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298 results for “abundance distribution”

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dryad36/100

Data from: Odonate species occupancy frequency distribution and abundance – occupancy relationship patterns in temporal and permanent water bodies in a subtropical area

This paper investigates species richness and species occupancy frequency distributions (SOFD) as well as patterns of abundance-occupancy relationship (SAOR) in Odonata (dragonflies and damselflies) in a subtropical area. A total of 82 species and 1983 individuals were noted from 73 permanent and temporal water bodies (lakes and ponds) in the Pampa biome in southern Brazil. Odonate species occupancy ranged from 1 to 54. There were few widely distributed generalist species and several specialist species with a restricted distribution. About 70% of the species occurred in less than 10% of the water bodies, yielding a surprisingly high number of rare species, often making up the majority of the communities. No difference in species richness was found between temporal and permanent water bodies. Both temporal and permanent water bodies had odonate assemblages that fitted best with the unimodal satellite SOFD pattern. It seems that unimodal satellite SOFD pattern frequently occurred in the aquatic habitats. The SAOR pattern was positive and did not differ between permanent and temporal water bodies. Our results are consistent with a niche-based model rather than a metapopulation dynamics model.

opencc-zeroJul 2021View details →

zenodo36/100

Figure 4 in Abundance and distribution of Aculus schlechtendali on apple orchards in Southern of Brazil

Figure 4 Municipalities and its respective states (see color legend) from Southern Brazil

opencc-by-4.0Sep 2020View details →

dryad36/100

Data from: Abundant-core thinking clarifies exceptions to the abundant-center distribution pattern

Understanding variation in abundance within species' ranges is fundamental for ecological and evolutionary theory and applied conservation science. The abundant-center model provides a general hypothesis based on basic ecological principles and macroscale biogeographic patterns: abundance should peak near the center of a species' range, where environmental conditions are most favorable, and decline towards the periphery. Despite longstanding influence in ecological thinking, consistent support for the ubiquity of abundant-center distributions remains elusive, and recent assessments have questioned the value of this paradigm altogether. We suggest that revisiting the simplifying assumptions that underly the model provides a productive path forward by clarifying predictions and revealing expectations for alternative distribution patterns. Towards this end, we use standardized abundance surveys of North American birds to reassess the prevalence of abundant-center distributions in geographic and climate space, test whether deviations are associated with predictable violations of assumptions, and provide more robust expectations. After accounting for common methodological pitfalls, we find that geographic centrality is generally indicative of centrality in climate space (confirming a key model assumption) and that abundant-center distributions occurred in 71% of passerines. To better understand exceptions, we introduce the concept of abundant-core distributions, of which the abundant-center is a special case. We find that 87% of species fit abundant-core expectations, with abundances peaked and generally declining from a core region within the range. Abundance cores tended to deviate from geographic center where topographic features complicate correspondence between geography and environmental conditions (e.g. the climatically heterogenous West). Such deviations were often associated with truncated climatic availability, with core regions offset towards the continental edge or climate extremes. Overall, our analyses suggest that abundant-center thinking provides a useful generalization for understanding spatial variation in abundance for many species. However, as with any model, its assumptions must be assessed within the context of given applications.

opencc-zeroNov 2022View details →

dryad36/100

Bayesian species distribution models integrate presence-only and presence-absence data to predict deer distribution and relative abundance

Using geospatial data of wildlife presence to predict a species distribution across a geographic area is among the most common tools in management and conservation. The collection of high-quality presence-absence data through structured surveys is, however, expensive, and managers usually have access to larger amounts of low-quality presence-only data collected by citizen scientists, opportunistic observations, and culling returns for game species. Integrated Species Distribution Models (ISDMs) have been developed to make the most of the data available by combining the higher-quality, but usually scarcer and more spatially restricted presence-absence data, with the lower quality, unstructured, but usually more extensive presence-only datasets. Joint-likelihood ISDMs can be run in a Bayesian context using INLA (Integrated Nested Laplace Approximation) methods that allow the addition of a spatially structured random effect to account for data spatial autocorrelation. Here, we apply this innovative approach to fit ISDMs to empirical data, using presence-absence and presence-only data for the three prevalent deer species in Ireland: red, fallow and sika deer. We collated all deer data available for the past 15 years and fitted models predicting distribution and relative abundance at a 25 km2 resolution across the island. Models' predictions were associated to spatial estimates of uncertainty, allowing us to assess the quality of the model and the effect that data scarcity has on the certainty of predictions. Furthermore, we checked the performance of the three species-specific models using two datasets, independent deer hunting returns and deer densities based on faecal pellet counts. Our work clearly demonstrates the applicability of spatially-explicit ISDMs to empirical data in a Bayesian context, providing a blueprint for managers to exploit unexplored and seemingly unusable data that can, when modelled with the proper tools, serve to inform management and conservation policies.

