Individual processes shaping geographical patterns of biodiversity are increasingly understood, but their complex interactions on broad spatial and temporal scales remain beyond the reach of ...analytical models and traditional experiments. To meet this challenge, we built a spatially explicit, mechanistic simulation model implementing adaptation, range shifts, fragmentation, speciation, dispersal, competition, and extinction, driven by modeled climates of the past 800,000 years in South America. Experimental topographic smoothing confirmed the impact of climate heterogeneity on diversification. The simulations identified regions and episodes of speciation (cradles), persistence (museums), and extinction (graves). Although the simulations had no target pattern and were not parameterized with empirical data, emerging richness maps closely resembled contemporary maps for major taxa, confirming powerful roles for evolution and diversification driven by topography and climate.
The idea that simplicity of explanation is important in science is as old as science itself. However, scientists often assume that parsimonious theories, hypothesis and models are more plausible than ...complex ones, forgetting that there is no empirical evidence to connect parsimony with credibility. The justification for the parsimony principle is strongly dependent on philosophical and statistical inference. Parsimony may have a true epistemic value in the evaluation of correlative and predictive models, as simpler models are less prone to overfitting. However, when natural mechanisms are explicitly modelled to represent the causes of biological phenomena, the application of the parsimony principle to judge the plausibility of mechanistic models would entail an unsupported belief that nature is simple. Here, we discuss the challenges we face in justifying, measuring, and assessing the trade‐off between simplicity and complexity in ecological and evolutionary studies. We conclude that invoking the parsimony principle in ecology and evolution is particularly important in model‐building programs in which models are viewed primarily as an operational tool to make predictions (an instrumentalist view) and in which data play a prominent role in deciding the structure of the model. However, theoretical advances in ecology and evolutionary biology may be derailed by the use of the parsimony principle to judge explanatory mechanistic models that are designed to understand complex natural phenomena. We advocate a parsimonious use of the parsimony principle.
A contemporary goal in ecology is to determine the ecological and evolutionary processes that generate recurring structural patterns in mutualistic networks. One of the great challenges is testing ...the capacity of neutral processes to replicate observed patterns in ecological networks, since the original formulation of the neutral theory lacks trophic interactions. Here, we develop a stochastic-simulation neutral model adding trophic interactions to the neutral theory of biodiversity. Without invoking ecological differences among individuals of different species, and assuming that ecological interactions emerge randomly, we demonstrate that a spatially explicit multitrophic neutral model is able to capture the recurrent structural patterns of mutualistic networks (i.e., degree distribution, connectance, nestedness, and phylogenetic signal of species interactions). Nonrandom species distribution, caused by probabilistic events of migration and speciation, create nonrandom network patterns. These findings have broad implications for the interpretation of niche-based processes as drivers of ecological networks, as well as for the integration of network structures with demographic stochasticity.
Landscape dynamics are widely thought to govern the tempo and mode of continental radiations, yet the effects of river network rearrangements on dispersal and lineage diversification remain poorly ...understood. We integrated an unprecedented occurrence dataset of 4,967 species with a newly compiled, time-calibrated phylogeny of South American freshwater fishes-the most species-rich continental vertebrate fauna on Earth-to track the evolutionary processes associated with hydrogeographic events over 100 Ma. Net lineage diversification was heterogeneous through time, across space, and among clades. Five abrupt shifts in net diversification rates occurred during the Paleogene and Miocene (between 30 and 7 Ma) in association with major landscape evolution events. Net diversification accelerated from the Miocene to the Recent (c. 20 to 0 Ma), with Western Amazonia having the highest rates of in situ diversification, which led to it being an important source of species dispersing to other regions. All regional biotic interchanges were associated with documented hydrogeographic events and the formation of biogeographic corridors, including the Early Miocene (c. 23 to 16 Ma) uplift of the Serra do Mar and Serra da Mantiqueira and the Late Miocene (c. 10 Ma) uplift of the Northern Andes and associated formation of the modern transcontinental Amazon River. The combination of high diversification rates and extensive biotic interchange associated with Western Amazonia yielded its extraordinary contemporary richness and phylogenetic endemism. Our results support the hypothesis that landscape dynamics, which shaped the history of drainage basin connections, strongly affected the assembly and diversification of basin-wide fish faunas.
Aim
We aimed to dissect the spatial variation of the direct and indirect effects of climate and productivity on global species richness of terrestrial tetrapods.
Location
Global.
Time period
Present.
...Major taxa studied
Terrestrial tetrapods.
Methods
We used a geographically weighted path analysis to estimate and map the direct and indirect effects of temperature, precipitation and primary productivity on species richness of terrestrial tetrapods across the globe.
Results
We found that all relationships shift in magnitude, and even in direction, among taxonomic groups, geographical regions and connecting paths. Direct effects of temperature and precipitation are generally stronger than both indirect effects mediated by productivity and direct effects of productivity.
