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1. A new null model approach to quantify performance and significance for ecological niche models of species distributions

   https://doi.org/10.1111/jbi.13573  

   Bohl, Corentin L. ; Kass, Jamie M. ; Anderson, Robert P. ( May 2019 , Journal of Biogeography)

   Ecological niche modelling requires robust estimation of model performance and significance, but common evaluation approaches often yield biased estimates. Null models provide a solution but are rarely used in this field. We implemented an important modification to existing null model tests, evaluating null models with the same withheld records that were used to evaluate the real model. We built and evaluated models across a range of modelling scenarios and for various performance measures using the algorithmMaxentand the monk parakeet (Myiopsitta monachus).

   Native range in Southern America and global invasions predominantly in North/Central America and Europe.

   We tested the ability of models built under 15 scenarios (five sets of calibration records and three settings that varied the level of model complexity) to predict spatially independent evaluation data in the invaded range (in effect, testing the models under spatial transfer). We quantified performance with measures of discriminatory ability and overfitting based on area under the receiver operating characteristic curve (AUC) and the omission error rate. We estimated null distributions of these measures and calculated effect size and significance. We determined how these estimates varied across modelling scenarios, comparing with two tests existing in the literature.

   Performance varied starkly across modelling scenarios. As expected, the measures of overfitting agreed with each other and provided different information than that of discriminatory ability. However, high performance per se did not show strong association with high effect size and significance.

   Ecological niche models should be assessed with measures of effect size and significance based on appropriate null distributions, in contrast to several approaches existing in the literature. The proposed approach using independent evaluation data, implemented with our accompanying code and R package, allows such estimates for either the same or a different region/time period, and it merits use and continued development.

    

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2. Granular measures of agricultural land use influence lake nitrogen and phosphorus differently at macroscales

   https://doi.org/10.1002/eap.2187  

   Stachelek, Jemma ; Weng, W. ; Carey, C. C. ; Kemanian, A. R. ; Cobourn, K. M. ; Wagner, T. ; Weathers, K. C. ; Soranno, P. A. ( July 2020 , Ecological Applications)

   Agricultural land use is typically associated with high stream nutrient concentrations and increased nutrient loading to lakes. For lakes, evidence for these associations mostly comes from studies on individual lakes or watersheds that relate concentrations of nitrogen (N) or phosphorus (P) to aggregate measures of agricultural land use, such as the proportion of land used for agriculture in a lake’s watershed. However, at macroscales (i.e., in hundreds to thousands of lakes across large spatial extents), there is high variability around such relationships and it is unclear whether considering more granular (or detailed) agricultural data, such as fertilizer application, planting of specific crops, or the extent of near‐stream cropping, would improve prediction and inform understanding of lake nutrient drivers. Furthermore, it is unclear whether lake N and P would have different relationships to such measures and whether these relationships would vary by region, since regional variation has been observed in prior studies using aggregate measures of agriculture. To address these knowledge gaps, we examined relationships between granular measures of agricultural activity and lake total phosphorus (TP) and total nitrogen (TN) concentrations in 928 lakes and their watersheds in the Northeastern and Midwest U.S. using a Bayesian hierarchical modeling approach. We found that both lake TN and TP concentrations were related to these measures of agriculture, especially near‐stream agriculture. The relationships between measures of agriculture and lake TN concentrations were more regionally variable than those for TP. Conversely, TP concentrations were more strongly related to lake‐specific measures like depth and watershed hydrology relative to TN. Our finding that lake TN and TP concentrations have different relationships with granular measures of agricultural activity has implications for the design of effective and efficient policy approaches to maintain and improve water quality.

    

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3. Red riding on hood: exploring how galaxy colour depends on environment

   https://doi.org/10.1093/mnras/stad1218  

   Bhambhani, Pankaj C. ; Baldry, Ivan K. ; Brough, Sarah ; Hill, Alexander D. ; Lara-Lopez, M. A. ; Loveday, J. ; Holwerda, B. W. ( April 2023 , Monthly Notices of the Royal Astronomical Society)

