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A fully illustrated reference book giving an easy-to-understand introduction to compliant mechanisms A broad compilation of compliant mechanisms to give inspiration and guidance to those interested in using compliant mechanisms in their designs, the Handbook of Compliant Mechanisms includes graphics and descriptions of many compliant mechanisms. It comprises an extensive categorization of devices that can be used to help readers identify compliant mechanisms related to their application. It also provides chapters on the basic background in compliant mechanisms, the categories of compliant mechanisms, and an example of how the Compendium can be used to facilitate compliant mechanism design. * Fully illustrated throughout to be easily understood and accessible at introductory levels * Covers all aspects pertaining to classification, elements, mechanisms and applications of compliant mechanisms * Summarizes a vast body of knowledge in easily understood diagrams and explanations * Helps readers appreciate the advantages that compliant mechanisms have to offer * Practical approach is ideal for potential practitioners who would like to realize designs with compliant mechanisms, members and elements * Breadth of topics covered also makes the book a useful reference for more advanced readers Intended as an introduction to the area, the Handbook avoids technical jargon to assist non engineers involved in product design, inventors and engineers in finding clever solutions to problems of design and function.

Diversification rates vary greatly among taxa. Understanding how species-specific traits influence speciation rates will help elucidate mechanisms driving biodiversity over broad spatio-temporal scales. Ecological specialization and range size are two hypothesized drivers of speciation rates, yet each mechanism predicts both increases and decreases in speciation. We constructed a continuous index of specialization using avian bill morphology to determine the relative effect of specialization and range size and shape on speciation rates across 559 species within the Emberizoidea superfamily, a morphologically diverse New World clade. We found a significant positive correlation between specialization and speciation rate and a negative correlation with range size. Only the effect of specialization persisted after removing island endemics, however, suggesting that ecological specialization is an important driver of diversity across large macroevolutionary scales, and the relative importance of specific drivers may differ between islands and continents.

Humans are dominant global drivers of ecological and evolutionary change, rearranging ecosystems and natural selection. In the present article, we show increasing evidence that human activity also plays a disproportionate role in shaping the eco-evolutionary potential of systems—the likelihood of ecological change generating evolutionary change and vice versa. We suggest that the net outcome of human influences on trait change, ecology, and the feedback loops that link them will often (but not always) be to increase eco-evolutionary potential, with important consequences for stability and resilience of populations, communities, and ecosystems. We also integrate existing ecological and evolutionary metrics to predict and manage the eco-evolutionary dynamics of human-affected systems. To support this framework, we use a simple eco–evo feedback model to show that factors affecting eco-evolutionary potential are major determinants of eco-evolutionary dynamics. Our framework suggests that proper management of anthropogenic effects requires a science of human effects on eco-evolutionary potential.

While foraging, animals often trade off between food and safety, reducing feeding in response to increased predation risk. This response, however, may not be a viable option for animals that are energetically compromised. Many single-species studies have shown that hungry animals select habitats within which foraging opportunities are greater even if predation pressures are higher, but it is unclear whether these patterns can be extrapolated to entire communities. Here, we examined the stopover habitat use of 28 frugivorous landbird species along the coast of Maine, USA, during an energetically demanding period of the annual cycle, fall migration. Across 6 stopover sites, we determined whether or not a tradeoff existed between using safe habitat patches (patches with high woody plant stem density) and patches with high food resources (patches with high fruit abundance). Controlling for raptor abundance at a site, landbird migrants were captured at higher rates in sites where no tradeoff existed, suggesting that birds avoided staying in sites where there was a predation risk–foraging tradeoff. At all sites, regardless of the presence or absence of a tradeoff, longer-distance migrants used patches with high food availability more frequently than shorter-distance migrants; patch use by shorter-distance migrants was explained by habitat cover alone. Our findings suggest that, for the Gulf of Maine, birds reduce predation risk at the scale of a stopover site, and differences in habitat selection at finer patch scales are mediated by migration strategy.

