La ecología e historia de vida de muchas especies de serpiente siguen siendo poco conocidas debido a su naturaleza secreta. El análisis morfológico de los caracteres mensurales (medidas corporales cuantitativas) ofrece un enfoque útil para examinar la evolución inter e intraespecífica en respuesta a las presiones ambientales. Aquí, examinamos la divergencia morfológica, el dimorfismo sexual y las respuestas evolutivas a la elevación y las clinas latitudinales en dos especies hermanas de coloridos imitadores de serpientes de coral, Lampropeltis pyromelana y L. knoblochi, a través del análisis de caracteres mensurales de especímenes de museos. Nuestros resultados revelan una diferenciación morfológica limitada entre las dos especies y sexos. Se recuperan correlaciones débiles entre la morfología y la geografía, con tendencias muy similares para las dos especies a lo largo de gradientes latitudinales, pero diferentes patrones a lo largo de la elevación. Se requieren estudios futuros que incorporen datos genómicos y dietéticos para dilucidar aún más las respuestas adaptativas a los gradientes ambientales en Lampropeltis.
El declive global en las poblaciones de abejas ha incrementado la preocupación en torno a su conservación y a los servicios críticos de polinización que proporcionan. Implementar un monitoreo eficaz de su diversidad y tendencias poblacionales depende de métodos de muestreo robustos; no obstante, la eficiencia de dichas metodologías varía entre regiones, hábitats y taxones. El estado de Colorado alberga más de 1000 especies de abejas; sin embargo, las zonas ubicadas al oeste de las Montañas Rocosas han sido escasamente estudiadas en contraste con la región oriental del Front Range. Para abordar esta brecha, evaluamos la eficacia de múltiples técnicas de muestreo activas y pasivas para estudiar las comunidades de abejas nativas y sus asociaciones florales en el oeste de Colorado. Entre junio y agosto de 2024, muestreamos 64 parcelas en ecosistemas de matorral, pastizal, zona alpina y bosque mediante trampas de veleta azul, trampas de plato de cuatro colores y tres métodos activos: colecta dirigida, red de golpeo y red aérea. En total se recolectamos 4872 abejas que representaron 39 géneros. Halictidae constituyó la familia más abundante (65.7%), seguida por Apidae (19.5%) y Megachilidae (6.8%). Las trampas de veleta azul capturaron el mayor número de individuos, principalmente Apidae, incluido Bombus occidentalis, mientras que la captura dirigida generó la mayor riqueza taxonómica (33 géneros). Las trampas de plato amarillas atrajeron altas cantidades de abejas, pero baja diversidad, dominadas por Halictidae. Aunque con la red aérea y la red de golpeo se capturaron menos abejas, estas aportaron géneros únicos que no aparecieron en otros métodos. Las abejas visitaron 26 familias de plantas con flor, y Asteraceae, Fabaceae, Plantaginaceae, Malvaceae y Brassicaceae representaron más del 76% de las observaciones. Observamos las cinco familias de abejas en Melilotus officinalis, Sphaeralcea coccinea y Cirsium spp. Ningún método de muestreo registró la diversidad completa de abejas, lo que destaca la necesidad de combinar enfoques activos y pasivos. Este estudio constituye una de las evaluaciones más completas hasta la fecha sobre el muestreo de abejas en el oeste de Colorado y aporta orientación práctica para fortalecer el monitoreo, mejorar la comparabilidad de los datos y apoyar la conservación de estos polinizadores ante su declive global.
