Isolated teeth of small theropods from the El Gallo Formation, Baja California, Mexico

Over recent decades, the eastern North Pacific Ocean (ENP) has undergone significant climate-driven change, characterized by rising sea surface temperatures (SSTs), a northward expansion of the North Pacific Transition Zone (NPTZ), and more frequent marine heatwaves. Juvenile North Pacific loggerhead sea turtles ( Caretta caretta ), a highly mobile species sensitive to environmental variability, have emerged as a sentinel species within the region. When North Pacific loggerheads migrate from the eastern subtropical gyre to coastal habitat, they do so offshore of the Baja California Peninsula, Mexico. Analysis of an extensive satellite tracking data set (n=285,1997–2023) revealed no prior observations of juveniles entering the colder, nutrient-rich waters of the northern California Current System (CCS). However, the gradual northward shift of loggerhead foraging habitat has been observed in parallel with an increasingly oligotrophic NPTZ. In 2024, four of 28 satellite-tracked individuals deviated from historic migratory routes and entered the northern CCS. To understand the physical mechanisms that enabled these novel movements, we integrated SST, chlorophyll-a concentrations, and surface current conditions experienced by these individuals and compared them to historical records within the region. During September-October 2024, these turtles reached 45°N latitude, where they encountered strong eastward flow within the North Pacific Current (NPC), thermally suitable conditions, and enhanced productivity. These conditions created a transient, high-latitude migratory corridor into the northern CCS. While three of these turtles benefited from reaching enhanced forage habitat in the California Current System, one likely suffered cold-stunning upon entry into suboptimal waters. The other 24 turtles remained south of the NPC, in the subtropical gyre. Our study represents the first confirmed use of a new, northern CCS migratory corridor by juvenile North Pacific loggerhead sea turtles. These findings expand on the conceptual framework of the ‘thermal corridor hypothesis,’ which suggests that sea turtles opportunistically exploit anomalously warm conditions to reach foraging habitats along the North American coast. They also emphasize the role of additional environmental drivers, such as advective current systems, in these movements. Under accelerated climate change, such transient pathways may become increasingly prevalent, with significant implications for conservation planning and fisheries management.

We assembled and annotated a chromosome-level genome for the Western Spadefoot, Spea hammondii (Anura, Scaphiopodidae) representing one of only three amphibians included in the California Conservation Genomics Project (CCGP). Spea hammondii is a vernal pool breeding anuran native to California and northwestern Baja California which has undergone both range contractions and local extirpations across its distribution, primarily due to habitat loss and degradation and drought. The species is recognized by the state of California as a Species of Special Concern and is proposed for listing under the United States Endangered Species Act. Using the established CCGP pipeline, this S. hammondii genome was produced using Pacific Biosciences HiFi long-reads and Omni-C proximity ligation, resulting in a de novo genome assembly 1.14Gb in length, distributed across 479 scaffolds (scaffold N50 = 120.8Mb; largest scaffold = 183.6Mb) with a BUSCO completeness score of 90.9% using a conserved tetrapod ortholog set. Our assembly shows high base accuracy (quality value [QV] = 63.7) and low frameshift error in coding regions (QV 50.42). Annotation of this genome yielded 20,434 genes with a BUSCO completeness score of 94.7%. This genome assembly, in combination with range-wide resequencing data from CCGP, will facilitate statewide population genomic assessments to delineate conservation units, quantify inbreeding and genomic load, and test for adaptive variation associated with vernal pool hydrology and drought tolerance, all of which are important considerations in the proposed federal listing.

Abstract High‐pressure rocks from subduction complexes are key records of the physical and chemical processes that operate on the subduction interface, but interpretation of these records requires accurate structural understanding of where they formed in the subduction zone and the mechanisms by which they were exhumed. We present new geologic mapping, outcrop‐scale observations, and geochronology from subduction‐zone assemblages at Punta Prieta Ridge on Cedros Island, Baja California (Mexico), to investigate the history of subduction, exhumation, and structural assembly of these rocks. The rocks of Punta Prieta Ridge are exposed in the footwalls of high‐ and low‐angle normal faults that carry Cretaceous forearc basin strata and attenuated mantle sections of the Cedros Island Ophiolite in their hangingwalls. The footwall rocks are subduction‐zone assemblages organized into distinct nappes that decrease in metamorphic grade and degree of strain structurally downward. Garnet‐amphibolite and blueschist blocks within the subduction complex yield 40 Ar/ 39 Ar cooling ages between 172 and 144 Ma and are hosted in siliciclastic rocks which yield detrital zircon maximum depositional ages between 92 and 72 Ma. Based on field evidence and age relationships, we interpret the occurrence of older higher‐grade blocks in younger clastic matrix to be depositional rather than the result of tectonic mixing. We then present a model for their exhumation and assembly via multiple cycles of extensional unroofing of the subduction complex and sedimentary recycling of high‐pressure rocks back into the subduction trench. We conclude by comparing the record of subduction on Cedros Island to other parts of the Cordillera.

