AICc Weight Research Articles

Mathematical model to calculate the total number of decays in Peptide Receptor Radionuclide Therapy using nonlinear mixed effect modelling

The calculation of an individual total number of decays or time-integrated activities (TIAs) of a radiopharmaceutical for kidneys is desirable for dosimetry in molecular radiotherapy. The accuracy of the TIAs calculation relies heavily on the chosen fit model. Therefore, this study aimed to determine the best mathematical model of 177Lu-DOTATATE in peptide receptor radionuclide therapy (PRRT) using the nonlinear mixed effect (NLME) and model selection method. Pharmacokinetics data of 177Lu-DOTATATE in the kidneys of ten PRRT patients were obtained from the literature (PMID: 33443063). Eleven sums of exponential (SOE) functions were fitted to the pharmacokinetics data in the NLME framework. The model selection was performed based on the goodness of fit test and the corrected Akaike Information Criterion (AICc). The goodness of fit was evaluated based on the fitted graphs visualization, coefficient of variations (CV<50%), and the off-diagonal elements of the correlation matrix (-0,8≤CM≤0,8). In general, all SOE functions were successfully fitted to the pharmacokinetic data of 177Lu-DOTATATE in kidneys. The function was selected as the best mathematical model with an AICc weight of 77.58 %.

(074) Not just a matter of labels: The Importance of Distinguishing Between Sexual Desire, and Mental and Genital Sexual Arousal

Abstract Introduction While researchers and clinicians have long discussed sexual desire and sexual arousal as two distinct entities, the DSM has moved from treating them separately (DSM-IV) to amalgamating desire and arousal disorders into one single diagnosis (“Female Sexual Interest/Arousal Disorder”; DSM-5). Consistent with the idea of combining them, the original publication of the FSFI found a single factor for desire and arousal (Rosen et al, 2000). Experts in sexual medicine, however, have opposed the use of this single diagnostic entity (Goldstein et al., 2017). Furthermore, Meston and colleagues have provided extensive data showing that among women, a distinction should also be made between mental and genital arousal, given the low concordance between the two. Objective The aim of these analyses was to clarify the distinction between three constructs of female sexual function: sexual desire (SD); mental sexual arousal (MSA); and genital sexual arousal/lubrication. Methods A sample of 138 female university students completed the FSFI. Structural equation modelling was used to test the goodness of fit of four different models examining the structure of the SD, MSA and lubrication subscales. The first model includes only a single factor (Fig. 1), the second and third models include two factors (Fig. 2 and 3), and the fourth model includes three factors (Fig. 4), thus maintaining the distinction between the three constructs. Results Factor loadings and correlations for the four models are presented in Figures 1-4, and although all questions loaded well on the latent factors in all four models (with the exception of fantasy in model 3), the fit indices differed significantly across models. Specifically, models 1 and 2 did not fit the data well (CFI = .64; TLI = .55; RMSEA = .21, Figure 1; CFI = .67; TLI = .58; RMSEA = .21 Figure 2). The third model showed improvement, but still did not fit the data well (CFI = .90; TLI = .87; RMSEA = .11; Figure 3), whereas the fourth model did fit the data well (CFI = .93; TLI = .91; RMSEA = .09; Figure 4). Moreover, the fourth model was found to be the best fitting model: AICc weight = .999, showing 99.9% certainty that the fourth model is the best model (1,427 times more likely to be the best model as compared to the third model). Correlations among constructs in the final model were low (r = .25) to moderate (r = 62). Conclusions Although the DSM-5 and a plethora of research have combined and confounded sexual desire and arousal as if they are the same, the current study shows that the subjective experience of these constructs are clearly differentiated. Moreover, although it has been claimed that the distinction between MSA and lubrication might be theoretically, but not clinically, relevant (Meston &amp; Stanton, 2018), consensus in terminology is essential to move toward a more accurate understanding of sexual desire, and mental and genital sexual arousal. Doing so will also enable the use of appropriate measures and labels in the context of new research and in reference to past literature. Disclosure No

Landscape factors and allochthonous congeneric species influence Callithrix aurita occurrence in Brazilian Atlantic Forest remnants.

