trait composition of freshwater plant communities.

Effects of dams decrease zooplankton functional β‐diversity in river‐associated lakes

Additional co-authors: Gana Gecheva, Patrick Grillas, Jennifer Hauxwell, Seppo Hellsten, Jan Hjort, Mark V. Hoyer, Agnieszka Kolada, Minna Kuoppala, Torben Lauridsen, En‒Hua Li, Balazs A. Lukacs, Marit Mjelde, Alison Mikulyuk, Roger P. Mormul, Jun Nishihiro, Beat Oertli, Laila Rhazi, Mouhssine Rhazi, Laura Sass, Christine Schranz, Martin Sondergaard, Takashi Yamanouchi, Qing Yu, Haijun Wang, Xiao‒Ke Zhang, Jani Heino

/pdf/global-variation-in-the-beta-diversity-of-lake-macrophytes-4wdsm5pxm9.pdf

Gana Gecheva

Papers

Global variation in the beta diversity of lake macrophytes is driven by environmental heterogeneity rather than latitude