ABSTRACT Aims Data from participatory science projects are widely used to understand species distributions. However, participatory science data often contain biases that can obscure real patterns. We address two sources of sampling bias: location uncertainty of individual records and spatially heterogeneous sampling effort. A variety of data processing and modelling strategies have been used to address these biases, without consensus on their relative effectiveness. We test several strategies using data from iNaturalist, a large repository of participatory science data. Location Twenty‐four amphibian ranges of varying sizes and locations within the continental United States. Method We fit species distribution models with iNaturalist data for 24 amphibian species to compare the effectiveness of strategies intended to improve distribution estimates. We examined three categories of strategies: (1) filtering out records with high location uncertainty, (2) thinning to reduce heterogeneous effort, and (3) observation models that account for heterogeneous effort without removing data. We evaluated the predictive accuracy of each approach using validation data from systematic surveys with constant effort and known locations. Results The strategies we tested generally had little effect on predictive accuracy as measured by AUC, with no consistent pattern across species. Instead, we found that the minimal change in performance was influenced by the species‐specific search process, the distribution of records, and the resolution of the analysis. Main Conclusion None of the strategies we tested consistently improve model performance, but our results provide a foundation for a species‐ and analysis‐specific approach. Further improvement in model performance may require additional information or novel methods.
ABSTRACT Aim Major declines in native biodiversity are occurring globally. Although these patterns are well‐documented in marine and terrestrial ecosystems, large river studies are uncommon, regularly focus on a few freshwater species and often rely on inconsistent methods. By sampling the full fish assemblage in a large river, we evaluated whether (1) downriver reaches are more susceptible to invasion than upriver reaches; (2) habitat specialists differ in their longitudinal river position; and (3) decadal changes are present and, if so, which potential drivers explain them. Location 240 km of the Willamette River, Oregon, USA. Methods We assessed a fish assemblage of 41 native and nonnative fishes along the Willamette River using consistent methods between two decades and explored a synthesis of potential drivers to explain native fish patterns and focus future efforts. Results Our findings revealed a decadal decline in abundance of native fishes that was outpaced by an increase in numbers and richness of nonnative fishes, especially downriver. Biogeographic patterns suggest that the greatest decline for native backwater fishes occurred downriver, whereas the greatest decline for small cold‐stream native fishes was upriver. Sixty percent of individual native species showed evidence of a decline in abundance or apparent occupancy between decades. Cascadian sucker ( Catostomus bondi , part of the mountain sucker complex) had river‐wide declines in both abundance and apparent occupancy. Main Conclusions Our results suggest a transition in the river assemblage, pointing to an emerging ecological shift longitudinally, with spatial structuring differences between upriver and downriver reaches. We show decadal shifts in biodiversity, with warmer temperatures and increasing nonnative fishes being likely drivers for declines in native fishes. Collectively, these spatial and temporal differences in the fish community underscore the need to identify underlying causes of change and conserve native biodiversity.
ABSTRACT Aim Many mammals of the order Carnivora are key ecosystem predators. In the American continent, they have a complex biogeographical history, shaped by processes of colonization and adaptive radiation that have generated a high diversity of lineages. However, under the global biodiversity crisis, this group faces increasing extinction risk, and conservation efforts have focused mainly on species richness while neglecting evolutionary relationships. We aimed to assess the distribution of evolutionary diversity in carnivores of the American continent and its relationship with biological and geographical variables to recognize species and areas with unique evolutionary value. Location American continent. Methods We evaluated 104 carnivore species of the Americas. Using data from public literature, we calculated Evolutionary Distinctiveness (ED), Evolutionarily Distinct and Globally Endangered (EDGE; EDGE2), and Biogeographically weighted Evolutionary Distinctiveness (BED) metrics. In addition, we explored the relationship between evolutionary scores with body size, altitudinal and latitudinal distribution of species, and mapped spatial patterns of richness and evolutionary metrics to identify priority areas for conservation. Results The evolutionary diversity of carnivores was unevenly distributed across regions and taxonomic groups. In terrestrial species, all evolutionary scores decreased with altitude, and only ED followed a unimodal pattern with latitude, concentrating in the tropical belt; in marine species, ED clustered in the temperate zones of the Northern Hemisphere. A positive relationship was detected between body size and ED in marine species, and a negative relationship was observed with BED in terrestrial species and across all carnivores. Spatial patterns of richness were consistent with those of ED, EDGE and EDGE2 scores, but differed from those obtained with BED scores. Main Conclusion Our findings demonstrate the importance of incorporating evolutionary metrics into the prioritization of American carnivores as a means to safeguard their evolutionary history and to optimize conservation planning and resource allocation from a comprehensive perspective.
ABSTRACT Aim Understanding how life history strategies vary among sympatric taxa along environmental gradients is fundamental to predicting biodiversity responses to climate change. We evaluated how mechanistic linkages between life‐history strategies and environmental change operate in montane small mammals (specifically glires and insectivores). We then assessed how these linkages can inform monitoring and management decisions. Location A 2200‐m elevational gradient in the Minshan Mountains, Southwestern China. Methods Based on a 27‐year small mammal abundance dataset (3294 individuals, 46 species) from 219 quadrats along the gradient, we tested three hypothesized drivers of life history evolution (food availability, climatic seasonality, and mortality risk). Using community‐weighted mean (CWM) traits, multivariate ordination, and trait–environment analyses, we assessed the responses of small mammal community‐level life history strategies to elevation and environmental variables. Results Glires responded to food limitation by shifting toward slower life histories with increasing elevation, characterized by reduced fecundity, delayed maturity, and longer gestation length. In contrast, insectivores adopted a faster pace of life in response to greater climatic seasonality, maximizing reproductive output through shorter generation lengths. These contrasting life history patterns were further associated with divergent responses to mortality risk arising from predation and winter constraints. Main Conclusions Our comparative analyses suggest that selection pressures act differently on glires and insectivores, leading to the divergent life history patterns observed along elevational gradients. Future monitoring efforts should target climate‐driven variation in seasonal resource pulses, which in turn may influence the community dynamics of montane small mammals. This is particularly critical for data‐deficient insectivores, given their unique reproductive timing and heightened vulnerability to physiological and energetic limitations.
ABSTRACT Aim The endemic freshwater fish fauna of New Zealand has been severely impacted by drainage modifications and the introduction of salmonid predators. We aim to test for the impacts of anthropogenic population fragmentation on genetic diversity in a critically endangered endemic fish, to inform future conservation management of this species. Location Teviot River and surrounding drainages, South Island, New Zealand. Methods We generate and analyse a genome‐wide data set comprising 47,754 SNPs across 275 Galaxias specimens to assess genetic diversity across the range of a critically endangered freshwater fish, G . ‘Teviot’. We conduct phylogenetic, STRUCTURE and genetic diversity analyses to evaluate the evolutionary relationships of Teviot River populations in the context of major anthropogenic river drainage alterations in this region. Results Our analysis reveals genetic divergences linked to anthropogenic population fragmentation, with the deepest phylogeographic splits within G . ‘Teviot’ correlated with the first Lake Onslow dam (constructed in 1890). We also show that subsequent drainage modifications (water‐race connections) are associated with the apparent introgressive spread of alleles from a newly recognised candidate taxon, G . ‘Manor Burn’, into upper Teviot populations. Counterintuitively, the Lake Onslow dam appears to have buffered lower Teviot populations from this anthropogenic introgression. Main Conclusions We identify key genetically diverse, yet non‐introgressed, populations of G . ‘Teviot’ as suitable sources for potential translocations to genetically safeguard this critically endangered fish species.