The buffy-tufted-ear marmoset (Callithrix aurita) is a small primate endemic to the Brazilian Atlantic Forest biome, and one of the 25 most endangered primates in the world, due to fragmentation, loss of habitat, and invasion by allochthonous Callithrix species. Using occurrence data for C. aurita from published data papers, we employed model selection using Akaike Information Criterion corrected for small samples and cumulative AICc weight (w +) to evaluate whether fragment size, distance to fragments with allochthonous species, altitude, connectivity, and surrounding matrices influence the occurrence of C. aurita within its distributional range. Distance to fragments with C. jacchus (w + = 0.94) and nonvegetated areas (w + = 0.59) correlated negatively with C. aurita occurrence. Conversely, the percentage of agriculture and pasture mosaic (w + = 0.61) and the percentage of savanna formation (w + = 0.59) in the surrounding matrix correlated positively with C. aurita occurrence. The findings indicate that C. aurita is isolated in forest fragments surrounded by potentially inhospitable matrices, along with proximity of a more generalist and invasive species, thereby increasing the possibility of introgressive hybridization. The findings also highlighted the importance of landscape elements and allochthonous congeneric species for C. aurita conservation, besides indicating urgency for allochthonous species management. Finally, the approach used here can be applied to improve conservation studies of other endangered species, such as C. flaviceps, which is also endemic to the Brazilian Atlantic Forest and faces the same challenges.

Recovering an endangered vole and its habitat may help control invasive house mice

Greater understanding of intraguild dynamics in rodent communities and of how house mice, Mus musculus, interact with wild sympatric rodents is needed. House mice can be a particularly virulent invasive species, presenting a potential threat to native biodiversity. In the Mojave Desert, western harvest mice, Reithrodontomys megalotis and the endangered Amargosa vole, Microtus californicus scirpensis, inhabit a fragmented desert wetland ecosystem. The Amargosa vole relies heavily on bulrush, Schoenoplectus americanus, for food, as well as thermal and predator refuge. We used two species occupancy models and estimated activity pattern overlap to explore spatial and temporal interactions within this rodent guild. For each species pairing, we compared the relative performance of a series of candidate occupancy models, with the most supported model structures and components distinguished by AICc and AICc weight. We found that voles reduced the detectability of western harvest mice and house mice, but did not spatially exclude them. Our findings also suggested that voles were more detectable in bulrush stands as bulrush cover increased, whereas house mice and western harvest mice were negatively associated with bulrush cover. House mice and western harvest mice had high activity pattern overlap, (Δ̂4 0.89, 95% CI = 0.85-0.96), which was greater with each other than with voles (Δ̂4 0.69, 95% CI = 0.57-0.75 and Δ̂4 0.66, 95% CI = 0.49-0.70, respectively). House mice were also more detectable in the presence of western harvest mice, suggesting niche overlap or an attraction to them. Our observations suggest that, during the summer months, Amargosa voles could be a limiting factor on the behaviour and/or population densities of smaller rodent species in bulrush habitat. Drought exacerbated habitat changes may have contributed to house mouse expansion and vole decline in the region. While a deeper understanding of trophic dynamics is required, continued efforts to preserve the endangered Amargosa vole and it's habitat may also help mitigate any potential harm caused by free-living house mice in these desert wetlands.

Habitat area and environmental filters determine avian richness along an elevation gradient in mountain peatlands

Globally, relationships between avian richness and elevation in mountain ecosystems typically reflect one of four well‐documented patterns, but the mechanisms responsible for these patterns are poorly understood. We investigated which pattern best described bird species richness in peatlands of the Upper Bow Basin of the Canadian Rocky Mountains (1300–2000 m a.s.l.) and used a model competition framework to investigate possible mechanisms. Avian richness displayed a plateauing (cubic) relationship in response to increasing elevation (AICc weight = 0.48). Log richness was significantly positively related to log peatland area (R2 = 0.42, p = 0.001); however, and once we accounted for the richness–area relationship (area was not related to elevation (R2 = 0.13, p = 0.083)), the richness–elevation relationship was best described by a negative linear model rather than a cubic model (AICc weight = 0.69, R2 = 0.39). Consequently, we reject the neutral model of the mid‐domain effect and conclude that peatland area and one or more environmental filters are simultaneously driving relationships between avian richness and elevation in Rocky Mountain peatlands. Multicausality likely explains why researchers in different geographies observe inconsistent patterns between richness and elevation: drivers and interactions among drivers may vary spatially. Importantly, Natural Subregion was a stronger predictor of avian species richness than elevation per se (AICc weight = 0.96), suggesting that the responsible environmental filter(s) is relatively homogenous within ecological land classes (e.g. primary productivity) rather than directly variable with elevation (e.g. temperature). The results also lend insight into priorities for future research on richness–elevation patterns in mountain birds.

