Calls for transforming biological curricula have emphasized a need for improving quantitative skill development in STEM education. To address this, we designed six interdisciplinary modules to develop quantitative reasoning competencies for a sophomore-level Cell Biology course. After a comprehensive curriculum alignment procedure between a four-year institution and its primary community college sending institutions, we determined module topics, then developed and implemented the modules. We assessed the effects of the modules on student proficiencies using validated pre-post measurements of specific quantitative competencies. Students showed significant total growth in quantitative goals for all modules and for each module individually, even though modules varied widely in difficulty. Transfer students were equally able as direct entry students to gain in quantitative proficiency across the modules, which is an improvement over the findings of a previous study. Additionally, both transfer and direct entry students exposed to more modules had a higher score on a global assessment of quantitative and biological concepts. Attitude assessments showed that students had an overall positive experience with the modules. Our results suggest that adding quantitative modules to core biology courses can promote student understanding of quantitative concepts for both direct entry and transfer students and can benefit transfer students in particular.

Female song has been significantly understudied compared with male song, and our understanding of how this elaborate signal trait may function has been limited as a result. Reconstruction of ancestral singing behaviors indicate that Orchard Orioles ( Icterus spurius ) have reduced female song compared with tropical ancestors. In this study, we found that male and female orioles on their breeding territories responded more strongly by all metrics to male song playback than to female song playback. Given the high degree of qualitative variation in female song and the reduced response to female playback, our results suggest that female song in Orchard Orioles may be under relaxed selection pressure. Sexual dimorphism in the complexity and frequency of songs in many lineages likely evolved as a result of a reduction or loss of female song. However, little research has investigated the functional significance of these reduced or infrequent female songs. More research is required to investigate the specific selection pressures that may be acting on female singing behavior in songbirds.

The introduction of nonnative grazers and plants, as well as alterations to native fire regimes in grassland systems, can directly and indirectly affect the abundance of arthropods. In this study, we used sweep-net sampling at two sites occupied by the critically endangered Florida grasshopper sparrow (Ammodramus savannarum floridanus Mearns) in Osceola County, Florida, to assess how the abundance of all arthropods (orders pooled) and the four most common arthropod orders varied between native dry prairie and semi-improved cattle pasture habitat (2015-2016). We also examined the role of time since fire and fire season on arthropod abundance in both habitat types. The abundance of all arthropods, Hemiptera, Orthoptera, and Coleoptera was higher in pasture than dry prairie, but the mean body length of Orthoptera was smaller in pasture. Fire year and fire season did not affect arthropod abundance when data from both sites were combined. However, when examined separately, Orthoptera at the dry prairie site were more abundant in habitat burned in the current year than previous years, supporting the hypothesis that Florida grasshopper sparrows preferentially select recently burned prairies because they support greater resource availability. Orthoptera at the pasture site showed no significant response to fire year or season. This study is important because it is the first to compare arthropod prey abundance for Florida grasshopper sparrows across dry prairie and pasture habitat and has important implications for prescribed fire management.

Despite impressive results in restoring physical performance in rodent models, treatment with renin–angiotensin system (RAS) inhibitors, such as Lisinopril, have highly mixed results in humans, likely, in part, due to genetic variation in human populations. To date, the genetic determinants of responses to drugs, such as RAS inhibitors, remain unknown. Given the complexity of the relationship between physical traits and genetic background, genomic studies which predict genotype- and age-specific responses to drug treatments in humans or vertebrate animals are difficult. Here, using 126 genetically distinct lines of Drosophila melanogaster, we tested the effects of Lisinopril on age-specific climbing speed and endurance. Our data show that functional response and sensitivity to Lisinopril treatment ranges from significant protection against physical decline to increased weakness depending on genotype and age. Furthermore, genome-wide analyses led to identification of evolutionarily conserved genes in the WNT signaling pathway as being significantly associated with variations in physical performance traits and sensitivity to Lisinopril treatment. Genetic knockdown of genes in the WNT signaling pathway, Axin, frizzled, nemo, and wingless, diminished or abolished the effects of Lisinopril treatment on climbing speed traits. Our results implicate these genes as contributors to the genotype- and age-specific effects of Lisinopril treatment and because they have orthologs in humans, they are potential therapeutic targets for improvement of resiliency. Our approach should be widely applicable for identifying genomic variants that predict age- and sex-dependent responses to any type of pharmaceutical treatment.