   Galaxy populations are known to exhibit a strong colour bimodality, corresponding to blue star-forming and red quiescent subpopulations. The relative abundance of the two populations has been found to vary with stellar mass and environment. In this paper, we explore the effect of environment considering different types of measurements. We choose a sample of 49 911 galaxies with 0.05 < z < 0.18 from the Galaxy And Mass Assembly survey. We study the dependence of the fraction of red galaxies on different measures of the local environment as well as the large-scale `geometric’ environment defined by density gradients in the surrounding cosmic web. We find that the red galaxy fraction varies with the environment at fixed stellar mass. The red fraction depends more strongly on local environmental measures than on large-scale geometric environment measures. By comparing the different environmental densities, we show that no density measurement fully explains the observed environmental red fraction variation, suggesting the different measures of environmental density contain different information. We test whether the local environmental measures, when combined together, can explain all the observed environmental red fraction variation. The geometric environment has a small residual effect, and this effect is larger for voids than any other type of geometric environment. This could provide a test of the physics applied to cosmological-scale galaxy evolution simulations as it combines large-scale effects with local environmental impact.

    

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4. Weighting effective number of species measures by abundance weakens detection of diversity responses

   https://doi.org/10.1111/1365-2664.13345  

   Cao, Yong ; Hawkins, Charles P. ; Magrach, ed., Ainhoa ( February 2019 , Journal of Applied Ecology)

   The effective number of species (ENS) has been proposed as a robust measure of species diversity that overcomes several limitations in terms of both diversity indices and species richness (SR). However, it is not yet clear ifENSimproves interpretation and comparison of biodiversity monitoring data, and ultimately resource management decisions.

   We used simulations of five stream macroinvertebrate assemblages and spatially extensive field data of stream fishes and mussels to show (a) how differentENSformulations respond to stress and (b) how diversity–environment relationships change with values ofq, which weightENSmeasures by species abundances.

   Values ofENSderived from whole simulated assemblages with all species weighted equally (true SR) steadily decreased as stress increased, andENS‐stress relationships became weaker and more different among assemblages with increased weighting.

   The amount of variation inENSacross the fish and mussel assemblages that was associated with environmental gradients decreased with increasingq.

   Synthesis and applications. Species diversity is valued by many human societies, which often have policies designed to protect and restore it. Natural resources managers and policy makers may use species richness and diversity indices to describe the status of ecological communities. However, these traditional diversity measures are known subject to limitations that hinder their interpretation and comparability. The effective number of species (ENS) was proposed to overcome the limitations. Unfortunately, our analyses show thatENSdoes not improve interpretability of how species diversity responds to either stress or natural environmental gradients. Moreover, incorporating the relative abundance of individuals in different species (evenness) into diversity measures as implemented inENScan actually weaken detection of diversity responses. Natural resources managers and policy makers therefore need to be cautious when interpreting diversity measures, includingENS, whose values are jointly influenced by richness and evenness. We suggest that both researchers and practitioners measure and report three aspects of diversity (species richness, evenness, and composition) separately when assessing and monitoring the diversity of ecological communities.

    

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5. Comparing Subjective Similarity of Automated Driving Styles to Objective Distance-Based Similarity

   https://doi.org/10.1177/00187208221142126  

   Kamaraj, Amudha V. ; Lee, Joonbum ; Domeyer, Joshua E. ; Liu, Shu-Yuan ; Lee, John D. ( January 2023 , Human Factors: The Journal of the Human Factors and Ergonomics Society)

   This study explores subjective and objective driving style similarity to identify how similarity can be used to develop driver-compatible vehicle automation.

   Similarity in the ways that interaction partners perform tasks can be measured subjectively, through questionnaires, or objectively by characterizing each agent’s actions. Although subjective measures have advantages in prediction, objective measures are more useful when operationalizing interventions based on these measures. Showing how objective and subjective similarity are related is therefore prudent for aligning future machine performance with human preferences.

   A driving simulator study was conducted with stop-and-go scenarios. Participants experienced conservative, moderate, and aggressive automated driving styles and rated the similarity between their own driving style and that of the automation. Objective similarity between the manual and automated driving speed profiles was calculated using three distance measures: dynamic time warping, Euclidean distance, and time alignment measure. Linear mixed effects models were used to examine how different components of the stopping profile and the three objective similarity measures predicted subjective similarity.

   Objective similarity using Euclidean distance best predicted subjective similarity. However, this was only observed for participants’ approach to the intersection and not their departure.

   Developing driving styles that drivers perceive to be similar to their own is an important step toward driver-compatible automation. In determining what constitutes similarity, it is important to (a) use measures that reflect the driver’s perception of similarity, and (b) understand what elements of the driving style govern subjective similarity.

    

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