A high performance asymmetric electrochemical supercapacitor with a mass loading of 10 mg·cm–² on each planar electrode has been fabricated by using a graphene–nickel cobaltite nanocomposite (GNCC) as a positive electrode and commercial activated carbon (AC) as a negative electrode. Due to the rich number of faradaic reactions on the nickel cobaltite, the GNCC positive electrode shows significantly higher capacitance (618 F·g-¹) than graphene–Co3O4 (340 F∙g-¹) and graphene–NiO (375 F∙g-¹) nanocomposites synthesized under identical conditions. More importantly, graphene greatly enhances the conductivity of nickel cobaltite and allows the positive electrode to charge/discharge at scan rates similar to commercial AC negative electrodes. This improves both the energy density and power density of the asymmetric cell. The asymmetric cell composed of 10 mg GNCC and 30 mg AC displayed an energy density in the range of 19.5 Wh∙kg-¹ with an operational voltage of 1.4 V. At high sweep rate, the system is capable of delivering an energy density of 7.6 Wh∙kg-¹ at a power density of about 5600 W∙kg-¹. Cycling results demonstrate that the capacitance of the cell increases to 116% of the original value after the first 1600 cycles due to a progressive activation of the electrode, and maintains 102% of the initial value after 10000 cycles

Natural hybrid zones can be used to dissect the mechanisms driving key evolutionary processes by allowing us to identify genomic regions important for establishing reproductive isolation and that allow for transfer of adaptive variation. We leverage wholegenome data in a system where two bird species, the saltmarsh (Ammospiza caudacuta) and Nelson’s (A. nelsoni) sparrow, hybridize despite their relatively high background genetic differentiation and past ecological divergence. Adaptive introgression is plausible in this system because Nelson’s sparrows are recent colonists of saltwater marshes, compared to the specialized saltmarsh sparrow that has a longer history of saltmarsh adaptation. Comparisons among whole-genome sequences of 34 individuals from allopatric and sympatric populations show that ongoing gene flow is shaping the genomic landscape, with allopatric populations exhibiting genome-wide F ST estimates close to double of that observed in sympatry. We characterized patterns of introgression across the genome and identify regions that exhibit biased introgression into hybrids from one parental species. These regions offer compelling candidates for genes related to tidal marsh adaptations suggesting that adaptive introgression may be an important consequence of hybridization. These findings highlight the value of considering the landscapes of both genome-wide introgression and divergence when characterizing the evolutionary forces that drive speciation.