Investigamos la comunidad de líquenes epífitos que crece sobre arbustos tolerantes a la sal alrededor de los márgenes de las playas del Desierto de la Gran Cuenca. Se analizaron datos de 82 sitios dentro y alrededor de playas en toda la región. De las 29 especies de líquenes epífitos encontrados, una comunidad núcleo constante compuesta por ocho especies coexistió habitualmente en la mayoría de los sitios de playa. Dos de estas especies son nuevas para la ciencia: Lecania clairii sp. nov., similar a L. fuscella, pero que produce de forma consistente un pigmento púrpura en el epihimenio, presenta ascos estrictamente octospóricos, paráfisis fuertemente capitadas y pigmentadas, y células más marcadamente engrosadas en la corteza anfitecial. Rinodina salinaria sp. nov. es similar y coexiste con R. lobulata, pero carece sistemáticamente del pigmento Sedifolia-gray, sus apotecios permanecen inmersos por más tiempo y posee ascosporas más pequeñas. El líquen más abundante encontrado fue Calogaya ferrugineoides, que hasta hace poco únicamente se conocía en Asia Central. Otra especie de esa región, Calogaya polycarpoides, se registra por primera vez en Norteamérica. Dos hongos liquenícolas son comunes en esta comunidad, Arthonia molendoi y otra especie nueva para la ciencia, Lichenochora endocalogaya sp. nov. Esta última es similar a L. xanthoriae, pero se presenta en un hospedero diferente Calogaya ferrugineoides en lugar de Rusavskia elegans, y no induce la formación de agallas. Se analizó el rango y la ecología de esta comunidad halófita y se comparan con otras comunidades epífitas presentes en el Desierto de la Gran Cuenca.
Un análisis enfocado en microquímicos de tejido óseo de June Sucker Chasmistes liorus, amenazada a nivel federal, (Utah Lake, UT, USA) fue incitado por sospecho de reclutamiento natural de individuos de origines desconocidos (es decir, individuos no marcados). Usamos espectrometría de masas con plasma inductivamente acoplado con ablación láser para analizar composiciones elementales de áreas discretas de radios de aletas pectorales (es decir, núcleo natal, borde) correspondiente a fuentes natales posibles de June Sucker (n = 98). El Análisis Discriminante Cuadrático (por sus siglas en inglés QDA) fue usado para diferenciar cuatro posibilidades de fuentes natales: un criadero, dos poblaciones de refugia, y Utah Lake (origen salvaje). Los cocientes elementales del tejido óseo que proporcionaron poder discriminatorio fueron: Mg/Ca, loge K/Ca, loge Mn/Ca, loge Sr/Ca, and loge Ba/Ca. Composiciones elementales de especímenes del criadero y Utah Lake fueron diferenciados, utilizado QDA, aunque un traslape sustancial existió entre las dos poblaciones de refugia. Análisis de radios de aletas pectorales de 263 June Sucker de origen desconocido (es decir, no marcados) colectados entre 2016 y 2020 corroboraron la presencia de reclutas salvajes con origen natal de 11%–13% de muestras asignadas a Utah Lake. El resto de de los especímenes de peces no marcados fueron del criadero (87%–89%), con Fisheries Experimental Station (Logan, UT) siendo la fuente natal numéricamente dominante de estos especímenes. La presencia de varias clases de tamaño de reclutas salvajes indicó que reclutamiento ha ocurrido episódicamente. Nuestro estudio confirma el uso de microquímica de partes duras como un efectivo técnico analítico para determinar origen de especímenes, que combinamos con métodos de muestro no letales (es decir, extracción de una sección de radios de la aleta pectoral), para hablar a un problema de conservación específica, e informar la recuperación de esta especie amenazada a nivel federal.
Los caracoles de manantial del género Pyrgulopsis en el oeste de América del Norte han representado un desafío para los taxónomos durante mucho tiempo. La delimitación de los límites entre especies se ha visto complicada por la presencia de taxones crípticos o aún por descubrir, la sobreestimación o subestimación de sus áreas de distribución, la existencia de complejos de especies que representan un número desconocido de estas, y la presencia de especies descritas que resultan ser sinónimas de otros taxones. Para abordar estos problemas, se llevaron a cabo un conjunto de análisis moleculares de delimitación de especies utilizando secuencias de hasta dos genes mitocondriales y dos nucleares de más de 5000 ejemplares que representaron 140 de los 151 taxones actualmente reconocidos. Estos análisis reafirmaron la mayoría de las hipótesis de especie, respaldaron la sinonimia de algunos taxones y la redefinición de límites entre especies en otros, y aportaron evidencia sobre la presencia de numerosos taxones nuevos o crípticos. Surgieron algunas discrepancias entre métodos y genes respecto a los límites entre las especies, particularmente dentro del complejo de especies P. pilsbryana. Además, observamos casos de hibridación reciente y posibles taxones de origen híbrido. Aunque estos análisis aclararon muchas de las hipótesis sobre las especies dentro del género, una mayor resolución taxonómica de este grupo requerirá un muestreo de campo más intensivo y con una cobertura espacial más amplia, combinado con una mayor representación genética de individuos. Se prevé que la compleja historia evolutiva de los miembros de Pyrgulopsis represente un reto constante para la caracterización de la biodiversidad de este taxón.
