Natural History Note Differential Response To Circularly Polarized Light By The Jewel Scarab Beetle Chrysina Gloriosa

Circularly polarized light is rare in the terrestrial environment, and cuticular reflections from scarab beetles are one of the few natural sources. Chrysina gloriosa LeConte 1854, a scarab beetle found in montane juniper forests of the extreme southwestern United States and northern Mexico, are camouflaged in juniper foliage; however, when viewed with right circularly polarizing filters, the beetles exhibit a stark black contrast. Given the polarization-specific changes in the appearance of C. gloriosa, we hypothesized that C. gloriosa can detect circularly polarized light. We tested for phototactic response and differential flight orientation of C. gloriosa toward different light stimuli. Chrysina gloriosa exhibited (a) positive phototaxis, (b) differential flight orientation between linear and circularly polarized light stimuli of equal intensities, and (c) discrimination between circularly polarized and unpolarized lights of different intensities consistent with a model of circular polarization sensitivity based on a quarter-wave plate. These results demonstrate that C. gloriosa beetles respond differentially to circularly polarized light. In contrast, Chrysina woodi Horn 1885, a close relative with reduced circularly polarized reflection, exhibited no phototactic discrimination between linear and circularly polarized light. Circularly polarized sensitivity may allow C. gloriosa to perceive and communicate with conspecifics that remain cryptic to predators, reducing indirect costs of communication.Integrative Biolog

Poison Frog Colors Are Honest Signals Of Toxicity, Particularly For Bird Predators

Antipredator defenses and warning signals typically evolve in concert. However, the extensive variation across taxa in both these components of predator deterrence and the relationship between them are poorly understood. Here we test whether there is a predictive relationship between visual conspicuousness and toxicity levels across 10 populations of the color-polymorphic strawberry poison frog, Dendrobates pumilio. Using a mouse-based toxicity assay, we find extreme variation in toxicity between frog populations. This variation is significantly positively correlated with frog coloration brightness, a viewer-independent measure of visual conspicuousness (i.e., total reflectance flux). We also examine conspicuousness from the view of three potential predator taxa, as well as conspecific frogs, using taxon-specific visual detection models and three natural background substrates. We find very strong positive relationships between frog toxicity and conspicuousness for bird-specific perceptual models. Weaker but still positive correlations are found for crab and D. pumilio conspecific visual perception, while frog coloration as viewed by snakes is not related to toxicity. These results suggest that poison frog colors can be honest signals of prey unpalatability to predators and that birds in particular may exert selection on aposematic signal design.Integrative Biolog

Aposematic Signal Variation Predicts Male-Male Interactions in a Polymorphic Poison Frog

Many species use conspicuous “aposematic” signals to communicate unpalatability/unprofitability to potential predators. Although aposematic traits are generally considered to be classic examples of evolution by natural selection, they can also function in the context of sexual selection, and therefore comprise exceptional systems for understanding how conspicuous signals evolve under multifarious selection. We used males from a highly territorial poison frog species in a dichotomous choice behavioral test to conduct the first examination of how aposematic signal variation influences male–male interactions. Our results reveal two behavioral patterns: (1) male dorsal brightness influences the behaviors of male conspecifics such that males approach and call to brighter males more frequently and (2) a male\u27s dorsal brightness predicts his own behavior such that bright males approach stimulus frogs faster, direct more calls to bright stimulus frogs, and exhibit lower advertising call pulse rates (a fitness‐related trait). These findings indicate the potential for sexual selection by male–male competition to impact aposematic signal evolution

Preparing Teachers For Tomorrow: A Case Study of TEACH-NOW Graduate School of Education

