Macrosystem community assembly patterns are predicted by foundation tree species genetic connectivity and environment across the American Southwest

Macrosystems ecology is an emerging science that aims to integrate traditionally distinct disciplines to predict how hierarchical interacting processes influence the emergence of complex patterns across local to regional and global scales. Despite increased focus on cross-scale relationships and cross-disciplinary integration, few macroecology studies incorporate genetic-based processes. Here we used a community genetics approach to investigate the pattern-process relationships underlying the emergence of macroscale biodiversity patterns. We tested the hypothesis that environmental variation, geography, and genetic connectivity in a foundation tree species differentially predict associated community assembly patterns from local to continental scales. Using genome-wide SNP data, we assessed genetic connectivity as a function of genetic similarity and structure in Fremont cottonwood (Populus fremontii) across its distribution throughout the southwestern US and México. For the same trees, we measured community composition, diversity, and abundance of leaf modifying arthropods and sequenced targeted amplicons of twig fungal endophytes. Five key findings emerged. (1) We identified three primary and six secondary population genetic groups within P. fremontii, which occupy distinct climate niches. (2) Both the leaf modifying arthropod and fungal endophyte communities were significantly differentiated across host tree ecotypes, with genetic distance among sampling locations explaining 13-17% of respective macroscale community structure. (3) For arthropods, environmental distance was the strongest driver of community similarity. (4) Conversely, host genetic connectivity was the most important contributor to macroscale endophyte community structure, with no significant contribution of environmental distance. (5) Furthermore, we observed a shift in the strength of interspecific relationships, with host genetics most strongly influencing associated communities at the intermediate population scale. Our findings suggest that genetic connectivity and environmental variation play integrated roles in macroscale community assembly, and their relative importance changes with scale. Thus, conservation genetic management of the diversity harbored within foundation species is vital for sustaining associated regional biodiversity.

Últimos refúgios da onça-parda (Puma concolor) no Brasil: áreas prioritárias para a conservação sob a perspectiva da modelagem de distribuição geográfica

A modelagem de distribuição geográfica de espécies é uma importante ferramenta da biogeografia que atende ações conservacionistas ou permite abordagens teóricas sobre a distribuição das espécies. No presente estudo, modelamos a distribuição geográfica da onça-parda (Puma concolor) no Brasil através de quatro algoritmos (Environmental Distance, GARP, Maximum Entropy, BioClim). Os dados de ocorrência da onça-parda foram obtidos a partir da plataforma speciesLink e mediante revisão de literatura. Foram selecionadas as variáveis bioclimáticas disponíveis na homepage do WorldClim (www.worldclim.com). Ao todo, foram obtidos 280 registros de onça-parda no Brasil. Os modelos gerados indicam que a Caatinga, Pantanal, Mata Atlântica (ao norte do rio São Francisco) e Pampa representam os biomas com menor adequabilidade ambiental. Em contrapartida, a porção de Mata Atlântica localizada na região sudeste sob influência da Serra do Mar e limítrofe ao Cerrado, representa uma das áreas com maior probabilidade de abrigar populações de Puma concolor. Cerrado e Amazônia também apresentaram média e alta adequabilidade ambiental. Essas informações indicam a necessidade do estabelecimento de novas áreas protegidas onde a probabilidade de ocorrência foi inferior ao esperado. Adicionalmente, medidas que minimizem os impactos da caça e aumentem a conectividade da paisagem devem ser fortalecidas no sentido de assegurar a persistência dessas populações em médio e longo prazo.

The effect of navigation method and visual display on distance perception in a large-scale virtual building

Immersive virtual reality (VR) technology has become a popular method for fundamental and applied spatial cognition research. One challenge researchers face is emulating walking in a large-scale virtual space although the user is in fact in a small physical space. To address this, a variety of movement interfaces in VR have been proposed, from traditional joysticks to teleportation and omnidirectional treadmills. These movement methods tap into different mental processes of spatial learning during navigation, but their impacts on distance perception remain unclear. In this paper, we investigated the role of visual display, proprioception, and optic flow on distance perception in a large-scale building by manipulating four different movement methods. Eighty participants either walked in a real building, or moved through its virtual replica using one of three movement methods: VR-treadmill, VR-touchpad, and VR-teleportation. Results revealed that, first, visual display played a major role in both perceived and traversed distance estimates but did not impact environmental distance estimates. Second, proprioception and optic flow did not impact the overall accuracy of distance perception, but having only an intermittent optic flow (in the VR-teleportation movement method) impaired the precision of traversed distance estimates. In conclusion, movement method plays a significant role in distance perception but does not impact the configurational knowledge learned in a large-scale real and virtual building, and the VR-touchpad movement method provides an effective interface for navigation in VR.

