.
The effects of habitat fragmentation on biodiversity are widely debated. Some studies report positive effects, whereas others link habitat fragmentation to biodiversity loss. “Fragmentation per se” refers to habitat fragmentation independently of habitat loss, or when its effect is controlled, and mainly relates to how habitat patches are spatially distributed (i.e. habitat configuration) and how this organization influences biodiversity. Here we evaluated the habitat amount hypothesis, which postulates that habitat cover is the main factor determining species diversity in fragmented landscapes. We analyzed the effects of landscape structure of a tropical dry forest in the Colombian Caribbean region on the taxonomic and (SES) functional richness of medium- to large-bodied mammals. We assessed 256 landscapes along a gradient of forest cover. We calculated landscape composition (forest cover) and configuration metrics (number of patches and edge density) in multiple nested scales. For each landscape, we estimated species richness, forest-dependent species richness, non-forest-dependent species richness, and the standardized effect size of functional richness. We evaluated the effects of landscape structure using AICc-based model comparison and model averaging. We found that species richness was positively affected by edge density, negatively affected by the number of patches, and moderately positively affected by forest cover. We also found that forest-dependent species richness was positively related to forest cover, whereas non-forest-dependent species richness showed a positive effect of edge density. We also detected a moderate negative effect of the number of patches on the standardized effect size of functional richness. These results indicate that the habitat amount hypothesis is not fully supported and suggest that conservation strategies should prioritize preserving and increasing the total amount of habitat, while also considering landscape configuration in tropical dry forest of the Colombian Caribbean.
Understanding the forces modulating the intraspecific correspondence between trophic niche and functional morphology is key to predicting how species may respond to climate change. Despite a strong diet–morphology correspondence being a common assumption of niche models, we still know little about how functional morphology predicts trophic niche within species. Here, we found that the relatively high and temporally consistent individual trophic specialization in Urotrygon rogersi was not driven by body size and sex. On the contrary, jaw shape and function were affected by sex and locality. These morphological changes occurred along the Z-axis, which underscores the importance of quantifying three-dimensional phenotypic variation within species. These morphofunctional differences could be driven by evolutionary and/or developmental constraints or represent advantages for both reproductive processes and the processing of prey items found in different substrates. Contrary to the diet-morphology correspondence found in fish species from species-poor communities and environments with relatively predictable prey dynamics, our results support theoretical expectations and findings of recent experimental studies suggesting that interindividual differences in digestive performance or behavior might have a more significant role than trophic morphology in driving patterns of intraspecific trophic variation in environments with high variability in prey dynamics and species-rich communities.
Tropical dry forests host essential mutualistic interactions between bats and plants, yet the intense fragmentation of these ecosystems threatens the persistence and structure of floral visitation networks. In Neotropical landscapes, these interactions exhibit high spatial and temporal variability driven by resource availability, plant turnover, and the mobility of bat pollinators. Despite substantial advances, community-level assessments that integrate β-diversity, modularity, and functional traits remain scarce, limiting our understanding of how bat–flower networks respond to habitat fragmentation. Here we show, using interaction-network and β-diversity analyses across eight fragments of Tropical Dry Forest in southwestern Colombia, that the bat–flower network is strongly modular and specialized, with modules primarily shaped by local plant composition. We found that species turnover, especially among plants, is the dominant component of β-diversity in interactions, whereas rewiring among co-occurring species is low and unrelated to geographic distance between fragments. We also demonstrate that four bat species form the cohesive core of the network and that morphological attributes such as body condition and face-skull ratio negatively predict their capacity to connect modules. These findings reveal how plant heterogeneity and bat mobility jointly determine network cohesion and functional redundancy in fragmented landscapes. Understanding these mechanisms is crucial for forecasting the resilience of bat–plant mutualisms under increasing anthropogenic pressures in tropical dry forests.
We present a three-parameter, self-similar family of steady, axisymmetric, nonrelativistic solutions that unifies the morphology, kinematics, and viscous transport of accretion–ejection flows. The triplet (α ,β ,γ ) governs the radial power-law indices of angular velocity, density, and kinematic viscosity, respectively. In the inviscid limit, the geometric index α continuously organizes the flow topology—from flared, toroidal envelopes ( α <2 ) through the cylindrical limit ( α =2 ) to collimated, jet-like funnels ( α>2 )—while the stratification index β controls mass loading and helical pitch. Introducing a scale-free viscosity ν (r)∝ r^γ preserves separability and yields an analytic viscous correction ∝ r^γ -1 to the meridional velocities, with amplitude set by a coupling V_γ . This framework provides closed-form expressions for velocity fields, streamlines, and stream surfaces, enabling quantitative morphology diagnostics such as the opening-angle profile ψ (θ ) and contour-based RMSE for direct comparison with simulations or observations. The resulting (α ,β ,γ ) atlas defines a transparent analytic baseline for global HD/GRMHD models, clarifies how viscosity tilts self-similar stream surfaces, and offers benchmark solutions for reduced or physics-informed neural network surrogates.
In this work we study the differentiability for the Sobolev norm of W^k,1(M) in the sense of Gâteaux , where (M, g) is an arbitrary closed Riemannian manifold.
