Invertebrate focal taxa that can act as information surrogates for broader patterns of biodiversity are of increasing interest to conservation practitioners. Scarabaeine dung beetles have been widely ...proposed as an ideal group for biodiversity inventory and monitoring, they satisfy all of the criteria of an ideal focal taxon, and they have already been used in ecological research and biodiversity survey and conservation work in many regions of the world. Here I review the characteristics that make the Scarabaeinae suitable for this purpose and suggest future directions for the broader use of this group as a focal taxon.
Human presence and activity in tropical forest is thought to exert top-down regulation over the various 'green-world' pathways of plant-based foodwebs. However, these effects have never been explored ...for the 'brown-world' pathways of fecal-detritus webs. The strong effects of humans on tropical game mammals are likely to indirectly influence fecal detritivores (including Scarabaeine dung beetles), with subsequent indirect impacts on detrivore-mediated and plant-facilitating detrital processes. Across a 380-km gradient of human influence in the western Brazilian Amazon, we conducted the first landscape-level assessment of human-induced cascade effects on the fecal detritus pathway, by coupling data on human impact, game mammal and detritivore community structure, and rate measurements of a key detritus process (i.e. dung beetle-mediated secondary seed dispersal). We found evidence that human impact indirectly influences both the diversity and biomass of fecal detritivores, but not detritivore-mediated processes. Cascade strength varied across detritivore groups defined by species' traits. We found smaller-bodied dung beetles were at higher risk of local decline in areas of human presence, and that body size was a better predictor of cascade structure than fecal resource manipulation strategy. Cascade strength was also stronger in upland, unflooded forests, than in seasonally flooded forests. Our results suggest that the impact of human activity in tropical forest on fecal-detritus food web structure is mediated by both species' traits and habitat type. Further research will be required to determine the conditions under which these cascade effects influence fecal-detritus web function.
Comparative analyses that link information on species' traits, environmental change, and organism response have rarely identified unambiguous trait correlates of vulnerability. We tested if species' ...traits could predict local-scale changes in dung beetle population response to three levels of forest conversion intensity within and across two biogeographic regions (the Neotropics and Afro-Eurasian tropics). We combined biodiversity surveys, a global molecular phylogeny, and information on three species' traits hypothesized to influence vulnerability to forest conversion to examine (1) the consistency of beetle population response across regions, (2) if species' traits could predict this response, and (3) the cross-regional consistency of trait-response relationships. Most beetle populations declined following any degree of forest conversion; these declines were strongest for Neotropical species. The relationship between traits and population trend was greatly influenced by local and biogeographic context. We discuss the ability of species' traits to explain population trends and suggest several ways to strengthen trait-response models.
Sea Level Rise (SLR) caused by climate change is impacting coastal wetlands around the globe. Due to their distinctive biophysical characteristics and unique plant communities, freshwater tidal ...wetlands are expected to exhibit a different response to SLR as compared with the better studied salt marshes. In this study we employed the Sea Level Affecting Marshes Model (SLAMM), which simulates regional- or local-scale changes in tidal wetland habitats in response to SLR, and adapted it for application in a freshwater-dominated tidal river system, the Hudson River Estuary. Using regionally-specific estimated ranges of SLR and accretion rates, we produced simulations for a spectrum of possible future wetland distributions and quantified the projected wetland resilience, migration or loss in the HRE through the end of the 21st century. Projections of total wetland extent and migration were more strongly determined by the rate of SLR than the rate of accretion. Surprisingly, an increase in net tidal wetland area was projected under all scenarios, with newly-formed tidal wetlands expected to comprise at least 33% of the HRE's wetland area by year 2100. Model simulations with high rates of SLR and/or low rates of accretion resulted in broad shifts in wetland composition with widespread conversion of high marsh habitat to low marsh, tidal flat or permanent inundation. Wetland expansion and resilience were not equally distributed through the estuary, with just three of 48 primary wetland areas encompassing >50% of projected new wetland by the year 2100. Our results open an avenue for improving predictive models of the response of freshwater tidal wetlands to sea level rise, and broadly inform the planning of conservation measures of this critical resource in the Hudson River Estuary.
