Terrestrial Growth Research Articles

The monoicous secondarily aquatic liverwort Ricciocarpos natans as a model within the radiation of derived Marchantiopsida

Liverworts represent one of six embryophyte lineages that have a Devonian, or earlier, origin, and are, at present, represented by only Marchantia polymorpha as an established model. Ricciocarpos natans is a secondarily monoicous aquatic liverwort with a worldwide distribution, being found on all continents except Antarctica. Ricciocarpos, a monotypic genus, forms a sister relationship with Riccia, the largest genus of the Marchantiopsida (~250 species), diverging from their common ancestor in the mid-Cretaceous. R. natans is typically found on small stagnant ponds and billabongs (seasonal pools), where it assumes a typical ‘aquatic’ form with long scale keels for stabilization on the water surface. But, as water bodies dry, plants may become stranded and subsequently shift their development to assume a ‘terrestrial’ form with rhizoids anchoring the plants to the substrate. We developed R. natans as a model to address a specific biological question — what are the genomic consequences when monoicy evolves from ancestral dioicy where sex is chromosomally determined? However, R. natans possesses other attributes that makes it a model to investigate a variety of biological processes. For example, it provides a foundation to explore the evolution of sexual systems within Riccia, where it appears monoicy may have evolved many times independently. Furthermore, the worldwide distribution of R. natans postdates plate tectonic driven continent separation, and thus, provides an intriguing model for population genomics. Finally, the transition from an aquatic growth form to a terrestrial growth form is mediated by the phytohormone abscisic acid, and represents convergent evolution with a number of other aquatic embryophytes, a concept we explore further here.

The relationship between temperature, growth rate and body condition of Bufo bufo toadlets prior to their first hibernation

Abstract The effect of environmental temperature on the growth and body condition of common toad (Bufo bufo) toadlets was studied during their first terrestrial growth season, following metamorphosis, at a pond in south Dorset, UK, between 2010 and 2021. Toadlet samples were collected annually on the first day of emergence and then approximately once a week until late September/early October. In total, 15-19 samples were collected annually depending on the duration of the toadlet activity season. Toadlet snout-vent length (mm) and body mass (mg) of each captured toadlet was measured and their body condition (Scaled Mass Index: SMI) estimated both annually and for each annual quarter season. Toadlet growth rate and SMI varied between years and were significantly correlated with the duration of their first growth season and its lowest recorded temperature. Growth rate declined as the duration of the growth season increased whilst the reverse was true for SMI. Growth rates also increased as temperatures increased and vice versa for SMI. SMI was inversely correlated to growth rate and suggest that toadlets may enter their first hibernation larger, but in poorer condition, following warm summers than cool summers, and that this may have the potential to reduce their survivorship during a following mild winter. Assuming that similar relationships, between growth rates, body condition and environmental temperatures are not restricted to toadlets during their first terrestrial growth season, then this scenario may also be applicable to subsequent juvenile stages, further increasing the potential consequences for individual survival and fitness.

Exposure to Amphibian Chytrid Fungus Alters Terrestrial Growth and Feeding Rate in Metamorphic Anurans

Population declines and extinctions associated with infectious diseases of wildlife are increasing in both frequency and severity. Response to infectious disease varies among species and individuals, with some appearing asymptomatic and others experiencing rapid mortality. The amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), has been associated with widespread population declines and species extinctions, yet in some geographic regions it elicits a range of sublethal responses that may influence population dynamics in ways that are currently not understood. Our central objective was to evaluate growth and feeding behavior of terrestrial juvenile American Toads (Anaxyrus americanus) and Northern Leopard Frogs (Lithobates pipiens) following exposure to Bd. We manipulated foraging effort through the presence or absence of refugia for prey. We found that both amphibian species grew less when exposed to the pathogen, though the mechanisms contributing to this effect appear not to be the same. American Toads ate equal to or more in feeding trials when exposed to Bd than when unexposed, yet those exposed to Bd still experienced growth limitations. Conversely, Northern Leopard Frogs consumed the same quantity of food no matter their exposure status, but refugia presence had an effect on feeding. These results suggest that sublethal effects of disease can have ecologically relevant impacts in amphibians that can result in reduced size, likely because of high metabolic costs of disease response. Size is both a predictor of time to reproduction and fecundity, and reductions in individual growth may have important consequences for populations.

