EL LÍMITE SUR DE LA REGIÓN MEDITERRÁNEA DE BAJA CALIFORNIA, CON BASE EN SUS TETRÁPODOS ENDÉMICOS

To determine the southern limit of the mediterranean region in Baja California I analized the distribution of most tetrapods that breed in the area. I concluded that the limit of this community coincides with Arroyo del Rosario (aprox. 30º Lat. N), although mediterranean taxa begin to dissapear since Arroyo de San Telmo (Aprox. 30°57' Lat. N). Some desert species come in from the south and reach as far north as Ensenada (31°52' Lat. N). So, this area is largely a transitional zone. Of all tetrapods that breed in the area, 4 species and 54 subspecies are endemic to the American mediterraneum (Baja California and California, U.S.A.), and several of these are insular.Con el fin de determinar el límite sur de la región mediterránea Bajacaliforniana analicé la distribución de la mayoría de los tetrápodos que se reproducen en el noroeste de Baja California. Concluí que este límite coincide con el Arroyo del Rosario (aproximadamente 30º N), aunque hay un empobrecimiento de taxa mediterráneos desde el Arroyo de San Telmo (aproximadamente 30°57' N). Algunas especies desérticas llegan desde el sur hasta Ensenada (31°52' N). Así, el mediterráneo Bajacaliforniano es en gran medida una zona transicional. Cuatro especies y 54 subespecies de todas las que se reproducen en la región son endémicas del mediterráneo americano (Baja California y California, E.U.A.), y de éstas, varias son insulares

Historical Exploitation of the California Sea Lion, Zalophus californianus, in México

The exploitation of California sea lions, Zalophus californianus, in Mexican waters can be divided into four periods as defined by political characteristics of the country: Prehispanic, Colonial, Independent, and Postrevolutionary. During the first period (pre 1533), Native Americans took sea lions at low levels. During the second (1534–1821) and the third (1822–1911) periods, most exploitation was by foreigners and was incidental to other marine mammal harvests. During the Postrevolutionary period (after 1911), sea lions were exploited by Mexican and U.S. citizens for several commercial uses. Exploitation officially ended in 1982, although some small-scale poaching still occurs

HERPETOFAUNA DEL RANCHO LAS PAPAS, JALISCO, LLANURAS DE OJUELOS-AGUASCALIENTES, MÉXICO

As part of a project focused on evaluating the potential of modified habitats for biological conservation in the Llanos de Ojuelos-Aguascalientes physiographic subprovince in central Mexico, we inventoried the amphibians and reptiles of Rancho Las Papas, Jalisco, between May 1999 and September 2005. This ranch contains grassland, native and cultivated nopaleras (communities of prickly pear, Opuntia spp.), ravine xerophyllous scrub, and ephemeral and permanent water bodies. In this ranch we have documented 5 species of amphibians and 13 of reptiles, 9 of which are protected by the Mexican government. Our data show that relatively small areas that area subject to agriculture and animal ranching have a conservation potential for amphibians and reptiles under certain land management schemes. It is possible to preserve the region´s herpetofauna in ways that are compatible with productive activities.Como parte de un proyecto para evaluar el potencial que los hábitats modificados tienen para la conservación biológica en la subprovincia fisiográfica de los Llanos de Ojuelos-Aguascalientes de la Mesa Central, entre mayo de 1999 y septiembre de 2005 inventariamos los anfibios y reptiles del Rancho Las Papas, Jalisco, México. El rancho incluye hábitat de pastizal, nopaleras silvestres y cultivadas, matorral xerófilo en una cañada y cuerpos de agua efímeros y permanentes. En este rancho hemos documentado 5 especies de anfibios y 13 de reptiles, de las cuales 9 están incluidas en la NOM-059-SEMARNAT-2001. Los datos muestran que áreas relativamente pequeñas y sujetas a agricultura y ganadería tienen un potencial de conservación para anfibios y reptiles bajo ciertas pautas de manejo. Es posible preservar la herpetofauna de la región de forma compatible con el uso del suelo para la producción de satisfactores antrópicos

Status of the isolated, threatened Valle de la Trinidad round-tailed ground squirrel, Baja California, Mexico

In 1927 Lawrence M. Huey described a new subspecies of round-tailed ground squirrel (Xerospermophilus tereticaudus apricus) from the southernmost extreme of the species, in the geographically isolated valley ‘Valle de la Trinidad’ in Baja California, Mexico. The valley has been subject to extensive agricultural conversion and severe overgrazing, which had already begun when X. t. apricus was described. Despite the loss of natural habitat, a single remaining population of this isolated subspecies was re-discovered in 2015. Acoustic surveys documented individuals at 195 of 456 points sampled. The population does not appear to be adversely affected and may actually benefit from some disturbance from cattle. The densest populations were found in open communities of large leguminous trees or shrubs, principally mesquite, which may be critical seasonal diet components. Conservation considerations are discussed