Scaling up private land conservation to meet recovery goals for grassland birds.

Long‐term population declines have elevated recovery of grassland avifauna to among the highest conservation priorities in North America. Because most of the Great Plains is privately owned, recovery of grassland bird populations depends on voluntary conservation with strong partnerships between private landowners and resource professionals. Despite large areas enrolled in voluntary practices through U.S. Department of Agriculture's Lesser Prairie‐chicken (Tympanuchus pallidicinctus) Initiative (LPCI), the effectiveness of Farm Bill investments for meeting wildlife conservation goals remains an open question. Our objectives were to evaluate extents to which Conservation Reserve Program (CRP) and LPCI‐grazing practices influence population densities of grassland birds; estimate relative contributions of practices to regional bird populations; and evaluate percentages of populations conserved relative to vulnerability of species. We designed a large‐scale impact‐reference study and used the Integrated Monitoring in Bird Conservation Regions program to evaluate bird population targets of the Playa Lakes Joint Venture. We used point transect distance sampling to estimate density and population size for 35 species of grassland birds on private lands enrolled in native or introduced CRP plantings and LPCI‐prescribed grazing. Treatment effects indicated CRP plantings increased densities of three grassland obligates vulnerable to habitat loss, and LPCI grazing increased densities of four species requiring heterogeneity in dense, tall‐grass structure (α = 0.1). Population estimates in 2016 indicated the practices conserved breeding habitat for 4.5 million birds (90% CI: 4.0–5.1), and increased population sizes of 16 species , totaling 1.8 million birds (CI: 1.4–2.4). Conservation practices on private land benefited the most vulnerable grassland obligate species (AICc weight = 0.53). By addressing habitat loss and degradation in agricultural landscapes, conservation on private land provides a solution to declining avifauna of North America and scales up to meet population recovery goals for the most imperiled grassland birds.

Multi-Model Approach on Growth Estimation and Association With Life History Trait for Elasmobranchs

Age and growth information is essential for stock assessment of fish, and growth model selection may influence the accuracy of stock assessment and subsequent fishery management decision making. Previous descriptions of the age and growth of elasmobranchs relied mainly on the von Bertalanffy growth model (VBGM). However, it has been noted that sharks, skates and rays exhibit significant variety in size, shape, and life history traits. Given this variation, the VBGM may not necessarily provide the best fit for all elasmobranchs. This study attempts to improve the growth estimates by using multi-model approach to test four growth models—the VBGM, the two-parameter VBGM, the Robertson (Logistic) and the Gompertz models to fit observed or simulated length-at-age data for 38 species (44 cases) of elasmobranchs. The best-fit growth model was selected based on the bias corrected Akaike’s Information Criterion (AICc), the AICc difference, the AICc weight, the Bayesian Information Criterion (BIC), and the Leave-one-out cross-validation (LOOCV). The VBGM and two-parameter VBGM provide the best fit for species with slow growth and extended longevity (L∞ &amp;gt; 100 cm TL, 0.02 &amp;lt; k &amp;lt; 0.25 yr–1), such as pelagic sharks. For fast-growing small sharks (L∞ &amp;lt; 100 cm TL, kr or kg &amp;gt; 0.2 yr–1) in deep waters and for small-sized demersal skates/rays, the Robertson and the Gompertz models provide the best fit. The best-fit growth models for small sharks in shallow waters are the two-parameter VBGM and the Robertson model. Although it was found that the best-fit growth models for elasmobranchs were associated with their life history trait, exceptions were also noted. Therefore, a multi-model approach incorporating with the best-fit model selected for each group in this study was recommended in growth estimation for elasmobranchs.

