Factors affecting nectar sugar composition in chiropterophilic plants

AbstractMost pollinators prefer the sugars present in the nectar they consume, so it has been hypothesized that they have molded nectar trait evolution. However, nectar-feeding bats do not exhibit preferences for the sugars present in their diet. We analyzed the role that biochemical and ecological factors could play in shaping the nectar traits of chiropterophilic plants. We studied nectar traits and flower production in 49 plant species. We evaluated the relationship between nectar concentration and sugar composition using phylogenetically independent contrasts and if nectar traits were related to flower production using a Manova. We found that 42 species produced high hexoses nectars, and 7 species produced sucrose rich nectars. Phylogenetically independent contrasts showed that nectar concentration was negatively related to glucose content, positively related to fructose content, and was not related to sucrose content. A negative relationship was found from glucose and fructose contents to sucrose content, and glucose content was negatively related to fructose content. Finally, we did not found any relationship between nectar traits and the plants’ flowering strategies. We conclude that bat physiology and the relative low evolutionary time of the interaction between plants and bats may determine the lack of pattern in the nectar characteristics of chiropterophilic plants

Aves en paisajes modificados por actividades humanas

Los paisajes que se generan por actividades humanas pueden ser diversos y complejos, o extremadamente simplificados. Las aves responden rápidamente a cambios en la estructura, tamaño y conformación de los parches de hábitats donde están presentes, por lo que, pueden funcionar como importantes bioindicadores. En este capítulo se muestran los resultados de 12 años de estudiar las respuestas de las aves a actividades humanas en diferentes regiones de México. Se utilizó una aproximación de gradientes de perturbación para explorar como las aves responden a la antropización de sus hábitats, donde se midió tanto su riqueza de especies y sus abundancias, como aspectos demográficos, conductuales y fisiológicos de diferentes especies. Se encontró que los patrones de riqueza de especies, abundancias, y estructura de comunidades se repiten en los paisajes estudiados en diferentes zonas del país, sin importar el clima y/o el tipo de vegetación original que dominaba en la zona. A nivel fisiológico, las respuestas de diferentes especies son muy variables, permitiendo entender de forma mecanística sus capacidades para sobrevivir en sitios perturbados. Debido a que existe una gran diversidad de respuestas a la perturbación humana por las aves, no es sencillo utilizar a especies particulares como bioindicadores. Sin embargo, se encontró que la estructura de comunidades y el comportamiento de estos animales nos ofrecen información crucial para evaluar la calidad de los hábitats modificados por actividades humanas. Finalmente, el manejo adecuado de hábitats modificados por actividades humanas permite recuperar comunidades de aves complejas y diversas, similares a las que existían antes de la perturbación humana. Palabras clave: Comunidades de aves, ecofisiología animal, ecología urbana, restauración ecológica, conservación de la avifaun

How do people perceive urban trees? Assessing likes and dislikes in relation to the trees of a city

Cities are systems that include natural and human-created components. When a city grows without proper planning, it tends to have low environmental quality. If improving environmental quality is intended, people's opinion should be taken into account for a better acceptance of urban management decisions. In this study, we assessed people's perception of trees by conducting a survey with a controlled sample of citizens from the city of Morelia (west-central Mexico). Citizens liked both native and exotic tree species and rejected mainly exotic ones. Preference for trees were related to tree attributes; such as size. Trees that dropped leaves or tended to fall were not liked. The most-mentioned tree-related benefits were oxygen supply and shade; the most mentioned tree-related damages were accidents and infrastructure damage. The majority of respondents preferred trees near houses to increase tree density. Also, most respondents preferred trees in green areas as well as close to their houses, as they consider that trees provide oxygen. The majority of the respondents thought more trees were needed in the city. In general, our results show that although people perceive that trees in urban areas can cause damages, they often show more interest for the benefits related to trees and consider there should be more trees in cities. We strongly suggest the development of studies that broaden our knowledge of citizen preferences in relation to urban vegetation, and that further policy making takes their perception into account when considering creating new urban green areas, regardless of their type or size.</p

Ampliación del ámbito geográfico-altitudinal y uso de hábitats suburbanos por la mascarita pico grueso (Geothlypis poliocephala) Geographic-altitudinal range extension and suburban habitat use of the Grey-crowned Yellowthroat (Geothlypis poliocephala)

Se presenta el primer registro de la mascarita pico grueso (Geothlypis poliocephala) para la región del Eje Neovolcánico Transversal, México. Los sitios donde registramos/capturamos esta especie se encuentran en los suburbios de la ciudad de Morelia, 427 m arriba del ámbito altitudinal descrito para la especie. Esto puede deberse a 2 factores: 1) la urbanización que genera hábitats propicios para la especie en su periferia, y 2 ) el incremento de la temperatura en la región en la que se encuentra la ciudad de Morelia. Ambos factores facilitan que esta especie de tierras bajas pueda habitar en áreas de mayor altitud. Así, nuestros registros sugieren que la mascarita pico grueso puede catalogarse como especie potencial a utilizar hábitats suburbanos cuando éstos son similares a los hábitats en los que se distribuye de manera natural.<br>The first record of the Grey-crowned Yellowthroat (Geothlypis poliocephala) in the Transmexican Volcanic Belt biogeographic region (Mexico), within the Morelia city suburbs is presented. Sites were this parulid was sighted / captured were located 427 m higher than its described altitudinal range. This could be due to 2 factors: 1) urbanization generates suitable habitats for this species in periurban areas, and 2) temperature values have increased in the region where the city of Morelia is located. These factors allow that a lowland bird species can inhabit in more elevated areas. Thus, our records suggest that the Grey-crowned Yellowthroat can be catalogued as potential to use suburban environments when these are similar to those used by the species on its natural distribution area