Biology Commons^™

Why Did The Bear Cross The Road? Comparing The Performance Of Multiple Resistance Surfaces And Connectivity Modeling Methods, Samuel A. Cushman, Jesse S. Lewis, Erin Landguth

Biological Sciences Faculty Publications

There have been few assessments of the performance of alternative resistance surfaces, and little is known about how connectivity modeling approaches differ in their ability to predict organism movements. In this paper, we evaluate the performance of four connectivity modeling approaches applied to two resistance surfaces in predicting the locations of highway crossings by American black bears in the northern Rocky Mountains, USA. We found that a resistance surface derived directly from movement data greatly outperformed a resistance surface produced from analysis of genetic differentiation, despite their heuristic similarities. Our analysis also suggested differences in the performance of different connectivity …

Nmp-7 Inhibits Chronic Inflammatory And Neuropathic Pain Via Block Of Cab3.2 T-Type Calcium Channels And Activation Of Cb2 Receptors, N. Daniel Berger, Vinicius M. Gadotti, Ravil R. Petrov, Kevin Chapman, Philippe Diaz, Gerald W. Zamponi

Biological Sciences Faculty Publications

Background: T-type calcium channels and cannabinoid receptors are known to play important roles in chronic pain, making them attractive therapeutic targets. We recently reported on the design, synthesis and analgesic properties of a novel T-type channel inhibitor (NMP-7), which also shows mixed agonist activity on CB₁ and CB₂ receptors in vitro. Here, we analyzed the analgesic effect of systemically delivered NMP-7 (intraperitoneal (i.p.) or intragstric (i.g.) routes) on mechanical hypersensitivity in inflammatory pain induced by Complete Freund’s Adjuvant (CFA) and neuropathic pain induced by sciatic nerve injury.

Results: NMP-7 delivered by either i.p. or i.g. routes produced …

Experimental Evolution: Prospects And Challenges, Frank Rosenzweig, Gavin Sherlock

Biological Sciences Faculty Publications

No abstract provided.

Experimental Microbial Evolution: History And Conceptual Underpinnings, Julian Adams, Frank Rosenzweig

Biological Sciences Faculty Publications

We chronicle and dissect the history of the field of Experimental Microbial Evolution, beginning with work by Monod. Early research was largely carried out by microbiologists and biochemists, who used experimental evolutionary change as a tool to understand structure-function relationships. These studies attracted the interest of evolutionary biologists who recognized the power of the approach to address issues such as the tempo of adaptive change, the costs and benefits of sex, parallelism, and the role which contingency plays in the evolutionary process. In the 1980s and 1990s, an ever-expanding body of microbial, physiological and biochemical data, together with new technologies …

The Valley-Of-Death: Reciprocal Sign Epistasis Constrains Adaptive Trajectories In A Constant, Nutrient Limiting Environment, Kami E. Chiotti, Daniel J. Kvitek, Karen H. Schmidt, Gregory Koniges, Katja Schwartz, Elizabeth A. Donckels, Frank Rosenzweig, Gavin Sherlock

Biological Sciences Faculty Publications

The fitness landscape is a powerful metaphor for describing the relationship between genotype and phenotype for a population under selection. However, empirical data as to the topography of fitness landscapes are limited, owing to difficulties in measuring fitness for large numbers of genotypes under any condition. We previously reported a case of reciprocal sign epistasis (RSE), where two mutations individually increased yeast fitness in a glucose-limited environment, but reduced fitness when combined, suggesting the existence of two peaks on the fitness landscape. We sought to determine whether a ridge connected these peaks so that populations founded by one mutant could …

Astrocyte-Specific Regulation Of Hmecp2 Expression In Drosophila, David Hess-Homeier, Chia-Yu Fan, Tarun Gupta, Ann-Shyn Chiang, Sarah J. Certel

Biological Sciences Faculty Publications

Alterations in the expression of Methyl-CpG-binding protein 2 (MeCP2) either by mutations or gene duplication leads to a wide spectrum of neurodevelopmental disorders including Rett Syndrome and MeCP2 duplication disorder. Common features of Rett Syndrome (RTT), MeCP2 duplication disorder, and neuropsychiatric disorders indicate that even moderate changes in MeCP2 protein levels result in functional and structural cell abnormalities. In this study, we investigated two areas of MeCP2 pathophysiology using Drosophila as a model system: the effects of MeCP2 glial gain-of-function activity on circuits controlling sleep behavior, and the cell-type specific regulation of MeCP2 expression. In this study, we first examined …