Bat Occupancy Based on Mist-Netting Surveys in a Montane Landscape in Northern Andes

Occupancy models have not been commonly used in studies focused on bat ecology, although they offer an opportunity to include site covariates along environmental gradients as well as factors that influence detection probability (e.g., lunar illumination). Here we assessed the influence of elevation and forest cover on occupancy and the effect of lunar illumination on detectability of bat species in the Northern Andes of Peru. We captured 1,052 bats, belonging to three families and 26 species, over two survey periods (2008–2010 and 2014–2015) at 14 sites. The most detected species were the frugivorous Artibeus glaucus, Carollia brevicauda, C. perspicillata, Platyrrhinus ismaeli, P. nigellus, Sturnira erythromos, and S. oporaphilum. Detection probability (p) of both Artibeus planirostris, C. brevicauda and C. perspicillata were significantly related to the survey period, while S. erythromos and S. oporaphilum detectability was associated with lunar illumination. Elevation was marginally positively associated with S. erythromos occupancy, with a moderate relative explanatory power based on AICc weight. We did not find support for an effect of forest cover on bat occupancy. The estimation of both bat occupancy (Ψ) and detectability (p) provides the basis for the design of monitoring programs with a spatiotemporal approach and constitutes a critical component in the context of land-use change and changing climate. For bat species in montane habitats, we suggest that S. erythromos is a useful species for use in monitoring programs, based on both occupancy, and detection probability, as well as its adaptability to montane areas.

Growing-season frost is a better predictor of tree growth than mean annual temperature in boreal mixedwood forest plantations.

Increase in frost damage to trees due to earlier spring dehardening could outweigh the expected increase in forest productivity caused by climate warming. We quantified the impact of growing-season frosts on the performance of three spruce species (white, black, and Norway spruce) and various seed sources with different frost tolerance in two plantations, established on both sides of the eastern Canadian boreal-temperate forest ecotone. The objectives of this study were to determine (a) if spruce species and seed sources planted in sites far from their natural provenance would be less adapted to local site conditions, leading to increased frost damage and reduced height growth; (b) at which height above the ground growing-season frosts ceased to damage apical meristems; and (c) if height growth was best predicted by extreme climatic events (growing-season frosts) or by mean annual or summer temperature. At each site and for all spruce species and seed sources, we cross-sectioned spruce trees at different heights above the ground. Tree rings were cross-dated and screened for frost rings, which were then given a severity score based on cellular damage. Frost severity reduced height growth of all spruce species and provenances at both sites. Height growth of the non-native Norway spruce was the most reduced by frost severity and was the smallest species at both sites. Frost caused the highest growth reduction in white spruce at the boreal mixedwood site and had the least effect on black spruce at both sites. For all spruce species, height growth was affected up to 2m above the ground. Model selection based on corrected Akaike's information criteria (AICc) identified that minimum temperature in May was by far the best climate variable predicting tree growth (AICc weight=1), highlighting the importance of considering extreme climatic events, which are likely to increase in the future.

Large mammals generate both top-down effects and extended trophic cascades on floral-visitor assemblages

AbstractCascading effects of high trophic levels onto lower trophic levels have been documented in many ecosystems. Some studies also show evidence of extended trophic cascades, in which guilds dependent on lower trophic levels, but uninvolved in the trophic cascade themselves, are affected by the trophic cascade due to their dependence on lower trophic levels. Top-down effects of large mammals on plants could lead to a variety of extended trophic cascades on the many guilds dependent on plants, such as pollinators. In this study, floral-visitor and floral abundances and assemblages were quantified within a series of 1-ha manipulations of large-mammalian herbivore density in an African savanna. Top-down effects of large mammals on the composition of flowers available for floral visitors are first shown, using regressions of herbivore activity on metrics of floral and floral-visitor assemblages. An extended trophic cascade is also shown: the floral assemblage further altered the assemblage of floral visitors, according to a variety of approaches, including a structural equation modelling approach (model with an extended trophic cascade was supported over a model without, AICc weight = 0.984). Our study provides support for extended trophic cascades affecting floral visitors, suggesting that trophic cascades can have impacts throughout entire communities.

