13 pages, 5 figures, 1 table, supporting information https://doi.org/10.1111/geb.13956.-- Data Availability Statement: All data and code are deposited in Zenodo (https://zenodo.org/records/14479422), Aim: We assess the role of spatial distance and depth difference in shaping beta diversity patterns across abyssal seascape regions. We measured the decrease of faunistic similarity across the northeast Pacific seafloor, to test whether species turnover rates differ between deep and shallow-abyssal biogeographical provinces and whether these patterns vary across functionally or taxonomically different biotic groups. Location: Abyssal NE Pacific Ocean. Time Period: Present. Major Taxa Studied: Benthic Invertebrates (13 Phyla). Methods: We examined the relationship between compositional similarity (β) and spatial distance, distance-decay, in benthic megafauna communities (animals > 10 mm) based on seabed imagery data (> 36,000 specimens in 402 species) collected across 28 abyssal seascape locations spanning a total of 4000 km. By comparing the statistical parameters (intercept and slope) of decay curves, we investigated whether distance-decay patterns differ (i) between communities above and below the carbonate compensation depth (~4400 m at N Pacific), (ii) among taxa with contrasting life-habits and (ii) across dominant phyla. Results: We found steeper species turnover rates in communities below 4400 m and variations in distance-decay patterns across biotic groups. Turnover was higher for taxa facultatively growing on hard-substratum patches (polymetallic nodules) than for sediment-dwelling or swimming organisms. Cnidaria and Porifera, respectively, depicted the most and least evident spatial decays in community similarity. Main Conclusions: We demonstrate the utility of combining seabed imaging with distance-decay modelling to capture macroecological patterns in poorly explored deep-sea ecosystems. Our results suggest that chemical boundaries associated with depth are a very relevant niche-sorting mechanism driving large-scale beta-diversity patterns and an association between species life-habits and dispersal limitation in abyssal seabed communities. These findings have important implications for biodiversity conservation plans in the deep ocean, amid the need to protect vast abyssal seascape ecosystems from globally rising human threats, This work was supported by the UK Natural Environment Research Council funded Seabed Mining and Resilience to Experimental impact (SMARTEX) project (grant reference NE/T003537/1). Novel methods for distance- decay analyses used in this study were developed through grant no. PID2020-112935GB-I00/AEI/10.13039/501100011033 to A.B. and C.G.R. D.J.A. received funding from UC Santa Barbara's Benioff Ocean Science Laboratory. J.M.D. was funded by UK Natural Environment Research Council's Climate Linked Atlantic Sector Science project (NE-R015953/1) and AtlantiS project (NE/Y005589/1). A.M.S. was funded by laCaixa Foundation (Fellowship Code LCF/BQ/DI21/11860043). [...] With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

1. The herbivorous flea beetles (Chrysomelidae: Alticini) have evolved a masquerading strategy by hiding among their own feeding damage. Similarities between beetle bodies and their feeding damage may act as a defence that reduces detection by visual predators.

2. We analyse the evolutionary origin of flea beetles' camouflage using the French fauna (284 species) as a case study. We assess two competing hypotheses: (H1) the type of leaf tissue is the primary determinant of the colour and size of beetle species feeding on them, because each type of leaf tissue may have a tendency to result in a particular type of damage or, (H2) the morphological characteristics of the beetle explain the damage pattern, because beetle species evolve strategies to produce feeding damage that matches its own characteristics.

3. We assessed bipartite networks of feeding interactions (beetle species and host plants). Beetle-host interactions were non-randomly distributed and highly modular, with more than 25% of the network modules showing beetle colour and size distributions significantly different from null expectations.

4. Our results suggest that the evolutionary origin of flea beetles masquerading can be partially explained by both hypotheses. Some host plants seem to restrict feeding damage appearance on their leaves, favouring the survival of specific beetles with matching colour and size (H1). However, in most plant taxa, it is suggested, the existence of beetle-associated constraints exert a selective pressure for the beetle to damage leaves in a particular way, similar to its own colour and size (H2)