ECOLOGÍA REPRODUCTIVA DEL BOBO CAFÉ (SULA LEUCOGASTER) EN TRES ISLAS DEL PACÍFICO TROPICAL MEXICANO

Resumen ∙ El Bobo Café (Sula leucogaster) es un ave marina que anida en islas de mares tropicales y subtropicales. En el Pacífico mexicano ha sido objeto de varios estudios, pero, aún se conoce muy poco de la dinámica poblacional de sus colonias y la influencia de variables oceánicas sobre ellas. Estudiamos la ecología reproductiva del Bobo Café en tres islas del Pacífico mexicano: Pajarera y Cocinas, en Bahía Chamela, Jalisco y Peña Blanca, en Colima. Realizamos visitas mensuales a cada isla de enero de 2008 a diciembre de 2009. En 2008 hubo más nidos que en 2009, el número máximo estimado de parejas reproductoras en cada año (2008 y 2009 respectivamente) fue de 724 y 758 en Cocinas, 895 y 1,071 en Pajarera y 15,215 y 15,801 en Peña Blanca. Observamos nidos activos durante todo el año, pero la mayor densidad en ambos años ocurrió de abril a julio, coincidiendo con valores más altos de la temperatura superficial del mar y más bajos de concentración de clorofila a. El periodo reproductivo estuvo asociado con la presencia de masas de agua cálida, lo que es opuesto al patrón observado en colonias del Golfo de California, pero coincide con la presencia de peces migratorios. Así, los ajustes en la fenología reproductiva parecen asociados con condiciones locales favorables para la crianza de pollos (disponibilidad local de ciertas presas) durante el periodo cálido. Los parámetros reproductivos considerados indican que Peña Blanca, la colonia más grande, tiene las mejores condiciones para la reproducción (tamaño de puesta mayor, huevos más grandes y mejor éxito de eclosión). Las diferencias entre años y colonias parecen relacionadas con la variabilidad oceánica, la cual afecta a escala local la disponibilidad de presas. Con base en el número de individuos, que la hacen una de las colonias más grandes de la costa Pacífico mexicana, Peña Blanca califica para ser designada como un Área Importante para la Conservación de las Aves (AICA). Abstract ∙ Breeding ecology of the Brown Booby (Sula leucogaster) in three islands of the Mexican tropical Pacific Ocean The Brown Booby (Sula leucogaster) is a seabird that breeds in islands of tropical and subtropical seas. In the Mexican Pacific, it has been the subject of several studies, but little was known on the dynamics of its colonies and the influence of oceanic variables on them. We studied the breeding ecology of the Brown Booby at three southern Mexico islands: Pajarera and Cocinas in Bahía Chamela, Jalisco, and Peña Blanca in Colima. We visited each island monthly from January 2008 to December 2009. There were more nests in 2008 than in 2009, estimated maximum annual colony size (2008 and 2009, respectively) was 724 and 758 breeding pairs at Cocinas, 895 and 1,071 at Pajarera, and 15,215 and 15,801 at Peña Blanca. We observed active nesting year‐round, but the highest densities in both years were from April to July, when sea surface temperature was higher and levels of chlorophyll a, lower. The breeding period was associated with the presence of warm water masses, which is the opposite to the pattern previously recorded in Gulf of California colonies, but coincided with the presence of migratory fish. This difference in breeding phenology seems an adaptation to match local conditions (prey availability) during chick rearing. Breeding parameters (higher clutch size, egg volume, hatching success) point out that Peña Blanca, the largest colony, was superior to the other colonies in terms of breeding. Differences among years and colonies seem related to oceanic variability, which affects the local availability of prey. Based on the size of the colony, which makes it one of the largest colonies along the Mexican Pacific coast, the Peña Blanca colony qualifies to be nominated as Important Bird Area (IBA).

JAK‐STAT signaling shapes the NF‐κB response in CLL towards venetoclax sensitivity or resistance via Bcl‐XL

Preventing or overcoming resistance to the Bcl-2 inhibitor venetoclax is an emerging unmet clinical need in patients with chronic lymphocytic leukemia (CLL). The upregulation of anti-apoptotic Bcl-2 members through signaling pathways within the tumor microenvironment appears as a major factor leading to resistance to venetoclax. Previously, we reported that T cells can drive resistance through CD40 and non-canonical NF-κB activation and subsequent Bcl-XL induction. Moreover, the T cell-derived cytokines IL-21 and IL-4 differentially affect Bcl-XL expression and sensitivity to venetoclax via unknown mechanisms. Here, we mechanistically dissected how Bcl-XL is regulated in the context of JAK-STAT signaling in primary CLL. First, we demonstrated a clear antagonistic role of IL-21/STAT3 signaling in the NF-κB-mediated expression of Bcl-XL, whereas IL-4/STAT6 further promoted the expression of Bcl-XL. In comparison, Bfl-1, another NF-κB target, was not differentially affected by either cytokine. Second, STAT3 and STAT6 affected Bcl-XL transcription by binding to its promoter without disrupting the DNA-binding activity of NF-κB. Third, in situ proximity ligation assays (isPLAs) indicated crosstalk between JAK-STAT signaling and NF-κB, in which STAT3 inhibited canonical NF-κB by accelerating nuclear export, and STAT6 promoted non-canonical NF-κB. Finally, NF-κB inducing kinase (NIK) inhibition interrupted the NF-κB/STAT crosstalk and re-sensitized CLL cells to venetoclax. In conclusion, we uncovered distinct crosstalk mechanisms that shape the NF-κB response in CLL towards venetoclax sensitivity or resistance via Bcl-XL, thereby revealing new potential therapeutic targets

