Bernal Rodríguez-Herrera

Frugivorous Bats Maintain Functional Habitat Connectivity in Agricultural Landscapes but Rely Strongly on Natural Forest Fragments

Anthropogenic changes in land use threaten biodiversity and ecosystem functioning by the conversion of natural habitat into agricultural mosaic landscapes, often with drastic consequences for the associated fauna. The first step in the development of efficient conservation plans is to understand movement of animals through complex habitat mosaics. Therefore, we studied ranging behavior and habitat use in Dermanura watsoni (Phyllostomidae), a frugivorous bat species that is a valuable seed disperser in degraded ecosystems. Radio-tracking of sixteen bats showed that the animals strongly rely on natural forest. Day roosts were exclusively located within mature forest fragments. Selection ratios showed that the bats foraged selectively within the available habitat and positively selected natural forest. However, larger daily ranges were associated with higher use of degraded habitats. Home range geometry and composition of focal foraging areas indicated that wider ranging bats performed directional foraging bouts from natural to degraded forest sites traversing the matrix over distances of up to three hundred meters. This behavior demonstrates the potential of frugivorous bats to functionally connect fragmented areas by providing ecosystem services between natural and degraded sites, and highlights the need for conservation of natural habitat patches within agricultural landscapes that meet the roosting requirements of bats.

Life in a mosaic landscape: anthropogenic habitat fragmentation affects genetic population structure in a frugivorous bat species

Bats are often considered highly mobile and hence less susceptible to habitat fragmentation than other animals. We tested this basic assumption by studying populations of Dermanura watsoni, a frugivorous phyllostomid bat, inhabiting forest fragments in an agriculturally dominated landscape in northeastern Costa Rica. We used the mitochondrial D-loop DNA-sequence data to examine genetic diversity and population structure. A significant population differentiation (FSTxa0=xa00.05, pxa0<xa00.001) over a geographical scale of approximately 20xa0km was detected. Genetic diversity within fragments correlated with patch size and the amount of suitable habitat in the surrounding matrix. The composition of the matrix in close proximity to the fragments explained variation in genetic diversity best. However, only habitat parameters measured from 1986 land cover conditions can explain current genetic diversity, and not those from 2001. Our study demonstrates that bats, despite their high mobility, are not secure from genetic erosion in anthropogenically modified landscapes. Population differentiation can occur on a surprisingly small geographic scale and after short time periods. Our findings illustrate the importance of considering several points in time when testing for an influence of habitat parameters as it might be decades until they are reflected by genetic diversity.

An automatic acoustic bat identification system based on the audible spectrum

Abstract Nowadays the task of monitoring bat species is a very difficult task because of several factors. The main ones are the difficulty of creating databases automatically and the particularities of the vocalizations of bats. For this reason, it is common to extract bat calls manually from a recording and treat them individually. We propose a new form of identification and labeling process based on adapting bat calls to the audible spectrum and significantly reducing the noise of its spectrogram. This process can be performed automatically from a recording made in a natural area. Our database consists of 189xa0h of recordings obtained in various natural areas in Costa Rica. 50 bats calls of 7 different classes are extracted from this database. We have obtained an average error of 2.7% and 3 of the 7 classes have an error below 1%.

Tropical bat as mammalian model for skin carotenoid metabolism

Significance We have discovered that a mammalian species, a bat called the Honduran white bat Ectophylla alba, displays a yellow carotenoid pigment called lutein in its bare skin. Even though carotenoid-based coloration has been found in birds, fish, amphibians, and reptiles, there are no reports of any extant mammals showing these pigments in their skin or hair. The implications of this finding may be profound for human health, as carotenoids are essential micronutrients. Lutein in particular is involved in the preservation of the macula of the eye. The Honduran white bat, with its ability to assimilate and deposit lutein in its bare skin, may be the sought-after mammalian model needed for enhancing studies on carotenoid function and metabolism. Animals cannot synthesize carotenoid pigments de novo, and must consume them in their diet. Most mammals, including humans, are indiscriminate accumulators of carotenoids but inefficiently distribute them to some tissues and organs, such as skin. This limits the potential capacity of these organisms to benefit from the antioxidant and immunostimulatory functions that carotenoids fulfill. Indeed, to date, no mammal has been known to have evolved physiological mechanisms to incorporate and deposit carotenoids in the skin or hair, and mammals have therefore been assumed to rely entirely on other pigments such as melanins to color their integument. Here we use high-performance liquid chromatography (HPLC) in combination with time-of-flight mass spectrometry (HPLC-TOF/MS) to show that the frugivorous Honduran white bat Ectophylla alba colors its skin bright yellow with the deposition of the xanthophyll lutein. The Honduran white bat is thus a mammalian model that may help developing strategies to improve the assimilation of lutein in humans to avoid macular degeneration. This represents a change of paradigm in animal physiology showing that some mammals actually have the capacity to accumulate dietary carotenoids in the integument. In addition, we have also discovered that the majority of the lutein in the skin of Honduran white bats is present in esterified form with fatty acids, thereby permitting longer-lasting coloration and suggesting bright color traits may have an overlooked role in the visual communication of bats.