Inter-Calibration Of Satellite Passive Microwave Land Observations From Amsr-E And Amsr2 Using Overlapping Fy3b-Mwri Sensor Measurements, Jinyang Du, John S. Kimball, Jiancheng Shi, Lucas Alan Jones, Shengli Wu, Ruijing Sun, Hu Yang

Biological Sciences Faculty Publications

The development and continuity of consistent long-term data records from similar overlapping satellite observations is critical for global monitoring and environmental change assessments. We developed an empirical approach for inter-calibration of satellite microwave brightness temperature (T_b) records over land from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) and Microwave Scanning Radiometer 2 (AMSR2) using overlapping Tb observations from the Microwave Radiation Imager (MWRI). Double Differencing (DD) calculations revealed significant AMSR2 and MWRI biases relative to AMSR-E. Pixel-wise linear relationships were established from overlapping T_b records and used for calibrating MWRI and AMSR2 records to the AMSR-E …

Retrievals Of All-Weather Daily Air Temperature Using Modis And Amsr-E Data, Keunchang Jang, Sinkyu Kang, John S. Kimball, Suk Young Hong

Biological Sciences Faculty Publications

Satellite optical-infrared remote sensing from the Moderate Resolution Imaging Spectroradiometer (MODIS) provides effective air temperature (T_a) retrieval at a spatial resolution of 5 km. However, frequent cloud cover can result in substantial signal loss and remote sensing retrieval error in MODIS T_a. We presented a simple pixel-wise empirical regression method combining synergistic information from MODIS Ta and 37 GHz frequency brightness temperature (T_b) retrievals from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) for estimating surface level T_a under both clear and cloudy sky conditions in the United …

Combining Demographic And Genetic Factors To Assess Population Vulnerability In Stream Species, Erin Landguth, C. C. Muhlfeld, R. S. Waples, L. Jones, Winsor H. Lowe, Diane C. Whited, J. Lucotch, H. Neville, Gordon Luikart

Biological Sciences Faculty Publications

Accelerating climate change and other cumulative stressors create an urgent need to understand the influence of environmental variation and landscape features on the connectivity and vulnerability of freshwater species. Here, we introduce a novel modeling framework for aquatic systems that integrates spatially explicit, individual-based, demographic and genetic (demogenetic) assessments with environmental variables. To show its potential utility, we simulated a hypothetical network of 19 migratory riverine populations (e.g., salmonids) using a riverscape connectivity and demogenetic model (CDFISH). We assessed how stream resistance to movement (a function of water temperature, fluvial distance, and physical barriers) might influence demogenetic connectivity, and hence, …

The Genomic Architecture Of Population Divergence Between Subspecies Of The European Rabbit, Miguel Carneiro, Frank W. Albert, Sandra Afonso, Ricardo J. Pereira, Hernan Burbano, Rita Campos, Jose Melo-Ferreira, Jose A. Blanco-Aguiar, Rafael Villafuerte, Michael W. Nachman, Jeffrey M. Good, Nuno Ferrand

Biological Sciences Faculty Publications

The analysis of introgression of genomic regions between divergent populations provides an excellent opportunity to determine the genetic basis of reproductive isolation during the early stages of speciation. However, hybridization and subsequent gene flow must be relatively common in order to localize individual loci that resist introgression. In this study, we used next-generation sequencing to study genome-wide patterns of genetic differentiation between two hybridizing subspecies of rabbits (Oryctolagus cuniculus algirus and O. c. cuniculus) that are known to undergo high rates of gene exchange. Our primary objective was to identify specific genes or genomic regions that have resisted …

Are Local Filters Blind To Provenance? Ant Seed Predation Suppresses Exotic Plants More Than Natives, Dean Pearson, Nadia S. Icasatti, Jose L. Hierro, Benjamin J. Bird

Biological Sciences Faculty Publications

The question of whether species’ origins influence invasion outcomes has been a point of substantial debate in invasion ecology. Theoretically, colonization outcomes can be predicted based on how species’ traits interact with community filters, a process presumably blind to species’ origins. Yet, exotic plant introductions commonly result in monospecific plant densities not commonly seen in native assemblages, suggesting that exotic species may respond to community filters differently than natives. Here, we tested whether exotic and native species differed in their responses to a local community filter by examining how ant seed predation affected recruitment of eighteen native and exotic plant …

