In this paper we discuss how yeast, fungi ubiquitously present in sugar-rich fruit, can influence the interaction between frugivores and fleshy-fruited plants via ethanol. We suggest that plants, the seeds of which are mostly dispersed by vertebrates, exploit the ethanol from alcoholic fermentation by yeast in their seed dispersal strategy. Moderate consumption of ethanol, i.e., at concentrations close to those in naturally ripening fruit, by frugivores may have beneficial short- and long-term effects for these potential dispersers, whereas consumption of larger quantities may have negative short- and long-term effects. Ethanol vapor emanating from palatable fruit may act as an odor cue, guiding bats and other frugivores to the fruit, and aiding them to assess its quality. In addition, we suggest that ingested ethanol may be an appetitive stimulant. We also evaluate the possibility that ethanol within fruit may be used as a source of energy by frugivorous vertebrates. Our preliminary data indicate that Egyptian fruit bats (Rousettus aegyptiacus) can use the odor of ethanol to assess food suitability, but also that it may not serve as an attractant over short distances (i.e., <1 m). Instead, ethanol is avoided at concentrations greater than 1%, a value which might typically characterize overripe and otherwise unpalatable fruit. Our initial results further indicate that Egyptian fruit bats significantly decrease their food consumption if it contains 1 or 2% ethanol. Overall, ethanol may play diverse roles in the nutritional ecology and behavior of fruit-eating bats, and in the interaction between frugivores and plants, in general.

Frugivorous bats from the Old and New World use odor cues to locate and assess fruit condition. We hypothesized that Egyptian fruit bats (Rousettus aegyptiacus) use as odor cues those volatile compounds that increase in emission rate as fruit ripens. We examined whether the smell of fermentation products may indicate the degree of ripeness to fruit bats. We analyzed volatile compounds in the headspace (the gas space above a fruit in a closed container) of dates (Phoenix dactylifera) and rusty figs (Ficus rubiginosa), both of which are consumed by fruit bats, to elucidate which compounds originate from fermentative pathways and to determine which change in emission rate during ripening. Ethanol, acetaldehyde, and acetic acid were the only volatile compounds detected as products of fermentation in both fruits. In dates, emission rates of these compounds increased during maturation, whereas in rusty figs, they decreased or remained constant. Methanol, although not a fermentation product, increased in emission rate during ripening in both fruits. We found that R. aegyptiacus was neither attracted nor deterred by the smell of methanol at any of the concentrations used. Although the odor of ethanol emanating from food containing concentrations similar to those found in ripe fruit did not attract the bats, at relatively high concentrations (> or =1%), the smell of ethanol deterred them. Thus, ethanol at high concentrations may serve as a signal for bats to avoid overripe, unpalatable fruit.

<p>El páramo de Rabanal en Colombia es considerado un reservorio hídrico para la región del altiplano<br />cundiboyacense, y ha sufrido un grave deterioro por actividades humanas. Los inventarios de la biodiversidad son útiles para ejecutar planes adecuados de conservación de especies y sus ecosistemas; por ello, se realizó un inventario de aves y mamíferos del sector Matanegra en Rabanal, municipio de Ventaquemada (Boyacá). Para el registro de aves se emplearon recorridos y puntos de observación, detecciones ad libitum y redes de niebla. Para el estudio de mamíferos se usaron recorridos de observación, trampas de captura en vivo y búsqueda de rastros. Se registraron 57 especies de aves y 14 de mamíferos, entre las que se destacan taxo nes con distribución restringida (Anas andium, Colinus cristatus bogotensis, Fulica americana columbiana, Gallinago nobilis, Eriocnemis cupreoventris, Conirostrum rufum, Atlapetes pallidinucha, Myioborus ornatus, Sporagra spinescens, Cryptotis thomasi y Thomasomys niveipes); en categoría de amenaza (Cuniculus taczanowskii y Nasuella olivacea), y se presentan 39 nuevos registros para la zona. El número de especies en Rabanal es bajo, comparado con áreas protegidas en Boyacá y Cundinamarca; sin embargo, a pesar de la intervención antrópica, Rabanal aún contiene elementos típicos de ecosistemas andinos. Se recomienda adelantar procesos pedagógicos con la comunidad local para mitigar los impactos sobre el páramo.</p>

Urbanization is one of the most pervasive processes of landscape transformation, responsible for novel selection agents promoting functional community homogenization. Bats may persist in those environments, but the mechanisms responsible for their adaptability and the spatial scales in which the landscape imposes environmental filtering remain poorly studied in the Neotropics. We tested the hypothesis that landscape composition interacts with the spatial scale to affect the functional diversity of phyllostomids in an urban-rural gradient. Based on functional traits, we calculated indices of functional richness, divergence, evenness, and community-weighted means of morphological traits, and classified species into functional groups. We evaluated the changes in those variables in response to forest, grassland, and urbanized areas at 0.5, 1.25, and 2km scales. The number of functional groups, functional richness, and functional evenness tended to be higher in areas far from cities and with higher forest cover, whereas functional divergence increased in more urbanized areas. Our results show that the mean value of wing loading in the assemblage was negatively associated with landscape transformation at several spatial scales. However, environmental filtering driven by grass cover was particularly robust at the 0.5km scale, affecting big-sized species with long-pointed wings. Retaining natural forest in cattle ranging systems at ~12 km 2 appears to favor the functional evenness and number of functional groups of phyllostomids. Recognizing the scale of the effect on phyllostomid functional responses appears to be a fundamental issue for elucidating the spatial extent to which phyllostomid conservation planning in urban-rural landscapes should be addressed.

Ethanol occurs in fleshy fruit as a result of sugar fermentation by both microorganisms and the plant itself; its concentration [EtOH] increases as fruit ripens. At low concentrations, ethanol is a nutrient, whereas at high concentrations, it is toxic. We hypothesized that the effects of ethanol on the foraging behavior of frugivorous vertebrates depend on its concentration in food and the body condition of the forager. We predicted that ethanol stimulates food consumption when its concentration is similar to that found in ripe fruit, whereas [EtOH] below or above that of ripe fruit has either no effect, or else deters foragers, respectively. Moreover, we expected that the amount of food ingested on a particular day of feeding influences the toxic effects of ethanol on a forager, and consequently shapes its feeding decisions on the following day. We therefore predicted that for a food-restricted forager, ethanol-rich food is of lower value than ethanol-free food. We used Egyptian fruit bats (Rousettus aegyptiacus) as a model to test our hypotheses, and found that ethanol did not increase the value of food for the bats. High [EtOH] reduced the value of food for well-fed bats. However, for food-restricted bats, there was no difference between the value of ethanol-rich and ethanol-free food. Thus, microorganisms, via their production of ethanol, may affect the patterns of feeding of seed-dispersing frugivores. However, these patterns could be modified by the body condition of the animals because they might trade-off the costs of intoxication against the value of nutrients acquired.