Plant-Pollinator Coextinctions and the Loss of Plant Functional and Phylogenetic Diversity

<div><p>Plant-pollinator coextinctions are likely to become more frequent as habitat alteration and climate change continue to threaten pollinators. The consequences of the resulting collapse of plant communities will depend partly on how quickly plant functional and phylogenetic diversity decline following pollinator extinctions. We investigated the functional and phylogenetic consequences of pollinator extinctions by simulating coextinctions in seven plant-pollinator networks coupled with independent data on plant phylogeny and functional traits. Declines in plant functional diversity were slower than expected under a scenario of random extinctions, while phylogenetic diversity often decreased faster than expected by chance. Our results show that plant functional diversity was relatively robust to plant-pollinator coextinctions, despite the underlying rapid loss of evolutionary history. Thus, our study suggests the possibility of uncoupled responses of functional and phylogenetic diversity to species coextinctions, highlighting the importance of considering both dimensions of biodiversity explicitly in ecological studies and when planning for the conservation of species and interactions. </p> </div

Declines in functional diversity (FD) following simulated plant-pollinator coextinctions in seven pollination networks (A-G).

<p>Circles: declines following plant-pollinator coextinctions. Dotted lines: declines following random plant extinctions in the absence of coextinctions. Solid lines above and below the dotted lines represent best- and worst-case scenarios, respectively.</p

Autocorrelation analyses.

<p>(A) Autocorrelation in persistence among plant species close to each other in the functional dendrogram. (B) Autocorrelation in persistence among phylogenetically close plant species. (C) Autocorrelation in functional originality among phylogenetically close plant species. Moran’s I values were calculated with respect to the first distance class in the correlogram. </p

Relative declines in FD and PD.

<p>Relative difference between declines in FD (A) and PD (B) under a plant-pollinator coextinction scenario and declines under a random scenario of plant extinctions in the absence of coextinctions. Positive and negative deviations from the random expectation are shown in green and red, respectively. Closed squares = Albrecht, closed triangles = Devoto, closed circles = Dicks, crosses = Hegland, open triangles = Junker, open circles = Memmott, diamonds = Weiner. Vertical dotted line indicates values when 50% of plant species have been lost. </p

Amphibian Beta Diversity in the Brazilian Atlantic Forest: Contrasting the Roles of Historical Events and Contemporary Conditions at Different Spatial Scales

<div><p>Current patterns of biodiversity distribution result from a combination of historical and contemporary processes. Here, we compiled checklists of amphibian species to assess the roles of long-term climate stability (Quaternary oscillations), contemporary environmental gradients and geographical distance as determinants of change in amphibian taxonomic and phylogenetic composition in the Brazilian Atlantic Forest. We calculated beta diversity as both variation in species composition (CBD) and phylogenetic differentiation (PBD) among the assemblages. In both cases, overall beta diversity was partitioned into two basic components: species replacement and difference in species richness. Our results suggest that the CBD and PBD of amphibians are determined by spatial turnover. Geographical distance, current environmental gradients and long-term climatic conditions were complementary predictors of the variation in CBD and PBD of amphibian species. Furthermore, the turnover components between sites from different regions and between sites within the stable region were greater than between sites within the unstable region. On the other hand, the proportion of beta-diversity due to species richness difference for both CBD and PBD was higher between sites in the unstable region than between sites in the stable region. The high turnover components from CBD and PBD between sites in unstable <i>vs</i> stable regions suggest that these distinct regions have different biogeographic histories. Sites in the stable region shared distinct clades that might have led to greater diversity, whereas sites in the unstable region shared close relatives. Taken together, these results indicate that speciation, environmental filtering and limited dispersal are complementary drivers of beta-diversity of amphibian assemblages in the Brazilian Atlantic Forest.</p></div

Standardized effect size (SES) values for phylogenetic beta diversity (PBD, A = UniFrac_Total, B = UniFrac_Turn and C = UniFrac_PD) components among 44 sites in Brazilian Atlantic Forest.

<p>Values between dashed lines indicate that PBD components have no difference with respect to null expectation. Symbol colors indicate the region where the sites occur in the southern range of Brazilian Atlantic Forest. Black circles indicate SES between sites within stable region (Quaternary Climatic Stability). Gray circles indicates SES between sites within unstable region (Quaternary Climatic Oscillations). White circles indicate SES between unstable and stable sites (different regions).</p

Partition of the variance of Compositional Beta Diversity (CBD, β_jac, β_jtu and β_jne) and Phylogenetic Beta Diversity (PBD, UniFrac_Total, UniFrac_Turn and UniFrac_PD) components explained by geographical distance (Space), current environmental gradients (Environ) and long-term climatic conditions (refugia) for 44 sites in the southern range of Brazilian Atlantic Forest.

<p>Res  =  unexplained variance. “-”  =  variation explained <0.</p

Distribution of the10% highest values of annual precipitation for the current time, the two last glacial maximum period (LGM), and the intersection of the three maps.

<p>Symbols (in the intersection map) indicate the 44 sites in the southern range of Brazilian Atlantic Forest. Dark shading indicates stable regions. White circles represent sites in an unstable region (Quaternary Climatic Oscillations). White triangles represent sites in a stable region (Quaternary Climatic Stability). Abbreviations of each site as in Appendix S1 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109642#pone.0109642.s002" target="_blank">File S1</a>.</p

Statistical values of fit, power and explanation of path models for the residual connectance and proportion of monophages.

<p>TLI: Tucker-Lewis Fit Index; CFI: Comparative Fit Index; RMSEA: Root Mean Square Error of Approximation. Statistical power was calculated using the approach by MacCallum et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115606#pone.0115606.ref032" target="_blank">32</a>].</p><p>Statistical values of fit, power and explanation of path models for the residual connectance and proportion of monophages.</p

Path analyses of residual connectance in plant-insect networks of (A) all herbivores, (B) endophages, and (C) exophages, explained by land use intensity, proportion of exotic plants, plant taxonomic span, herbivore taxonomic span, and average taxonomic distinctness (AvTD) of plants and of insects.

<p>Numbers on paths between variables are standardized path coefficients (scaled by the standard deviations of the variables). Green arrows represent positive effects and red arrows represent negative effects. The thickness of lines and arrows is proportional to effect size.</p