Assessment of habitat quality and landscape connectivity for forest-dependent cracids in the Sierra Madre del Sur Mesoamerican biological corridor, Mexico

Assessing landscape connectivity allows us to identify critical areas that impede or facilitate the movement of organisms and their genes and to plan their conservation and management. In this article, we assessed landscape connectivity and ecological condition of the habitat patches of a highly biodiverse region in Chiapas, Mexico. We employed data of three cracid species with different characteristics in habitat use and mobility. The habitat map of each species was derived from a spatial intersection of the models of potential distribution and a high-resolution map of current land cover and land use. The ecological condition of vegetation types was evaluated using 75 field plots. Structure of landscape was estimated by fragmentation metrics, while functional connectivity was assessed using spatially explicit graph analysis. The extent of suitable habitat for Oreophasis derbianus, Penelopina nigra, and Penelope purpurascens correspond to 25%, 46%, and 55% of the study area (5,185.6 km2), respectively. Although the pine-oak forests were the most fragmented vegetation type, habitats of the three species were well connected, and only 4% to 9% of the fragments located on the periphery of the corridor had low connectivity. Landscape connectivity depends mainly on land uses with an intermediate and lower ecological condition (secondary forests and coffee agroforestry systems). Therefore, we suggest that in addition to promoting the improvement in connectivity in fragmented forests, conservation efforts should be aimed at preventing the conversion of mature forests into agricultural uses and maintaining agroforestry systems

Bird Behaviour during Prey-Predator Interaction in a Tropical Forest in México

Birds emit alarm calls, considered as honest signals, because they communicate the presence of a predator or potential threat. We evaluated behavioural events of birds responding to vocal and visual stimuli of a nocturnal predator (black-and-white owl Ciccaba nigrolineata) and a diurnal predator (collared forest falcon Micrastur semitorquatus). We analysed variations in behavioural events seasonally (reproductive and nonbreeding) and by bird size, as well as their relationship with the vegetation structure and landscape. The study was performed during the breeding (March-May) and non-breeding seasons (February, June and July) of 2016 in Chiapas, Mexico. We used four transects with different vegetation types and land uses. The most frequent behavioural response by birds to the vocal stimuli of the black-and-white owl and the collared forest-falcons was vocal, during the breeding season, and small species responded the most to the stimuli (p = 0.008) and (p < 0.015), respectively. We identified two vegetation and two landscape variables associated in 36% of probability for the prey to respond to black-and-white owl vocal stimuli, three variables of vegetation and one of the landscape in 37% for the collared forest-falcon stimuli. Potential prey animals modify the behaviour, which allows them to detect, evade or confront a predator

ESTRUCTURA ESPACIO‐TEMPORAL DE LA DIVERSIDAD TAXONÓMICA Y FUNCIONAL DE COLIBRÍES EN LA RESERVA DE LA BIOSFERA EL TRIUNFO, CHIAPAS, MÉXICO