Demographic senescence in the aquatic plant Lemna gibba L. (Araceae)

Senescence is progressive, age-related bodily deterioration, accompanied at the population level by declines in average survival and fecundity (i.e., ‘demographic senescence’). Demographic senescence of plants has been investigated in only a few species, including small, floating macrophytes in the genus Lemna (family Araceae, subfamily Lemnoideae – the ‘duckweeds’). Unlike most plant species, Lemna ramets exhibit determinate growth, potentially rendering them more likely to experience demographic senescence. Here, our objective was to investigate senescence in a Lemna species not previously studied in this context, L. gibba L., toward the long-term goal of conducting cross-species comparative analyses. In a longitudinal lab study, we investigated a cohort of 334 individual L. gibba fronds, whose survival and reproduction we followed daily from birth (defined by the date a focal frond detached from its parent) to death (defined by the date a focal frond’s last daughter detached). We fit survival data to exponential, Weibull, Gompertz, and logistic models, the first of which represents ‘no senescence’. The logistic model was found to have the greatest support (AICC weight >0.99), indicating strong age-related declines in survival. We fit reproduction data using a generalized estimating equation approach, which showed a significant age-related decline in the predicted probability of daily reproduction – from 0.61 at age 3 days to 0.23 at age 52 days (i.e., after excluding the first two days of reproduction data to account for the initial, pre-reproductive phase of the L. gibba lifecycle). These age-related declines provide strong evidence that L. gibba does exhibit demographic senescence, consistent with evidence from congeneric species.

General allometric scaling of net primary production agrees with plant adaptive strategy theory and has tipping points

Summary Allometric scaling of net primary production (NPP) with plant biomass (B) is important to ecological carbon dynamics and energetics. Metabolic theory predicts a nonlinear power law for NPP scaling, based on fractal vascular systems, resulting in a linear model when using log NPP/log B axes that are standard in allometry. Alternatively, two other hypotheses predict nonlinear models for log‐transformed data, with potential tipping points. Size‐based competition may cause a quadratic curve as larger plants limit NPP by smaller plants. More inclusively, the plant adaptive strategies hypothesis predicts a sigmoidal curve to represent those same competitive effects, plus stress and ruderal adaptations that maintain relatively low NPP in habitats that are abiotically limiting or disturbed. We evaluated all three hypotheses for terrestrial vascular plants, using information theoretic model selection based on the Akaike Information Criterion (AICc). Published data (N = 709) were organised in subsets according to reported organisational level and plant growth form. Alternative curves were compared for a general model (using all data) and per subset. Potential tipping points were estimated using segmented regression. The plant adaptive strategies hypothesis was supported in general (AICc weight = 1·00) and via internal consistency for five of six subsets (86% of data). Competition was supported as affecting NPP at greater B, where quadratic and sigmoidal models often coincided. Only non‐woody assemblages most plausibly fit a power law model, perhaps related to sparse data at lowest B. Synthesis. Adaptive strategies and corresponding environmental conditions appear to constrain terrestrial net primary production scaling relative to metabolic theory's ideal. Moreover, tipping points in general nonlinear net primary production scaling (at c. 38 and 360 g m−2 B) indicate thresholds for rapid changes in net primary production given changing B that occurs via changing climate, human appropriation and land use.

Depredation Patterns and Northern Bobwhite Nest Success in Field Borders

Northern bobwhite (Colinus virginianus) populations have declined because of habitat loss and fragmentation. Field borders provide additional habitat for northern bobwhites and other wildlife that depend on early-succession habitat. However, their proximity to woods as well as other edge types may result in increased bobwhite nest depredation. We examined if northern bobwhite nest survival in field borders decreased with increasing proximity to edges such as woods, crop fields, ditches, and roads; effects of year, camera presence, and field border width also were considered. We examined if snakes are the primary nest predator with 24-hr video camera surveillance. We searched for and monitored northern bobwhite nests on ~ 77 ha of field borders in southeast North Carolina during summers 2010 and 2011. We found 26 nests and monitored them every 3–4 days. Fourteen nests were monitored with cameras. We built nest survival models using the covariates of distance to nearest woody edge, crop field, ditch, and road as well as year, camera effect, and field border width. The most explanatory model was constant northern bobwhite nest survival with an estimated daily nest survival 6 SE of 0.9512 6 0.0119 (AICc weight 1⁄4 0.23). Models with covariates suggested similar daily nest survival rates. Four snake and two mammalian predation events were recorded on camera. Distance to edge types and field border width did not appear to influence the outcome of nests in an agriculture-dominated landscape. Thus, landowners and managers in an agriculture-dominated landscape may have flexibility with field border placement and distance to edge type as they relate to nest success.