Coccidioidomycosis (Valley fever), caused by Coccidioides spp. fungi, is a reemerging, neglected fungal disease endemic to arid and semiarid regions of the Americas. Environmental detection remains challenging because of spatial heterogeneity, seasonal variability, low DNA abundance, PCR inhibitors, and lack of standardized methods. We conducted environmental surveillance in Baja California, Mexico, an understudied region near the US-Mexico border, by collecting 74 soil samples from active rodent burrows across 5 locations. We evaluated droplet digital PCR (ddPCR) for Coccidioides detection and compared ddPCR with nested PCR targeting the internal transcribed spacer 1 region. ddPCR demonstrated greater sensitivity, detecting Coccidioides spp. DNA at all sampling sites, whereas nested PCR detected Coccidioides spp. DNA from only 1 site. Although additional work is required to rigorously quantify sensitivity and specificity, ddPCR could help identify Coccidioides environmental hotspots, thus enabling public health interventions, such as warning communities of areas that pose higher risk for infection.

Climatic response of conifer species in Baja California, Mexico

Spatial richness patterns of large pelagic fishes in the Eastern Pacific Ocean.

State of deep-sea science and conservation in the Northeast Pacific: implications for policy and management

The green sea turtle (Chelonia mydas) is listed as an endangered species in Mexico and presents significant conservation challenges due to its changing migratory patterns throughout its life stages and the thousands of kilometers it travels between its birthplace and foraging grounds. To understand the natal origins of green sea turtle populations of the Baja California peninsula, samples were collected over two years from two populations at opposite sides in the Baja California peninsula, with one located in the middle of the Gulf of California (Bahía de Los Ángeles [BLA]) and the other on the Pacific Western coast (Complejo Lagunar Ojo de Liebre [CLOL]), both located in Mexico. The mitochondrial DNA control region was sequenced and compared with potential source populations in the Pacific Ocean. The mixed-stock analysis indicated that both Baja California populations originate from nesting sites in the Eastern Pacific, primarily from the Revillagigedo Islands and the coast of Michoacán. Statistical analysis was used to evaluate the contribution of turtles originating from the Revillagigedo Islands and the coast of Michoacán to both sites, which found that statistically both Revillagigedo and Michoacán contribute the same number of individuals to the BLA and CLOL zones (Bayes Factor <1.9 for both populations [1.59 and 1.14, respectively]).

The Cape Striped Racer (Masticophis aurigulus) is an elusive snake endemic to Baja California Sur, Mexico. Earlier reports of its diet are unverified, and both its geographic distribution and elevational range are inconsistently documented. Here, we announce ingestion by M. aurigulus of an Erinnyis moth pupa and the lizard Petrosaurus thalassinus, representing the only confirmed prey for this species. We also document new records that extend the distribution of M. aurigulus to the Sierra Las Cacachilas, Sierra La Gata, Sierra El Novillo, and western Sierra La Laguna. These records clarify that the species is not restricted to the higher elevations of the Sierra La Laguna as often indicated, yet the known upper and lower limits remain imprecise (sea level to 1750 m, approximately). We underscore the evergreen need for ecological and distributional information to be based on independently verifiable evidence.