Abstract Background The innate immune response is an evolutionarily conserved process that is essential for survival in multicellular organisms. As individuals age, immune functions decline, a phenomenon known as immunosenescence, reducing one’s ability to fight infections. While immunosenescence is a universal feature of aging, the rate at which immune functions decline with age varies greatly among individuals and this variation has a genetic component. However, we have limited knowledge of the actual genes that contribute to this variation. Methods Here, we used 183 genetically distinct genotypes of the Drosophila Genetic Reference panel (DGRP) to assess their ability to clear an infection at one and five weeks of age. We then carried out a genome-wide association study (GWAS) to identify candidate genes that contribute to differences in immune responses among genotypes at each age. Results We found that, on average, the ability to clear infection declined by 70% with age. However, the effect of age on clearance ability varied significantly among genotypes. We identified a total of 242 single nucleotide polymorphisms (SNPs) and 107 candidate genes associated with variation in clearance ability. Polymorphisms in 48 genes were associated with clearance in 1 week old flies and fifty-nine genes were associated with clearance ability at 5 weeks of age. Only one gene, a G-coupled protein receptor, CG31760, was a candidate at both ages. Of the 107 candidate genes, 25 were mapped to genetic networks. Conclusion Our results identify candidate genes that could be targets for age-appropriate therapeutic treatments to maintain or restore immune function in the elderly.

Emergent biological processes result from complex interactions within and across levels of biological organization, ranging from molecular to environmental dynamics. Powerful theories, database tools, and modeling methods have been designed to characterize network connections within levels, such as those among genes, proteins, biochemicals, cells, organisms, and species. Here, we propose that developing integrative models of organismal function in complex environments can be facilitated by taking advantage of these methods to identify key nodes of communication across levels of organization. Mapping key drivers or connections among levels of organization will provide data and leverage to model potential rule-sets by which organisms respond and adjust to perturbations at any level of biological organization.

Molecular identification is increasingly used to speed up biodiversity surveys and laboratory experiments. However, many groups of organisms cannot be reliably identified using standard databases such as GenBank or BOLD due to lack of sequenced voucher specimens identified by experts. Sometimes a large number of sequences are available, but with too many errors to allow identification. Here we address this problem for parasitoids of Drosophila by introducing a curated open-access molecular reference database, DROP (Drosophila parasitoids). Identifying Drosophila parasitoids is challenging and poses a major impediment to realize the full potential of this model system in studies ranging from molecular mechanisms to food webs, and in biological control of Drosophila suzukii. In DROP (http://doi.org/10.5281/zenodo.4519656), genetic data are linked to voucher specimens and, where possible, the voucher specimens are identified by taxonomists and vetted through direct comparison with primary type material. To initiate DROP, we curated 154 laboratory strains, 856 vouchers, 554 DNA sequences, 16 genomes, 14 transcriptomes, and 6 proteomes drawn from a total of 183 operational taxonomic units (OTUs): 114 described Drosophila parasitoid species and 69 provisional species. We found species richness of Drosophila parasitoids to be heavily underestimated and provide an updated taxonomic catalogue for the community. DROP offers accurate molecular identification and improves cross-referencing between individual studies that we hope will catalyze research on this diverse and fascinating model system. Our effort should also serve as an example for researchers facing similar molecular identification problems in other groups of organisms.

Populations with different densities often show genetically based differences in life histories. The divergent life histories could be driven by several agents of selection, one of which is variation in per-capita food levels. Its relationship with population density is complex, as it depends on overall food availability, individual metabolic demand, and food-independent factors potentially affecting density, such as predation intensity. Here, we present a case study of two populations of a small live-bearing freshwater fish, one characterized by high density, low predation risk, low overall food availability, and presumably low per-capita food levels, and the other by low density, high predation risk, high overall food availability, and presumably high per-capita food levels. Using a laboratory experiment, we examined whether fish from these populations respond differently to food limitation, and whether size at birth, a key trait with respect to density variation in this species, is associated with any such differential responses. While at the lower food level growth was slower, body size smaller, maturation delayed, and survival reduced in both populations, these fitness costs were smaller in fish from the high-density population. At low food, only 15% of high-density fish died, compared to 75% of low-density fish. This difference was much smaller at high food (0% vs. 15% mortality). The increased survival of high-density fish may, at least partly, be due to their larger size at birth. Moreover, being larger at birth enabled fish to mature relatively early even at the lower food level. We demonstrate that sensitivities to food limitation differ between study populations, consistent with selection for a greater ability to tolerate low per-capita food availability in the high-density population. While we cannot preclude other agents of selection from operating in these populations simultaneously, our results suggest that variation in per-capita food levels is one of those agents.

