Modeling connectivity in landscape genetics: applications, optimization and assessing uncertainty

Connectivity modeling and corridor identification are an essential part of landscape genetics and important tools for the future of conservation biology. The previous decade has shown a steadily increasing interest and rise in publications in landscape genetics. This enthusiasm has led to advances in the methods and theoretical background of the field; however, there remain important, yet unresolved, challenges. Many of these are related to validation and uncertainty testing for resistance surfaces (hypotheses of connectivity). These fundamental issues need to be addressed before landscape genetics can gain the full recognition of a scientific discipline such as population genetics or landscape ecology. The results herein not only describe the application of traditional landscape genetic techniques to empirical data, but also explore two new major approaches to improving connectivity modeling and corridor identification. In the first new approach, general theory is advanced using resistant kernel modeling by assessing a wide range of potential resistance surfaces to broadly model species distribution, connectivity, and response to habitat fragmentation and loss. Resistant kernel models allow generality across several species based on abiotic (human footprint) and life-history traits (dispersal ability and population size) for the entire Western United States. The second approach is to introduce a genetic algorithm for optimizing the process of resistance map fitting to empirical data. Optimization has three benefits. The first is removing the potential bias of expert opinion. The second is making possible multimethod evaluations of model uncertainty using different statistical tests, genetic distance metrics, and connectivity models. Lastly, optimization allows one to compare a large number of models enabling sensitivity analysis testing (e.g. leave-one-out populations, loci, or individuals). Together optimization and sensitivity analysis provide better, and more consistent, identification of landscape corridors and illustrate where models fail due to sensitivity to noisy genetic data. Described herein is a more rigorous framework of resistance map fitting and testing to help alleviate drawing faulty inferences in landscape genetic studies

Lighting The Way To Solar: A Guide On Residential Solar Incentives For Those Who Call Normal, Il Home.

The path to installing a solar photovoltaic (PV) system on one’s own roof can be both confusing and expensive. Although the cost of solar is declining, it remains a barrier to many potential adopters. To combat this and promote clean energy, the government at both state and federal levels offer incentives including personal tax credits, direct cash payments, loan programs and solar renewable energy credits. This research study pertains to single family homeowners serviced by the Ameren utility company in Normal, IL. However, the framework of this study may be applicable to other residents within the United States who want to understand what incentive structures are available to them. After explaining the incentives that are available, this study works to match the most compatible incentives with single-family homeowners. These groups are then used as representatives in our System Advisor Models (SAM) which are generated for each group paired with each incentive with all other parameters equal at a specified standard. Through comparative analysis, financial feasibility is determined based on the incentives impact on initial costs of installation and simple payback period. The significance of this study is to show residents what the available options are, along with the benefits in hopes of increasing the rate of residential solar adoption in Normal, IL.https://ir.library.illinoisstate.edu/urs2021tec/1003/thumbnail.jp

The Mid-IR Spectral Effects of Darkening Agents and Porosity on the Silicate Surface Features of Airless Bodies

We systematically measured the mid-IR spectra of different mixtures of three silicates (antigorite, lizardite, and pure silica) with varying effective porosities and amounts of darkening agent (iron oxide and carbon). These spectra have broad implications for interpretation of current and future mission data for airless bodies, as well as for testing the capabilities of new instruments. Serpentines, such as antigorite and lizardite, are common to airless surfaces, and their mid-IR spectra in the presence of darkening agents and different surface porosities would be typical for those measured by spacecraft. Silica has only been measured in the plumes of Enceladus and presents exciting possibilities for other Saturn-system surfaces due to long range transport of E-ring material. Results show that the addition of the IR-transparent salt, KBr, to simulate surface porosity affected silicate spectra in ways that were not predictable from linear mixing models. The strengthening of silicate bands with increasing pore space, even when only trace amounts of KBr were added, indicates that spectral features of porous surfaces are more detectable in the mid-IR. Combining iron oxide with the pure silicates seemed to flatten most of the silicate features, but strengthened the reststrahlen band of the silica. Incorporating carbon with the silicates weakened all silicate features, but the silica bands were more resistant to being diminished, indicating silica may be more detectable in the mid-IR than the serpentines. We show how incorporating darkening agents and porosity provides a more complete explanation of the mid-IR spectral features previously reported on worlds such as Iapetus

