Postzygotic isolation in Drosophila simulans and D. mauritiana

The study of speciation requires examination of barriers that produce and maintain species separation. Using Drosophila simulans and D. mauritiana, this thesis focuses on post-zygotic isolating mechanisms, which occur after the formation of interspecies hybrids. This study aims to examine the genetic causes of male hybrid sterility and decreased hybrid female lifespan. Quantitative trait locus (QTL) mapping using flies with an attached-X chromosome, identified seven autosomal QTLs that contribute to hybrid sterility. Separately, reduction in hybrid female lifespan was noted for females bearing an attached-X chromosome and was more severe in individuals who were mated. This reduction is caused by a recessive factor on the X chromosome interacting with a dominant autosomal factor. This study is the first to create a hybrid sterility QTL map in Drosophila simulans and D. mauritiana and also succeeded in characterizing the understudied phenomenon of reduced hybrid lifespan in this species pair

Use of Online Hybrid Supplemental Teaching in Field-Based Teacher Education Programs

University faculty who implement field-based teacher education programs experience challenges providing instruction for clinical, site-embedded university-based students. These issues can include a lack of common times to meet with students, limited access to meeting space to provide direct instruction, and changes in the school schedule. A number of these barriers may be addressed by adding elements of online instruction to traditional in-person classes, making the course, in effect, a hybrid one. In this study, the researchers analyzed the perspectives of university-based, special education focused instructors and clinical partners on the barriers, needs, benefits, and content related to implementing hybrid instruction in field-based settings. The hybrid content would supplement special education teacher education candidates\u27 learning as they developed their skills for supporting students with special needs. Five university faculty and two field-based PK-12 partners involved in special education teacher preparation participated in in-depth, open-ended phone interviews. Data analysis included identifying themes using a constant comparative qualitative approach. The participants recommended several supports they considered necessary for using technology to teach their students successfully. Rather than a temporary pandemic measure, the authors suggest that hybrid instruction offers a promising approach to support pre-service teachers in the field going forward

Chopping skyrmions from magnetic chiral domains with uniaxial stress in magnetic nanowire

<p>Results from log-linear models comparing visits to patches by <i>Notomys alexis</i> in different habitats and with and without predator odors.</p

Prey selection and dietary flexibility of three species of mammalian predator during an irruption of non-cyclic prey

Predators often display dietary shifts in response to fluctuating prey in cyclic systems, but little is known about predator diets in systems that experience non-cyclic prey irruptions. We tracked dietary shifts by feral cats (Felis catus), red foxes (Vulpes vulpes) and dingoes (Canis dingo) through a non-cyclic irruption of small mammalian prey in the Simpson Desert, central Australia. We predicted that all three predators would alter their diets to varying degrees as small mammals declined post irruption, and to test our predictions we live-trapped small mammals through the irruption event and collected scats to track predator diets. Red foxes and dingoes included a broader variety of prey in their diets as small mammals declined. Feral cats did not exhibit a similar dietary shift, but did show variable use and selectivity of small mammal species through the irruption cycle. Results were largely consistent with prior studies that highlighted the opportunistic feeding habits of the red fox and dingo. They also, however, showed that feral cats may exhibit less dietary flexibility in response to small mammal irruptions, emphasizing the importance of tracking predator diets before, during and after irruption events

Quantification of habitat fragmentation reveals extinction risk in terrestrial mammals

Although habitat fragmentation is often assumed to be a primary driver of extinction, global patterns of fragmentation and its relationship to extinction risk have not been consistently quantified for any major animal taxon. We developed high-resolution habitat fragmentation models and used phylogenetic comparative methods to quantify the effects of habitat fragmentation on the world's terrestrial mammals, including 4,018 species across 26 taxonomic Orders. Results demonstrate that species with more fragmentation are at greater risk of extinction, even after accounting for the effects of key macroecological predictors, such as body size and geographic range size. Species with higher fragmentation had smaller ranges and a lower proportion of high-suitability habitat within their range, andmost high-suitability habitat occurred outside of protected areas, further elevating extinction risk. Our models provide a quantitative evaluation of extinction risk assessments for species, allow for identification of emerging threats in species not classified as threatened, and provide maps of global hotspots of fragmentation for the world's terrestrial mammals. Quantification of habitat fragmentation will help guide threat assessment and strategic priorities for global mammal conservation