Riparian Research and Management: Past, Present, Future: Volume 1

Fifty years ago, riparian habitats were not recognized for their extensive and critical contributions to wildlife and the ecosystem function of watersheds. This changed as riparian values were identified and documented, and the science of riparian ecology developed steadily. Papers in this volume range from the more mesic northwestern United States to the arid Southwest and Mexico. More than two dozen authors—most with decades of experience—review the origins of riparian science in the western United States, document what is currently known about riparian ecosystems, and project future needs. Topics are widespread and include: interactions with fire, climate change, and declining water; impacts from exotic species; unintended consequences of biological control; the role of small mammals; watershed response to beavers; watershed and riparian changes; changes below large dams; water birds of the Colorado River Delta; and terrestrial vertebrates of mesquite bosques. Appendices and references chronicle the field’s literature, authors, “riparian pioneers,” and conferences

Some ecological characteristics of three dry farming systems in the San Luis Potosi Plateau, Mexico

In order to understand the ecological characteristics of three dry farming systems in the semiarid San Luis Potosi Plateau, Mexico, a one year study was conducted. The systems studied were a purely rainfed field, a field on an alluvial fan irrigated with runoff water, and a field in a bottomland irrigated with water diverted from an ephemeral stream. Three treatments, farmed, edge and unfarmed, were established in a Randomized Block design, with three replications, for each system. The major conclusions of this research were the following. During the summer, climate is resposible for a concentration of the communities's production and reproduction. Climate is also of paramount importance to agriculture. Rainy periods, on the other hand, decreased the activity of animals. None of the farming systems had detrimental effect on soil fertility. Only slight modifications of soil temperature and air temperature and humidity resulted from farming. A general overview of all the results did not provide evidence that all farming systems decrease biotic richness and diversity. The effects depended on the type of system, its isolation, and the natural vegetation adjacent to it. Herbs were enhanced by farming only when the natural system was relatively free of them. Farming did not have important effects on invertebrates. Birds were negativelly affected by farming, whenever the unfarmed areas included an arboreal stratum. Also, insectivorous birds responded differently than non-insectivores. Rodents were affected negatively by farming in two of the systems, and this could be linked to habitat simplicity. In one case, dense herb cover was associated with very high rodent populations. In general the data adjusted to the hypothesis that structurally more heterogeneous agroecosystems hold more diverse biotas. The concepts of "farmland biota" and "edge effect" were not supported by this study. Edges were ocasionally superior, and only when they included more complex plant communities than either side. A mosaic of heterogeneous farmlands and natural vegetation attracts certain rodents and birds, increasing environmental diversity.hydrology collectio

Effects of the 1997-1998 El Niño and 1998-1999 La Niña events on breeding waterbirds and sea lions in the Upper Gulf of California, México

En 1998 y 1999 revisé las colonias de aves acuáticas que anidan en Isla San Jorge, La Purinera e Isla Montague, en el norte del Golfo de California, al igual que la de lobos marinos de la Isla San Jorge. Encontré que El Niño coincidió con que los bobos cafés de San Jorge dejaran de anidar y se ausentaran de la isla, al tiempo que llegaban varios miles de bobos de patas azules. Las condiciones de El Niño coincidieron con un incremento en el número de individuos anidantes de gallitos menor, elegante y máximo y de rayadores, en Montague. Ni los patos buzo orejones en San Jorge, ni los gallitos menores en La Purinera, ni las garzas níveas, perros de agua , gaviotas risueñas, ni gallitos picogrueso, en Montague, parecen haber sido afectados. Los lobos marinos en San Jorge duplicaron aproximadamente su población, sin que esto repercutiera sobre la producción de crías. La Niña coincidió con un regreso de las poblaciones de las especies anteriores a las condiciones previas a El Niño. Además, durante 1999 en San Jorge anidaron gaviotas plomas y patos buzo de Brandt. Esa gaviota había dejado de anidar hacía mucho tiempo en San Jorge, y el pato buzo nunca se había registrado anidando ahí. Es prematuro concluir si estos registros fueron resultado de La Niña o de fenómenos en otra escala. doi: https://doi.org/10.22201/igeof.00167169p.2003.42.3.94