Review and performance evaluation of trait-based between-community dissimilarity measures

1. In the recent years a variety of indices have been proposed with the aim of quantifying functional dissimilarity between communities. These indices follow different approaches to account for between-species similarities in the calculation of community dissimilarity, yet they all have been proposed as straightforward tools. 2. In this paper we reviewed the trait-based dissimilarity indices available in the literature, contrasted the approaches they follow, and evaluated their performance in terms of correlation with an underlying environmental gradient using individual-based community simulations with different gradient lengths. We tested how strongly dissimilarities calculated by different indices correlate with environmental distances. Using random forest models we tested the importance of gradient length, the choice of data type (abundance vs. presence/absence), the transformation of between-species similarities (linear vs. exponential), and the dissimilarity index in the predicting correlation value. 3. We found that many indices behave very similarly and reach high correlation with environmental distances. There were only a few indices (e.g. Rao's DQ, and representatives of the nearest neighbour approach) which performed regularly poorer than the others. By far the strongest determinant of correlation with environmental distance was the gradient length, followed by the data type. The dissimilarity index and the transformation method seemed not crucial decisions when correlation with an underlying gradient is to be maximized. 4. Synthesis: We provide a framework of functional dissimilarity indices and discuss the approaches they follow. Although, these indices are formulated in different ways and follow different approaches, most of them perform similarly well. At the same time, sample properties (e.g. gradient length) determine the correlation between trait-based dissimilarity and environmental distance more fundamentally.

Distribution of Foliicolous Lichen Strigula and Genetic Structure of S. multiformis on Jeju Island, South Korea

Strigula is a pantropic foliicolous lichen living on the leaf surfaces of evergreen broadleaf plants. In South Korea, Strigula is the only genus of foliicolous lichen recorded from Jeju Island. Several Strigula species have been recorded, but the ecology of Strigula in South Korea has been largely unexplored. This study examined the distribution and genetic structure of Strigula on Jeju Island. The distribution was surveyed and the influence of environmental factors (e.g., elevation, forest availability, and bioclimate) on the distribution was analyzed using a species distribution modeling analysis. In addition, the genetic variations and differentiation of Strigula multiformis populations were analyzed using two nuclear ribosomal regions. The distribution of Strigula was largely restricted to a small portion of forest on Jeju Island, and the forest availability was the most important factor in the prediction of potential habitats. The genetic diversity and differentiation of the S. multiformis population were found to be high and were divided according to geography. On the other hand, geographic and environmental distance did not explain the population differentiation. Distribution and population genetic analysis suggested that the available habitat and genetic exchange of Strigula on Jeju Island are limited by the lack of available forest in the lowlands.

Differences among regions in environmental predictors of primate community similarity affect conclusions about community assembly

Understanding why ecological communities contain the species they do is a long-standing question in ecology. Two common mechanisms that affect the species found within communities are dispersal limitation and environmental filtering. Correctly identifying the relative influences of these mechanisms has important consequences for our understanding of community assembly. Here variable selection was used to identify the environmental variables that best predict tropical forest primate community similarity in four biogeographic regions: the Neotropics, Afrotropics, Madagascar and the island of Borneo in South-East Asia. The environmental variables included net primary productivity and altitude, as well as multiple temperature, precipitation and topsoil variables. Using the best environmental variables in each region, Mantel and partial Mantel tests were used to reanalyse data from a previously published study. The proportion of variance explained increased for each region. Despite increases, much of the variation remained unexplained for all regions (R2: Africa = 0.45, South America = 0.16, Madagascar = 0.28, Borneo = 0.10), likely due to different evolutionary and biogeographic histories within each region. Nonetheless, substantial variation among regions in the environmental variables that best predicted primate community similarity were documented. For example, none of the 14 environmental variables was included for all four regions, yet each variable was included for at least one region. Contrary to prior results, environmental filtering was an important assembly mechanism for primate communities in tropical forests worldwide. Geographic distance more strongly predicted African and South American communities whereas environmental distance more strongly predicted Malagasy and Bornean communities. These results suggest that dispersal limitation structures primate communities more strongly than environmental filtering in Africa and in South America whereas environmental filtering structures primate communities more strongly than dispersal limitation in Madagascar and Borneo. For communities defined by genera, environmental distance more strongly predicted primate communities than geographic distance in all four regions, which suggests that environmental filtering is a more influential assembly mechanism at the genus level. Therefore, a more nuanced consideration of environmental variables affects conclusions about the influences of environmental filtering and dispersal limitation on primate community structure.