RESUMEN ∙ La diversidad taxonómica y funcional de las comunidades de aves está determinada por la distribución espacio‐temporal y la densidad de las poblaciones de las especies que las integran. La diversidad puede variar según el gradiente de elevación, en general al aumentar la elevación se reduce la riqueza de especies, como es el caso en algunas comunidades de colibríes (Trochilidae). En este estudio se evaluó la distribución, la densidad, la diversidad taxonómica y funcional de tres comunidades de colibríes en diferentes elevaciones y temporadas en la Reserva de la Biosfera El Triunfo, Chiapas, México. Establecimos transectos en tres elevaciones (300 a 2500 m s.n.m.), los cuales se recorrieron durante tres temporadas (secas, lluvias y post‐lluvias) de 2015 a 2016. Asimismo, obtuvimos datos morfométricos de las especies para analizar rasgos funcionales (i.e., masa corporal, longitud y curvatura del pico) y evaluar la diversidad funcional de las comunidades. Los resultados indican que la mayor diversidad de colibríes ocurrió en la elevación media, y no hubo variación significativa de la diversidad entre temporadas. De acuerdo a los rasgos funcionales medidos, solo la masa corporal mostró diferencias con la altura, siendo mayor en elevaciones altas. Los valores de la diversidad funcional obtenidos fueron similares entre elevaciones, pero la divergencia fue mayor en la elevación baja, y la especialización fue mayor en elevaciones media y baja. Esto indica una diferenciación de nichos en la elevación baja y un efecto ambiental en la elevación alta, lo que estructuraría las comunidades de colibríes en nuestro sitio de estudio.Abstract ∙ Spatio‐temporal structure of the taxonomic and functional diversity of hummingbirds at the biosphere reserve El Triunfo, Chiapas, Mexico The taxonomic and functional diversity of bird communities is determined by the spatio‐temporal distribution and population density of their constitutive species. Diversity can change along environmental gradients and one of these patterns shows that as the elevation increases bird richness is reduced, as has been observed in some communities of hummingbirds. We evaluated the distribution, taxonomic and functional structure of three hummingbird (Trochilidae) communities at El Triunfo Biosphere Reserve, Chiapas, Mexico. We established transects where we performed counts at three elevations (300 to 2500 m a.s.l.) and during three seasons (dry, rainy, and post‐rainy) from 2015 to 2016. We also obtained morphometric data from the species to analyze functional traits (i.e., body mass, length, and curvature of the bill) and functional diversity. The results indicate that the highest species diversity of hummingbirds occurred at intermediate elevation, and that there was no significant variation in diversity among seasons. Out of the functional traits measured only body mass showed differences, being higher at high elevations. Functional diversity values were similar across elevations, but the divergence was higher at low elevations, and the degree of specialization was higher at medium and low elevations. This suggests a differentiation of niches at low elevations and an environmental filtering effect at high elevation, which structure hummingbird communities at our study site

Variación de la diversidad de aves de sotobosque en el parque nacional lagos de Montebello, Chiapas, México

To understand the spatial and temporal variation of the understory bird diversity, we estimated species diversity in four sites (Las Grutas, Vivero, Yalmutz y Yalhuech) with different vegetation type and management regimes in the Lagos de Montebello National Park, Chiapas from July 1997 to June 1998. We identified 71 bird species; 50 residents and 21 migrants. Families with more species were Parulidae (15), Tyrannidae (9) and Turdidae (8). Most of species were recorded to a single site (63.4%) and only 9.8% were distributed in all four sites. The highest relative frequencies of total captures were for Chlorospingus ophtalmicus (0.197), Catharus ustulatus (0.110), Lampornis viridipallens (0.083) and Myioborus miniatus (0.072). Capture number varied among sites, while Vivero showed the maximum values, Las Grutas showed the minimum. Yalmutz had the highest species richness (36), and Las Grutas the lowest (24). The highest diversity (Simpson reciprocal 16.41) and evenness (0.68) was recorded in Las Grutas, which was the site less disturbed and showed one of the last remnants of montane cloud forest. However, Yalmutz showed the highest values of Shannon diversity (4.37), and high values of both exclusive (14) and rare species (21). Yalmutz showed a mix of elements of pines and broadleaves and it was the second site with less disturbance by human activities. The higher species richness and abundance was during the dry season. The National Park Lagos de Montebello showed an important bird species diversity for the environmental variation and different stage of disturbance. The persistence of bird populations and their conservation in the region will depend on the remaining of nondisturbed environments and the quality of secondary and managed forests.Para entender la variación espacial y temporal de la diversidad de aves de sotobosque, evaluamos la diversidad de especies en cuatro sitios (Las Grutas, Yalmutz, Vivero y Yalhuech) con diferentes tipos de vegetación y manejo dentro del Parque Nacional Lagos de Montebello, Chiapas, de julio de 1997 a junio de1998. Identificamos 71 especies de aves: 50 fueron residentes y 21 migratorias. Las familias mejor representadas fueron Parulidae (15), Tyrannidae (9) y Turdidae (8). La mayor proporción de especies registradas fueron exclusivas para un solo sitio (63.4%) y tan solo 9.8% se distribuyó en los cuatro sitios. Las mayores frecuencias relativas de captura total fueron para Chlorospingus ophtalmicus (0.197), Catharus ustulatus (0.110), Lampornis viridipallens (0.083) y Myioborus miniatus (0.072). El número de capturas varió entre los cuatro sitios estudiados, donde el bosque mixto de coníferas y latifoliadas (Vivero) presentó los valores máximos y el bosque mesófilo (Las Grutas) los mínimos. Yalmutz tuvo la mayor riqueza de especies (36), y Las Grutas la menor (24). La mayor diversidad derivada del reciproco de Simpson (16.41) y uniformidad (0.68), se registraron en Las Grutas, que fue el sitio menos perturbado y con los últimos remanentes de bosque mesófilo de montaña. Sin embargo, Yalmutz presentó los valores más altos en diversidad de Shannon (4.37), así como el mayor número tanto de especies exclusivas (14) como raras (21). Yalmutz presentó una mezcla de elementos de coníferas y latifoliadas, y fue el segundo sitio con un menor grado de perturbación por actividades antropogénicas. La mayor riqueza de especies y abundancia de individuos se presentó durante la temporada seca. El Parque Nacional Lagos de Montebello presenta una importante diversidad de especies de aves por la variación en ambientes y grados de perturbación que presenta. Sin embargo, la persistencia de las poblaciones de aves y su conservación en la región dependerá tanto de la permanencia de ambientes no perturbados y de la calidad de los ambientes secundarios y manejado