Phagocytosis is an essential function of the innate immune response. This process is carried out by phagocytic hemocytes whose primary function is to recognize a wide range of particles and destroy microbial pathogens. As organisms age, this process begins to decline, yet little is known about the underlying mechanisms or the genetic basis of immunosenescence. Here, an injection based in vivo phagocytosis assay is used to assess age related changes in different aspects of phagocytosis, such as binding, engulfment, and degradation of internalized particles, by quantifying phagocytic events in hemocytes in adult Drosophila. Drosophila melanogaster has become an ideal model to investigate age related changes in innate immune function for many reasons. For one, many genetic components and functions of the innate immune response, including phagocytosis, are evolutionarily conserved between Drosophila and mammals. Because of that, results obtained from using this protocol are likely to be widely relevant to understanding the age related changes in immune function in a variety of organisms. Additionally, we note that this method provides quantitative estimates of hemocyte phagocytic ability, which could be useful for a variety of research topics, and need not be limited to studies of aging.

Physical resiliency declines with age and comorbid conditions. In humans, angiotensin-converting enzyme (ACE) has been associated with attenuation of the decline in physical performance with age. ACE-inhibitor compounds, commonly prescribed for hypertension, often have beneficial effects on physical performance however the generality of these effects are unclear. Here, we tested the effects of the ACE-inhibitor Lisinopril on life span, and age-specific speed, endurance, and strength using three genotypes of the Drosophila melanogaster Genetic Reference Panel. We show that age-related decline in physical performance and survivorship varies with genetic background. Lisinopril treatment increased mean life span in all Drosophila Genetic Reference Panel lines, but its effects on life span, speed, endurance, and strength depended on genotype. We show that genotypes with increased physical performance on Lisinopril treatment experienced reduced age-related protein aggregation in muscle. Knockdown of skeletal muscle-specific Ance, the Drosophila ortholog of ACE, abolished the effects of Lisinopril on life span, implying a role for skeletal muscle Ance in survivorship. Using transcriptome profiling, we identified genes involved in stress response that showed expression changes associated with genotype and age-dependent responsiveness to Lisinopril. Our results demonstrate that Ance is involved in physical decline and demonstrate genetic variation in phenotypic responses to an ACE inhibitor.

Most organisms exhibit physiological decline with advancing age and understanding the causes of this decline is a fundamental goal of aging research. Insect models have been a key model for understanding the general process of aging (Hughes and Reynolds (Annu Rev Entomol 50:421–445, 2005); Lee et al. (Entomol Res 45:1–8, 2015)) although most studies to date have focused on understanding factors regulating life span. However, there is growing awareness that understanding the physiological and genetic basis of age-related decline in traits that influence healthspan (e.g., locomotion, and the immune response to infection) will provide new insight into the process of senescence. This chapter updates my previous review (Leips 2009) on the use of insects as models of immunosenescence. In preparing this update it became clear that while insects have provided insights into the causes of immunosenescence, they have yet to be fully exploited in this area. The hope is that by highlighting particular areas where insects have advanced our knowledge of immunosenescence, it will stimulate greater use of insects to address questions for which they are particularly well-suited.

Many studies have investigated species diversity patterns across space and time, but few have explored patterns of coexistence of tightly interacting species. We documented species diversity patterns in a host-parasitoid system across broad geographic location and seasons. We calculated species diversity (H and e(H)') and compared the relationship between community similarity and geographic distances of frugivorous Drosophila host (Diptera: Drosophilidae) and Leptopilina parasitoid (Hymenoptera: Figitidae) communities across Eastern North America, from New Hampshire to Florida, at two time points during the breeding season. We also analyzed the influence of environmental factors on species assemblages via constrained correspondence analysis and lastly calculated cluster dendrograms to identify potential host-parasitoid interactions. We found that the composition of Drosophila-Leptopilina communities varied significantly with latitude. Interestingly, diversity increased with increasing latitude, a trend counter to latitudinal patterns of diversity observed in many other taxa. We also found seasonal effects of monthly temperature range and precipitation on host biodiversity patterns across geographic locations. Cluster dendrograms nominated potential parasitoid-hosts and competitive interactions to be validated in the future studies. The present study fills an important gap of knowledge in North American Drosophila-Leptopilina species diversity patterns and lays the groundwork for future ecological and evolutionary studies in this system.

Multicellular organisms display an enormous range of life history (LH) strategies and present an evolutionary conundrum; despite strong natural selection, LH traits are characterized by high levels of genetic variation. To understand the evolution of life histories and maintenance of this variation, the specific phenotypic effects of segregating alleles and the genetic networks in which they act need to be elucidated. In particular, the extent to which LH evolution is constrained by the pleiotropy of alleles contributing to LH variation is generally unknown. Here, we review recent empirical results that shed light on this question, with an emphasis on studies employing genomic analyses. While genome-scale analyses are increasingly practical and affordable, they face limitations of genetic resolution and statistical power. We describe new research approaches that we believe can produce new insights and evaluate their promise and applicability to different kinds of organisms. Two approaches seem particularly promising: experiments that manipulate selection in multiple dimensions and measure phenotypic and genomic response and analytical approaches that take into account genome-wide associations between markers and phenotypes, rather than applying a traditional marker-by-marker approach.

