Functional beta-diversity patterns reveal deterministic community assembly processes in eastern North American trees

2012 ◽  
Vol 22 (6) ◽  
pp. 682-691 ◽  
Author(s):  
Andrew Siefert ◽  
Catherine Ravenscroft ◽  
Michael D. Weiser ◽  
Nathan G. Swenson
Author(s):  
Miguel Muñoz Mazón ◽  
J. Sebastián Tello ◽  
Manuel J. Macía ◽  
Jonathan A. Myers ◽  
Peter M. Jørgensen ◽  
...  

2020 ◽  
Vol 4 ◽  
Author(s):  
Alex Laini ◽  
Arne J. Beermann ◽  
Rossano Bolpagni ◽  
Gemma Burgazzi ◽  
Vasco Elbrecht ◽  
...  

Taxonomic sufficiency represents the level of taxonomic detail needed to detect ecological patterns to a level that match the requirement of a study. Most bioassessments apply the taxonomic sufficiency concept and assign specimens to the family or genus level given time constraints and the difficulty to correctly identify species. This holds particularly true for stream invertebrates because small and morphologically similar larvae are hard to distinguish. Low taxonomic resolution may hinder detecting true community dynamics, which thus leads to incorrect inferences about community assembly processes. DNA metabarcoding is a new, affordable and cost-effective tool for the identification of multiple species from bulk samples of organisms. As it provides high taxonomic resolution, it can be used to compare results obtained from different identification levels. Measuring the effect of taxonomic resolution on the detection of community dynamics is especially interesting in extreme ecosystems like intermittent streams to test if species at intermittent sites are subsets of those from perennial sources or if independently recruiting taxa exist. Here we aimed to compare the performance of morphological identification and metabarcoding to detect macroinvertebrate community dynamics in the Trebbia River (Italy). Macroinvertebrates were collected from four perennial and two intermittent sites two months after flow resumption and before the next dry phase. The identification level ranged from family to haplotype. Metabarcoding and morphological identifications found similar alpha diversity patterns when looking at family and mixed taxonomic levels. Increasing taxonomic resolution with metabarcoding revealed a strong partitioning of beta diversity in nestedness and turnover components. At flow resumption, beta diversity at intermittent sites was dominated by nestedness when family-level information was employed, while turnover was evidenced as the most important component when using Operational Taxonomic Units (OTUs) or haplotypes. The increased taxonomic resolution with metabarcoding allowed us to detect species adapted to deal with intermittency, like the chironomid Cricotopus bicinctus and the ephemeropteran Cloeon dipterum. Our study thus shows that family and mixed taxonomic level are not sufficient to detect all aspects of macroinvertebrate community dynamics. High taxonomic resolution is especially important for intermittent streams where accurate information about species-specific habitat preference is needed to interpret diversity patterns induced by drying and the nestedness/turnover components of beta diversity are of interest to understand community assembly processes.


2020 ◽  
Vol 195 (2) ◽  
pp. 166-180
Author(s):  
Clarke A. Knight ◽  
Jessica L. Blois ◽  
Benjamin Blonder ◽  
Marc Macias-Fauria ◽  
Alejandro Ordonez ◽  
...  

2020 ◽  
Vol 17 (4) ◽  
pp. 865-886 ◽  
Author(s):  
Paulo Bonifácio ◽  
Pedro Martínez Arbizu ◽  
Lénaïck Menot

Abstract. In the abyssal equatorial Pacific Ocean, most of the seafloor of the Clarion-Clipperton Fracture Zone (CCFZ), a 6 million km2 polymetallic nodule province, has been preempted for future mining. In light of the large environmental footprint that mining would leave and given the diversity and the vulnerability of the abyssal fauna, the International Seabed Authority has implemented a regional management plan that includes the creation of nine Areas of Particular Environmental Interest (APEIs) located at the periphery of the CCFZ. The scientific principles for the design of the APEIs were based on the best – albeit very limited – knowledge of the area. The fauna and habitats in the APEIs are unknown, as are species' ranges and the extent of biodiversity across the CCFZ. As part of the Joint Programming Initiative Healthy and Productive Seas and Oceans (JPI Oceans) pilot action “Ecological aspects of deep-sea mining”, the SO239 cruise provided data to improve species inventories, determine species ranges, identify the drivers of beta diversity patterns and assess the representativeness of an APEI. Four exploration contract areas and an APEI (APEI no. 3) were sampled along a gradient of sea surface primary productivity that spanned a distance of 1440 km in the eastern CCFZ. Between three and eight quantitative box cores (0.25 m2; 0–10 cm) were sampled in each study area, resulting in a large collection of polychaetes that were morphologically and molecularly (cytochrome c oxidase subunit I and 16S genes) analyzed. A total of 275 polychaete morphospecies were identified. Only one morphospecies was shared among all five study areas and 49 % were singletons. The patterns in community structure and composition were mainly attributed to variations in organic carbon fluxes to the seafloor at the regional scale and nodule density at the local scale, thus supporting the main assumptions underlying the design of the APEIs. However, the APEI no. 3, which is located in an oligotrophic province and separated from the CCFZ by the Clarion Fracture Zone, showed the lowest densities, lowest diversity, and a very low and distant independent similarity in community composition compared to the contract areas, thus questioning the representativeness and the appropriateness of APEI no. 3 to meet its purpose of diversity preservation. Among the four exploration contracts, which belong to a mesotrophic province, the distance decay of similarity provided a species turnover of 0.04 species km−1, an average species range of 25 km and an extrapolated richness of up to 240 000 polychaete species in the CCFZ. By contrast, nonparametric estimators of diversity predict a regional richness of up to 498 species. Both estimates are biased by the high frequency of singletons in the dataset, which likely result from under-sampling and merely reflect our level of uncertainty. The assessment of potential risks and scales of biodiversity loss due to nodule mining thus requires an appropriate inventory of species richness in the CCFZ.


2020 ◽  
Vol 47 (6) ◽  
pp. 1373-1382
Author(s):  
Hiroshi Ikeda ◽  
Mac A. Callaham ◽  
Richard P. Shefferson ◽  
Evelyn S. Wenk ◽  
Carlos Fragoso

2010 ◽  
Vol 26 (5) ◽  
pp. 521-531 ◽  
Author(s):  
David Laurencio ◽  
Lee A. Fitzgerald

Abstract:Disentangling local and historical factors that determine species diversity patterns at multiple spatial scales is fundamental to elucidating processes that govern ecological communities. Here we investigated how environmental correlates may influence diversity at local and regional scales. Primarily utilizing published species lists, amphibian and reptile alpha and beta diversity were assessed at 17 well-surveyed sites distributed among ecoregions throughout Costa Rica. The degree to which regional species diversity patterns were related to environmental variables and geographic distance was determined using Canonical Correspondence Analysis and Mantel tests. Amphibian alpha diversity was highest in lowland Pacific sites (mean = 43.3 species) and lowest at the high elevation site (9 species). Reptile alpha diversity values were high for both lowland Atlantic (mean = 69.5 species) and lowland Pacific (mean = 67 species) sites and lowest for the high elevation site (8 species). We found high species turnover between local sites and ecoregions, demonstrating the importance of beta diversity in the determination of regional diversity. For both amphibians and reptiles, beta diversity was highest between the high-elevation site and all others, and lowest among lowland sites within the same ecoregion. The effect of geographic distance on beta diversity was minor. Ecologically significant climatic variables related to rain, temperature, sunshine and insolation were found to be important determinants of local and regional diversity for both amphibians and reptiles in Costa Rica.


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