How Epiphytic Are Filmy Ferns? A Semi-Quantitative Approach

Similar to plants in many other families, members of the Hymenophyllaceae use numerous substrates for growth, e.g., soil, rocks or tree bark. However, substrate preference does not only differ among species but can also vary among members of the same species. There have been several attempts in the past to appropriately capture this variation, but none proved feasible or was replicated in any subsequent work. In our approach, we use textual information from numerous sources like checklists, floras and species descriptions to come up with a quantitative index of the preference of 450 species of filmy ferns (=c. 75% of all species of the family) for epiphytic, lithophytic or terrestrial growth. We show that the majority of species have clear habitat preferences, while strict habitat specificity is rather uncommon. Our compilation will be an important input for future ecological and phylogenetic studies in this family, but the presented approach is of much more general interest: it is immediately applicable to other taxonomic groups and should eventually allow us to replace the current approach of assigning species to distinct categories (epiphyte, lithophyte or terrestrial) by one that finally reflects biological variability more appropriately.

Survival on land: A dark-grown seedling searching for path.

To initiate its development into a plant, a small dark-grown seedling (prior to its emergence from the ground) must penetrate through the growth media. The path that the seedling takes during this journey has yet to be explained. As such, we conducted non-destructive tests using CT scans to observe the growth of dark-grown seedlings in soil over time; we also developed a model to simulate the dynamics of an emerging seedling, and to examine effects of various growth medium conditions, including Lunar soil. It was previously postulated that, with gravitropism in a terrestrial growth medium, a dark-grown seedling would grow directly upright. However, our CT scan results showed that dark-grown soybean seedlings departed from the vertical path in soil, as far as a lateral distance of approximately 10mm. The phenomenon of the non-straight path was also demonstrated by the model results. Through simulations, we found that an emerging seedling naturally weaves through the particles of growth medium, in search for the path of least resistance. As a result, the seedling ends up travelling a longer distance. Compared with a seedling that was artificially forced to take a straight path in a growth media, the seedling taking the natural path encountered significantly lower resistances (20% lower) from the growth medium, while travelled 12% longer distance during the emergence process. A seedling encountered a much higher impedance in Lunar soil. Our results suggest that taking the path of least resistance, in addition to shaping and orientating itself for mechanical advantage, are strategies evolved by plant species that have contributed to its vast success. An understanding of plant behavior and survival strategies on Earth lay the foundation for future research in agriculture in novel environments, including on celestial bodies.

Re‐terrestrialization in the phylogeny of epiphytic plant lineages: Microsoroid ferns as a case study

AbstractThe fern family Polypodiaceae, with over 1600 species, is not only one of the most species‐rich families of ferns, but also a major contributor to the vascular epiphytic diversity throughout the tropics. Although the vast majority of species belonging to this family prefer to grow as epiphytes, several species colonize successfully rheophytic, lithophytic, and even terrestrial habitats. Here, we explore the hypothesis that non‐epiphytic habitat preferences, including terrestrial growth, evolved secondarily with epiphytes being the plesiomorphic habitat preference. The results of phylogenetic analyses, based on dense taxon sampling and four chloroplast DNA regions, were integrated with divergence time estimates and ancestral character state reconstructions to test these predictions. Both fossils and secondary calibration data were incorporated to obtain divergence time estimations. The results support the prediction of multiple transitions from epiphytic/lithophytic to terrestrial/rheophytic habitats occurring mainly in the Microsoreae lineage. The change in niche preferences coincides with niche colonization opportunities created by climatic fluctuations and geographical changes during the Oligocene and Miocene periods.