Limitations To Estimating Bacterial Cross-Species Transmission Using Genetic And Genomic Markers: Inferences From Simulation Modeling, Julio A. Benavides, Paul C. Cross, Gordon Luikart, Scott Creel

Biological Sciences Faculty Publications

Cross-species transmission (CST) of bacterial pathogens has major implications for human health, livestock, and wildlife management because it determines whether control actions in one species may have subsequent effects on other potential host species. The study of bacterial transmission has benefitted from methods measuring two types of genetic variation: variable number of tandem repeats (VNTRs) and single nucleotide polymorphisms (SNPs). However, it is unclear whether these data can distinguish between different epidemiological scenarios. We used a simulation model with two host species and known transmission rates (within and between species) to evaluate the utility of these markers for inferring CST. …

Oroya Fever And Verruga Peruana: Bartonelloses Unique To South America, Michael F. Minnick, Burt E. Anderson, Amorce Lima, James M. Battisti, Phillip G. Lawyer, Richard J. Birtles

Biological Sciences Faculty Publications

Bartonella bacilliformis is the bacterial agent of Carrión's disease and is presumed to be transmitted between humans by phlebotomine sand flies. Carrión's disease is endemic to high-altitude valleys of the South American Andes, and the first reported outbreak (1871) resulted in over 4,000 casualties. Since then, numerous outbreaks have been documented in endemic regions, and over the last two decades, outbreaks have occurred at atypical elevations, strongly suggesting that the area of endemicity is expanding. Approximately 1.7 million South Americans are estimated to be at risk in an area covering roughly 145,000 km2 of Ecuador, Colombia, and Peru. Although disease …

Granivory Of Invasive, Naturalized, And Native Plants In Communities Differentially Susceptible To Invasion, B. M. Connolly, Dean Pearson, R. N. Mack

Biological Sciences Faculty Publications

Seed predation is an important biotic filter that can influence abundance and spatial distributions of native species through differential effects on recruitment. This filter may also influence the relative abundance of nonnative plants within habitats and the communities’ susceptibility to invasion via differences in granivore identity, abundance, and food preference. We evaluated the effect of postdispersal seed predators on the establishment of invasive, naturalized, and native species within and between adjacent forest and steppe communities of eastern Washington, USA that differ in severity of plant invasion. Seed removal from trays placed within guild-specific exclosures revealed that small mammals were the …

Morphological Variability In Tree Root Architecture Indirectly Affects Coexistence Among Competitors In The Understory, Erik T. Aschehoug, Ragan M. Callaway

Biological Sciences Faculty Publications

Interactions between plants can have strong effects on community structure and function. Variability in the morphological, developmental, physiological, and biochemical traits of plants can influence the outcome of plant interactions and thus have important ecological consequences. However, the ecological ramifications of trait variability in plants are poorly understood and have rarely been tested in the field. We experimentally tested the effects of morphological variation in root architecture of Quercus douglasii trees in the field on interactions between understory plants and community composition. Our results indicate that variability among Q. douglasii tree root systems initiates a striking reversal in the competitive …

Surface Water Inundation In The Boreal-Artic: Potential Impacts On Regional Methane Emissions, J. D. Watts, John S. Kimball, Annett Bartsch, Kyle C. Mcdonald

Biological Sciences Faculty Publications

Northern wetlands may be vulnerable to increased carbon losses from methane (CH₄), a potent greenhouse gas, under current warming trends. However, the dynamic nature of open water inundation and wetting/drying patterns may constrain regional emissions, offsetting the potential magnitude of methane release. Here we conduct a satellite data driven model investigation of the combined effects of surface warming and moisture variability on high northern latitude (45° N) wetland CH₄ emissions, by considering (1) sub-grid scale changes in fractional water inundation (Fw) at 15 day, monthly and annual intervals using 25 km resolution satellite microwave retrievals, and (2) …

Ex Uno Plures: Clonal Reinforcement Drives Evolution Of A Simple Microbial Community, Margie A. Kinnersley, Jared Wenger, Evgueny Kroll, Julian Adams, Gavin Sherlock, Frank Rosenzweig