Los pájaros carpinteros de Lewis (Melanerpes lewis) actúan como forrajeadores oportunistas conocidos por su propensión a capturar insectos en vuelo. Aquí describo observaciones de un grupo de carpinteros que forrajeaba activamente sobre invertebrados acuáticos a lo largo de una barra de cantos rodados en el tramo superior del río Rogue, Oregón. Las aves se posaban sobre los cantos expuestos y exploraban el agua somera que fluía entre ellos; durante este comportamiento capturaban y consumían presas invertebradas. En este hábitat de aguas poco profundas habitaba un conjunto abundante y diverso de invertebrados, y entre los taxones consumidos identifiqué caracoles y ninfas grandes de plecópteros.
northern pocket gopher (Thomomys talpoides) is a common species widely distributed across southwestern Canada and the American West. It is fossorial and occupies numerous habitats. Thomomys talpoides contains many distinct populations and defined subspecies. The subspecies T. t. quadratus occupies sagebrush regions of Oregon and northeastern California. Little information is available on T. t. quadratus, and almost no information pertains to its general natural history. On 14 May 2025 in Lassen County, California, I observed 2 northern pocket gophers foraging at the entrance of a burrow. They repeatedly stored vegetation in their cheek pouches or directly pulled plants into the burrow. The occurrence of both gophers together indicates reproductive individuals since the species is typically fiercely territorial and solitary outside the breeding season. The 2 gophers may not represent a mated pair but could be individuals nesting in a shared burrow network. This observation offers insight into food items, physical environment, and breeding phenology of this little-studied population at the periphery of the T. talpoides range.
Euphilotes pallescens arenamontana, the Sand Mountain blue butterfly, is of conservation concern due to its small geographic range, a single locality in the arid western United States, as well as recreational activities that potentially impact the larval host plant, Eriogonum nummulare, Kearney's buckwheat. Thus, the Sand Mountain blue is a case study for the confluence of stressors affecting a rare insect in a hot spot of climate change. We investigate the population status of E. p. arenamontana, changes in vegetation composition, habitat features, and pollination of the host plant and primary nectar source. Adult butterfly counts were conducted in the years 2006, 2022, and 2023, and variables that include the cover of E. nummulare and habitat disturbance were used to examine habitat characteristics; we also quantified the presence of ants, which are important mutualists for E. p. arenamontana caterpillars. We observed a decline in adult numbers between 2006 and more recent years. The best predictors for caterpillar presence were buckwheat inflorescences, ant abundance, and the presence of adults, while the best predictor of adult butterfly presence was percent cover of buckwheat. Vegetation composition has changed between 2006 and 2024, with a reduction in E. nummulare plants, and a small subset of the flying insect community was found to be carrying the majority of E. nummulare pollen. We use these results to assess the conservation status of E. p. arenamontana and consider whether additional protections are needed for this rare butterfly in a hot spot of climate and land use change.
Excess mercury (Hg) and selenium (Se) from mining and combustion of fossil fuels are major aquatic pollutants around the world, and both can have negative effects on aquatic organisms, including reduced reproductive success in fishes. However, due to the high binding affinity of these elements, recent evidence suggests their individual toxicities may be reduced if they occur in similar molar concentrations. In the San Juan River basin, the Four Corners Power Plant, San Juan Generating Station, and Navajo Mine, which make up one of the largest coal mine and power generating complexes in the world, recently reduced their Hg emissions by >90%. Despite this reduction, dry Hg deposition rates have increased in the San Juan River basin. One species potentially impacted by this increase in Hg is the endangered Colorado Pikeminnow (Ptychocheilus lucius), which was reestablished in the San Juan River basin through stocking efforts after its previous extirpation. In this study, we compared the concentrations of Hg and Se in Colorado Pikeminnow tissue samples collected in 2009 to samples collected in 2019 and 2020. We found increased concentrations of both Hg and Se in the 2019-2020 samples compared to those from 2009. Concentrations of Hg in tissues increased with fish size, while Se concentrations decreased with fish size. The percentage of individuals above the Environmental Protection Agency guidelines increased between time periods for both Hg (6.9% to 57.9%) and Se (0% to 15.9%). The Se:Hg ratio decreased with increasing fish size in 2019-2020 samples but was always greater than 1, suggesting potential protective effects. Given that the recovery of Colorado Pikeminnow in the San Juan River is limited by natural reproduction, understanding potential reproductive effects of Hg and Se will be important for gauging their threat and prioritizing management actions aimed at recovering the species.