Inter-individual variability is the range of phenotypes within a population and can shape adaptive responses to environmental change. However, how temperature influences this variability remains unclear despite its importance for predicting population resilience to warming. We tested how rearing temperature (15°C and 22°C) affects both trait means and variability in time to stage, size, oxygen consumption rate (V˙O2) and swim speed in Baja California chorus frog (Pseudacris hypochondriaca) tadpoles. Mean time to stage and morphological traits decreased at 22°C, while mass-specific V˙O2 and swim speed increased. Variance (s2, absolute variation) was lower at 22°C for time to stage and mass, higher for mass-specific V˙O2, and similar for length and swim speed. Coefficient of variation (CV, relative variation) was higher at 22°C for mass, tail length and depth, and mass-specific V̇O2, indicating trait-specific changes in canalization. Log-transformed Q10 response ratios for trait means (lnRRQ10), variance (lnVRQ10) and CV (lnCVRQ10) revealed strong thermal sensitivity for means but more limited and trait-specific responses in variability. Thus, temperature effects on variability are trait-specific and variability does not always change with, or in the same direction as, trait means. These phenotypic changes may have ecological consequences that influence physiological performance during subsequent life stages. This article is part of the theme issue 'Embracing variability in comparative physiology: why it matters and what to do with it'.

Obligately intracellular rickettsiae cause a broad spectrum of disease in humans and animals, ranging from mild illness to life-threatening infections. Multiple species co-circulate along the southern United States of America-northern Mexico border, yet their seroprevalence in susceptible hosts remains incompletely understood. Dogs serve as key amplifying hosts for several of these pathogens, including Rickettsia rickettsii and Rickettsia massiliae, and have been shown to be infected by flea-borne Rickettsia typhi and Rickettsia felis. To better characterize exposure and potential co-infection patterns, we conducted a large binational seroepidemiologic study of 779 dogs from urban households and shelter settings across seven subregions along both sides of the border. Using a custom multiplex micro-immunofluorescence assay, we simultaneously screened for antibodies to R. rickettsii, R. massiliae, R. typhi, and R. felis. Overall, 41.2% of dogs were seroreactive to at least one pathogen, with the highest seroprevalence for R. felis (19.3%), followed by R. massiliae (15.7%), R. typhi (14.5%), and R. rickettsii (9.8%). Co-seroreactivity was common, particularly between R. typhi and R. felis, with 34.2% of R. typhi-seroreactive samples also seroreactive to R. felis, and 16.7% exhibiting high titers to both. In contrast, R. rickettsii and R. massiliae showed limited overlap (15.2% co-seroreactive; 6.4% with high titers), suggesting possible cross-protection or competitive exclusion. Spatial analyses revealed distinct geographic patterns: R. massiliae predominated in western Baja California, R. rickettsii was concentrated in Mexicali and the Rio Grande Valley, and R. felis was widely distributed. Seroreactivity patterns were generally consistent across age and sex but varied modestly between shelter and neighborhood dogs, particularly for R. typhi. These findings highlight the complex ecology of rickettsial pathogens in a binational context, underscore the importance of dogs as sentinels for human risk, and provide a foundation for future studies on vector-host-pathogen interactions, cross-protective immunity, and spatial epidemiological risk.

Kelp forests are experiencing extreme declines globally, yet local social-ecological factors may mediate their responses to climate perturbations. Using a combination of long-term field surveys (2016–2023) and satellite data (2004–2023), we examined the regional effects of the 2014–2016 marine heatwaves regime on kelp forest ecosystems along a 600 km latitudinal gradient in Baja California, Mexico. We documented three distinct geographical subregion trajectories: (1) a remarkable resilience of giant kelp Macrocystis pyrifera , at its thermal limits in the southern subregion, recovering 95% of the historical canopy area despite experiencing the highest temperatures; (2) understory-dominated state in the mid-subregion, with a 96% decrease in M. pyrifera canopy, where understory brown macroalgae filled the ecological niche left by declining giant kelp, maintained by moderate herbivore densities; and (3) a shift to an urchin barren alternative stable state in the northern subregion, characterized by a 2,485% increase in herbivore densities from 2016 to 2023 —dominated by purple sea urchin Strongylocentrotus purpuratus (44%)— and a 95% reduction in giant kelp canopy area compared to pre-warming baseline. The southern subregion’s resilience was associated with high predators’ (10.26 ± 5.63 per 60 m²) and low herbivores’ (25.20 ± 8.89 per 60 m²) densities, dominated by turban snails Megastraea spp. (83%) with S. purpuratus absent. In contrast, the northern subregion’s shift from kelp forests to urchin barrens coincided with low predator abundances (5.05 ± 2.32 per 60 m²), potentially linked to fragmented fisheries management. Our findings challenge the assumption that range-edge populations are inherently more vulnerable to warming and underscore how local biological factors and management approaches can either enhance or compromise ecosystem resilience to climate stress. These divergent trajectories suggest that while temperature acts as an initial driver of change, the persistence of alternative states is governed by ecological feedback involving predator-herbivore dynamics, herbivores’ assemblages, and management contexts, providing insights for developing climate-adaptive conservation strategies under intensifying global environmental change.