Biological Sciences Faculty Publications

A major goal of genetics is to define the relationship between phenotype and genotype, while a major goal of ecology is to identify the rules that govern community assembly. Achieving these goals by analyzing natural systems can be difficult, as selective pressures create dynamic fitness landscapes that vary in both space and time. Laboratory experimental evolution offers the benefit of controlling variables that shape fitness landscapes, helping to achieve both goals. We previously showed that a clonal population of E. coli experimentally evolved under continuous glucose limitation gives rise to a genetically diverse community consisting of one clone, CV103, that …

Identification Of Novel Small Rnas And Characterization Of The 6s Rna Of Coxiella Burnetii, Indu Warrier, Linda D. Hicks, James M. Battisti, Rahul Raghavan, Michael F. Minnick

Biological Sciences Faculty Publications

Coxiella burnetii, an obligate intracellular bacterial pathogen that causes Q fever, undergoes a biphasic developmental cycle that alternates between a metabolically-active large cell variant (LCV) and a dormant small cell variant (SCV). As such, the bacterium undoubtedly employs complex modes of regulating its lifecycle, metabolism and pathogenesis. Small RNAs (sRNAs) have been shown to play important regulatory roles in controlling metabolism and virulence in several pathogenic bacteria. We hypothesize that sRNAs are involved in regulating growth and development of C. burnetii and its infection of host cells. To address the hypothesis and identify potential sRNAs, we subjected total RNA …

Spring Hydrology Determines Summer Net Carbon Uptake In Northern Ecosystems, Yonghong Yi, John S. Kimball, Rolf H. Reichle

Biological Sciences Faculty Publications

Increased photosynthetic activity and enhanced seasonal CO₂ exchange of northern ecosystems have been observed from a variety of sources including satellite vegetation indices (such as the normalized difference vegetation index; NDVI) and atmospheric CO₂ measurements. Most of these changes have been attributed to strong warming trends in the northern high latitudes (50° N). Here we analyze the interannual variation of summer net carbon uptake derived from atmospheric CO₂ measurements and satellite NDVI in relation to surface meteorology from regional observational records. We find that increases in spring precipitation and snow pack promote summer net carbon uptake of …

Octopamine Neuromodulation Regulates Gr32a-Linked Aggression And Courtship Pathways In Drosophila Males, Jonathan C. Andrews, Maria Paz Fernàndez, Qin Yu, Gregory Patrick Leary, Adelaine K. W. Leung, Michael P. Kavanaugh, Edward A. Kravitz, Sarah J. Certel

Biological Sciences Faculty Publications

Chemosensory pheromonal information regulates aggression and reproduction in many species, but how pheromonal signals are transduced to reliably produce behavior is not well understood. Here we demonstrate that the pheromonal signals detected by Gr32a-expressing chemosensory neurons to enhance male aggression are filtered through octopamine (OA, invertebrate equivalent of norepinephrine) neurons. Using behavioral assays, we find males lacking both octopamine and Gr32a gustatory receptors exhibit parallel delays in the onset of aggression and reductions in aggression. Physiological and anatomical experiments identify Gr32a to octopamine neuron synaptic and functional connections in the suboesophageal ganglion. Refining the Gr32a-expressing population indicates that mouth Gr32a …

Structure Of A Mitochondrial Cytochrome C Conformer Competent For Peroxidase Activity, Levi J. Mcclelland, Tung-Chung Mou, Margaret E. Jeakins-Cooley, Stephen R. Sprang, Bruce E. Bowler

Biological Sciences Faculty Publications

At the onset of apoptosis, the peroxidation of cardiolipin at the inner mitochondrial membrane by cytochrome c requires an open coordination site on the heme. We report a 1.45-Å resolution structure of yeast iso-1-cytochrome c with the Met80 heme ligand swung out of the heme crevice and replaced by a water molecule. This conformational change requires modest adjustments to the main chain of the heme crevice loop and is facilitated by a trimethyllysine 72-to-alanine mutation. This mutation also enhances the peroxidase activity of iso-1-cytochrome c. The structure shows a buried water channel capable of facilitating peroxide access to the active …