Greater sage-grouse (Centrocercus urophasianus; hereafter, sage-grouse) populations have declined across their range, resulting in high conservation concerns among state and federal wildlife managers. While interspecific nest parasitism by chukar (Alectoris chukar) on sage-grouse nests has been observed previously, the parasitic effects benefiting or harming the reproduction of either species are unknown. Additionally, while chukar eggs have been documented in sage-grouse nests previously, we know of no documented occurrences of chukar chicks parasitizing sage-grouse broods. Here, we report a novel observation of interspecific brood parasitism on a 9-day-old sage-grouse brood by a chukar chick in the Virginia Mountains of northwestern Nevada. Because chukar are an introduced exotic species whose western North American distribution largely overlaps sage-grouse distribution, understanding the dynamics and implications of brood parasitism may inform wildlife management strategies and conservation efforts for sage-grouse throughout their range.
montane, pine-dominated forests in the western United States are home to the Pandora moth, Coloradia pandora, a large lepidopteran species that has a 2-year life cycle, generally alternating between "moth years" and "larval years." During the latter, larvae descend from their feeding locations in the pine canopy, disperse across the ground, and burrow in the soil for pupation. This study examines the nature of larval movement on trees as well as on and in the ground; the time required for the various phases during the day of descent; and parasitoid and environmental threats during ground dispersal. Locomotion during descent from trees was relatively slow at 0.64 cm/s (range 0.44-0.93 cm/s). Larvae slowed further as they transitioned from tree boles to the ground and were initially unsteady. Once on the ground, larvae quickly recovered and were able to move significantly faster (1.63 cm/s, range 1.23-2.08 cm/s) than during descent from the boles. About 10% of dispersing larvae were attacked by ovipositing tachinid flies and larvipositing sarcophagid flies. Larvae being attacked by parasitoids or traveling in full sun at high temperatures increased their speed to the point that locomotion appeared poorly coordinated. This apparently stressful locomotion was often followed by the affected animals burrowing only a centimeter below the surface of the loose soil, duff, and pine needles. Shallow burrowing by larvae stressed by heat or parasitoid attack may result in a positive feedback in terms of vulnerability because the resulting pupae would in turn be more exposed to several additional threats. Moreover, a warming climate would likely exacerbate a number of these linked causes of larval and pupal mortality.
The Sierra de Bustamante is a mountain range considered a priority terrestrial region in the northwestern section of the state of Nuevo Leon. Despite its significance for ecotourism, livestock ranching, and hunting, this area, close to the Sierra Madre Oriental, has not been studied in terms of its vertebrate richness, specifically that of mammals. Our objectives were to provide a mammal inventory and determine species preferences in relation to vegetation association and elevation. We conducted 15 field trips from September 2016 to August 2017 to survey mammals by using camera traps, mist nets, and Sherman live traps. Our efforts revealed the presence of 17 mammal species; other evidence (historical records, museum specimens, photographs) adds 15 species, for a total of 32 mammal species known for the region. The species accumulation curve resulting from our fieldwork suggests that the 17 species we detected represented 74% of the species currently present. The study region is now characterized by the presence of the introduced North African oryx (Oryx dammah) and the absence of large carnivores such as Puma concolor, Ursus americanus, Lynx rufus, and Urocyon cinereoargenteus. Of the 32 species of mammals from this region, 7 are protected by federal law. Our results strongly support the proposal that this region of Nuevo Leon merits increased protection and management of its native mammalian fauna.