opencc-zeroNov 2022View details →

dryad36/100

Intra‐season variations in distribution and abundance of humpback whales in the West Antarctic Peninsula using cruise vessels as opportunistic platforms

Following the near collapse of several whale populations in the Southern Ocean, some baleen whale stocks are on the rise again. Combined with the recent increase in fishery of Antarctic Krill (Euphausiia superba) around the Western Antarctic Peninsula (WAP) there is a growing need to quantify several aspects of some of these whale species in this area. In this study we use data collected from tourist vessels performing several trips during the Austral summer to quantify the beginning of the foraging season for Antarctic Humpback whales, estimate abundance, as well as use predictive habitat model to identify potential areas for interaction between this species and fishing vessels. The following dataset includes the GPS track of both vessels and all marine mammal and seabird observations collected on two ships between late November 2019 and mid-January 2020. These data were gathered following standard Distance Sampling protocols, recorded in Logger2010 software (<a href="http://www.marineconservationresearch.co.uk/downloads/logger-2000-rainbowclick-software-downloads/">http://www.marineconservationresearch.co.uk/downloads/logger-2000-rainbowclick-software-downloads/</a>), stored in MS Access database files and subset in .RData files for analysis.

opencc-zeroNov 2022View details →

dryad36/100

Data for: Aspects of distribution, abundance, habitat, and life history of the Caddo Madtom (Noturus taylori), a narrow endemic of the Ouachita Highlands

The Caddo Madtom, Noturus taylori, is a small catfish endemic to the Ouachita Mountain ecoregion in Arkansas, with habitat altered by land use practices and reservoir dams. We examined aspects of distribution, abundance, habitat, and life history of N. taylori during seasonal sampling from winter 2016 through fall 2017. Our sampling data were concordant with previous studies that suggested N. taylori is more widespread and has higher catch per unit effort in the Caddo River drainage when compared to the upper Ouachita River drainage. We did not detect N. taylori in the Little Missouri River drainage, where it is presumed extirpated. A total of 370 individuals ranging from 14–76 mm (mean = 45.1 mm) standard length (SL) were collected during seasonal samples. Length-frequency analyses estimated a maximum age of 3 years for N. taylori, and we identified three discernable age classes with the emergence of young-of-year (age 0 cohort) in summer: age 0 (up to ~40 mm SL); age 1 (~41–60 mm SL); and age 2+ (>60 mm SL). Sites where N. taylori was captured had an average depth of 20.6 cm, an average base velocity of 0.18 m/sec, and were dominated primarily by a mix of gravel, pebble, and cobble. Despite the relatively higher abundances of N. taylori in the Caddo River, we recommend that long-term, periodic monitoring of N. taylori would be an important conservation tool to assess potential future changes in distribution, habitat, occurrence, and abundance. Future studies that implement occupancy and habitat suitability modeling are needed to better understand suitable and preferred habitat of N. taylori.

opencc-zeroMay 2023View details →

zenodo36/100

Unveiling global species abundance distributions - Callaghan et al. 2023 - Nature Ecology and Evolution

This repository represents some data and code to reproduce the main figures from Callaghan et al. 2023. Unveiling the global species abundance distributions of Eukaryotes. Nature Ecology and Evolution.

opencc-by-4.0Jun 2023View details →

dryad36/100

How environmental factors affect the abundance and distribution of two congeneric species of Amazonian frogs

In this study, we test the hypothesis that, at a fine scale, environmental variables influence differently sister species that live in sympatry and are phylogenetically closely related. We sampled two Amazonian anuran species, Phyzelaphryne miriamae and Phyzelaphryne sp., in 11 permanent sampling modules distributed across ~600 km in the Purus-Madeira Interfluve between 2013 and 2014. Using mixed generalized linear models, we found that the species have distinct environmental associations, which may facilitate their coexistence in sympatry. Phyzelaphryne miriamae was more frequent in environments with low precipitation and low water tables, suggesting this species is better adapted to live in drier places. In contrast, Phyzelaphryne sp. appeared to be a generalist regarding to habitat and resource use. These patterns are in accordance with the hypothesis that environmental variables influence sister species differently on a fine scale. Phyzelaphryne miriamae is larger than Phyzelaphryne sp., which may make it more resistant to dehydration, allowing it to explore drier environments. In conclusion, our results are in concordance with the hypothesis that the evolution of characteristics resulting from selection may have reduced competition for resources between closely related species, thus facilitating coexistence in sympatry.

opencc-zeroSep 2023View details →

dryad36/100