Land-acquisition strategies employed by conservation organizations vary in their flexibility. Conservation-planning theory largely fails to reflect this by presenting models that are either extremely ...inflexible—parcel acquisitions are irreversible and budgets are fixed—or extremely flexible—previously acquired parcels can readily be sold. This latter approach, the selling of protected areas, is infeasible or problematic in many situations. We considered the value to conservation organizations of increasing the flexibility of their land-acquisition strategies through their approach to financing deals. Specifically, we modeled 2 acquisition-financing methods commonly used by conservation organizations: borrowing and budget carry-over. Using simulated data, we compared results from these models with those from an inflexible fixed-budget model and an extremely flexible selling model in which previous acquisitions could be sold to fund new acquisitions. We then examined 3 case studies of how conservation organizations use borrowing and budget carry-over in practice. Model comparisons showed that borrowing and budget carry-over always returned considerably higher rewards than the fixed-budget model. How they performed relative to the selling model depended on the relative conservation value of past acquisitions. Both the models and case studies showed that incorporating flexibility through borrowing or budget carry-over gives conservation organizations the ability to purchase parcels of higher conservation value than when budgets are fixed without the problems associated with the selling of protected areas. Las estrategias de adquisición de tierras empleadas por las organizaciones de conservación varían en su flexibilidad. La teoría para la planificación de la conservación fracasa enormemente en la representación de esto ya que presenta modelos que son extremadamente inflexibles - la adquisición de lotes es irreversible y los presupuestos están fijados - o extremadamente flexibles - los lotes adquiridos previamente pueden venderse de inmediato. Esta estrategia previa, la venta de áreas protegidas, es inviable o problemática en muchas situaciones. Consideramos el valor que tiene para las organizaciones de conservación incrementar la flexibilidad de sus estrategias de adquisición de suelo a través de su estrategia para los acuerdos de financiamiento. En específico, modelamos dos métodos de adquisición-financiamiento utilizados comúnmente por las organizaciones de conservación: el préstamo y el arrastre del presupuesto. Con el uso de datos simulados comparamos los resultados de estos modelos con aquellos de un modelo inflexible con presupuesto fijo y de un modelo extremadamente flexible de ventas, en el cual las adquisiciones previas podían venderse para financiar nuevas adquisiciones. Después examinamos tres estudios de caso sobre cómo las organizaciones de la conservación utilizan el préstamo y el remanente del presupuesto en la práctica. La comparación entre los modelos mostró que el préstamo y el remanente del presupuesto siempre devolvían recompensas considerablemente más altas que el modelo con el presupuesto fijo. Su desempeño en relación con el modelo de ventas dependió del valor de conservación relativo de las adquisiciones previas. Tanto los modelos como los estudios de caso mostraron que incorporar la flexibilidad por medio del préstamo o el arrastre del presupuesto otorga a las organizaciones de conservación la habilidad de comprar lotes con un valor más alto de conservación que cuando los presupuestos están fijados y sin los problemas asociados con la venta de áreas protegidas.
Insect macroecology and conservation biogeography studies are disproportionately scarce, especially in the Neotropics. Dung beetles are an ideal focal taxon for biodiversity research and ...conservation. Using distribution and body size data on the ecologically important Phanaeini, the best-known Neotropical dung beetle tribe, we determined elevational patterns of species richness, endemism, body size, and elevational range in Bolivia, specifically testing Bergmann's and Rapoport's rule. Richness of all 39 species and of 15 ecoregional endemics showed a hump-shaped pattern peaking at 400 m, but overall declined strongly with elevation up to 4000 m. The relationship between endemic and total species richness appeared to be curvilinear, providing only partial support for the null hypothesis that species-rich areas are more likely to be centers of endemism by chance alone. An elevational increase in the proportion of ecoregional endemics suggests that deterministic factors also appear to influence endemism in the Andes. When controlling for the effect of area using different species-area relationships, the statistically significant richness peak became more pronounced and shifted upslope to 750 m. Larger species did not have higher elevational mid-points, and mean body size decreased significantly with elevation, contradicting Bergmann's rule. Rapoport's rule was supported: species with higher elevational mid-points had broader elevational ranges, and mean elevational range increased significantly with elevation. The elevational decrease of phanaeine richness is in accordance with studies that demonstrated the combined influence of temperature and water availability on species diversity, but also is consistent with niche conservatism. For invertebrates, confirmation of Rapoport's and refutation of Bergmann's rule appear to be scale-invariant general patterns. Analyses of biogeographic patterns across elevational gradients can provide important insights for identifying conservation priorities. Phanaeines with narrow elevational ranges on isolated low-elevation mountains in eastern Bolivia are at greatest climate-change related extinction risk from range-shift gaps and mountaintop extinctions.
Threats to biodiversity outpace the resources of the conservation community and necessitate careful prioritization of conservation actions. I suggest that targeting the regions where biogeographic ...assemblages intersect-"biogeographic crossroads"-is a strategy that may achieve significant conservation economy by focusing on areas that satisfy many conservation criteria. I used a combination of data on Scarabaeine beetles in Bolivia and on other taxa and locations from the literature to consider the short- and long-term benefits of conserving these biogeographic crossroads. Biogeographic crossroads are areas of high species richness and beta diversity, often across many taxonomic groups. They are also regions where representativeness can be achieved with relative efficiency. Recent evidence that ecotones may be loci of evolution suggests that evolutionary processes such as speciation and coevolution may be conserved at biogeographic crossroads. Biogeographic crossroads appear to be areas of high conservation priority and opportunity in both the short and long term and require increased attention in the process of setting conservation priorities.
