303 research outputs found
Climate-Induced Changes in Spring Snowmelt Impact Ecosystem Metabolism and Carbon Fluxes in an Alpine Stream Network
No full textAlthough stream ecosystems are recognized as an important component of the global carbon cycle, the impacts of climate-induced hydrological extremes on carbon fluxes in stream networks remain unclear. Using continuous measurements of ecosystem metabolism, we report on the effects of changes in snowmelt hydrology during the anomalously warm winter 2013/2014 on gross primary production (GPP), ecosystem respiration (ER), and net ecosystem production (NEP) in an Alpine stream network. We estimated ecosystem metabolism across 12 study reaches of the 254 km2 subalpine Ybbs River Network (YRN), Austria, for 18 months. During spring snowmelt, GPP peaked in 10 of our 12 study reaches, which appeared to be driven by PAR and catchment area. In contrast, the winter precipitation shift from snow to rain following the low-snow winter in 2013/2014 increased spring ER in upper elevation catchments, causing spring NEP to shift from autotrophy to heterotrophy. Our findings suggest that the YRN transitioned from a transient sink to a source of carbon dioxide (CO2) in spring as snowmelt hydrology differed following the high-snow versus low-snow winter. This shift toward increased heterotrophy during spring snowmelt following a warm winter has potential consequences for annual ecosystem metabolism, as spring GPP contributed on average 33% to annual GPP fluxes compared to spring ER, which averaged 21% of annual ER fluxes. We propose that Alpine headwaters will emit more within-stream respiratory CO2 to the atmosphere while providing less autochthonous organic energy to downstream ecosystems as the climate gets warmer
Major and Minor Scales: A Survey of Scale Morphology Across Squamate Reptiles
No full textMorphological diversity in squamate reptiles is well documented. Variation in diet habits, locomotion, habitat use, and many other behaviors has led to the radiation of one of the most speciose vertebrate groups. Despite large studies using osteological, physiological, and genomic data to infer phylogenies of the monophyletic order Squamata, the use of integumentary characters has been few and far between. This investigation serves as a preliminary foray into the possible use of scale morphology to address phylogenetic questions. One hundred and fifty three taxa including members from each of the 67 squamate families were scored for 180 integumentary characters. Among these 180 characters, 81 were from a previous study and 99 new characters were proposed. Only 159 of the 180 characters were applied in the analysis. Use of digital microscopy and high-resolution 3D imaging assisted in scoring. It was found that some of these traits may provide discrimination among higher-level clades on a morphospace. Multiple Correspondence Analysis was used to identify character state contribution to the variation seen in the dataset, as well as plot taxa in morphospace. Ancestral state reconstruction of key characters also gives confidence that certain characters may help identify trends in recent squamate evolution. Clades tend to share similar overlap pattern, scale distribution, and often three-dimensional texture of the scale. Use of these data may also resolve the uncertain placement of some fossilized lizards in amber which retain their integument
NUBENOCEPHALUS SECUNDUS INFECTION IN FIVE SPECIES OF DAMSELFLIES (ODONATA: COENAGRIONIDAE) IN EAST TEXAS
No full textDamselfly parasites are diverse and highly susceptible to ectoparasites and endoparasites. Damselflies are commonly parasitized by gregarines (Apicomplexa: Eugregarinida) which inhabit the gut of its host. Gregarines are ubiquitous protozoan parasites that infect aquatic and terrestrial invertebrates all over the world except for Antarctica. More than 1,600 gregarine species have been described, however, only a small percentage of invertebrates have been surveyed for apicomplexan parasites, thus the biodiversity of gregarines is underestimated. Gregarines are highly thought to be host-specific, with some studies suggesting a one-host-to-one gregarine species ratio. However, a survey of damselflies in the genus Argia found Nubenocephalus secundus infecting at least seven species. It has additionally been reported from Ischnura ramburii and an unidentified species of Nubenocephalus was reported from Ischnura hastata and Ischnura posita. The objective of this project was to survey adults of the damselflies Argia sedula, Argia translata, Argia tibialis, Enallagma civile, and Ischnura posita and measure if the Nubenocephalus infecting each of these species is N. secundus. All host species were collected among three sites in Walker County, TX: Harmon Creek and the pond at the Pineywoods Environmental Research Lab and Cook Pond. Adult damselfly populations were dissected and examined for gregarine infection from May 2022 through August 2023. Using a combined approach of observing for morphological characteristics, a multivariate analysis of variance (MANOVA) on gregarine trophozoites and a centroid clustering on sporonts, we observed that the Nubenocephalus species infecting A. sedula and A. translata is N. secundus. However, the gregarine infecting the other three damselfly species was not N. secundus but another gregarine species. Additional data collection, including the collection of oocysts, is necessary to determine which species of gregarine is infecting A. tibialis, E. civile, and I. posita
Nest Box Microclimates and Parental Care Behavior: A Suburban and Rural Comparison