Editorial : Drivers of small-mammal community structure in tropical savannas

Tropical and subtropical savanna ecosystems (TSE; Figure 1) contribute 30% of terrestrial primary productivity globally (Grace et al., 2006), while covering 20% of the land area of the Neotropics, sub-Saharan Africa, southern Asia, and northern Australia (Bond, 2016). The tremendous productivity of intact TSE is consumed by—among others—a diverse mammalian fauna of small herbivores and omnivores and both native and domestic large herbivores. Much of it, though, is pre-emptively consumed by fire. Large fires are conspicuously concentrated in regions of TSE, particularly sub-Saharan Africa, the Cerrado of Brazil, and northern Australia (Giglio et al., 2021). Herbivores help shape fire regimes, and fire regimes in turn shape herbivory (Young et al., 2022). We opened this Research Topic because, relative to their counterparts in tropical forests and temperate grasslands, the ecological roles of smaller mammals (small rodents, marsupials, shrews, etc.) in TSE are poorly understood (Schieltz and Rubenstein, 2016). Our particular focus was what habitat-related factors drive species composition, abundance, diversity, and trophic and nontrophic relationships. We invited participation of small-mammal ecological researchers with field experience on all four continents hosting TSE.http://www.frontiersin.org/Ecology_and_Evolutionam2024Mammal Research InstituteZoology and EntomologyNon

Mesopredator management: effects of red fox control on the abundance, diet and use of space by feral cats

Apex predators are subject to lethal control in many parts of the world to minimize their impacts on human industries and livelihoods. Diverse communities of smaller predators&mdash;mesopredators&mdash;often remain after apex predator removal. Despite concern that these mesopredators may be \u27released\u27 in the absence of the apex predator and exert negative effects on each other and on co-occurring prey, these interactions have been little studied. Here, we investigate the potential effects of competition and intraguild predation between red foxes (Vulpes vulpes) and feral cats (Felis catus) in south-eastern Australia where the apex predator, the dingo (Canis dingo), has been extirpated by humans. We predicted that the larger fox would dominate the cat in encounters, and used a fox-removal experiment to assess whether foxes affect cat abundance, diet, home-range and habitat use. Our results provide little indication that intraguild predation occurred or that cats responded numerically to the fox removal, but suggest that the fox affects some aspects of cat resource use. In particular, where foxes were removed cats increased their consumption of invertebrates and carrion, decreased their home range size and foraged more in open habitats. Fox control takes place over large areas of Australia to protect threatened native species and agricultural interests. Our results suggest that fox control programmes could lead to changes in the way that cats interact with co-occurring prey, and that some prey may become more vulnerable to cat predation in open habitats after foxes have been removed. Moreover, with intensive and more sustained fox control it is possible that cats could respond numerically and alter their behaviour in different ways to those documented herein. Such outcomes need to be considered when estimating the indirect impacts of fox control. We conclude that novel approaches are urgently required to control invasive mesopredators at the same time, especially in areas where apex predators are absent

Aerosol-Assisted Chemical Vapor Deposited Thin Films for Space Photovoltaics

Copper indium disulfide thin films were deposited via aerosol-assisted chemical vapor deposition using single source precursors. Processing and post-processing parameters were varied in order to modify morphology, stoichiometry, crystallography, electrical properties, and optical properties in order to optimize device-quality material. Growth at atmospheric pressure in a horizontal hot-wall reactor at 395 C yielded best device films. Placing the susceptor closer to the evaporation zone and flowing a more precursor-rich carrier gas through the reactor yielded shinier, smoother, denser-looking films. Growth of (112)-oriented films yielded more Cu-rich films with fewer secondary phases than growth of (204)/(220)-oriented films. Post-deposition sulfur-vapor annealing enhanced stoichiometry and crystallinity of the films. Photoluminescence studies revealed four major emission bands (1.45, 1.43, 1.37, and 1.32 eV) and a broad band associated with deep defects. The highest device efficiency for an aerosol-assisted chemical vapor deposited cell was 1.03 percent

Episodic population fragmentation and gene flow reveal a trade-off between heterozygosity and allelic richness

In episodic environments like deserts, populations of some animal species exhibit irregular fluctuations such that populations are alternately large and connected or small and isolated. Such dynamics are typically driven by periodic resource pulses due, for example, to large but infrequent rainfall events. The repeated population bottlenecks resulting from fragmentation should lower genetic diversity over time, yet species undergoing these fluctuations appear to maintain high levels of genetic diversity. To resolve this apparent paradox, we simulated a metapopulation of constant size undergoing repeat episodes of fragmentation and change in gene flow to mimic outcomes experienced by mammals in an Australian desert. We show that episodic fragmentation and gene flow have contrasting effects on two measures of genetic diversity: heterozygosity and allelic richness. Specifically, fragmentation into many, small subpopulations, coupled with periods of infrequent gene flow, preserves allelic richness at the expense of heterozygosity. In contrast, fragmentation into a few, large subpopulations maintains heterozygosity at the expense of allelic richness. The strength of the trade-off between heterozygosity and allelic richness depends on the amount of gene flow and the frequency of gene flow events. Our results imply that the type of genetic diversity maintained among species living in strongly fluctuating environments will depend on the way populations fragment, with our results highlighting different mechanisms for maintaining allelic richness and heterozygosity in small, fragmented populations