Cohesin Removal along the Chromosome Arms during the First Meiotic Division Depends on a NEK1-PP1γ-WAPL Axis in the Mouse

SummaryMammalian NIMA-like kinase-1 (NEK1) is a dual-specificity kinase highly expressed in mouse germ cells during prophase I of meiosis. Loss of NEK1 induces retention of cohesin on chromosomes at meiotic prophase I. Timely deposition and removal of cohesin is essential for accurate chromosome segregation. Two processes regulate cohesin removal: a non-proteolytic mechanism involving WAPL, sororin, and PDS5B and direct cleavage by separase. Here, we demonstrate a role for NEK1 in the regulation of WAPL loading during meiotic prophase I, via an interaction between NEK1 and PDS5B. This regulation of WAPL by NEK1-PDS5B is mediated by protein phosphatase 1 gamma (PP1γ), which both interacts with and is a phosphotarget of NEK1. Taken together, our results reveal that NEK1 phosphorylates PP1γ, leading to the dephosphorylation of WAPL, which, in turn, results in its retention on chromosome cores to promote loss of cohesion at the end of prophase I in mammals

Riqueza y abundancia de aves en áreas verdes en la ciudad de San Cristóbal de las Casas, Chiapas, México

Green areas in urban districts are important elements for bird conservation. In this study, we estimated bird abundance within green areas in the urban district of San Cristobal de Las Casas, state of Chiapas, Mexico. We identified a total of 75 bird species in ten green areas of different sizes from February of 2016 through July of 2016. We related bird presence to environmental variables at two geographical scales (local and landscape). Nonparametric analyses were used to compare richness and abundance of birds between green areas and size categories. The percentage of vegetation area was the most important variable that positively correlated with species richness and abundance. However, negative correlations were found between species richness and abundance and the percentage coverage of canopy, buildings, pavement and sampled green areas. The spatial heterogeneity of vertical vegetation structure in green areas was important to increase the diversity of avifauna. The maintenance and increase of green areas in cities is important to protect and increase the diversity of birds in urban areas.Las áreas verdes en las ciudades se han considerado elementos importantes para la conservación de la avifauna. En este estudio se presentan estimaciones de riqueza y abundancia de aves, así como su relación con las áreas verdes en la ciudad de San Cristóbal de Las Casas, Chiapas, México. Identificamos un total de 75 especies de aves en diez áreas verdes de diferente tamaño de febrero a julio de 2016 y relacionamos su presencia con variables ambientales a dos escalas geográficas (local y de paisaje). Se utilizaron análisis no paramétricos para comparar la riqueza y abundancia de las aves entre áreas verdes y categorías de tamaño. El porcentaje de superficie total ocupada por vegetación fue la variable más importante al correlacionarse positivamente con la riqueza y abundancia de las aves. Mientras que el porcentaje de cobertura de dosel, de construcciones, de pavimento y de áreas verdes muestreadas se correlacionaron negativamente con la riqueza y abundancia de aves. La heterogeneidad espacial de la estructura vegetal vertical en las áreas verdes fue importante para incrementar la diversidad de la avifauna. El mantenimiento e incremento de áreas verdes en ciudades es significativo para proteger y aumentar la diversidad de aves en áreas urbanas

