More Like this

1. Does island ontogeny dictate the accumulation of both species richness and functional diversity?

   https://doi.org/10.1111/geb.13420  

   Kraemer, Andrew C. ; Roell, Yannik E. ; Shoobs, Nate F. ; Parent, Christine E. ( October 2021 , Global Ecology and Biogeography)

   The accumulation of functional diversity in communities is poorly understood. Conveniently, the general dynamic model of island biogeography (GDM) makes predictions for how such diversity might accumulate over time. In this multiscale study of land snail communities on 10 oceanic archipelagos located in various regions of the globe, we test hypotheses of community assembly in systems where islands serve as chronosequences along island ontogeny.

   Ten volcanic archipelagos.

   From 23 Ma to the present.

   Endemic land snails.

   Initially, we assembled geological island characteristics of area, isolation and ontogeny for all studied islands. We then characterized island‐scale biotic variables, including the species diversity and functional diversity of snail communities. From these data, we assessed relationships between island and snail community variables as predicted by the GDM, focusing initially on the islands of the Galápagos archipelago and thereafter with a broader analysis of 10 archipelagoes.

   As in other studies of island assemblages, in Galápagos we find a hump‐shaped curve of species richness, with depauperate snail faunas on early‐ontogeny islands, increasing species richness on mid‐ontogeny islands and low species richness on islands in late ontogeny. We find exceptionally low functional diversity on early‐ontogeny islands that increases through mid‐ontogeny, whereas late‐ontogeny islands exhibit a range of functional diversity. The analysis including all 10 archipelagos indicates a major role of archipelago‐specific factors. In both sets of analyses, functional diversity is exceptionally low on early‐ontogeny islands, and island ontogeny is a significant predictor of morphology.

   Consistent patterns of functional diversity across island ontogeny on all examined archipelagos indicate a common role for habitat filtering, ecological opportunity and competition in a diversity of systems, leading to predictable changes in functional diversity and average morphology through island ontogeny, whereas patterns of species richness appear subject to archipelago‐specific factors.

    

   more » « less
2. Rarity and beta diversity assessment as tools for guiding conservation strategies in marine tropical subtidal communities

   https://doi.org/10.1111/ddi.12896  

   Carlos‐Júnior, Lélis A. ; Spencer, Matthew ; Neves, Danilo Mesquita ; Moulton, Timothy Peter ; Pires, Débora de Oliveira ; e Castro, Clovis Barreira ; Ventura, Carlos Renato Rezende ; Ferreira, Carlos Eduardo Leite ; Serejo, Cristiana Silveira ; Oigman‐Pszczol, Simone ; et al ( January 2019 , Diversity and Distributions)

   Our aim was to uncover patterns of distribution of marine subtidal rocky reef communities across six taxonomic groups and decompose the relative roles of species loss and turnover in total community variation. Additionally, we propose an easily calculated index that can be used to highlight areas with unique species composition for conservation planning. We estimated the strengths of associations between environmental factors and species richness and rarity.

   Ilha Grande Bay, Brazil, covering about 150,000 ha harbouring different marine habitats.

   We used the Marine Rapid Assessment Protocol at 42 sites to gather information on environmental variables and species in six subtidal marine groups. We determined “singular” sites as the regions harbouring higher numbers of rare species. Then, we estimated the roles of species loss and turnover on the observed total variation among sites. We used Generalized Linear Model to partition the relative importance of the selected environmental factors in driving variation in species richness and singularity.

   The singularity index and richness showed that the bay could be divided into three subregions for subtidal communities. Richness and rarity were structured at different spatial scales and associated with environmental variables related to water productivity and nutrients but varied among taxonomic groups. Community variation over space was largely associated with turnover of species.

   Higher singularity and richness on the western side of the bay and around the main island suggested that these regions should be conservation priorities, but high species turnover across the whole bay indicated that portions of the central channel should be included in conservation strategies. This draws attention to the importance of community variation rather than just species numbers in conservation and management planning. The high species turnover indicated that these rocky reefs have high beta diversity when compared to other studied biological systems.

    

   more » « less
3. Phylogeography of the highly dispersible landscape‐dominant woody species complex, Metrosideros , in Hawaii

   https://doi.org/10.1111/jbi.13650  

   Stacy, Elizabeth_Ann ; Sakishima, Tomoko ( June 2019 , Journal of Biogeography)

   Little is known about how diversification occurs within long‐lived, highly dispersible and continuously distributed groups. We examined the distribution of genetic variation within the woody genusMetrosiderosacross the Hawaiian Islands for insights into how diversification occurs within this animal‐pollinated, wind‐dispersed group. Among Hawaiian plants,Metrosiderosis unique in its formation of continuous stands within islands that span a remarkable range of environments and comprise numerous predominantly single‐island taxa.

   Hawaiian Islands.

   Metrosideros.

   We performed population genetic analyses of variation at nine nuclear microsatellite loci from 1,486 adults of 23Metrosiderosmorphotypes sampled from five main Hawaiian Islands plus additional Pacific Island populations.