Effects of extraction methods for a new source of biostimulant from Sargassum horneri on the growth of economically important red algae, Neopyropia yezoensis

Sargassum horneri is a major bloom forming species in Korea and China. It is important to find a way to utilize the huge biomass of Sargassum horneri in the region. Seaweed-derived biostimulants are primarily derived from brown algae and are known to improve terrestrial crop growth and tolerance to abiotic stresses. Neopyropia yezoensis is the most important seaweed cultured species in Korea, and research is required to increase heat resistance as a solution against climate change. In this study, various extraction methods were used to obtain Sargassum horneri extract, and it was applied to Neopyropia yezoensis to evaluate the effect on physiological activity. Metabolites of Sargassum horneri were extracted by using four different methods: boiling (SBE), soaking (SSE), autoclaving (SAE) and ethanol (SEE). The SBE, SSE and SAE derived extracts showed increased tolerance to high-temperature stress that had inhibited the growth of Neopyropia yezoensis, and show improved growth compared to the control group. The SBE and SSE extraction methods improved the content of phycobiliprotein, but also the SBE increased superoxide dismutase (SOD) activity. Based on the results of this study, the boiling extraction method appears to be the most suitable method for the extraction of plants stimulants from Sargassum horneri.

Is overwintering mortality driving enigmatic declines? Evaluating the impacts of trematodes and the amphibian chytrid fungus on an anuran from hatching through overwintering.

Emerging infectious diseases are increasing globally and are an additional challenge to species dealing with native parasites and pathogens. Therefore, understanding the combined effects of infectious agents on hosts is important for species' conservation and population management. Amphibians are hosts to many parasites and pathogens, including endemic trematode flatworms (e.g., Echinostoma spp.) and the novel pathogenic amphibian chytrid fungus (Batrachochytrium dendrobatidis [Bd]). Our study examined how exposure to trematodes during larval development influenced the consequences of Bd pathogen exposure through critical life events. We found that prior exposure to trematode parasites negatively impacted metamorphosis but did not influence the effect of Bd infection on terrestrial growth and survival. Bd infection alone, however, resulted in significant mortality during overwintering-an annual occurrence for most temperate amphibians. The results of our study indicated overwintering mortality from Bd could provide an explanation for enigmatic declines and highlights the importance of examining the long-term consequences of novel parasite exposure.

Larval development and survival of pond-breeding anurans in an agricultural landscape impacted more by phytoplankton than surrounding habitat.

The destruction of freshwater habitat is a major contributor to biodiversity loss in aquatic ecosystems. However, created or restored wetlands could partially mitigate aquatic biodiversity loss by increasing the amount of available habitat across a landscape. We investigated the impact of surrounding terrestrial habitat and water quality variables on suitability for two species of pond-breeding amphibians (bullfrogs [Lithobates catesbeianus] and Blanchard's cricket frogs [Acris blanchardi]) in created permanent wetlands located on an agricultural landscape. We examined tadpole growth and survival in field enclosures placed in ponds surrounded by agricultural, forested, or grassland habitats. We also evaluated the potential for carryover effects of the aquatic environment on terrestrial growth and overwinter survival of cricket frog metamorphs. We found that habitat adjacent to ponds did not predict tadpole growth or survival. Rather, phytoplankton abundance, which showed high variability among ponds within habitat type, was the only predictor of tadpole growth. Cricket frogs emerged larger and earlier from ponds with higher phytoplankton abundance; bullfrogs were also larger and at a more advanced developmental stage in ponds with higher levels of phytoplankton. Overwinter survival of cricket frogs was explained by size at metamorphosis and there were no apparent carryover effects of land use or pond-of-origin on overwinter growth and survival. Our results demonstrate that created ponds in human-dominated landscapes can provide suitable habitat for some anurans, independent of the adjacent terrestrial habitat.