Diversidad y composición de aves del Parque Nacional Lagunas de Montebello, Chiapas, México

Actualmente los ambientes heterogéneos son los que predominan en los paisajes tropicales, por lo que estudiar la diversidad y la composición de especies en las comunidades avifaunísticas ha permitido entender la variación y la estructura de las mismas. Asimismo, esta información permite implementar estrategias de manejo y conservación en estos ambientes. En este estudio se evaluó la diversidad y composición espacial y temporal de la comunidad de aves en el Parque Nacional Lagunas de Montebello, Chiapas, en diferentes tipos de bosques y condiciones (bosques de pino, pino-encino, pino-encino-liquidambar, bosque mesófilo, vegetación riparia y zonas intervenidas). El muestreo se realizó de febrero a julio de 2017 en 110 puntos de conteo separados cada 300 m. En total se registraron 3,143 aves de 123 especies. La diversidad medida con el orden q= 1 fue de 41.67 y con q= 2 fue de 24.79 especies efectivas. La temporada de lluvias presentó una mayor diversidad de especies de aves que en secas. Los gremios mejor representados fueron los granívoros-frugívoros-insectívoros, los insectívoros y los omnívoros. Las zonas con intervención, así como los bosques de pino y la vegetación riparia presentaron la mayor diversidad de especies. En contraste, el bosque mesófilo de montaña, de pino-encino-liquidambar y de pino-encino presentaron especies raras y vulnerables como Setophaga chrysoparia, Pharomachrus mocinno y Penelopina nigra. Este estudio permite identificar sitios de monitoreo y de manejo forestal para el mejor ordenamiento en el parque nacional.Heterogeneous environments predominate in tropical landscapes, then studying diversity and composition of species in avian communities has allowed understand how it vary and is structured. This information also allows implementing management and conservation strategies in these environments. This study evaluated the diversity and spatial and temporal composition of the bird community in Lagunas de Montebello National Park, Chiapas, in different types of forests and conditions (pine forests, pine-oak, pine-oak-liquidambar, mountain cloud forest, riparian vegetation and modified areas). Sampling was carried out from February to July 2017 at 110 counting points every 300 m. In total, 3,143 birds of 123 species were recorded. The diversity measured with the order q= 1 was 41.67 and with q= 2 it was 24.79 effective species. Rainy season showed greater species diversity than dry season. The best represented guilds were granivores-frugivores-insectivores, insectivores and omnivores. The modified areas, as well as pine forest and riparian vegetation areas had the greatest diversity of species. In contrast, mountain cloud forest, pine-oak-liquidambar, and pine-oak forests had rare and vulnerable species such as Golden-cheeked Warbler, Resplendent Quetzal, and Highland Guan. This study allows to identify sites for monitoring and forest management that will allow for better planning in the national park

Composición y abundancia de búhos en el Parque Nacional Sierra de San Pedro Mártir, Baja California, México