Uncoupling Reproduction From Metabolism Extends Chronological Lifespan In Yeast, Saisubramanian Nagarajan, Arthur L. Kruckeberg, Karen H. Schmidt, Evgueny Kroll, Morgan Hamilton, Kate Mcinnerney, Ryan Summers, Timothy Taylor, Frank Rosenzweig

Biological Sciences Faculty Publications

Studies of replicative and chronological lifespan in Saccharomyces cerevisiae have advanced understanding of longevity in all eukaryotes. Chronological lifespan in this species is defined as the agedependent viability of nondividing cells. To date this parameter has only been estimated under calorie restriction, mimicked by starvation. Because postmitotic cells in higher eukaryotes often do not starve, we developed a model yeast system to study cells as they age in the absence of calorie restriction. Yeast cells were encapsulated in a matrix consisting of calcium alginate to form ~3 mm beads that were packed into bioreactors and fed ad libitum. Under these …

A Satellite Data Driven Biophysical Modeling Approach For Estimating Northern Peatland And Tundra Co2 And Ch4 Fluxes, J. D. Watts, John S. Kimball, F. J. W. Parmentier, T. Sachs, J. Rinne, D. Zona, W. Oechel, T. Tagesson, M. Jackowicz-Korczynski, M. Aurela

Biological Sciences Faculty Publications

The northern terrestrial net ecosystem carbon balance (NECB) is contingent on inputs from vegetation gross primary productivity (GPP) to offset the ecosystem respiration (Reco) of carbon dioxide (CO₂) and methane (CH₄) emissions, but an effective framework to monitor the regional Arctic NECB is lacking. We modified a terrestrial carbon flux (TCF) model developed for satellite remote sensing applications to evaluate wetland CO₂ and CH₄ fluxes over pan-Arctic eddy covariance (EC) flux tower sites. The TCF model estimates GPP, CO2 and CH4 emissions using in situ or remote sensing and reanalysis-based climate data as inputs. …

Inactivation Of Genes For Antigenic Variation In The Relapsing Fever Spirochete Borrelia Hermsii Reduces Infectivity In Mice And Transmission By Ticks, Sandra J. Raffel, James M. Battisti, Robert J. Fischer, Tom G. Schwan

Biological Sciences Faculty Publications

Borrelia hermsii, a causative agent of relapsing fever of humans in western North America, is maintained in enzootic cycles that include small mammals and the tick vector Ornithodoros hermsi. In mammals, the spirochetes repeatedly evade the host’s acquired immune response by undergoing antigenic variation of the variable major proteins (Vmps) produced on their outer surface. This mechanism prolongs spirochete circulation in blood, which increases the potential for acquisition by fast-feeding ticks and therefore perpetuation of the spirochete in nature. Antigenic variation also underlies the relapsing disease observed when humans are infected. However, most spirochetes switch off the bloodstream …

Snowshoe Hares Display Limited Phenotypic Plasticity To Mismatch In Seasonal Camouflage, Marketa Zimova, L. Scott Mills, Paul M. Lukacs, Michael S. Mitchell

Ecosystem and Conservation Sciences Faculty Publications

As duration of snow cover decreases owing to climate change, species undergoing seasonal colour moults can become colour mismatched with their background. The immediate adaptive solution to this mismatch is phenotypic plasticity, either in phenology of seasonal colour moults or in behaviours that reduce mismatch or its consequences. We observed nearly 200 snowshoe hares across a wide range of snow conditions and two study sites in Montana, USA, and found minimal plasticity in response to mismatch between coat colour and background. We found that moult phenology varied between study sites, likely due to differences in photoperiod and climate, but was …

Insights Into The Development And Evolution Of Exaggerated Traits Using De Novo Transcriptomes Of Two Species Of Horned Scarab Beetles, Ian A. Warren, J. Cristobal Vera, Annika Johns, Robert Zinna, James H. Marden, Douglas J. Emlen, Ian Dworkin, Laura C. Lavine

Biological Sciences Faculty Publications

Scarab beetles exhibit an astonishing variety of rigid exo-skeletal outgrowths, known as ‘‘horns’’. These traits are often sexually dimorphic and vary dramatically across species in size, shape, location, and allometry with body size. In many species, the horn exhibits disproportionate growth resulting in an exaggerated allometric relationship with body size, as compared to other traits, such as wings, that grow proportionately with body size. Depending on the species, the smallest males either do not produce a horn at all, or they produce a disproportionately small horn for their body size. While the diversity of horn shapes and their behavioural ecology …

