Frontiers of Biogeography

A map of science based on citation patterns. Adapted from Rosvall & Bergstrom (2008) PNAS, 105, 1118, available from http://www.eigenfactor.org/.

The Amazon drainage basin (Amazonia) contains the largest continuous area of tropical rainforest in the world and is the most species-rich terrestrial ecosystem on Earth. In biogeographical terms, the Amazon rainforest is still somewhat of a mystery, beset by data shortfalls in many taxonomic groups, lacking systematic surveys and faced with the challenge of collecting and collating data over a vast area. Nevertheless, considerable progress has been made over the last 20 years, leading to new insights from diverse fields of study. One of the most exciting developments has been the creation of large international research networks which are collating and synthesizing information from widely scattered permanent botanical plots. Data from these networks and other studies are providing valuable new insights on contemporary biodiversity patterns and processes in Amazonia. Here we review the major findings of these networks and discuss the factors that correlate with and may explain the spatial distribution of Amazonian tree species and the factors that may underpin the emergent patterns of functional traits and diversity across the Amazon Basin.

Despite years of research on small mammal disturbance effects on plant diversity, predicting the direction and magnitude of these effects remains elusive. Models such as the intermediate disturbance hypothesis, the perturbation hypothesis, or the ecosystem engineering hypothesis of small mammal disturbance, show considerable overlap but fail to account for key variable interactions and thus provide mainly post hoc explanations. Recent reviews have emphasized the importance of small mammals to basic and applied ecology. Re‐examining the mechanisms underlying their disturbance effects is thus timely. Here I present the Slope‐Hump Model, which integrates previous models and insights from the literature, and which is capable of predicting the direction and relative magnitude of disturbance effects on plant diversity. These predictions qualitatively match the results of recent meta‐analyses. The model also suggests new patterns and predictions that can stimulate both pure and applied ecology research.

In severe and variable conditions, specialized resource selection strategies should be less frequent because extinction risks increase for species that depend on a single and unstable resource. Psithyrus (Bombus subgenus Psithyrus) are bumblebee parasites that usurp Bombus nests and display inter‐specific variation in the number of hosts they parasitize. Using a phylogenetic comparative framework, we show that Psithyrus species at higher elevations display a higher number of hosts species compared with species restricted to lower elevations. Species inhabiting high elevations also cover a larger temperature range, suggesting that species able to occur in colder conditions may benefit from recruitment from populations occurring in warmer conditions. Our results provide evidence for an ‘altitudinal niche breadth hypothesis’ in parasitic species, showing a decrease in the parasites’ specialization along the elevational gradient, and also suggesting that Rapoport’s rule might apply to Psithyrus.

The opportunity to reflect broadly on the accomplishments, prospects, and reach of a field may present itself relatively infrequently. Each biennial meeting of the International Biogeography Society showcases ideas solicited and developed largely during the preceding year, by individuals or teams from across the breadth of the discipline. Here, we highlight challenges, developments, and opportunities in biogeography from that biennial synthesis. We note the realized and potential impact of rapid data accumulation in several fields, a renaissance for inter-disciplinary research, the importance of recognizing the evolution-ecology continuum across spatial and temporal scales and at different taxonomic, phylogenetic and functional levels, and re-exploration of classical assumptions and hypotheses using new tools. However, advances are taxonomically and geographically biased, key theoretical frameworks await tools to handle, or strategies to simplify, the biological complexity seen in empirical systems. Current threats to biodiversity require unprecedented integration of knowledge and development of predictive capacity that may enable biogeography to unite its descriptive and hypothetico-deductive branches and establish a greater role within and outside academia.