Unified models of biological diversity across organizational levels (genes, species, communities) provide key insight into fundamental ecological processes. Theory predicts that the strength of the correlation between species abundance and genetic diversity should be related to community age in closed communities (i.e. abundant species accumulate more genetic diversity over time than rare species). Following this rationale, we hypothesize that historical climatic events are expected to impact assembly processes, hence affecting both the species abundance distribution (SAD) and the species genetic distribution (SGD) in continental communities. Therefore, we predict that, if the congruence between SADs and SGDs depends on community age, then higher congruence would be observed in localities where climate has been more stable since the Last Glacial Maximum (LGM). We tested this prediction using relative abundance and nucleotide diversity (cox1-5′) data from 20 communities of leaf beetles along a latitudinal transect in the Iberian Peninsula. We observed that the congruence between SAD and SGD curves, measured as the correlation between the species' rank orders in both distributions, was significantly related to the change in mean annual temperature since the LGM, but not to current climatic conditions. Our results suggest that, despite the high connectivity of continental communities, historical climatic stability is still a relevant predictor of the congruence between species abundance and genetic diversity. Hence, the degree of congruence between SADs and SGDs could be used as a proxy of community stability, related not only to historical climatic variation but also to any other disrupting factors, including human pressure.

Aim: (i) To assess the dependence between the form of the decrease in biological similarity with distance (distance-decay) and species range size and (ii) to introduce the use of a sigmoidal model, the Gompertz function, as a flexible alternative able to fit distance-decay models under a wide variety of species range sizes.
Location: Applicable worldwide.
Methods: We computed distance-decay curves from simulated communities to assess how the species range sizes shape the functional form of distance-decay patterns (i.e. negative exponential, power-law or sigmoidal [Gompertz] relationships). Simulations were performed using different sample sizes and species detection probabilities. We also used distribution data of South American mammals to explore the relationship between species range size and the distance-decay form in an empirical dataset.
Results: Our simulations showed that the power-law is the best supported model when range sizes tend to be small. An increase in range sizes leads to a negative exponential relationship, taking the shape of a sigmoidal (Gompertz) relationship with the largest range size values. Similar results have been found in the distance-decay pattern of South American mammals. Remarkably, the Gompertz function fits the data reasonably well in all scenarios.
Main conclusions: The functional form of distance-decay patterns depends on a key biogeographical attribute: species range size. This dependence makes it an interesting tool to detect biodiversity threats associated with species range expansion, such as the biotic homogenization of faunas. The Gompertz function is the mathematical model that best accommodates different frequency distributions of species range size and, thus, allows cross-taxa comparison of this biogeographical and ecological pattern.

Modelling how community similarity decays with spatial distance is a key tool for the study of the processes behind community variation (beta diversity). Distance-decay models are computed from pairwise metrics (i.e. community similarity and spatial distance between localities) and hence suffer from pairwise dependence in the data, precluding the use of standard significance tests. Besides, distance-decay patterns are inherently nonlinear because similarity is bounded between 1 and 0. However, the only standard method to assess model significance under pairwise dependency is the Mantel test, which considers a linear model. To allow the use of nonlinear models in the assessment of distance-decay patterns, we introduce here a nonlinear significance test combining a pseudo-R2 statistic with either permutations or block-site resampling with replacement

Distance-decay models fit parametric functions to assess the relationship between similarity and spatial or environmental distance. Despite the widespread use of distance-decay models in ecology and biogeography, no method has been previously developed and validated to assess the significance of differences between the pa-rameters (i.e. intercept and slope) of two distance-decay models. The pairwise autocorrelation of similarity and spatial distance affects the variance of parameter estimates, precluding the use of ordinary t-tests. Here, we provide a test statistic (zdep) for the equality of parameters between two distance-decay models. The test can be applied, independently, to any of the model parameters (i.e. intercept and/or slopes). The zdep statistic accounts for pairwise dependence, thus avoiding biases associated to the inflation of degrees of freedom, and it is based on the estimation of parameters' variance using site-block resampling. To validate the zdep statistic, type I and type II errors were empirically evaluated through a simulation study. We simulated six scenarios (three under the null and three under the alternative hypothesis) of distance-decay relationships using different functions: negative exponential, power-law or Gompertz function. We applied the zdep statistic and computed the proportion of rejections of the null hypothesis for α =0.01, 0.05 and 0.1 in each scenario. As a case-study, we also compared distance-decay parameters across several groups of Iberian vertebrates (cyprinids, frogs, lizards and snakes, bats, rodents and carnivores). In the simulation study, the zdep statistic showed a good approximation of the nominal level (α, type I error) and a good statistical power (1 type II error), the later increasing with sample size, as expected. In Iberian vertebrates, we found significant differences between ectotherms and endotherms, but not within these groups except between cyprinids and other ectotherms. The good performance of the zdep statistic makes it the best option to test for differences in parameters obtained from models fitted from data with pairwise dependence, as distance-decay models. It can also be used beyond distance-decay approaches to compare pa-rameters of any other regression models of pairwise dependent data (as genetic distances, for example).