Purpose This paper aims to conceptualize diasporic medication tourism and examine the factors influencing the revisit intention of diasporic medication tourists to the border city of Tijuana, Baja California. Design/methodology/approach Based on the push–pull model, four constructs were examined: medication availability (MA) and cultural proximity (CP) (push) and medication quality (MQ) and medication price (MP) (pull). An online survey was conducted with 384 diasporic medication tourists in Tijuana, Mexico, who reported repeated medication purchases from local pharmacies. Findings The results indicate that MA, CP and MQ significantly influence diasporic medication tourists’ revisit intention, while MP shows no significant effect. Practical implications The findings suggest that pharmacies and destination stakeholders in border regions can strengthen diasporic visitors’ loyalty by prioritizing consistent MA, culturally familiar service environments and credible quality assurance. At the policy level, enhanced binational coordination and regulatory clarity may support safe, efficient and culturally responsive pharmaceutical access for diasporic communities. Originality/value This study advances research on medication tourism by reframing diasporic medication travel as a trust-based and culturally embedded form of cross-border pharmaceutical mobility. It proposes a context-sensitive model suited to border regions where developed and developing pharmaceutical systems intersect.

Over 80% of tuberculosis cases in the United States are due to reactivation of untreated latent tuberculosis infection (LTBI), most of whom were foreign born. LTBI treatment can greatly lower the risk of progression to active TB disease, and shorter treatment regimens increase the potential of migrants and other persons in vulnerable conditions, to complete treatment. We conducted across-sectional study to assess willingness to complete a one-month course of LTBI treatment among internal and international migrants living in Tijuana, BC, Mexico, and to identify factors associated with treatment unwillingness between November 2020 and April 2021. Prior to administering TB skin tests (TST), participants were asked if they would accept LTBI treatment if indicated by test results and clinical examination. Recruitment occurred in migrant shelters throughout Tijuana and at a storefront office conducting research and harm reduction services for people who use drugs. Among 595 participants, 80.4% were living in shelters, 3.5% were recruited at shelters but living independently, and 16.1% were recruited through the storefront office. Overall, 71 (11.9%) indicated that they were unwilling to take LTBI treatment and 109 (18.3%) had positive TST results. Unwillingness to take LTBI treatment was more common among participants from the storefront office compared to the shelter (64.6% vs. 1.8%, p<0.001). Since only 1.8% of shelter participants were unwilling to receive treatment, multivariable Poisson regression with robust variance estimation via GEE for identifying factors independently associated with LTBI treatment unwillingness was restricted to storefront participants. Treatment unwillingness among storefront participants was positively associated with perceiving health status as "good" or "very good" (prevalence ratio [PR]=2.37, 95% confidence interval [CI]: 1.52, 3.99) and heroin use in the past six months (PR=1.70; 95% CI: 1.33, 2.19). Unstable housing was reported as a barrier to treatment. These findings suggest that most migrants in Tijuana were willing to receive short-course LTBI treatment if indicated, yet willingness was lower among those at greatest risk of TB. Efforts to increase testing and treatment, as well as further research on overcoming barriers to treatment willingness are needed.

This article presents research on the relationship between emotional intelligence and the effectiveness of business leaders in La Paz, Baja California Sur. This study does not evaluate objective work efficiency, but rather the perception that leaders have about their own performance and about the role that their emotional skills play in that performance. It is hypothesized that leaders with greater self-perception of emotional intelligence show higher levels of self-perception of effectiveness in the performance of their organizational functions. The research was carried out using a mixed approach, which combined the application of a structured questionnaire to 100 leaders of companies of different sizes: small, medium and large. In addition, six semi-structured interviews were conducted with selected leaders. The variables analyzed in the questionnaire include self-awareness, self-regulation, empathy, social skills and motivation, five competencies based on the model proposed by Daniel Goleman. The results show that leaders have predominantly positive self-perception in all the dimensions evaluated. Active listening (90%), emotion recognition (80%) and management of emotions and thoughts (80%) stand out, followed by motivation and a positive attitude (74%). Overall, the findings support the hypothesis, showing that greater emotional self-awareness is associated with a higher perception of effectiveness in business leadership. Likewise, the results suggest that emotional intelligence is a key resource to strengthen the perceived performance of leaders.