Redesigning undergraduate biology courses to integrate quantitative reasoning and skill development is critical to prepare students for careers in modern medicine and scientific research. In this paper, we report on the development, implementation, and assessment of stand-alone modules that integrate quantitative reasoning into introductory biology courses. Modules are designed to improve skills in quantitative numeracy, interpreting data sets using visual tools, and making inferences about biological phenomena using mathematical/statistical models. We also examine demographic/background data that predict student improvement in these skills through exposure to these modules. We carried out pre/postassessment tests across four semesters and used student interviews in one semester to examine how students at different levels approached quantitative problems. We found that students improved in all skills in most semesters, although there was variation in the degree of improvement among skills from semester to semester. One demographic variable, transfer status, stood out as a major predictor of the degree to which students improved ( transfer students achieved much lower gains every semester, despite the fact that pretest scores in each focus area were similar between transfer and nontransfer students). We propose that increased exposure to quantitative skill development in biology courses is effective at building competency in quantitative reasoning.

The heparan sulfate proteoglycan syndecans are transmembrane proteins involved in multiple physiological processes, including cell-matrix adhesion and inflammation. Recent evidence from model systems and humans suggest that syndecans have a role in energy balance and nutrient metabolism regulation. However, much remains to be learned about the mechanisms through which syndecans influence these phenotypes. Previously, we reported that Drosophila melanogaster Syndecan (Sdc) mutants had reduced metabolic activity compared to controls. Here, we knocked down endogenous Sdc expression in the fat body (the functional equivalent of mammalian adipose tissue and liver) to investigate whether the effects on metabolism originate from this tissue. We found that knocking down Sdc in the fat body leads to flies with higher levels of glycogen and fat and that survive longer during starvation, likely due to their extra energy reserves and an increase in gluconeogenesis. However, compared to control flies, they are also more sensitive to environmental stresses (e.g. bacterial infection and cold) and have reduced metabolic activity under normal feeding conditions. Under the same conditions, fat-body Sdc reduction enhances expression of genes involved in glyceroneogenesis and gluconeogenesis and induces a drastic decrease in phosphorylation levels of AKT and extracellular signal regulated kinase 1/2 (ERK1/2). Altogether, these findings strongly suggest that Drosophila fat body Sdc is involved in a mechanism that shifts resources to different physiological functions according to nutritional status.

The genus Leptopilina has historically been a poorly understood group. However, some species of Leptopilina are among the best-known model organisms for studying host-parasitoid interactions. As there is no identification system for Leptopilina in any part of the United States, we review species that were collected throughout their range in Eastern North America and those commonly used in laboratories. We provide a key for seven species, L. boulardi, L. heterotoma, L. clavipes, L. victoriae, L. decemflagella sp. n., L. maia sp. n. and L. leipsi sp. n., the last three of which are newly described here. This study is the first of its kind for Leptopilina species in North America, as our review and key were developed by examining a large number of specimens collected across broad chronological and geographic scales. This allowed us to account for the phenotypic variation within species, and helped us discover diagnostic characters. The geographic distribution and taxonomic information from this review provides a solid foundation for future research on Leptopilina.

Critical behaviours such as predation and mate choice often depend on vision. Visual systems are sensitive to the spectrum of light in their environment, which can vary extensively both within and among habitats. Evolutionary changes in spectral sensitivity contribute to divergence and speciation. Spectral sensitivity of the retina is primarily determined by visual pigments, which are opsin proteins bound to a chromophore. We recently discovered that photoreceptors in different regions of the retina, which view objects against distinct environmental backgrounds, coexpress different pairs of opsins in an African cichlid fish, Metriaclima zebra. This coexpression tunes the sensitivity of the retinal regions to the corresponding backgrounds and may aid in detection of dark objects, such as predators. Although intraretinal regionalization of spectral sensitivity in many animals correlates with their light environments, it is unknown whether variation in the light environment induces developmentally plastic alterations of intraretinal sensitivity regions. Here, we demonstrate with fluorescent in situ hybridization and qPCR that the spectrum and angle of environmental light both influence the development of spectral sensitivity regions by altering the distribution and level of opsins across the retina. Normally, M. zebra coexpresses LWS opsin with RH2Aα opsin in double cones of the ventral but not the dorsal retina. However, when illuminated from below throughout development, adult M. zebra coexpressed LWS and RH2Aα in double cones both dorsally and ventrally. Thus, environmental background spectra alter the spectral sensitivity pattern that develops across the retina, potentially influencing behaviours and related evolutionary processes such as courtship and speciation.