No full textNest boxes are often used to supplement or replace lost natural cavities. Although nest boxes are a common tool in conservation, their microclimates can be different from natural tree cavities, and they may be less insulative than natural cavities. Potentially hotter and drier artificial cavities may influence incubation, feeding behavior, and fitness of birds using them. This effect can be further exacerbated in habitats with less canopy cover such as urban and suburban areas. By comparing nest boxes used by Thryothorus ludovicianus (Carolina Wren) nesting in a suburban and a rural habitat, I hoped to better understand how nest-box microclimates can affect incubation behavior. I monitored internal and external temperature and humidity of the nest boxes with active wren nests. Video recordings of incubation behavior and feeding behaviors were taken during morning and afternoon sessions for two-hour periods. Despite differences found in temperature and humidity, I did not find significant differences between incubation and feeding behavior correlated with the differences between the rural and suburban habitats. Clutch size was found to be correlated with temperature while percentage of eggs hatched, and fledgling success were not strongly correlated with temperature, humidity, or habitat. With expanding urbanization and rising temperatures, understanding how to manage nest boxes to better aid the animals that use them is essential
Effect of Cell Culture Condition or Bisphenol A (BPA) Exposure on the Wound Healing Response In Vitro
No full textWound healing is a process comprised of overlapping phases: inflammation, tissue formation, reepithelization, and remodeling; all of which can be influenced by exogenous factors such as environmental pollutants. Bisphenol A (BPA), a monomer used in the manufacture of many plastics, is an endocrine-disrupting chemical that may influence cell proliferation and/or cellular migration during wound repair. Here I used an in vitro model of wound healing to investigate the effect of varying the composition of the cell culture media in conjunction with BPA exposure to determine how each of these factors may influence the kinetics of the wound healing response. Specifically, the degree of closure over 24 hours was measured in the presence or absence of bovine serum in the cell culture media in cells pre-exposed to varied concentrations of BPA. Using an algorithm developed for ImageJ to autonomously estimate the rate of wound closure, we found that the presence of serum in the culture media significantly increased this rate in (p ≤ 0.001). Prior exposure to BPA had no effect on the rate of wound closure, regardless of dose or cell culture condition (p ≥ 0.05). Collectively, these data suggest that serum growth factors are essential mediators of wound closure in vitro, whereas BPA exposure has no significant effect
Predictive Niche Modeling for the Identification of Maize Pathogens of Greatest concern in the United States
No full textMaize is one of the world’s most valuable food crops with 717 million metric tons produced annually. Its economic significance worldwide is second only to rice. Given the importance of maize, it is crucial to understand the potential range of pests and pathogens that pose a significant risk to the crop. Ecological niche modeling is used to identify the environmental requirements of these pests and pathogens. Models can be built using existing occurrence data and records of environmental conditions such as vegetative coverage, isothermality, altitude, temperature, and precipitation. In this study, I use pest occurrence location data from the Global Biodiversity Information Facility and bioclimatic variables from WorldClim to create generalized additive models (GAM), maximum entropy (MaxENT) models, boosted regression trees (BRT), ensemble, and CLIMEX models to predict suitable habitat for maize pests and pathogens in the US. Distribution models were made of insect pests of highest concern, including Lepidopterans Autographa gamma, Chilo partellus, Helicoverpa armigera, Spodoptera litura, and Thaumatotibia leucotreta, Coleopterans Diabrotica speciosa and Heteronychus arator, and the Hemipteran Laodelphax striatellus. Each of the forty models were then used to make maps of the potential geographical range that highlights areas that would be most suitable to the greatest number of pests. Coastal areas are susceptible to most maize pests and these maps convey the levels of risk associated with land near an ocean. These maps can be used to efficiently direct preventative action to high-risk areas
MICROBIOME COMPOSITION OF SOIL SEDIMENTS AT POLLUTED LOCATIONS OF RIVER GANGES, INDIA
No full textRiver Ganges is one of the major rivers in the world and the largest freshwater
river system in the Indian sub-continent. However, Ganges has been strongly affected by pollution due to various pollutants, including untreated sewage from industries and cities, pesticides from agriculture, and medical waste, recreational and religious activities. To understand the impact of the pollution on the microbiome composition, we analyzed the soil sediments collected from six different locations along the Ganges where unique anthropogenic activities have been reported. DNA was extracted from 18 soil sediment
samples collected from Rishikesh, Haridwar, Kanpur, Varanasi, Patna, and Kolkata. The V3-V4 region of the 16S rRNA gene was amplified using polymerase chain reaction, and the DNA was sequenced by Illumina Mi-Seq. The raw sequences were then processed and analyzed using Mothur-miseq SOP in Galaxy. Results reveal that all the locations share some dominant genera including Clostridium, Lachnospiracea, Roseburia, Faecalibacterium, Ruminococcus, Rhizobials, and Acidobacteria. but differ in the presence of several rare genera. The alpha (ꭤ) diversity was estimated using the Shannon