Endogenic and Exogenic Contributions to Visible-wavelength Spectra of Europa’s Trailing Hemisphere

The composition of Europa's trailing hemisphere reflects the combined influences of endogenous geologic resurfacing and exogenous sulfur radiolysis. Using spatially resolved visible-wavelength spectra of Europa obtained with the Hubble Space Telescope, we map multiple spectral features across the trailing hemisphere and compare their geographies with the distributions of large-scale geology, magnetospheric bombardment, and surface color. Based on such comparisons, we interpret some aspects of our spectra as indicative of purely exogenous sulfur radiolysis products and other aspects as indicative of radiolysis products formed from a mixture of endogenous material and magnetospheric sulfur. The spatial distributions of two of the absorptions seen in our spectra—a widespread downturn toward the near-UV and a distinct feature at 530 nm—appear consistent with sulfur allotropes previously suggested from ground-based spectrophotometry. However, the geographies of two additional features—an absorption feature at 360 nm and the spectral slope at red wavelengths—are more consistent with endogenous material that has been altered by sulfur radiolysis. We suggest irradiated sulfate salts as potential candidates for this material, but we are unable to identify particular species with the available data

Follow the Oxygen: Comparative Histories of Planetary Oxygenation and Opportunities for Aerobic Life

Aerobic respiration—the reduction of molecular oxygen (O_2) coupled to the oxidation of reduced compounds such as organic carbon, ferrous iron, reduced sulfur compounds, or molecular hydrogen while conserving energy to drive cellular processes—is the most widespread and bioenergetically favorable metabolism on Earth today. Aerobic respiration is essential for the development of complex multicellular life; thus the presence of abundant O_2 is an important metric for planetary habitability. O_2 on Earth is supplied by oxygenic photosynthesis, but it is becoming more widely understood that abiotic processes may supply meaningful amounts of O_2 on other worlds. The modern atmosphere and rock record of Mars suggest a history of relatively high O2 as a result of photochemical processes, potentially overlapping with the range of O_2 concentrations used by biology. Europa may have accumulated high O_2 concentrations in its subsurface ocean due to the radiolysis of water ice at its surface. Recent modeling efforts suggest that coexisting water and O2 may be common on exoplanets, with confirmation from measurements of exoplanet atmospheres potentially coming soon. In all these cases, O_2 accumulates through abiotic processes—independent of water-oxidizing photosynthesis. We hypothesize that abiogenic O_2 may enhance the habitability of some planetary environments, allowing highly energetic aerobic respiration and potentially even the development of complex multicellular life which depends on it, without the need to first evolve oxygenic photosynthesis. This hypothesis is testable with further exploration and life-detection efforts on O_2-rich worlds such as Mars and Europa, and comparison to O_2-poor worlds such as Enceladus. This hypothesis further suggests a new dimension to planetary habitability: “Follow the Oxygen,” in which environments with opportunities for energy-rich metabolisms such as aerobic respiration are preferentially targeted for investigation and life detection

Numerical simulation of transom-stern waves

The flow field generated by a transom-stern hullform is a complex, broad-banded, three-dimensional phenomenon marked by a large breaking wave. This unsteady multiphase turbulent flow feature is difficult to study experimentally and simulate numerically. The results of a set of numerical simulations, which use the Numerical Flow Analysis (NFA) code, of the flow around the Model 5673 transom stern at speeds covering both wet- and dry-transom operating conditions are shown in the accompanying fluid dynamics video. The numerical predictions for wet-transom and dry-transom conditions are presented to demonstrate the current state of the art in the simulation of ship generated breaking waves. The interested reader is referred to Drazen et al. (2010) for a detailed and comprehensive comparison with experiments conducted at the Naval Surface Warfare Center Carderock Division (NSWCCD).Comment: Fluid Dynamics Video for 2010 APS Division of Fluid Dynamics Gallery of Fluid Motion include