Anatomical adaptations in aquatic and wetland dicot plants: Disentangling the environmental, morphological and evolutionary signals

Understanding how plants adjust their internal structures to withstand adverse environmental conditions is vital for predicting their responses to ongoing environmental change. Plants have repeatedly evolved small water transporting conduits and large storage parenchyma tissues to cope with anoxia, freezing- or drought‐induced damages. However, how these adaptations evolved in unrelated taxa across hydrological and thermal gradients, remains unclear. Here we show that stem anatomical variations in 212 European aquatic and wetland dicots are driven by thermal and hydrological constraints via control over plant size, growth form, and leaf traits, while phylogenetic constraints have only a weak effect. Phylogenetic comparative analyses controlling for confounding factors showed that both waterlogging (anoxia) and low-temperature promote smaller plants with reduced vessel conduits and limited lignification, but extended parenchyma and hence storage and tissue renewal capacity to secure resilience to biomass loss induced by running water or frost disturbances. Decreasing water depth and anoxia promote larger wetland plants with thick-walled libriform fibers, large vessels with simple perforation plates securing high hydraulic efficiency, and semi-ring porous xylem with wide earlywood vessels in spring and narrow latewood vessels in summer, providing both efficiency and safety in water transport. The aquatic environment promotes plants with a large cortex zone with photosynthetic chlorenchyma and starch-storing parenchyma cells along with extensive air spaces that provide aeration and buoyancy. Low temperatures promote short-stature forbs with smaller vessels, scalariform perforation plate, extended parenchyma, resulting in reduced embolism risk. Although most anatomical variation was explained by differences between aquatic and wet terrestrial growth forms, environmental gradients, plant size, and leaf properties exerted a significant control on plant tissue structures not confounded by phylogenetic inertia. Distinct habitats, spread across broad thermal and hydrological gradients, harbor unrelated species with different evolutionary histories that have converged to similar anatomical and hence morphological structures.

Local and Systemic Effects of Brassinosteroid Perception in Developing Phloem.

The plant vasculature is an essential adaptation to terrestrial growth. Its phloem component permits efficient transfer of photosynthates between source and sink organs but also transports signals that systemically coordinate physiology and development. Here, we provide evidence that developing phloem orchestrates cellular behavior of adjacent tissues in the growth apices of plants, the meristems. Arabidopsis thaliana plants that lack the three receptor kinases BRASSINOSTEROID INSENSITIVE 1 (BRI1), BRI1-LIKE 1 (BRL1), and BRL3 ("bri3" mutants) can no longer sense brassinosteroid phytohormones and display severe dwarfism as well as patterning and differentiation defects, including disturbed phloem development. We found that, despite the ubiquitous expression of brassinosteroid receptors in growing plant tissues, exclusive expression of the BRI1 receptor in developing phloem is sufficient to systemically correct cellular growth and patterning defects that underlie the bri3 phenotype. Although this effect is brassinosteroid-dependent, it cannot be reproduced with dominant versions of known downstream effectors of BRI1 signaling and therefore possibly involves a non-canonical signaling output. Interestingly, the rescue of bri3 by phloem-specific BRI1 expression is associated with antagonism toward phloem-specific CLAVATA3/EMBRYO SURROUNDING REGION-RELATED 45 (CLE45) peptide signaling in roots. Hyperactive CLE45 signaling causes phloem sieve element differentiation defects, and consistently, knockout of CLE45 perception in bri3 background restores proper phloem development. However, bri3 dwarfism is retained in such lines. Our results thus reveal local and systemic effects of brassinosteroid perception in the phloem: whereas it locally antagonizes CLE45 signaling to permit phloem differentiation, it systemically instructs plant organ formation via a phloem-derived, non-cell-autonomous signal.