La composición y abundancia de búhos fueron determinadas estacionalmente en cuatro sitios del Parque Nacional Sierra de San Pedro Mártir, Baja California (PNSSPM), México, mediante la técnica de reclamo-escucha de octubre 2017 a agosto 2018. Un total de 60 registros de siete especies fueron obtenidos (Tecolote Oyamelero Norteño Aegolius acadicus, Búho de Cara Canela Asio otus, Búho Cornudo Bubo virginianus, Tecolote Californiano Glaucidium californicum, Tecolote del Oeste Megascops kennicottii, Tecolote Ojos Oscuros Psiloscops flammeolus, y Búho Moteado Strix occidentalis). La especie con mayor frecuencia promedio de registros (individuos/h) fue B. virginianus (4.04), mientras que las otras especies registraron frecuencias de 0.2 (S. occidentalis) a 1.1 (M. kennicottii y A. otus). Dos especies fueron residentes permanentes (B. virginianus y M. kennicottii), una visitante veraniega (A. acadicus), una visitante invernal (A. otus), y tres visitantes ocasionales (P. flammeolus, G. californicum y S. occidentalis). La riqueza de especies de búhos en el PNSSPM incrementó en invierno debido a la presencia de especies migratorias.The composition and abundance of owls were seasonally determined at four sites of the Sierra de San Pedro Mártir National Park, Baja California (PNSSPM), Mexico, by means of the call-listening technique from October 2017 to August 2018. A total of 60 records of seven species was obtained (Northern Saw-whet Owl Aegolius acadicus, Long-eared Owl Asio otus, Great Horned Owl Bubo virginianus, Northern Pygmy-Owl Glaucidium californicum, Western Screech-Owl Megascops kennicottii, Flammulated Owl Psiloscops flammeolus, and Spotted Owl Strix occidentalis). The species with the highest average frequency of records (individuals/h) was B. virginianus (4.04), while other species recorded frequencies from 0.2 (S. occidentalis) to 1.1 (M. kennicottii and A. otus). Two species were permanent residents (B. virginianus and M. kennicottii), one summer visitor (A. acadicus), one winter visitor (A. otus), and three occasional visitors (P. flammeolus, G. californicum and S. occidentalis). The species richness of owls in the PNSSPM increased in winter due to the presence of migratory species

Diversidad avifaunística y gremios tróficos en tres condiciones diferentes de cobertura vegetal selvática, al sureste de Chiapas, México

Los bosques, selvas y otras asociaciones vegetales han sufrido un proceso de degradación ambiental, atribuido a la deforestación y a la fragmentación con el objetivo de ampliar la frontera agrícola-pecuaria. Estos cambios ambientales no pasan desapercibidos para las comunidades faunísticas presentes, como las aves. Una manera confiable de conocer las posibles afectaciones antropogénicas en los ecosistemas es a través del análisis de los gremios tróficos aviares, ya que los cambios en la estructura de la vegetación condicionan la presencia de diferentes gremios tróficos. El objetivo principal del presente estudio fue analizar las variaciones en la riqueza, abundancia y composición de las comunidades de aves y los gremios tróficos en tres diferentes condiciones de cobertura vegetal (selva con regeneración SCR, ecotonos ECO, y un poblado POB), en una región de la Selva Lacandona, Chiapas, México. El muestreo se realizó durante cuatro meses del 2020 donde se recorrieron seis transectos de aproximadamente 2 km de longitud cada uno. Se registraron en total 6,190 individuos de 201 especies de aves. El ECO presentó la mayor riqueza de aves con 155 especies, seguido por la SCR (104 especies) y finalmente, el POB (101 especies). Sin embargo, el POB presentó la mayor abundancia de individuos (2,661 individuos) con respecto a las otras dos condiciones ambientales. La mayor semejanza de las comunidades avifaunísticas ocurrió entre el poblado y el ecotono (53 %). El mayor número de gremios tróficos también se registró en el ECO (15). En general, los insectívoros tuvieron una buena representatividad, particularmente en la SCR. Por el contrario, los granívoros estuvieron relacionados con los espacios abiertos y semiabiertos, desprovistos de vegetación arbórea (POB y ECO). Los frugívoros tuvieron mayor número de especies en el ECO, pero fueron más abundantes en el POB. Mientras que, los nectarívoros se observaron con mayor frecuencia en el POB. La deforestación y la fragmentación reducen el espacio físico de los ecosistemas y también alteran la disponibilidad de alimento para las aves. Lo anterior, se verá reflejado en la presencia-ausencia de los diferentes gremios tróficos y en las funciones ecológicas que son capaces de realizar.Recently many forests, tropical rain forest, and other plant associations have suffered a process of environmental degradation, attributed to deforestation andfragmentation, with the aim of expanding the agricultural-livestock frontier. These environmental changes have a measurable impact on the fauna communities present, such as birds. A reliable way of documenting the possible anthropogenic effects on ecosystems, is through the analysis of the avian trophic guilds since changes in the structure of the vegetation impacts the different trophic guilds. The main objective of this study was to analyze the variations in richness, abundance, and composition of the bird communities and trophic guilds in three different vegetation cover conditions (rain forest with regeneration SCR, ecotones ECO, and a village POB), in a region of the Lacandon rain forest region, Chiapas, Mexico. Sampling was carried four months of 2020 where six transects of approximately 2 km in length were walked. A total of 6190 individuals from 201 bird species were recorded. The ECO presented the highest richness of birds with 155 species, followed by the SCR (104 species) and finally, the POB (101 species). However, the POB presented the highest abundance of individuals (2661 individuals) with respect to the other two environmental conditions. The greatest similarity of bird communities occurred between the village and the ecotone (53%). The highest number of trophic guilds was also registered in ECO (15). In general, the insectivores were widely represented, particularly in the SCR. On the contrary, granivores were related to open and semi-open spaces, devoid of arboreal vegetation (POB and ECO). Frugivores had greater number of species in the ECO but were more abundant in the POB. Meanwhile, nectarivores were observed more frequently in the POB. Deforestation and fragmentation reduce the physical space of ecosystems and modify the availability of food for birds. This will be reflected in the presence-absence of the different trophic guilds and in the ecological functions they are able to perform