Distinct biological communities have high conservation value because they harbour species that cannot be preserved elsewhere. However, community uniqueness is scale-dependent: irreplaceability depends on whether community dissimilarity emerges at small or large spatial scales. To assess conservation value, here we integrate phylogenetic endemism with the spatial scaling of phylogenetic uniqueness in terrestrial vertebrates. We show that phylogenetic endemism is the most efficient single criterion to maximise global phylogenetic diversity within the smallest land area. Moreover, the spatial scaling of phylogenetic uniqueness allows distinguishing globally distinct but regionally less unique sites ‘(evolutionary hills)’, from highly irreplaceable sites even at small scales ‘(evolutionary islands)’, which support lower local diversity but host species that are both evolutionarily unique and threatened. This approach provides a non-heuristic and stable baseline to identify high-value biodiversity areas and offers a powerful tool for prioritising conservation efforts to safeguard evolutionary heritage effectively.

Spatial turnover of biological communities is determined by both dispersal and environmental constraints. However, we lack quantitative predictions about how these factors interact and influence turnover across genealogical scales. In this study, we have implemented a predictive framework based on approximate Bayesian computation (ABC) to quantify the signature of dispersal and environmental constraints in community turnover. First, we simulated the distribution of haplotypes, intra-specific lineages and species in biological communities under different strengths of dispersal and environmental constraints. Our simulations show that spatial turnover rate is invariant across genealogical scales when dispersal limitation determines the species ranges. However, when environmental constraint limits species ranges, spatial turnover rates vary across genealogical scales. These simulations were used in an ABC framework to quantify the role of dispersal and environmental constraints in 16 empirical biological communities sampled from local to continental scales, including several groups of insects (both aquatic and terrestrial), molluscs and bats. In seven datasets, the observed genealogical invariance of spatial turnover, assessed with distance–decay curves, suggests a dispersal-limited scenario. In the remaining datasets, the variance in distance–decay curves across genealogical scales was best explained by various combinations of dispersal and environmental constraints. Our study illustrates how modelling spatial turnover at multiple genealogical scales (species and intraspecific lineages) provides relevant insights into the relative role of dispersal and environmental constraints in community turnover.

We assess the role of spatial distance and depth difference in shaping beta diversity patterns across abyssal seascape regions. We measured the decrease of faunistic similarity across the northeast Pacific seafloor, to test whether species turnover rates differ between deep and shallow-abyssal biogeographical provinces and whether these patterns vary across functionally or taxonomically different biotic groups.

Spatial turnover of biological communities is determined by both dispersal and environmental constraints. However, we lack quantitative predictions about how these factors interact and influence turnover across genealogical scales. In this study, we have implemented a predictive framework based on approximate Bayesian computation (ABC) to quantify the signature of dispersal and environmental constraints in community turnover. First, we simulated the distribution of haplotypes, intra‐specific lineages and species in biological communities under different strengths of dispersal and environmental constraints. Our simulations show that spatial turnover rate is invariant across genealogical scales when dispersal limitation determines the species ranges. However, when environmental constraint limits species ranges, spatial turnover rates vary across genealogical scales. These simulations were used in an ABC framework to quantify the role of dispersal and environmental constraints in 16 empirical biological communities sampled from local to continental scales, including several groups of insects (both aquatic and terrestrial), molluscs and bats. In seven datasets, the observed genealogical invariance of spatial turnover, assessed with distance–decay curves, suggests a dispersal‐limited scenario. In the remaining datasets, the variance in distance–decay curves across genealogical scales was best explained by various combinations of dispersal and environmental constraints. Our study illustrates how modelling spatial turnover at multiple genealogical scales (species and intraspecific lineages) provides relevant insights into the relative role of dispersal and environmental constraints in community turnover., Agencia Estatal de Investigación | Ref. CGL2016-76637-P, Agencia Estatal de Investigación | Ref. PID2020-112935GB-I00, Agencia Estatal de Investigación | Ref. PGC2018- 099363-B-I00, Ministerio de Economía y Competitividad | Ref. RYC-2015-18241, Xunta de Galicia