Anatomical and neuromuscular variables strongly predict maximum knee extension torque in healthy men.

This study examined the relative influence of anatomical and neuromuscular variables on maximal isometric and concentric knee extensor torque and provided a comparative dataset for healthy young males. Quadriceps cross-sectional area (CSA) and fascicle length (l f) and angle (θ f) from the four quadriceps components; agonist (EMG:M) and antagonist muscle activity, and percent voluntary activation (%VA); patellar tendon moment arm distance (MA) and maximal voluntary isometric and concentric (60°s(-1)) torques, were measured in 56men. Linear regression models predicting maximum torque were ranked using Akaike's Information Criterion (AICc), and Pearson's correlation coefficients assessed relationships between variables. The best-fit models explained up to 72% of the variance in maximal voluntary knee extension torque. The combination of 'CSA+θ f+EMG:M+%VA' best predicted maximum isometric torque (R (2)=72%, AICc weight=0.38) and 'CSA+θ f+MA' (R (2)=65%, AICc weight=0.21) best predicted maximum concentric torque. Proximal quadriceps CSA was included in all models rather than the traditionally used mid-muscle CSA. Fascicle angle appeared consistently in all models despite its weak correlation with maximum torque in isolation, emphasising the importance of examining interactions among variables. While muscle activity was important for torque prediction in both contraction modes, MA only strongly influenced maximal concentric torque. These models identify the main sources of inter-individual differences strongly influencing maximal knee extension torque production in healthy men. The comparative dataset allows the identification of potential variables to target (i.e. weaknesses) in individuals.

Nest location influences hatching success in the Socotra Cormorant (Phalacrocorax nigrogularis) on Siniya Island, United Arab Emirates

Context Nest location is an important determinant of reproductive success in many seabirds. Better understanding of breeding ecology of threatened seabirds could help in their conservation. Aims We evaluated nest location and reproductive success in the globally Vulnerable, regionally endemic, Socotra cormorants on Siniya Island, United Arab Emirates, in relation to multiple habitat factors to assess the relative influence of each. Methods We measured hatching success, as an indication of reproductive success, on 14 study plots during the 2011–12 breeding season. We measured distances from each study plot to the nearest tree, road, predation area, sandy beach and lagoon. We used multiple logistic regression to determine the extent to which these explanatory factors influenced hatching success. We used an information theoretic approach to select the best model. Key results Hatching success was significantly related to tree cover, distance from beach and distance from heavily depredated areas (AICc weight = 0.613). Nests were significantly deeper (13.14 ± 0.35 cm) in unshaded areas compared with areas shaded by trees (10.8 ± 0.31 cm) (ANOVA: F2,12 = 24.93, P &lt; 0.001). Conclusions Thus, we conclude that shade provided by planted non-native trees is an important factor affecting nest location and hatching success. Deeper nests could aid incubation by lowering nest temperatures during peak incubation periods (August) when temperatures may exceed 48°C. Heavy predation pressure is affecting hatching success. Wind action could be preventing nesting near the sandy beach. Implications Planted non-native trees are advantageous to breeding Socotra cormorants, although planting trees is not advocated. High predation pressure from feral cats and red foxes is reducing hatching success of Socotra cormorants on the largest known colony in the United Arab Emirates. Feral cats should be eradicated whereas the red foxes could be managed as a precautionary measure to ensure the continued survival of this threatened seabird.