   American Samoa and Tahiti populations clustered most closely with the older islands. Results also revealed isolation by distance across the archipelago, clustering of populations predominantly by island, and evidence of multiple colonizations or back‐colonizations of three islands. The number of genetic clusters peaked on islands of intermediate age, coincident with peak morphotype richness. All islands comprised a broad range of genetic distances among taxa with the greatest overall genetic distance observed on Oahu. The two taxa that are distributed broadly across the archipelago were weakly but significantly differentiated only on volcanically active Hawaii Island, where they partition early‐ and late‐successional environments. One of these taxa was positioned centrally both within individual‐island splitstree networks and across the archipelago‐wide network.

   Distance‐dependent gene flow contributes to isolation ofMetrosiderosacross islands, especially on terminal islands. Morphological diversity likely accumulates rapidly within this group, likely associated with differential adaptation across heterogeneous environments, but isolation of gene pools through speciation within continuousMetrosiderosstands likely requires persistent disruptive selection where environments are stable for long periods. The generalist, wet‐forestM.polymorphavar.glaberrimamay play a central role in the generation of the group's many, largely island‐endemic, taxa.

    

   more » « less
4. Impact of plant diversity and management intensity on magnitude and stability of productivity in North American grazing lands

   https://doi.org/10.1111/avsc.12776  

   Sonnier, Grégory ; Augustine, David J ; Paudel, Shishir ; Porensky, Lauren M ; Silveira, Maria ; Toledo, David ; Azad, Shefali ; Boughton, Raoul K ; Browning, Dawn M ; Clark, Patrick E ; et al ( April 2024 , Applied Vegetation Science)

   Grasslands provide important provisioning services worldwide and their management has consequences for these services. Management intensification is a widespread land‐use change and has accelerated across North America to meet rising demands on productivity, yet its impact on the relationship between plant diversity and productivity is still unclear. Here, we investigated the relationship between plant diversity and grassland productivity across nine ecoclimatic domains of the continental United States. We also tested the effect of management intensification on diversity and productivity in four case studies.

   We acquired remotely sensed gross primary productivity data (GPP, 1986–2018) and plant diversity data measured at different spatial scales (1, 10, 100, 400 m²), as well as climate variables including the Palmer drought index from two ecological networks. We used general linear mixed models to relate GPP to plant diversity across sites. For the case study analysis, we used linear mixed models to relate plant diversity to management intensity, and tested if the management intensity influenced the relationship between GPP (mean and temporal variation) and drought.

   Across all sites, we observed positive relationships among species richness, productivity, and the temporal stability of mean annual biomass production. These relationships were not affected by the scale at which species richness was observed. In three out of the four case studies, we observed that management effects on species richness were only significant at broader scales (i.e., ≥10 m²) with no clear effect found at the commonly used 1‐m²quadrat scale. In one case study, species‐poor, intensively managed pastures presented the highest productivity but were more sensitive to dry conditions than less intensified pastures. However, in other case studies, we did not observe significant effects of management intensity on the magnitude or stability of productivity.

   Generalization across studies may be difficult and require the development of intensification indices general enough to be applied across diverse management strategies in grazilands. Understanding how management intensification affects grassland productivity will inform the development of sustainable intensification strategies.

    

   more » « less
5. Evaluating the potential of full‐waveform lidar for mapping pan‐tropical tree species richness

   https://doi.org/10.1111/geb.13158  

   Marselis, Suzanne M. ; Abernethy, Katharine ; Alonso, Alfonso ; Armston, John ; Baker, Timothy R. ; Bastin, Jean‐Francois ; Bogaert, Jan ; Boyd, Doreen S. ; Boeckx, Pascal ; Burslem, David F. R. P. ; et al ( July 2020 , Global Ecology and Biogeography)

   Mapping tree species richness across the tropics is of great interest for effective conservation and biodiversity management. In this study, we evaluated the potential of full‐waveform lidar data for mapping tree species richness across the tropics by relating measurements of vertical canopy structure, as a proxy for the occupation of vertical niche space, to tree species richness.

   Tropics.

   Present.

   Trees.

   First, we evaluated the characteristics of vertical canopy structure across 15 study sites using (simulated) large‐footprint full‐waveform lidar data (22 m diameter) and related these findings to in‐situ tree species information. Then, we developed structure–richness models at the local (within 25–50 ha plots), regional (biogeographical regions) and pan‐tropical scale at three spatial resolutions (1.0, 0.25 and 0.0625 ha) using Poisson regression.

   The results showed a weak structure–richness relationship at the local scale. At the regional scale (within a biogeographical region) a stronger relationship between canopy structure and tree species richness across different tropical forest types was found, for example across Central Africa and in South America [R²ranging from .44–.56, root mean squared difference as a percentage of the mean (RMSD%) ranging between 23–61%]. Modelling the relationship pan‐tropically, across four continents, 39% of the variation in tree species richness could be explained with canopy structure alone (R² = .39 and RMSD% = 43%, 0.25‐ha resolution).

   Our results may serve as a basis for the future development of a set of structure–richness models to map high resolution tree species richness using vertical canopy structure information from the Global Ecosystem Dynamics Investigation (GEDI). The value of this effort would be enhanced by access to a larger set of field reference data for all tropical regions. Future research could also support the use of GEDI data in frameworks using environmental and spectral information for modelling tree species richness across the tropics.

    

   more » « less