Formation of planetary systems by pebble accretion and migration

Super-Earths – planets with sizes between the Earth and Neptune – are found in tighter orbits than that of the Earth around more than one third of main sequence stars. It has been proposed that super-Earths are scaled-up terrestrial planets that also formed similarly, through mutual accretion of planetary embryos, but in discs much denser than the solar protoplanetary disc. We argue instead that terrestrial planets and super-Earths have two clearly distinct formation pathways that are regulated by the pebble reservoir of the disc. Through numerical integrations, which combine pebble accretion and N-body gravity between embryos, we show that a difference of a factor of two in the pebble mass flux is enough to change the evolution from the terrestrial to the super-Earth growth mode. If the pebble mass flux is small, then the initial embryos within the ice line grow slowly and do not migrate substantially, resulting in a widely spaced population of approximately Mars-mass embryos when the gas disc dissipates. Subsequently, without gas being present, the embryos become unstable due to mutual gravitational interactions and a small number of terrestrial planets are formed by mutual collisions. The final terrestrial planets are at most five Earth masses. Instead, if the pebble mass flux is high, then the initial embryos within the ice line rapidly become sufficiently massive to migrate through the gas disc. Embryos concentrate at the inner edge of the disc and growth accelerates through mutual merging. This leads to the formation of a system of closely spaced super-Earths in the five to twenty Earth-mass range, bounded by the pebble isolation mass. Generally, instabilities of these super-Earth systems after the disappearance of the gas disc trigger additional merging events and dislodge the system from resonant chains. Therefore, the key difference between the two growth modes is whether embryos grow fast enough to undergo significant migration. The terrestrial growth mode produces small rocky planets on wider orbits like those in the solar system whereas the super-Earth growth mode produces planets in short-period orbits inside 1 AU, with masses larger than the Earth that should be surrounded by a primordial H/He atmosphere, unless subsequently lost by stellar irradiation. The pebble flux – which controls the transition between the two growth modes – may be regulated by the initial reservoir of solids in the disc or the presence of more distant giant planets that can halt the radial flow of pebbles.

Establecimiento de Vanilla planifolia Andrews en acahual intercalado con Gliricidia sepium y Citrus sinensis

En México el cultivo de vainilla es considerado de gran importancia cultural y económica, por lo que en el presente trabajo el objetivo fue demostrar a los productores la manera correcta de sembrar la vainilla, así como el manejo y los debidos cuidados además de ayudar al acahual incorporando tutores de Gliricidia y Citrus para así generar mayores ingresos a la región que anteriormente sembraba la vainilla de manera silvestre y así mismo integrar a las personas de la región a formar parte de las actividades realizadas en los predios. Las variables de respuesta utilizadas fueron longitud y ancho de hojas, distancia entre nudos número de raíces terrestres y crecimiento de brotes comprobando que las condiciones climáticas de la Sierra de Otontepec Veracruz son muy viables para la siembra de esquejes de Vanilla planifolia Andrews y de esta manera orientando a las habitantes de la zona a sembrar esta planta ya que el experimento realizado resultó muy viable para los esquejes de vainilla.

Epigenomics in an extraterrestrial environment: organ-specific alteration of DNA methylation and gene expression elicited by spaceflight in Arabidopsis thaliana

BackgroundPlants adapted to diverse environments on Earth throughout their evolutionary history, and developed mechanisms to thrive in a variety of terrestrial habitats. When plants are grown in the novel environment of spaceflight aboard the International Space Station (ISS), an environment completely outside their evolutionary history, they respond with unique alterations to their gene expression profile. Identifying the genes important for physiological adaptation to spaceflight and dissecting the biological processes and pathways engaged by plants during spaceflight has helped reveal spaceflight adaptation, and has furthered understanding of terrestrial growth processes. However, the underlying regulatory mechanisms responsible for these changes in gene expression patterns are just beginning to be explored. Epigenetic modifications, such as DNA methylation at position five in cytosine, has been shown to play a role in the physiological adaptation to adverse terrestrial environments, and may play a role in spaceflight as well.ResultsWhole Genome Bisulfite Sequencing of DNA of Arabidopsis grown on the ISS from seed revealed organ-specific patterns of differential methylation compared to ground controls. The overall levels of methylation in CG, CHG, and CHH contexts were similar between flight and ground DNA, however, thousands of specifically differentially methylated cytosines were discovered, and there were clear organ-specific differences in methylation patterns. Spaceflight leaves had higher methylation levels in CHG and CHH contexts within protein-coding genes in spaceflight; about a fifth of the leaf genes were also differentially regulated in spaceflight, almost half of which were associated with reactive oxygen signaling.ConclusionsThe physiological adaptation of plants to spaceflight is likely nuanced by epigenomic modification. This is the first examination of differential genomic methylation from plants grown completely in the spaceflight environment of the ISS in plant growth hardware developed for informing exploration life support strategies. Yet even in this optimized plant habitat, plants respond as if stressed. These data suggest that gene expression associated with physiological adaptation to spaceflight is regulated in part by methylation strategies similar to those engaged with familiar terrestrial stress responses. The differential methylation maps generated here provide a useful reference for elucidating the layers of regulation of spaceflight responses.