Thesis advisor: Marilyn Cochran-SmithCurrent institutional and technological innovations are challenging face-to-face, college- and university-based teacher preparation programs as never before. Among those innovations are two emerging phenomena: New graduate schools of education (nGSEs) and fully online teacher preparation programs. nGSEs are new independent graduate schools that are not university-based but are state-authorized and approved as institutions of higher education to prepare teachers, endorse them for initial teacher certification, and grant master’s degrees (Cochran-Smith et al., 2019). Fully online teacher preparation programs are programs that relocate teacher preparation from the physical environments of the brick-and-mortar university to the digital environments of the internet and provide prospective teachers with flexible alternatives to face-to-face pathways. While both fully online teacher preparation programs and nGSEs have garnered enthusiastic media attention and critique, there is a very limited amount of in-depth knowledge about fully online teacher preparation programs and virtually no independent research on nGSEs. This dissertation helps to address those gaps in research. The central purpose of this dissertation was to examine the intersection of fully online teacher preparation and the phenomenon of teacher preparation at nGSEs by investigating teacher preparation at TEACH-NOW Graduate School of Education, a fully online, for-profit, nGSE headquartered in Washington, D.C. and rapidly expanding as a provider of initial teacher education. Intended to be descriptive and interpretive, this qualitative case study sought to understand the phenomenon of teacher preparation at TEACH-NOW from the perspectives of its participants. Based on qualitative analysis of multiple sources of evidence, the main argument of this dissertation is that TEACH-NOW operated at the nexus of a complex tension between the push to be innovative and the pull to be legitimate. Findings suggest that TEACH-NOW skillfully navigated that tension by establishing tight coherence around three key indicators of innovation (business model, technology, program structure) and by achieving major accepted markers of credibility within the larger teacher education organizational field. This dissertation also argues that TEACH-NOW’s approach to teacher preparation necessitated that teacher candidates self-manage their program experiences in accordance with their individual needs, circumstances, and preferences. The dissertation concludes with discussion of important themes and specific research, practice, and policy implications.Thesis (PhD) — Boston College, 2019.Submitted to: Boston College. Lynch School of Education.Discipline: Teacher Education, Special Education, Curriculum and Instruction

Polaro–cryptic mirror of the lookdown as a biological model for open ocean camouflage

With no object to hide behind in 3D space, the open ocean represents a challenging environment for camouflage. Conventional strategies for reflective crypsis (e.g., standard mirror) are effective against axially symmetric radiance fields associated with high solar altitudes, yet ineffective against asymmetric polarized radiance fields associated with low solar inclinations. Here we identify a biological model for polaro–crypsis. We measured the surface-reflectance Mueller matrix of live open ocean fish (lookdown, Selene vomer) and seagrass-dwelling fish (pinfish, Lagodon rhomboides) using polarization-imaging and modeling polarization camouflage for the open ocean. Lookdowns occupy the minimization basin of our polarization-contrast space, while pinfish and standard mirror measurements exhibit higher contrast values than optimal. The lookdown reflective strategy achieves significant gains in polaro–crypsis (up to 80%) in comparison with nonpolarization sensitive strategies, such as a vertical mirror. Lookdowns achieve polaro–crypsis across solar altitudes by varying reflective properties (described by 16 Mueller matrix elements mij) with incident illumination. Lookdowns preserve reflected polarization aligned with principle axes (dorsal–ventral and anterior–posterior, m22 = 0.64), while randomizing incident polarization 45° from principle axes (m33 = –0.05). These reflectance properties allow lookdowns to reflect the uniform degree and angle of polarization associated with high-noon conditions due to alignment of the principle axes and the sun, and reflect a more complex polarization pattern at asymmetrical light fields associated with lower solar elevations. Our results suggest that polaro–cryptic strategies vary by habitat, and require context-specific depolarization and angle alteration for effective concealment in the complex open ocean environment

Access to Primary Care: Comparing driving distance from Health Professional Shortage Area (HPSA) counties versus non-HPSA counties

The criteria used to identify Health Professional Shortage Areas dates back to the 1970’s and very little has changed since then. This study examined driving distance from patient address to provider address as one component of a geographical HPSA. Primary care-related services located in adjacent areas to whole-county HPSAs are considered excessively distant when travel time exceeds 30 minutes or the equivalent of 20 miles in this study. We found similarities in travel distance to primary care-related services from patients living in HPSA counties compared to those living in non-HPSA counties. This could indicate the need to re-examine HPSA definitions to more accurately identify truly underserved populations in rural areas

Identifying context-specific gene profiles of social, reproductive and mate preference behavior in a fish species with female mate choice