Increasing temperature and decreasing precipitation threaten the extent, persistence, and dynamics of snow across spatial scales, particularly ephemeral snow in Mediterranean mountain regions. This study estimates ephemeral snow cover and snow water equivalent (SWE) in the Sierra de San Pedro Mártir, Baja California, Mexico, using open-access datasets and remote sensing. Camera trap images and limited in situ data were used to calibrate the normalized difference snow index (NDSI) for snow detection and to estimate SWE and topographic effects on SWE from 2002 to 2023, encompassing wet, dry, and normal years. The optimal NDSI threshold for snow detection was 6.4 for MODIS Terra and 5.3 for MODIS Aqua, substantially lower than thresholds commonly reported for seasonal snowpacks in forested regions. In wet years, snowfall contributed up to 20% of annual precipitation, compared with ~13% in dry years. In normal years, the average SWE is 70 mm (24% of annual precipitation). SWE increased by 30% (91 mm) during wet years and decreased by 21% (55 mm) during dry years. Eastness (aspect) was the only statistically significant topographic predictor of SWE for MTerra, with higher SWE values observed on west-facing slopes. This study provides the first quantitative assessment of ephemeral SWE dynamics in a Mexican Mediterranean mountain system and establishes a framework for monitoring marginal snowpacks under increasing climatic variability.

Predicting how species will respond to global change requires understanding how environmental drivers shape both neutral and adaptive genetic variation across space. The kelp Eisenia arborea is a thermally tolerant foundation species spanning more than 3000 km of coastline and a broad latitudinal temperature gradient in the Northeast Pacific, yet how environmental and demographic processes influence genomic and population structure remain unclear. We used genome-wide ddRAD sequencing to investigate patterns of genetic diversity, connectivity and local adaptation in E. arborea across two depths and ~2700 km of coastline. We detected strong genetic differentiation between northern (British Columbia, Canada) and southern (Baja California, Mexico) populations, indicating limited gene flow across the species' broad range. Southern populations also had the lowest genetic diversity and highest inbreeding, broadly consistent with expectations for populations occupying environmentally marginal portions of a species' range. However, the two southernmost populations (~200 km apart) were highly similar and well connected, whereas mid-range sites were more differentiated, indicating that the geographic range edge population was not genetically isolated as is often hypothesised. Environmental association analyses identified SNPs correlated with both sea surface temperature and depth, revealing signals of local adaptation to broad climatic gradients and fine-scale habitat variation. The combination of high inbreeding, restricted connectivity and local adaptation highlights both the vulnerability and potential conservation value of distinct genetic units, especially warm-adapted southern populations, for maintaining the resilience of these Eisenia forests under ocean warming.

The evolving burden of drug use disorders in Mexico: Secondary data analysis from the global burden of disease study 2021.

Abstract Amagmatic geothermal systems in coastal locations are promising energy resources, yet the processes that localize and sustain their hot‐spring discharge remain unclear. We investigate La Jolla Beach (NW Baja California, Mexico)—one of the hottest known examples worldwide (∼100°C)—using large‐scale 3D coupled thermal–hydraulic simulations. The models are calibrated against observed temperature, salinity, surface area and location of the springs, and verified using meteoric‐water residence times. The results imply that a highly permeable coastal segment of the Agua Blanca Fault (ABF) transfers meteoric water from a hinterland recharge zone to the coast via deep (&gt;5 km) circulation. Within the coastal fault, dense seawater forms a hydraulic barrier to the meteoric water, while thermal buoyancy steepens the meteoric–seawater interface and creates a near‐vertical upflow plume that focuses hot, mixed fluids to the shoreline, resulting in high discharge temperatures. Tracer simulations indicate that deep fault flow is supplied approximately equally by infiltration through the exposed fault trace and by lateral inflow from the surrounding fractured country rocks. This underscores the system's inherently 3D nature and the capacity of regional faults to collect recharge from broad catchments, even where overall infiltration rates are low. Permeable sediments draped over a basement high and bounded by less‐permeable sediments focus the hot upwelling water at La Jolla Beach. Our findings explain the thermal‐hydraulic coupling that controls amagmatic coastal fault–controlled geothermal systems, providing a basis to assess the geothermal potential of analogous systems worldwide.