Space Food and Nutrition in a Long Term Manned Mission

Fulfillment of space exploration mission is key, but much more important are the lives of the explorers. Keeping the astronauts alive, jolly and healthy for long term manned mission has recently being a major and important research area. A major contribution seems to be the food they eat. For short term space manned missions, astronauts food could be taken along with them from Earth, but for manned missions to the Moon, Mars and Venus which are the current research destinations for long term space missions, they must find a means for their nutrition such as growing plants and finding any other alternatives for their survival. As most of these proposed missions have being designed to be one-way missions whereby the astronauts will not come back to the Earth. Good food and nutrition for astronauts help to keep their psychology and physiology in good shape. In this paper, solutions will be made on the various alternatives for feeding astronauts in the long term missions to various celestial bodies: Moon, Mars and Venus, where the atmosphere, gravity, soil, radiation and other conditions vary from one to the other and may not support germination, growth and development of plants. Therefore, review will be done on the following: having fore knowledge of how plants will grow on these celestial bodies by simulating their soils; using mathematical/theoretical models to get the growth rate of plants in relation to the gravity available on these celestial bodies using available data from terrestrial growth (1 g growth) and microgravity/microgravity simulations facilities; getting to know how the plants will be grown such as using greenhouse method as a result of the atmosphere and radiation in these celestial bodies; and other various alternatives for growing plants and having the astronauts well-nourished such as using aeroponics and hydroponics methods. A brief discussion will also be done on food choice for astronauts considering psychosocial and cultural factors.

Freed from a rocky embrace

Nitrogen Cycle Nitrogen availability is a central controller of terrestrial plant growth and, thereby, of the carbon cycle and global climate change. It has been widely assumed that the atmosphere is the main source of terrestrial nitrogen input. Surprisingly, Houlton et al. now show that bedrock is just as large a nitrogen source across major sectors of the global terrestrial environment. They used three diverse and largely independent assessments of the nitrogen mobility and reactivity of rocks in the surface environment. These approaches yielded convergent estimates pointing to the equal importance of the atmosphere and bedrock as nitrogen sources. Science , this issue p. [58][1] [1]: /lookup/doi/10.1126/science.aan4399

Estimating Plant-Available Water in the Ap Horizon Using Geospatial Analysis of Field and SSURGO Data

ABSTRACTSoil provides many of the requirements needed for terrestrial plant growth, including an adequate supply of water. Because the proportion of plant roots is usually greatest in the top 10 to 15 cm of soil, the soil moisture content in the Ap horizon is particularly important for plant growth and crop yields. Uncertainties in estimates of plant available water in the Ap horizon (AWAp) often arise from variabilities in field, laboratory and geospatial data at a farm scale. The objectives of this study were to quantify and compare AWAp estimates across the 147-ha Cornell University Willsboro research farm using four different approaches: a) AWAp calculated from values reported in the SSURGO database for available water capacity (AWC) and Ap thickness for the soil map units (SMUs) present on the farm, b) AWAp estimated from soil texture data reported for the SSURGO SMUs, c) AWAp estimated from soil texture data determined from soil cores taken across the farm that were then averaged within each SMU, and d) spatially interpolating the AWAp values predicted from soil cores across the entire farm irrespective of SMU boundaries. Available water in the Ap horizon varied with soil order in the general trend of Alfisols > Inceptisols > Entisols regardless of the estimation approach used. Field measurement-based estimates of AWAp were lower, in general than the reported SSURGO values and estimates based on reported texture in the SSURGO database. The higher abundance of coarse fragments in the Ap horizon of the soil cores collected on the farm partially explains the lower field measurement-based AWAp estimates. In the SSURGO database, values reported for AWC are frequently obtained from a selected pedon from a “type location” and not from the actual study location. These “type locations” can be located far from study sites and even in different states. Although collecting detailed field data may not always be possible due to the high costs of field and laboratory measurements, it is important to understand the potential benefits and limitations of making field-scale and regional AW estimates using the SSURGO database.