Sensory and social inputs interact with underlying gene suites to coordinate social behavior. Here we use a naturally complex system in sexual selection studies, the swordtail, to explore how genes associated with mate preference, receptivity, and social affiliation interact in the female brain under specific social conditions. We focused on 11genes associated with mate preference in this species (neuroserpin, neuroligin-3, NMDA receptor, tPA, stathmin-2, β-1 adrenergic receptor) or with female sociosexual behaviors in other taxa (vasotocin, isotocin, brain aromatase,α-1 adrenergic receptor, tyrosinehydroxylase). We exposed females to four social conditions, including pairings of differing mate choice complexity (large males, large/ small males, small males), and a social lcontrol (two females). Female mate preference differed significantly by context. Multiple discriminant analysis (MDA) of behaviors revealed a primary axis (explaining 50.2% between-group variance) highlighting differences between groups eliciting high preference behaviors (LL,LS) vs. other contexts, and a secondary axis capturing general measures distinguishing a non-favored group (SS) from other groups. Gene expression MDA revealed a major axis (68.4% between-group variance) that distinguished amongst differential male pairings and was driven by suites of “preference and receptivity genes”; whereas a second axis, distinguishing high affiliation groups (large males, females) from low (small males), was characterized by traditional affiliative-associated genes (isotocin, vasotocin). We found context-specific correlations between behavior and gene MDA, suggesting gene suites covary with behaviors in a socially relevant context. Distinct associations between “affiliative” and “preference” axes suggest mate preference maybe mediated by distinct clusters from those of social affiliation. Our results highlight the need to incorporate natural complexity of mating systems into behavioral genomics

Identifying Context-Specific Gene Profiles of Social, Reproductive, and Mate Preference Behavior in a Fish Species with Female Mate Choice

Sensory and social inputs interact with underlying gene suites to coordinate social behavior. Here we use a naturally complex system in sexual selection studies, the swordtail, to explore how genes associated with mate preference, receptivity, and social affiliation interact in the female brain under specific social conditions. We focused on 11 genes associated with mate preference in this species (neuroserpin, neuroligin-3, NMDA receptor, tPA, stathmin-2, β-1 adrenergic receptor) or with female sociosexual behaviors in other taxa (vasotocin, isotocin, brain aromatase, α-1 adrenergic receptor, tyrosine hydroxylase). We exposed females to four social conditions, including pairings of differing mate choice complexity (large males, large/small males, small males), and a social control (two females). Female mate preference differed significantly by context. Multiple discriminant analysis (MDA) of behaviors revealed a primary axis (explaining 50.2% between-group variance) highlighting differences between groups eliciting high preference behaviors (LL, LS) vs. other contexts, and a secondary axis capturing general measures distinguishing a non-favored group (SS) from other groups. Gene expression MDA revealed a major axis (68.4% between-group variance) that distinguished amongst differential male pairings and was driven by suites of “preference and receptivity genes”; whereas a second axis, distinguishing high affiliation groups (large males, females) from low (small males), was characterized by traditional affiliative-associated genes (isotocin, vasotocin). We found context-specific correlations between behavior and gene MDA, suggesting gene suites covary with behaviors in a socially relevant context. Distinct associations between “affiliative” and “preference” axes suggest mate preference may be mediated by distinct clusters from those of social affiliation. Our results highlight the need to incorporate natural complexity of mating systems into behavioral genomics

Sexual and social stimuli elicit rapid and contrasting genomic responses

Sensory physiology has been shown to influence female mate choice, yet little is known about the mechanisms within the brain that regulate this critical behaviour. Here we examine preference behaviour of 58 female swordtails, Xiphophorus nigrensis, in four different social environments (attractive and unattractive males, females only, non-attractive males only and asocial conditions) followed by neural gene expression profiling. We used a brain-specific cDNA microarray to identify patterns of genomic response and candidate genes, followed by quantitative PCR (qPCR) examination of gene expression with variation in behaviour. Our microarray results revealed patterns of genomic response differing more between classes of social stimuli than between presence versus absence of stimuli. We identified suites of genes showing diametrically opposed patterns of expression: genes that are turned ‘on’ while females interact with attractive males are turned ‘off’ when interacting with other females, and vice versa. Our qPCR results identified significant predictive relationships between five candidate genes and specific mate choice behaviours (preference and receptivity) across females exposed to males, with no significant patterns identified in female or asocial conditions or with overall locomotor activity. The identification of stimulus- and behaviour-specific responses opens an exciting window into the molecular pathways associated with social behaviour and mechanisms that underlie sexual selection