Coastal marshes are one of the world's most productive ecosystems. Consequently, they have been heavily used by humans for centuries, resulting in ecosystem loss. Direct human modifications such as road crossings and ditches and climatic Stressors such as sea-level rise and extreme storm events have the potential to further degrade the quantity and quality of marsh along coastlines. We used an 18-year marsh-bird database to generate population trends for 5 avian species (Rallus crepitans, Tringa semipalmata semipalmata, Ammodramus nelsonii subvirgatus, Ammodramus caudacutus, and Ammodramus maritimus) that breed almost exclusively in tidal marshes, and are potentially vulnerable to marsh degradation and loss as a result of anthropogenic change. We generated community and species trends across 3 spatial scales and explored possible drivers of the changes we observed, including marsh ditching, tidal restriction through road crossings, local rates of sea-level rise, and potential for extreme flooding events. The specialist community showed negative trends in tidally restricted marshes (-2.4% annually from 1998 to 2012) but was stable in unrestricted marshes across the same period. At the species level, we found negative population trends in 3 of the 5 specialist species, ranging from -4.2% to 9.0% annually. We suggest that tidal restriction may accelerate degradation of tidal marsh resilience to sea-level rise by limiting sediment supply necessary for marsh accretion, resulting in specialist habitat loss in tidally restricted marshes. Based on our findings, we predict a collapse of the global population of Saltmarsh Sparrows (A. caudacutus) within the next 50 years and suggest that immediate conservation action is needed to prevent extinction of this species. We also suggest mitigation actions to restore sediment supply to coastal marshes to help sustain this ecosystem into the future. Los humedales costeros son uno de los ecosistemas más productivos en el mundo. Consecuentemente, han sido utilizados intensivamente por los humanos durante siglos, resultando en la pérdida del ecosistema. Modificaciones humanas directas como caminos y zanjas, así como agentes climáticos estresantes como el incremento del nivel del mar y eventos de tormentas extremas tienen el potencial de degradar aun más la cantidad y calidad de humedales a lo largo de las costas. Utilizamos una base de datos de 18 años de aves de humedal para generar tendencias poblaciones de especies de aves (Rallus crepitans, Tringa semipalmata semipalmata, Ammodramus nelsonii subvirgatus, A. caudacutus, y A. maritimus) que se reproducen casi exclusivamente en marismas y que son potencialmente vulnerables a la degradación y pérdida de humedales como resultado de cambios antropogénicos. Generamos tendencias de la comunidad y de especies en 3 escalas espaciales y exploramos los posibles factores de los cambios observados, incluyendo la construcción de canales, la restricción de mareas por medio de caminos, tasas locales de incremento del nivel del el potencial de eventos de inundación extremos. La comunidad de especialistas mostró tendencias negativas en humedales restringidos por las mareas (-2.4% anualmente de 1998 a 2012), pero fue estable en humedales no restringidos. A nivel de especies, encontramos tendencias poblacionales negativas en 3 de las 5 especies especialistas que variaron entre -4.2% a 9% anualmente. Sugerimos que la restricción de mareas puede acelerar la degradación de la resiliencia de marismas al incremento del nivel del mar al limitar el aporte de los sedimentos necesarios para la acreción de marismas, lo cual resulta en la pérdida de habitat en marismas restringidas por las mareas. Con base en nuestros resultados, pronosticamos un colapso de la población global de A. caudacutus en los próximos 50 años y sugerimos que se requieren acciones de conservación inmediatas para prevenir la extinción de esta especie. También sugerimos acciones de mitigación para restaurar el aporte de sedimentos en los humedales costeros para ayudar a sostener este ecosistema en el futuro.

Primary and secondary male sexual traits can influence the interspecific interactions of hybridizing populations, yielding fitness consequences and either promoting or restricting gene flow. In this study, we evaluated the relative male fitness of two species of hybridizing tidal marsh endemics: saltmarsh (Ammospiza caudacutus) and Nelson's sparrows (A. nelsoni) and assessed the effects of male condition and competitive ability on resulting patterns of paternity and gene flow. We compared reproductive success (number of offspring sired) among saltmarsh, Nelson's, and hybrid sparrow males (n = 125) and modeled male fitness in relation to measured pre‐copulatory (body size, fat scores, and muscle scores) and post‐copulatory (cloacal protuberance (CP) volume and sperm length) male sexual traits across two sites within the center of the hybrid zone. We found saltmarsh sparrows had higher levels of skew in fertilization success than Nelson's and greater reproductive output than both Nelson's and hybrids, suggesting interspecific competition may occur. Body size was the best predictor of reproductive success, independent of male genotypes, providing evidence for a role of pre‐copulatory sexual selection. We also found evidence of post‐copulatory sexual selection and sperm competition contributing to patterns of hybridization, with CP volume and sperm length increasing with number of offspring sired. Differential mean fitness by species may influence patterns of hybridization and has the potential to drive asymmetrical introgression; however, the drivers of male fitness differed between species and sites, suggesting the level of sexual selection and resulting patterns of gene flow are context dependent and not stable across a small sptatial scale within the center of this mosaic hybrid zone. Overall, few interspecific offspring and nearly equal backcrossing in both parental species within the center of the hybrid zone suggest mechanisms such as reinforcement exist to limit hybridization and minimize asymmetric introgression. We used SNP genotypes to assess and compare male reproductive success in two inter‐breeding species of marsh sparrow—saltmarsh and Nelson's sparrow—and their hybrids. Saltmarsh sparrow males had higher reproductive output, greater variance in reproductive success, and higher levels of multiple paternity than Nelson's sparrows and hybrids. We found evidence for both pre‐copulatory (body size) and post‐copulatory (sperm competition) sexual selection, with drivers of fitness differing between the two species. Photo shows a pair of mating saltmarsh sparrows (credit: Grace McCulloch).