A Broadly Implementable Research Course In Phage Discovery And Genomics For First-Year Undergraduate Students, Tuajuanda C. Jordan, Sandra H. Burnett, Susan Carson, Steven M. Caruso, Karl Clase, Randall J. Dejong, John J. Dennehy, Dee R. Denver, David Dunbar, Sarah C. R. Elgin, Ann M. Findley, Chris R. Gissendanner, Urszula P. Golebiewska, Nancy Guild, Grant A. Hartzog, Wendy H. Grillo, Gail P. Hollowell, Lee E. Hughes, Allison Johnson, Rodney A. King, Lynn O. Lewis T, Wei Li, Frank Rosenzweig, Michael R. Rubin, Margaret S. Saha, James Sandoz, Christopher D. Shaffer, Barbara Taylor, Louise Temple, Edwin Vazquez, Vassie C. Ware, Lucia P. Barker, Kevin W. Bradley, Deborah Jacobs-Sera, Welkin H. Pope, Daniel A. Russell, Steven G. Cresawn, David Lopatto, Cheryl P. Bailey, Graham F. Hatfull

Biological Sciences Faculty Publications

Engaging large numbers of undergraduates in authentic scientific discovery is desirable but difficult to achieve. We have developed a general model in which faculty and teaching assistants from diverse academic institutions are trained to teach a research course for first-year undergraduate students focused on bacteriophage discovery and genomics. The course is situated within a broader scientific context aimed at understanding viral diversity, such that faculty and students are collaborators with established researchers in the field. The Howard Hughes Medical Institute (HHMI) Science Education Alliance Phage Hunters Advancing Genomics and Evolutionary Science (SEA-PHAGES) course has been widely implemented and has been …

Examining Historical And Current Mixed-Severity Fire Regimes In Ponderosa Pine And Mixed-Conifer Forests Of Western North America, Dennis C. Odion, Chad T. Hanson, Andre Arsenault, William L. Baker, Dominick A. Dellasala, Richard L. Hutto, Walt Klenner, Max A. Moritz, Rosemary L. Sherriff, Thomas T. Veblen, Mark A. Williams

Biological Sciences Faculty Publications

There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine (Pinus ponderosa Dougl. ex. Laws) and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees. However, there is increasing recognition from landscape-scale assessments that, prior to any significant effects of fire exclusion, fires and forest structure were more variable in these forests. Biota in these forests are also dependent on the resources made available by higher-severity fire. A better understanding of …

Invasive Plant Erodes Local Song Diversity In A Migratory Passerine, Yvette K. Ortega, Aubree Benson, Erick Greene

Biological Sciences Faculty Publications

Exotic plant invasions threaten ecosystems globally, but we still know little about the specific consequences for animals. Invasive plants can alter the quality of breeding habitat for songbirds, thereby impacting important demographic traits such as dispersal, philopatry, and age structure. These demographic effects may in turn alter song-learning conditions to affect song structure and diversity. We studied Chipping Sparrows (Spizella passerina) breeding in six savannas that were either dominated by native vegetation or invaded by spotted knapweed (Centaurea stoebe), an exotic forb known to diminish food resources and reproductive success. Here, we report that the prevalence of older birds was …

Developmental Link Between Sex And Nutrition; Doublesex Regulates Sex-Specific Mandible Growth Via Juvenile Hormone Signaling In Stag Beetles, Hiroki Gotoh, Hitoshi Miyakawa, Asano Ishikawa, Yuki Ishikawa, Yasuhiro Sugime, Douglas J. Emlen, Laura C. Lavine, Toru Miura

Biological Sciences Faculty Publications

Sexual dimorphisms in trait expression are widespread among animals and are especially pronounced in ornaments and weapons of sexual selection, which can attain exaggerated sizes. Expression of exaggerated traits is usually male-specific and nutrition sensitive. Consequently, the developmental mechanisms generating sexually dimorphic growth and nutritiondependent phenotypic plasticity are each likely to regulate the expression of extreme structures. Yet we know little about how either of these mechanisms work, much less how they might interact with each other. We investigated the developmental mechanisms of sex-specific mandible growth in the stag beetle Cyclommatus metallifer, focusing on doublesex gene function and its …