Climate mediates the effects of disturbance on ant assemblage structure

Many studies have focused on the impacts of climate change on biological assemblages, yet little is known about howclimate interacts with other major anthropogenic influences on biodiversity, such as habitat disturbance. Using a unique global database of 1128 local ant assemblages, we examined whether climate mediates the effects of habitat disturbance on assemblage structure at a global scale. Species richness and evenness were associated positively with temperature, and negatively with disturbance. However, the interaction among temperature, precipitation and disturbance shaped species richness and evenness. The effectwas manifested through a failure of species richness to increase substantially with temperature in transformed habitats at low precipitation. At low precipitation levels, evenness increased with temperature in undisturbed sites, peaked at medium temperatures in disturbed sites and remained low in transformed sites. In warmer climates with lower rainfall, the effects of increasing disturbance on species richness and evenness were akin to decreases in temperature of up to 98C. Anthropogenic disturbance and ongoing climate change may interact in complicated ways to shape the structure of assemblages, with hot, arid environments likely to be at greatest risk. © 2015 The Author(s) Published by the Royal Society. All rights reserved

Diversity and species composition of ants in arid and semi-arid regions of Iran

The general objective of this dissertation was to broaden the understanding of the impact of environmental and spatial factors on diversity and assemblage organization of ants in arid and semi-arid regions in Iran. My thesis included four stages: The first step included faunistical and taxonomical studies on the poorly known ant fauna of Iran. In the second step, I described and analyzed the diversity pattern of ants along a latitudinal gradient and in two main biomes of Iranian arid regions: steppe and desert. In the third step, ant diversity and composition was analyzed by a hierarchical partitioning approach, from a conservational perspective. In the fourth step, I analyzed the impact of environmental and spatial factors on ant species richness and species composition across the latitudinal gradient and in the Central Persian desert ecoregion. My results revealed that alpha species richness increased along the gradient, but beta diversity did not follow any specific trend. Multiscale analysis of the data showed a constant increase in species richness and diversity of ants across fine-to-broad scales. The steppe biome had higher numbers of species than the desert biome, but only at the highest scale. The two biomes represented two distinctive ant species compositions. Further analyses of hierarchical partitioning showed that the WWF’s ecoregions correctly represent the biogeographic components of ants in Iran and are appropriate scale for conserving of ant diversity. In one case, the boundaries of these four compositions, however, showed a deviation from the depicted boundaries by the WWF’s map, suggesting that the ecoregional boundaries should be considered as a subject for further tests of their robustness. Contemporary climate factors such as rainfall and temperature range and productivity have large influence on ant diversity and assemblage organizations

Global Habitat Suitability and Ecological Niche Separation in the Phylum Placozoa

<div><p>The enigmatic placozoans, which hold a key position in the metazoan Tree of Life, have attracted substantial attention in many areas of biological and biomedical research. While placozoans have become an emerging model system, their ecology and particularly biogeography remain widely unknown. In this study, we use modelling approaches to explore habitat preferences, and distribution pattern of the placozoans phylum. We provide hypotheses for discrete ecological niche separation between genetic placozoan lineages, which may also help to understand biogeography patterns in other small marine invertebrates. We, here, used maximum entropy modelling to predict placozoan distribution using 20 environmental grids of 9.2 km² resolution. In addition, we used recently developed metrics of niche overlap to compare habitat suitability models of three genetic clades. The predicted distributions range from 55°N to 44°S and are restricted to regions of intermediate to warm sea surface temperatures. High concentrations of salinity and low nutrient concentrations appear as secondary factors. Tests of niche equivalency reveal the largest differences between placozoan clades I and III. Interestingly, the genetically well-separated clades I and V appear to be ecologically very similar. Our habitat suitability models predict a wider latitudinal distribution for placozoans, than currently described, especially in the northern hemisphere. With respect to biogeography modelling, placozoans show patterns somewhere between higher metazoan taxa and marine microorganisms, with the first group usually showing complex biogeographies and the second usually showing “no biogeography.”</p></div

List of environmental variables used in this study for modelling the global distribution of the phylum Placozoa.

<p>See Tyberghein <i>et al</i> [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0140162#pone.0140162.ref019" target="_blank">19</a>] for full details of layers.</p

Global distribution of placozoans according to Eitel et al. [7] and unpublished data (see the text).

<p>Three red, green, and blue colors represent three investigated clades, clade I, III and V, respectively. Note that the number of localities on the map does not add to 79, because of points overlying in many localities.</p

Global maps showing predicted habitat suitability for placozoans based on a 10^th percentile training presence threshold (see text).

<p>Three red, green, and blue colors represent the three placozoan clades, clade I, III and V, respectively. Records with black colors belong to other clades. Yellow represents regions where at least two clades overlap.</p

The phylogram of placozoan haplotypes (species) based on 16S sequences and Bayesian inference (Modified after Eitel et al [7]).

<p>The three clades highlighted in red have been investigated this study.</p

Test AUC values for MaxEnt models of the global distribution for three placozoan clades based on single variable analysis.

<p>Variable values in bold indicate those chosen for final multi-layer models after taking the collinearity values into account. Each column (data sets) uses five different sets of variables.</p