Abstract: The Alto Balsas region is important for Mexican biodiversity due to the high levels of taxonomic turnover and richness of endemism. Unfortunately, habitat loss owing to human activities threats its conservation. The goal of this contribution is to describe the birds biodiversity in the Alto Balsas region in Guerrero, using species incidence data in seven habitat-types between 2006 and 2017. A total of 209 bird species was recorded, 53 of which represent effective taxonomic turnover (mean βsim 0.41 ± 0.28) between habitats. Fifty-eight species (27.7%) have some level of endemism, representing one of the most evolutionarily Mexican bird assemblages recorded. Twenty-five species (12%) are threatened, highlighting the military macaw (Ara militaris), a globally threatened bird. Both evolutionary history and the ecological gradient defined high taxonomic turnover rates, a complex functional identity, as well as biogeographic connectivity. Considering this aspects, and involving territorial surface, the Alto Balsas in Guerrero meets the criteria for its inclusion in the National System of Natural Protected Areas.

Resumen: El Alto Balsas es una región importante para la biodiversidad mexicana por sus altos niveles de recambio taxonómico y riqueza de endemismos. Desafortunadamente la pérdida de hábitat por actividades humanas amenaza su conservación. El objetivo de este trabajo es describir la biodiversidad de aves del Alto Balsas de Guerrero, a partir de datos de incidencia de especies en 7 tipos de hábitat entre 2006 y 2017. Se registraron 209 especies; 53 de ellas representan recambio neto entre tipos de hábitat (βsim promedio 0.41 ± 0.28). Cincuenta y ocho especies (27.7%) tienen alguna categoría de endemismo, lo que constituye una de las avifaunas evolutivamente más mexicanas que se han registrado. Veinticinco especies (12%) están amenazadas, destacando la guacamaya verde (Ara militaris), vulnerable a nivel global. El gradiente ecológico y la historia evolutiva de la región definieron altas tasas de recambio taxonómico, una compleja identidad funcional y conectividad biogeográfica. Considerando estos aspectos, junto con la extensión territorial involucrada, el Alto Balsas de Guerrero cumple con criterios para su inclusión en el Sistema Nacional de Áreas Naturales Protegidas.

Abstract Stress tolerance is a key attribute that must be considered when using yeast cells for industrial applications. High temperature is one factor that can cause stress in yeast. High environmental temperature in particular may exert a natural selection pressure to evolve yeasts into thermotolerant strains. In the present study, three yeasts (Saccharomyces cerevisiae, MC4, and Kluyveromyces marxianus, OFF1 and SLP1) isolated from hot environments were exposed to increased temperatures and were then compared with a laboratory yeast strain. Their resistance to high temperature, oxidative stress, and antioxidant response were evaluated, along with the fatty acid composition of their cell membranes. The SLP1 strain showed a higher specific growth rate, biomass yield, and biomass volumetric productivity while also showing lower duplication time, reactive oxygen species (ROS) production, and lipid peroxidation. In addition, the SLP1 strain demonstrated more catalase activity after temperature was increased, and this strain also showed membranes enriched in saturated fatty acids. It is concluded that the SLP1 yeast strain is a thermotolerant yeast with less oxidative stress and a greater antioxidant response. Therefore, this strain could be used for fermentation at high temperatures.