Polymorphisms are maintained over time by trade-offs that alternatively favor morphs over space or time. In a polyphenic population of amphibians (Arizona tiger salamander; Ambystoma mavortium nebulosum ), two morphs—paedomorphs and metamorphs—exhibit a trade-off in dispersal capacity. Larvae select between two discrete ontogenetic pathways based on environmental cues—adult paedomorphs remain in their permanent, natal pond, while adult metamorphs disperse between ponds of varying hydroperiods and overwinter in the terrestrial environment. This polyphenism is maintained in part by sex-specific reproductive advantages within each morph, with paedomorphic males achieving more reproductive opportunities and metamorphic females achieving higher egg production. In this study, we examined the role of a high-quality, primary prey taxon (fairy shrimp)—which is accessible to metamorphs only—in balancing the sex-specific component of this dispersal trade-off. Among the 95 metamorphs for which we evaluated diet and body condition, we found that most of the high-condition individuals were females that contained predominantly fairy shrimp in their stomachs. In addition, females specialized on fairy shrimp at much lower fairy shrimp densities than males, indicating that the consumption of this prey taxon may have differential fitness benefits across metamorph sexes. Our findings align with the expectations of parental investment theory, in which female reproductive success is most limited by the energetic resources necessary for egg production, while male reproductive success is limited predominantly by access to females. Significance statement Polymorphisms are a common source of phenotypic diversity in animal populations that are often maintained over time by trade-offs among morphs. In a subalpine amphibian population that exhibits a dispersal polyphenism, the dispersing morph (metamorph) can leave natal ponds and access a high-quality, ephemeral food resource (fairy shrimp) in ponds of nonpermanent hydroperiods. In this study, we quantify the spatiotemporal availability of this focal prey taxon and examine whether sex-specific foraging behavior among metamorphs could contribute to the persistence of this polyphenism. Our results suggest that fairy shrimp consumption allows metamorphs to realize benefits of the dispersal trade-off through high female fecundity. These findings emphasize the importance of considering intrapopulation variation in functional responses and how the behavior can contribute to the maintenance of polymorphisms.

Background Evolutionary processes, including selection and differential fitness, shape the introgression of genetic material across a hybrid zone, resulting in the exchange of some genes but not others. Differential introgression of molecular or phenotypic markers can thus provide insight into factors contributing to reproductive isolation. We characterized patterns of genetic variation across a hybrid zone between two tidal marsh birds, Saltmarsh ( Ammodramus caudacutus ) and Nelson’s ( A. nelsoni ) sparrows ( n  = 286), and compared patterns of introgression among multiple genetic markers and phenotypic traits. Results Geographic and genomic cline analyses revealed variable patterns of introgression among marker types. Most markers exhibited gradual clines and indicated that introgression exceeds the spatial extent of the previously documented hybrid zone. We found steeper clines, indicating strong selection for loci associated with traits related to tidal marsh adaptations, including for a marker linked to a gene region associated with metabolic functions, including an osmotic regulatory pathway, as well as for a marker related to melanin-based pigmentation, supporting an adaptive role of darker plumage (salt marsh melanism) in tidal marshes. Narrow clines at mitochondrial and sex-linked markers also offer support for Haldane’s rule. We detected patterns of asymmetrical introgression toward A. caudacutus , which may be driven by differences in mating strategy or differences in population density between the two species. Conclusions Our findings offer insight into the dynamics of a hybrid zone traversing a unique environmental gradient and provide evidence for a role of ecological divergence in the maintenance of pure species boundaries despite ongoing gene flow.