and Simpson index. Rishikesh exhibits the highest alpha diversity with a higher evenness but lowest richness compared to other locations indicating the pristine/upstream nature of the location when Kanpur had the highest richness but lesser evenness indicating an unbalanced community. Beta (β) diversity was estimated using Bray Curtis dissimilarity index. Varanasi shows the highest dissimilarity compared to other sampling locations whereas Kolkata showed the most similarity to other locations. It was also observed that both a large number core microbiota and unique bacteria mainly derived from human anthropogenic activities like bathing, fecal matter, cremations, and industrial and agricultural waste. The understanding of the microbiome community structure-function will further provide insights in essential nutrient cycles, including decomposition of organic compounds and primary production in aquatic food chains
Unexpected large evasion fluxes of carbon dioxide from turbulent streams draining the world’s mountains
No full textInland waters, including streams and rivers, are active components of the global carbon cycle.Despite the large areal extent of the world’s mountains, the role of mountain streams forglobal carbonfluxes remains elusive. Using recent insights from gas exchange in turbulentstreams, we found that areal CO2evasionfluxes from mountain streams equal or exceedthose reported from tropical and boreal streams, typically regarded as hotspots of aquaticcarbonfluxes. At the regional scale of the Swiss Alps, we present evidence that emitted CO2derives from lithogenic and biogenic sources within the catchment and delivered by thegroundwater to the streams. At a global scale, we estimate the CO2evasion from mountainstreams to 167 ± 1.5 Tg C yr−1, which is high given their relatively low areal contribution to theglobal stream and river networks. Ourfindings shed new light on mountain streams for globalcarbonfluxes.RIVE
LINEAR MORPHOMETRICS OF THE SPECIES SPHAERODACTYLUS GRANDISQUAMIS (GEKKOTA, SPHAERODACTYLIDAE) BASED ON X-RAY DATA
No full textRecent phylogenetic studies of Sphaerodactylus geckos from Puerto Rico recognized S. grandisquamis as a valid species. We can better understand evolutionary processes within and surrounding the Puerto Rican Islands with an available phylogeny for this species, distributed across the island.
In the most recent phylogenetic analysis of Sphaerodactylus geckos, S. macrolepis was reorganized into three species: 1) S. macrolepis, occurring in the American and British Virgin Islands and the eastern part of Culebra Island; 2) S. inigoi, occurring in Vieques Island and the western part of Culebra; and 3) S. grandisquamis, which is distributed across parts of Puerto Rico and some of the satellite islands such as Isla Piñeros. This taxonomic arrangement maintains the S. grandisquamis complex, which includes seven subspecies with more or less parapatric distributions.
Molecular studies have revealed that diversity within S. grandisquamis is greater than the morphological data indicated. In the mitochondrial DNA tree for the species, S. g. spanius formed two separate clusters. To investigate this issue, I derived anatomical data from digital X-rays of the skeletons of representative specimens from all the subspecies of the S. grandisquamis group. This group included the two clusters identified as S. g. spanius, were collected and compared in specimens from Puerto Rico and some from Isla Piñeros. After X-raying formalin-preserved specimens, 12 morphological measurements were obtained using ImageJ and further analyzed using a Multivariate Principal Component Analysis implemented in R. These measurements provided sufficient data to show a statistical difference between the larger known group of S. g. spanius and all other subspecies, indicating elevation-driven morphological variation. Results from a clinal analysis of elevation and temperature showed that specimens collected from high elevations and lower temperatures had larger limb bones, contradicting Allen’s revised rule, whereas an increase in size along an elevational cline fit with Bergmann’s ecogeographical rule. This study did not support recognition of specimens from Divisoria as a separate subspecies of S. g. spanius
Predictive Species Distribution Modeling of Molluscan Agricultural Pests to Assess the Probability of Future Invasions in the United States
No full textAs a result of the explosive increase in the globalization of the world’s economy, travel, and trade, the introduction of non-native invasive species, made either intentionally or accidentally, is a well-documented phenomenon. Industries such as the horticulture, pet, and live-food trades are all major culprits in the dispersal of non-native alien species around the globe. Invasive terrestrial gastropods pose a significant and understudied threat to United States agriculture, native biodiversity, and public health. Thus, the objective of this research is to make use of publicly available occurrence data sourced from the Global Biodiversity Information Facility (GBIF) to generate a suite of correlative and mechanistic predictive species distribution models including the General Additive Model (GAM), Maximum Entropy (MaxEnt), Boosted Regression Trees (BRT), CLIMEX, and weighted consensus ensemble forecasts to better identify areas of potentially suitable habitat for high-risk invasive terrestrial mollusk species in the continental US under both current and future climatic conditions. The results of this study have been used to generate a series of ranked species threat assessments which can ultimately be used to better inform domestic pest quarantine measures, long-term pest monitoring projects, and integrative pest-management strategies to further aid in the prevention and early detection of the successful establishment of high-risk invasive terrestrial gastropods here in the US as the global climate continues to change
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