The role of environmental filtering, geographic distance and dispersal barriers in shaping the turnover of plant and animal species in Amazonia

Abstract

To determine the effect of rivers, environmental conditions, and isolation by distance on the distribution of species in Amazonia. Location: Brazilian Amazonia. Time period: Current. Major taxa studied: Birds, fishes, bats, ants, termites, butterflies, ferns + lycophytes, gingers and palms. We compiled a unique dataset of biotic and abiotic information from 822 plots spread over the Brazilian Amazon. We evaluated the effects of environment, geographic distance and dispersal barriers (rivers) on assemblage composition of animal and plant taxa using multivariate techniques and distance- and raw-data-based regression approaches. Environmental variables (soil/water), geographic distance, and rivers were associated with the distribution of most taxa. The wide and relatively old Amazon River tended to determine differences in community composition for most biological groups. Despite this association, environment and geographic distance were generally more important than rivers in explaining the changes in species composition. The results from multi-taxa comparisons suggest that variation in community composition in Amazonia reflects both dispersal limitation (isolation by distance or by large rivers) and the adaptation of species to local environmental conditions. Larger and older river barriers influenced the distribution of species. However, in general this effect is weaker than the effects of environmental gradients or geographical distance at broad scales in Amazonia, but the relative importance of each of these processes varies among biological groups.

Assessing Biotic and Abiotic Interactions of Microorganisms in Amazonia through Co-Occurrence Networks and DNA Metabarcoding

“…Due to the high diversity and turnover in Amazonia, we could expect a neutral community assembly due to dispersion limitation [72,73] and a high redundancy of functional traits in the microbial community [74], which would result in less connected co-occurrence networks. However, here, we show that Amazonian microorganism communities form highly interconnected co-occurrence and co-exclusion networks when compared to those of other regions [12,75].…”

Assessing biotic and abiotic interactions of micro-organisms in Amazonia through co-occurrence networks and DNA metabarcoding

“…Due to the high diversity and turnover in Amazonia we could expected a neutral community assembly due to dispersion limitation [72,73] and a high redundancy of functional traits in the microbial community [74], which would result in less connected co-occurrence networks. However, here we show that Amazonian micro-organism communities form highly interconnected co-occurrence and co-exclusion networks when compared to those of other regions [75,12].…”

Niche evolution of the Neotropical tree genusOtobain the context of global biogeography of the nutmeg family, Myristicaceae

“…Fluctuating landscapes and fluvial barriers at the time may have fragmented populations, promoting divergence between those populations and securing species boundaries upon secondary contact. Supporting this, large rivers are important barriers to dispersal and gene flow in tropical birds (Hayes and Sewlal, 2004;Burney and Brumfield, 2009;Fernandes et al, 2014;Oliveira et al, 2017;Sandoval-H et al, 2017); by extension, they should also be significant barriers to the plants that they disperse as well (Nazareno et al, 2017;Dambros et al, 2020).…”