Water availability is the most frequently limiting factor to plant growth in big sagebrush ecosystems. Our goal was to identify (1) the role of understory species in the water balance of big sagebrush ecosystems of the upper Green River Basin of Wyoming and (2) the competitive effects of understory species on sagebrush growth. We measured volumetric water content using field sensors to calculate seasonal actual evapotranspiration (AET) and used SOILWAT2, a process-based simulation model, to further assess the contributions of evaporation and transpiration. We measured big sagebrush leaders as a metric of annual growth. We removed all understory species in the treatment plots at the beginning of the 2022 and 2023 growing seasons and compared AETs to those of intact understory plots. We found that the removal of understory species had small effects on overall seasonal AET. When we partitioned AET into its components using SOILWAT2, we found that removing understory species led to an increase in seasonal evaporation in both study years. The impact on transpiration was minimal. After partitioning transpiration by plant type, we found that big sagebrush was dominant in water use and capitalized on available water after understory removal under water-limited conditions. Under-story removal was associated with increased leader growth of sagebrush in the dry year (2022) but not in the wet year (2023), highlighting a potential competitive release of water resources favoring sagebrush. Our findings suggest that under-story removal has a limited impact on overall water balance but can affect evaporation and water availability for sagebrush.
-The Wee Thump Wilderness Area is a 6050-acre old-growth Joshua tree forest located in southern Nevada within the boundaries of the Avi Kwa Ame National Monument. We performed nighttime searches using ultraviolet lights to document scorpion species from May to August in 2021 and 2022. Our observations, combined with DNA sequencing, allowed us to identify 2 species of scorpion within the open desert habitat (Paravaejovis confusus, Paruroctonus becki) and another that was commonly found along roadside berms (Anuroctonus phaiodactylus). Information collected on species occurrence, particularly within protected wilderness areas, provides valuable ecological data that can fuel hypothesis-driven research as well as inform land management decisions.
Psilochalcis adenticulata Petersen (Hymenoptera: Chalcididae) was described based on a small number of male specimens retrieved from Malaise traps set in Utah's eastern Great Basin. Subsequent Malaise trap samples have yielded additional specimens of P. adenticulata, including females, from different sites in central Utah. The female of P. adenticulata is described for the first time. Distribution data showing the occurrence of P. adenticulata in 2 new states and 2 new counties in Utah are reported. Sexual size dimorphism for P. adenticulata is determined and discussed.
Island environments impose distinct ecological pressures that shape the evolution of complex traits. In snakes, body and head size are often related to diet, as gape limitation constrains the size of prey an individual can consume. Many venomous snakes exhibit ontogenetic venom expression variation that parallels shifts in prey selection over development, reflecting the integration of venom and morphology into a complex feeding phenotype. On Isla Cerralvo, the Baja pared to its mainland counterpart (Crotalus enyo enyo), potentially constraining prey size. We hypothesized that reduced head size would correspond with a lack of ontogenetic shift in venom expression in C. e. cerralvensis, as smaller heads may limit ontogenetic prey shifts. We sampled venom from island and mainland populations of C. enyo and assessed venom expression patterns across different size classes in each population. Although island and mainland rattlesnakes significantly differed a single venom phenotype independent of size. The absence of ontogenetic venom variation in island snakes, coupled with their smaller head sizes, suggests the integration of venom expression and cranial morphology as part of an integrated feeding phenotype and highlights the parallel evolution of functionally linked traits in response to unique ecological conditions.
Research on wildlife diets provides insights into the variety of prey items taken. In Mexico, the bobcat (Lynx rufus) is one of the most widely distributed feline species; however, data on its diet is limited in Mexico. This study evaluated the feeding habits of bobcats in a xerophilous scrubland in the Nopala-Hualtepec region of Hidalgo State during the dry season (February) and rainy season (September) of 2015 by analyzing scats. To assess differences in prey diversity between the 2 seasons, we calculated the Shannon-Weiner index (H '), the number of effective species, niche breadth, and standardized niche breadth. A total of 73 scat samples were collected, revealing 3 taxonomic categories and a total of 13 prey species consumed. Rodents had the highest percentage occurrence values in both seasons (71.79% in the dry season and 52.38% in the rainy season). Lagomorphs followed (23.08%, 40.48%), and then birds (5.13%, 7.14%). Among the 11 rodent species consumed, Sigmodon toltecus was the most frequent in the diet. We found a significant difference in prey diversity between the seasons: the dry season had 8.36 effective species (with a 95% confidence interval of 7.29-11.07), while the rainy season had only 4.99 effective species (with a 95% confidence interval of 4.57-6.87). Niche breadth and its standardized value were narrow during the dry season (B = 1.75, Bstan = 0.38) and slightly wider in the rainy season (B = 2.26, Bstan = 0.63). Overall, the diets of bobcats in this study area primarily consisted of small mammals. As noted in other studies, bird consumption was infrequent. Bobcats generally have a narrow food niche across their North American range, with their diet varying by location, but they predominantly consume small mammal species.