Main conclusions
Richness gradients seem to be driven primarily by effects of climate on organismal physiological limits and metabolic rates rather than by the amount of productive energy. Reptiles have the most distinct relationships across tetrapods, with a clear latitudinal pattern in the importance of temperature versus water.
Explaining how heterogeneous spatial patterns of species diversity emerge is one of the most fascinating questions of biogeography. One of the great challenges is revealing the mechanistic effect of ...environmental variables on diversity. Correlative analyses indicate that productivity is associated with taxonomic, phylogenetic, and functional diversity of communities. Surprisingly, no unifying body of theory have been developed to understand the mechanism by which spatial variation of productivity affects the fundamental processes of biodiversity. Based on widely discussed verbal models in ecology about the effect of productivity on species diversity, we developed a spatially explicit neutral model that incorporates the effect of primary productivity on community size and confronted our model's predictions with observed patterns of species richness and evolutionary history of Australian terrestrial mammals. The imposed restrictions on community size create larger populations in areas of high productivity, which increases community turnover and local speciation, and reduces extinction. The effect of productivity on community size modeled in our study causes higher accumulation of species diversity in productive regions even in the absence of niche‐based processes. However, such a simple model is not capable of reproducing spatial patterns of mammal evolutionary history in Australia, implying that more complex evolutionary mechanisms are involved. Our study demonstrates that the overall patterns of species richness can be directly explained by changes in community sizes along productivity gradients, supporting a major role of processes associated with energetic constraints in shaping diversity patterns.
Abstract
Aim
To evaluate the effect of biogeographical history on climatic niche diversification.
Location
Simulated clades evolving in South America.
Methods
We modelled species evolution under ...neutral community dynamics and purposely assumed that climatic niche is an emergent property of species. This assumption allows us to better understand whether phylogenetic niche conservatism could be observed when climatic niche is only constrained by biogeographical processes of dispersal and speciation. We varied speciation and dispersal probability, calculating phylogenetic signal of niche overlap and distance between niche centroids for each emergent artificial biota. We then compared the phylogenetic signal of our model with the expectation of climatic niche evolution under Brownian motion (BM).
Results
We found that phylogenetic signal of climatic niche in the spatially explicit neutral model is usually higher than expected by chance, but lower than expected by BM evolution. Because simulated climatic niches have lower phylogenetic signal than expected by BM evolution, standard ecological and evolutionary interpretation would suggest that climatic niche evolved with little variation over time caused by strong evolutionary constraints. However, our model assumes that climatic niche does not evolve by adaptive forces and is only a consequence of stochastic dispersal and speciation over space and time.
Main conclusions
Our study reinforces the strong imprints of biogeographical processes on climatic niche evolution, even when no adaptive forces are driving niche diversification. Therefore, although testing phylogenetic signal is the most common approach in studies evaluating phylogenetic patterns in climatic niche conservatism, our results reinforce previous claims that these patterns alone are not capable of distinguishing the possible effect of space in the retention of climatic niche. Biogeographical processes alone can leave imprints in patterns of climatic niche overlap between related species. A careful evaluation of macroevolutionary models underlying phylogenetic patterns of niche variation among species is important to avoid pitfalls related to interpretation of mechanisms of niche diversification.
Identifying deforested areas with high potential for natural forest recovery can be used as an aid for ecological restoration projects at large‐scale. However, accurate predictions that infer the ...resilience (i.e. recovery rate after deforestation) and stability (i.e. the ability of the ecosystem to maintain its functions) of early second‐growth forests are scarce at a regional scale. Here, we investigated the effect of climate, soil and topography on the resilience and stability of 165 early second‐growth forests throughout the Brazilian Atlantic Forest. We also built prediction maps of potential resilience and stability to identify where reforestation could be optimized in the early stages of forest succession. We assessed the resilience and stability through an interannual plant primary productivity time series using a normalized difference vegetation index. Our analysis reveals that resilience was mainly associated with isothermality (i.e. diurnal temperature oscillation relative to the annual temperature oscillation) and precipitation of the warmest quarter. In turn, stability was mainly associated with the probability of bedrock occurrence, annual precipitation and precipitation seasonality. The prediction maps show a spatial pattern in which potential resilience and stability increase from north to south of the Atlantic Forest. Forest restoration can be optimized in regions with high potential resilience and stability, such as an isolated area on the north coast in the Bahia state and the southern region. However, restoration may require active practices and management in regions with low potential for both ecosystem properties, such as the north inland in the Bahia and Minas Gerais states. This ecosystemic approach can help achieve Atlantic Forest restoration commitments.
Identifying deforested areas with high potential for natural forest recovery can be used as an aid for ecological restoration projects at large‐scale. However, accurate predictions that infer the resilience and stability of early second‐growth forests are scarce at a regional scale. Here, we investigated the effect of climate, soil and topography on the resilience and stability of 165 early second‐growth forests throughout the Brazilian Atlantic Forest. We also built prediction maps of potential resilience and stability to identify where reforestation could be optimized in the early stages of forest succession. Furthermore, we assessed the resilience and stability through an interannual plant primary productivity time series using a normalized difference vegetation index.
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