Predicting the resting sites of Eurygaster integriceps Put. (Hemiptera: Scutelleridae) using a geographic information system

Sunn pest Eurygaster integriceps Puton is the most destructive insect pest of wheat and barley in Iran. This pest is a univoltine insect that feeds and reproduces in the fields for only 2–3 months of the year and spends the rest of the year in resting sites. In Sunn pest management programs, the pest populations in the fields are estimated by monitoring populations in the resting sites. The objectives of this study were to find variables associated with Sunn pest resting sites, using statistical tools and a geographic information system; and predict resting sites using these variables. This study was conducted in East Azarbaijan province of Iran. Six hundred points were sampled during a three year study. The twelve topographic and environmental variables including elevation, relative elevation, slope, aspect, north–south aspect data, landshape, slope steepness, slope configuration, topographic position, soil moisture potential, sun index and normalized difference vegetation index (NDVI) were examined. The models and variables were evaluated using corrected Akaike’s information criterion (AICC). NDVI, relative elevation, elevation, topographic position, soil moisture potential, north–south aspect and aspect which had high AICC weight were used in the prediction model. The resting sites of Sunn pest in Marand County of East Azarbaijan province was predicted using the model obtained with the purpose of testing it. Comparing the predicted resting sites with the actual ones revealed that large parts of the predicted areas in south were in accordance with the actual resting sites in Marand. The generated prediction map for E. integriceps can have several applications. Targeted monitoring and management of overwintering populations of Sunn pest using this map will save time and money.

Influence of ocean and freshwater conditions on Columbia River sockeye salmonOncorhynchus nerkaadult return rates

In recent years, returns of adult sockeye salmon Oncorhynchus nerka to the Columbia River Basin have reached numbers not observed since the 1950s. To understand factors related to these increased returns, we first looked for changes in freshwater production and survival of juvenile migrants. We then evaluated productivity changes by estimating smolt-to-adult return rates (SAR) for juvenile migration years 1985–2010. We found SAR varied between 0.2 and 23.5%, with the highest values coinciding with recent large adult returns. However, the largest adult return, in 2012, resulted not from increased survival, but from increased smolt production. We evaluated 19 different variables that could influence SARs, representing different facets of freshwater and ocean conditions. We used model selection criteria based on small-sample corrected AIC to evaluate the relative performance of all two- and three-variable models. The model with April upwelling, Pacific Northwest Index (PNI) in the migration year, and PNI in the year before migration had 10 times the AICc weight as the second-best-supported model, and R2 = 0.82. The variables of April ocean upwelling and PNI in the migration year had high weights of 0.996 and 0.927, respectively, indicating they were by far the best of the candidate variables to explain variations in SAR. While our analyses were primarily correlative and limited by the type and amount of data currently available, changes in ocean conditions in the northern California Current system, as captured by April upwelling and PNI, appeared to play a large role in the variability of SAR.

Importance of Biogeomorphic and Spatial Properties in Assessing a Tidal Salt Marsh Vulnerability to Sea-level Rise

We evaluated the biogeomorphic processes of a large (309 ha) tidal salt marsh and examined factors that influence its ability to keep pace with relative sea-level rise (SLR). Detailed elevation data from 1995 and 2008 were compared with digital elevation models (DEMs) to assess marsh surface elevation change during this time. Overall, 37 % (113 ha) of the marsh increased in elevation at a rate that exceeded SLR, whereas 63 % (196 ha) of the area did not keep pace with SLR. Of the total area, 55 % (169 ha) subsided during the study period, but subsidence varied spatially across the marsh surface. To determine which biogeomorphic and spatial factors contributed to measured elevation change, we collected soil cores and determined percent and origin of organic matter (OM), particle size, bulk density (BD), and distance to nearest bay edge, levee, and channel. We then used Akaike Information Criterion (AICc) model selection to assess those variables most important to determine measured elevation change. Soil stable isotope compositions were evaluated to assess the source of the OM. The samples had limited percent OM by weight (<5.5 %), with mean bulk densities of 0.58 g cm-3, indicating that the soils had high mineral content with a relatively low proportion of pore space. The most parsimonious model with the highest AICc weight (0.53) included distance from bay's edge (i.e., lower intertidal) and distance from levee (i.e., upper intertidal). Close proximity to sediment source was the greatest factor in determining whether an area increased in elevation, whereas areas near landward levees experienced subsidence. Our study indicated that the ability of a marsh to keep pace with SLR varied across the surface, and assessing changes in elevation over time provides an alternative method to long-term accretion monitoring. SLR models that do not consider spatial variability of biogeomorphic and accretion processes may not correctly forecast marsh drowning rates, which may be especially true in modified and urbanized estuaries. In light of SLR, improving our understanding of elevation change in these dynamic marsh systems will play a crucial role in forecasting potential impacts to their sustainability and the survival of these ecosystems.