Host size influences the effects of four isolates of an amphibian chytrid fungus.

Understanding factors that influence host–pathogen interactions is key to predicting outbreaks in natural systems experiencing environmental change. Many amphibian population declines have been attributed to an amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd). While this fungus is widespread, not all Bd‐positive populations have been associated with declines, which could be attributed to differences in pathogen virulence or host susceptibility. In a laboratory experiment, we examined the effects of Bd isolate origin, two from areas with Bd‐associated amphibian population declines (El Copé, Panama, and California, USA) and two from areas without Bd‐related population declines (Ohio and Maine, USA), on the terrestrial growth and survival of American toad (Anaxyrus americanus) metamorphs reared in larval environments with low or high intraspecific density. We predicted that (1) Bd isolates from areas experiencing declines would have greater negative effects than Bd isolates from areas without declines, and (2) across all isolates, growth and survival of smaller toads from high‐density larval conditions would be reduced by Bd exposure compared to larger toads from low‐density larval conditions. Our results showed that terrestrial survival was reduced for smaller toads exposed to Bd with variation in the response to different isolates, suggesting that smaller size increased susceptibility to Bd. Toads exposed to Bd gained less mass, which varied by isolate. Bd isolates from areas with population declines, however, did not have more negative effects than isolates from areas without recorded declines. Most strikingly, our study supports that host condition, measured by size, can be indicative of the negative effects of Bd exposure. Further, Bd isolates’ impact may vary in ways not predictable from place of origin or occurrence of disease‐related population declines. This research suggests that amphibian populations outside of areas experiencing Bd‐associated declines could be impacted by this pathogen and that the size of individuals could influence the magnitude of Bd's impact.

Fault-related fold kinematics recorded by terrestrial growth strata, Sant Llorenç de Morunys, Pyrenees Mountains, NE Spain

Foreland basin growth strata are ideal recorders of deformation rates and kinematics in tectonically active regions. This study develops a high-resolution chronostratigraphic age model to determine folding rates in the Eocene-Oligocene terrestrial growth strata of the Berga Conglomerate Group, NE Spain. The Berga Conglomerate Group was sampled for rock magnetic, magnetostratigraphic, and magnetic susceptibility (χ) cyclostratigraphy analyses. Analysis of rock magnetic measurements indicate a mixed mineral assemblage with both paramagnetic and ferromagnetic minerals. A new magnetic reversal stratigraphy constrains the time frame of folding and is in agreement with previous interpretations. Time series analysis of χ variations show statistically significant power at expected orbital frequencies and provides precession-scale (20 kyr) temporal resolution. Strain measurements including anisotropy of magnetic susceptibility (AMS) fabrics and bedding plane strain worm burrow distortion are consistent with fixed hinge, flexural folding kinematics. Fault-related folding was modeled using χ cyclostratigraphy timing and strain measurement kinematic constraints. The onset of folding was at 33.85 Ma and the end of deformation is less constrained but is younger than 31.06 Ma. Deformation and sediment accumulation rates are unsteady at 20 kyr time scales but appear artificially steady at polarity chron time scales.

Terrestrial Growth in Northern Leopard Frogs Reared in the Presence or Absence of Predators and Exposed to the Amphibian Chytrid Fungus at Metamorphosis

Abstract Pathogens can have a range of effects on organisms across environmental gradients; although lethal effects may receive greater attention, sublethal impacts can have important population- and community-level impacts. In this laboratory study, we examined the effects of exposure to the amphibian chytrid fungus (Batrachochytrium dendrobatidis [Bd]) on Northern Leopard Frog (Lithobates pipiens) metamorphs that had been reared in the presence or absence of crayfish (Orconectes rusticus) predators in aquatic environments to determine whether prior predator exposure influenced the effect of Bd on terrestrial growth and survival of frogs. Although Bd exposure following metamorphosis did not impact Northern Leopard Frog survival, exposure did significantly reduce terrestrial growth, indicating that Bd exposure can have consequences that can indirectly impact populations, because size of amphibians is positively correlated with overwinter survival and fecundity. Exposure to predators during larval developm...