Colorado pikeminnow (Ptychocheilus lucius) was historically one of the most abundant fish species in the Lower Colorado River. It was listed as endangered in 1967 and by 1978 had been extirpated from the Lower Colorado River basin. Repatriation of Colorado pikeminnow into the Colorado River downstream of Glen Canyon Dam is one action managers could take to facilitate species recovery. Arguments against repatriation of Colorado pikeminnow into the Lower Colorado River basin are commonly based on concerns about potential adverse impacts to existing populations of other threatened Colorado River fish species such as humpback chub (Gila cypha) and razorback sucker (Xyrauchen texanus). We evaluated maximum vertical gape of Colorado pikeminnow along with 6 introduced nonnative predators across a wide range of sizes and compared those gape measurements to maximum body depths of humpback chub and razorback suckers to evaluate the potential predation risks that reintroduced Colorado pikeminnow could pose. We also conducted laboratory trials to evaluate predation vulnerability of juvenile humpback chub and razorback suckers to adult Colorado pikeminnow. Juvenile humpback chub and razorback suckers outgrow the gape of all but the largest Colorado pikeminnow (>600 mm total length) by the time they reach 225 mm total length. Juvenile humpback chub and razorback suckers also have unique morphological adaptations and behaviors which appear to limit predation vulnerability to Colorado pikeminnow. Our data indicate that Colorado pikeminnow are capable of consuming prey that are 100% of their maximum anatomical gape. Humpback chub exhibited 47% higher survival than flannelmouth suckers (Catostomus latipinnis) at equivalent sizes when exposed to predation by Colorado pikeminnow. For both humpback chub and razorback suckers, survival dramatically increases as the proportion of body depth to Colorado pikeminnow gape increases. Relationships of gape to body depth and evidence from other coevolved predator-prey relationships indicate that reintroduction of the Colorado pikeminnow is unlikely to have adverse population-level impacts on coevolved Colorado River native fishes.
Rock Bass (Ambloplites rupestris) is a recent invader in the lower Lake Washington ecosystem whose potential impacts to this system are not known. We assessed changes in the relative abundance of Rock Bass and other centrarchid basses and documented the diet of Rock Bass during months of juvenile salmonid migrations (February-July). Rock Bass were collected primarily with gill nets in littoral zones of Lake Washington (2022-2024) and the Lake Washington Ship Canal (2018-2019, 2021-2023; LWSC). We sampled 3 areas in Lake Washington and 1 area of the LWSC, and in all 4 areas, Rock Bass were relatively more abundant than Largemouth Bass (Micropterus salmoides) or Smallmouth Bass (M. dolomieu). At the south end of Lake Washington (near Cedar River outlet), Rock Bass preyed heavily on migrating Sockeye Salmon (Oncorhynchus nerka) fry from February to April. Juvenile salmonids were rarely consumed in the other areas of Lake Washington and the LWSC and made up a minor component of the diet. Other major prey items of Rock Bass in Lake Washington consisted of signal crayfish (Pacifastacus leniusculus), adult Threespine Stickleback (Gasterosteus aculeatus), juvenile Yellow Perch (Perca flavescens), sculpin (Cottus spp.), opossum shrimp (Neomysis mercedis), and aquatic insects; however, the importance of these prey items varied widely among areas, years, and size classes. In 2018 and 2019 during low Threespine Stickleback abundance, Rock Bass in the LWSC consumed mostly crayfish and small invertebrates. During years in which Threespine Stickleback populations were high (2021-2023), Rock Bass in the LWSC consumed primarily adult Threespine Stickleback, crayfish, and opossum shrimp. As Rock Bass grew, they became progressively more piscivorous; however, some level of piscivory was observed in all size groups. Because Rock Bass are now abundant and have a broad diet, they have the potential to impact the Lake Washington and LWSC food webs through a variety of pathways.
