Expanding the Distribution of Prosthechea jauana (Orchidaceae) in the Pantepui and Highlighting the Urgent Need for Conservation Strategies in the Region in Face of Climate Change

Prosthechea jauana has been recognized as an orchid species endemic to the Venezuelan tepui. The first record of P. jauana in Brazil is presented here, also from a tepui in the Southern phytogeographical district of Pantepui in the Serra do Aracá, at the northern border of the Amazonas state. A detailed morphological description and images of the specimen are presented, as well as an updated distribution map, preliminary conservation status assessment, and taxonomic notes about the species. In addition, we provide species' distribution models for P. jauana based on current and future bioclimatic data. Future projections suggest that the geographic distribution of P. jauana will likely be severely affected, with ~79% of its suitable habitat being reduced by 2041-2060 and ~92% by 2061-2080. Prosthechea jauana could represent a flag species and an example of how climate change may affect the endemic Pantepui flora.

Phylogenetic diversity and structure in moist and dry upland forests in the semi-arid region of Brazil

Understanding the factors influencing variation in the diversity and structure of rich biological communities (e.g., Neotropical upland forests) is essential in the context of climate change. In this study, we examine how environmental filters (temperature, precipitation, and elevation) and distinct habitats (moist upland forests - MUF and dry upland forests - DHF) influence the phylogenetic diversity and structure of 54 tree communities (28 MHF and 26 DHF). We used the standardized effect size (ses) of the metrics phylogenetic diversity (ses.PD), mean pairwise distance (ses.MPD), and mean nearest neighbor distance (ses.MNTD) to quantify changes in tree community diversity and structure. Then, we assessed the relationships of the phylogenetic metrics with the environmental filters as predictors using generalized linear models (GLMs). Our results indicate that increasing temperature negatively affects the phylogenetic indices analyzed, leading to less diverse and more clustered communities. In contrast, increasing precipitation and elevation showed a significant positive relationship with the analyzed indices, directing communities towards greater phylogenetic diversity and random or overdispersed structure. Our findings also reveal that phylogenetic diversity and structure vary with habitat type. For example, while MUFs exhibit higher phylogenetic diversity and random structure, DUFs display lower phylogenetic diversity and clustered structure. In conclusion, our results suggest that the phylogenetic patterns exhibited by upland communities in the semiarid region are strongly related to climatic conditions and the habitat in which they are found. Therefore, if the predicted temperature increases and precipitation decreases in climate change scenarios for the semi-arid region materialize, these communities may face significant biodiversity loss.

OCBIL theory: a new science for old ecosystems

This paper is an introduction to the special issue of the Biological Journal of the Linnean Society entitled OCBIL theory: a new science for old ecosystems. Firstly, we elaborate on the origins and development of OCBIL theory, which argues that landscape age, climatic buffering and soil fertility are key environmental dimensions shaping ecological and evolutionary processes across different scales. We then consider the 21 contributions made in this special issue in terms of cutting edge advances in the Southern Hemisphere that test, explore and apply aspects of OCBIL theory at the end of its first decade of formal publication. More attempts at refutation are urged, as untested aspects remain controversial. Lastly, a concluding discussion is offered on promising new lines of enquiry to develop the theory further and ensure its global application to pressing conservation issues facing biological and cultural diversity. Although OCBILs are absent or rare in much of the postglacial and periglacial Northern Hemisphere, we demonstrate, in south-west Europe and North America, starting with California, that they are likely to be found, thus extending the implications and applications of OCBIL theory in new directions. We also propose that, in many ways, Noongar Aboriginal cosmology from south-west Australia has developed sophisticated insights about ancient uplands that are precursors to key ideas in OCBIL theory.