Survival of resident and translocated greater sage‐grouse in Strawberry Valley, Utah: A 13‐year study

AbstractSurvival of greater sage‐grouse (Centrocercus urophasianus) has been well described in large populations across the species range. Very little published information exists, however, on survival rates of translocated sage‐grouse or grouse from a long‐term (&gt;10 yr) study. Our objectives were to estimate seasonal and annual survival rates; assess differences in survival between resident and translocated, adult and yearling, and male and female sage‐grouse; identify environmental and behavioral factors associated with survival; and assess the influence of mammalian predator control on survival rates of radio‐marked sage‐grouse in Strawberry Valley, Utah from 1998 to 2010. We used a 2‐stage model selection approach using Akaike's Information Criterion corrected for sample size (AICc) with known‐fate models in Program MARK to evaluate the influences of seasonal, annual, demographic, and behavioral effects on survival rates of sage‐grouse. We captured and fitted 535 individual sage‐grouse (male and female, resident and translocated) with radio transmitters over a 13‐year period and monitored them weekly. The top model of survival, which accounted for 22% of the AICc weight, included 3 seasons that varied by year where rates were influenced by residency, sex, and whether a female initiated a nest. A group‐level covariate for the number of canids killed each year received some support as this variable improved model fit compared to identical models without it, although confidence intervals around β estimates overlapped zero slightly. All other demographic or environmental variables showed little or no support. Annual estimates of survival for females ranged between 28% and 84% depending on year and translocation source. Survival was consistently highest during the fall–winter months with a mean monthly survival rate of 0.97 (95% CI = 0.96–0.98). The lack of a control site and other potential confounding factors limit the extent of our inference with respect to predator control. Nonetheless, we suggest managers consider enhancing nesting habitat, translocating sage‐grouse, and possibly controlling predators to improve survival rates of sage‐grouse. © The Wildlife Society, 2013

The island species–area relationship: biology and statistics

AbstractAim We conducted the most extensive quantitative analysis yet undertaken of the form taken by the island species–area relationship (ISAR), among 20 models, to determine: (1) the best‐fit model, (2) the best‐fit model family, (3) the best‐fit ISAR shape (and presence of an asymptote), (4) system properties that may explain ISAR form, and (5) parameter values and interpretation of the logarithmic implementation of the power model.Location World‐wide.Methods We amassed 601 data sets from terrestrial islands and employed an information‐theoretic framework to test for the best‐fit ISAR model, family, and shape, and for the presence/absence of an asymptote. Two main criteria were applied: generality (the proportion of cases for which the model provided an adequate fit) and efficiency (the overall probability of a model, when adequate, being the best at explaining ISARs; evaluated using the mean overall AICc weight). Multivariate analyses were used to explore the potential of island system properties to explain trends in ISAR form, and to describe variation in the parameters of the logarithmic power model.Results Adequate fits were obtained for 465 data sets. The simpler models performed best, with the power model ranked first. Similar results were obtained at model family level. The ISAR form is most commonly convex upwards, without an asymptote. Island system traits had low descriptive power in relation to variation in ISAR form. However, the z and c parameters of the logarithmic power model show significant pattern in relation to island system type and taxon.Main conclusions Over most scales of space, ISARs are best represented by the power model and other simple models. More complex, sigmoid models may be applicable when the spatial range exceeds three orders of magnitude. With respect to the log power model, z‐values are indicative of the process(es) establishing species richness and composition patterns, while c‐values are indicative of the realized carrying capacity of the system per unit area. Variation in ISAR form is biologically meaningful, but the signal is noisy, as multiple processes constrain the ecological space available within island systems and the relative importance of these processes varies with the spatial scale of the system.