Remote-sensing systems typically produce imagery that averages information over tens or even hundreds of square meters – far too coarse to detect most organisms – so the remote sensing of ...biodiversity would appear to be a fool's errand. However, advances in the spatial and spectral resolutions of sensors now available to ecologists are making the direct remote sensing of certain aspects of biodiversity increasingly feasible; for example, distinguishing species assemblages or even identifying species of individual trees. In cases where direct detection of individual organisms or assemblages is still beyond our grasp, indirect approaches offer valuable information about diversity patterns. Such approaches derive meaningful environmental parameters from biophysical characteristics that are revealed by remote sensing.
ABSTRACT
Habitat fragmentation and the widespread creation of habitat edges have recently stimulated interest in assessing the effects of ecotones on biodiversity. Ecotones, natural or anthropogenic, ...can greatly affect faunal movement, population dynamics, species interactions, and community structure. Few data exist, however, on insect community response to forest–savanna ecotones, a natural analog to anthropogenically cleared areas adjacent to forest. In this study, the abundance, total biomass, average individual biomass, and distribution of scarabaeine dung beetles were examined at a sharp tropical evergreen forest–savanna ecotone in Santa Cruz, Bolivia. The abundance, total biomass, and average individual biomass of dung beetles varied significantly across the forest, edge, and savanna habitats. Species richness (Sobs) also varied significantly across the three habitats, but statistical estimations of true species richness (Sest) did not. Habitat specificity of the dung beetles in this study was extremely high. Of the 50 most common species collected during the study, only 2 species were collected in both the forest and savanna habitats, signaling nearly complete community turnover in just a few meters. Strong edge effects were evidenced by the decline in abundance, total biomass, and species richness at the forest‐savanna boundary.
RESÚMEN
La fragmentación de hábitats y la creación de grandes cantidades de áreas de borde han generado interés en evaluar los efectos de los ecotonos para la biodiversidad. Los ecotonos, ya sea naturales o antropogénicos, pueden afectar de manera significativa el movimiento faunístico, la dinámica de poblaciones, las interacciones interespecíficas, y la estructura de las comunidades. Existen muy pocos datos, sin embargo, sobre la respuesta de las comunidaes de insectos a ecotonos de bosque–savana. Este tipo de ecotono es un análogo natural de las áreas de bosque talado de orígen antropogénico. En este estudio, se examinaron la abundancia, biomasa total, biomasa individual promedio, y distribución de escarabajos coprófagos de la familia Scarabaeinae en un ecotono localizado entre bosque tropical perennifolio y savana en Santa Cruz, Bolivia. Se encontró que la abundancia, biomasa total, y biomasa individual promedio de los escarabajos coprófagos varió de manera significativa a través del bosque, el hábitat de borde y la savana. La riqueza de especies también varió significativamente a través de los tres habitats, pero las estimaciones estadísticas de la verdadera riqueza de especies no fueron significativas. La especificidad de hábitat de los escarabajos examinados en este estudio fije muy alta. De las 50 especies más comúnes colectadas durante el estudio, solamente 2 fueron colectadas tanto en bosque como en savana, indicando un reemplazo casi total en la composición de la comunidad en unos pocos metros. Los efectos de borde parecen ser fuertes, dada la disminución en abundancia, biomasa total, y riqueza de especies en la frontera bosque–savana.
Introduction
The Brazilian Atlantic Forest (BAF) is undergoing alarming deforestation, land overexploitation, and unregulated occupation. The Coastal Sandy Vegetation of BAF, known as Restinga, is ...under the most pressure of the BAF ecosystems. Understanding the effects of Restinga deforestation on biodiversity is a conservation priority.
Aims/Methods
We predicted the effect of landscape modifications on the large-scale spatial distribution of an endangered dung beetle (
Dichotomius schiffleri
) endemic to the BAF Restinga ecosystem. We tested the hypothesis that almost all the potential distribution area of this species has suffered from landscape modification, and reduced its spatial distribution. We used niche-based modeling approaches to predict the potential species distribution (climate-based models) and the species distribution under the current land-use scenario (landscape-based models). We then combined these models to predict the effects of landscape modification.
Results
The spatial distribution of
D. schiffleri
has decreased drastically as a consequence of landscape modification. The decreasing patch size, canopy cover percentage, and functional connectivity, and the increasing edge distance explain the decrease in the potential species distribution as predicted by climate variables.
Discussion
Suitable sites for this species are isolated in a vast matrix of pasture, tree plantations, and urban areas.
D. schiffleri
is sensitive to anthropogenic changes such as disturbances of preserved Restinga areas. Therefore, human coastal-plain land uses over the past five centuries pose multiple synergistic threats to the persistence of this species.
Implications for insect conservation
Our findings suggest an alarming trend toward species extinction in the near future, highlighting the need for specific conservation actions to protect Restinga biodiversity.
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