A mutation in the endonuclease domain of mouse MLH3 reveals novel roles for MutLγ during crossover formation in meiotic prophase I

During meiotic prophase I, double-strand breaks (DSBs) initiate homologous recombination leading to non-crossovers (NCOs) and crossovers (COs). In mouse, 10% of DSBs are designated to become COs, primarily through a pathway dependent on the MLH1-MLH3 heterodimer (MutLγ). Mlh3 contains an endonuclease domain that is critical for resolving COs in yeast. We generated a mouse (Mlh3DN/DN) harboring a mutation within this conserved domain that is predicted to generate a protein that is catalytically inert. Mlh3DN/DN males, like fully null Mlh3-/- males, have no spermatozoa and are infertile, yet spermatocytes have grossly normal DSBs and synapsis events in early prophase I. Unlike Mlh3-/- males, mutation of the endonuclease domain within MLH3 permits normal loading and frequency of MutLγ in pachynema. However, key DSB repair factors (RAD51) and mediators of CO pathway choice (BLM helicase) persist into pachynema in Mlh3DN/DN males, indicating a temporal delay in repair events and revealing a mechanism by which alternative DSB repair pathways may be selected. While Mlh3DN/DN spermatocytes retain only 22% of wildtype chiasmata counts, this frequency is greater than observed in Mlh3-/- males (10%), suggesting that the allele may permit partial endonuclease activity, or that other pathways can generate COs from these MutLγ-defined repair intermediates in Mlh3DN/DN males. Double mutant mice homozygous for the Mlh3DN/DN and Mus81-/- mutations show losses in chiasmata close to those observed in Mlh3-/- males, indicating that the MUS81-EME1-regulated crossover pathway can only partially account for the increased residual chiasmata in Mlh3DN/DN spermatocytes. Our data demonstrate that mouse spermatocytes bearing the MLH1-MLH3DN/DN complex display the proper loading of factors essential for CO resolution (MutSγ, CDK2, HEI10, MutLγ). Despite these functions, mice bearing the Mlh3DN/DN allele show defects in the repair of meiotic recombination intermediates and a loss of most chiasmata