Survey of wild mammal hosts of cutaneous leishmaniasis parasites in panama and costa rica.

The eco-epidemiology of American cutaneous leishmaniasis (ACL) is driven by animal reservoir species that are a source of infection for sand flies that serve as vectors infecting humans with Leishmania spp parasites. The emergence and re-emergence of this disease across Latin America calls for further studies to identify reservoir species associated with enzootic transmission. Here, we present results from a survey of 52 individuals from 13 wild mammal species at endemic sites in Costa Rica and Panama where ACL mammal hosts have not been previously studied. For Leishmania spp. diagnostics we employed a novel PCR technique using blood samples collected on filter paper. We only found Leishmania spp parasites in one host, the two-toed sloth, Choloepus hoffmanni. Our findings add further support to the role of two-toed sloths as an important ACL reservoir in Central America.

Energetics of tent roosting in bats: the case of Ectophylla alba and Uroderma bilobatum (Chiroptera: Phyllostomidae).

Roost selection in mammals is an important selective pressure, and many animals find shelter in previously existing structures. Furthermore, the microclimate of roosts is a crucial element for bat survival, and modified leaves are used for roosting (“tents”) by 22 species of bats. Our objective was to determine whether the inverted boat tents used by Ectophylla alba and pinnate tents used by Uroderma bilobatum provide energetic benefits. We measured the ambient temperature under modified and unmodified leaves (UMLs) of Heliconia imbricata and Cocos nucifera. We also measured temperature with (simulated bat presence) and without a heat source, and finally we measured bat energy expenditure at different temperatures. Our results show that when a heat source is present tents conserve heat better than a UML. The energy expenditure of E. alba and U. bilobatum increased up to 55% and 48%, respectively, with a decrease of temperature from 25°C to 20°C. We concluded that since the temperature at our study site drops below 25°C every night and remains that way until mid-morning, using a “tent” that maintains a temperature higher than ambient temperature, or close to 25°C degrees, provides an energetic advantage.

Networking Networks for Global Bat Conservation

Conservation networks link diverse actors, either individuals or groups, across space and time. Such networks build social capital, enhance coordination, and lead to effective conservation action. Bat conservation can benefit from network approaches because the taxonomic and ecological diversity of bats, coupled with the complexity of the threats they face, necessitates a wide range of expert knowledge to effect conservation. Moreover, many species and issues transcend political boundaries, so conservation frequently requires or benefits from international cooperation. In response, several regional bat conservation networks have arisen in recent years, and we suggest that, with the globalization of threats to bats, there is now a need for a global network to strengthen bat conservation and provide a unified voice for advocacy. To retain regional autonomy and identity, we advocate a global network of the regional networks and develop a roadmap toward such a meta-network using a social network framework. We first review the structure and function of existing networks and then suggest ways in which existing networks might be strengthened. We then discuss how regional gaps in global coverage might best be filled, before suggesting ways in which regional networks might be linked for global coverage.

Advance in the bat acoustic identification systems based on the audible spectrum using nonlinear dynamics characterization

Combination of linear and non-linear parameterization.As much as 12 chaos theory parameters are used.Simple and quick method of classification.Significant improvement of correct rate classification thanks chaos theory parameters. Frequential and time lineal parameters have shown a good performance in the recognition of bat species and nowadays there are many works which obtain those characteristics very accurately. However, it is necessary to move forward and test the capabilities of other characterizations on bioacoustics successfully used in other fields. In this work the chaos theory, which is an area of nonlinear dynamics systems, is applied to bat acoustic identification. The database used in the evaluation consists of 50 bat calls of seven different classes extracted from a previous work. The combinations of linear and nonlinear parameters have resulted in an average error of 1.8%, improving the accuracy in 0.42%. The differences to identify between the most difficult species and the easiest ones have been reduced.

Neotropical bats that co-habit with humans function as dead-end hosts for dengue virus

Several studies have shown Dengue Virus (DENV) nucleic acids and/or antibodies present in Neotropical wildlife including bats, suggesting that some bat species may be susceptible to DENV infection. Here we aim to elucidate the role of house-roosting bats in the DENV transmission cycle. Bats were sampled in households located in high and low dengue incidence regions during rainy and dry seasons in Costa Rica. We captured 318 bats from 12 different species in 29 households. Necropsies were performed in 205 bats to analyze virus presence in heart, lung, spleen, liver, intestine, kidney, and brain tissue. Histopathology studies from all organs showed no significant findings of disease or infection. Sera were analyzed by PRNT90 for a seroprevalence of 21.2% (51/241), and by PCR for 8.8% (28/318) positive bats for DENV RNA. From these 28 bats, 11 intestine samples were analyzed by RT-PCR. Two intestines were DENV RNA positive for the same dengue serotype detected in blood. Viral isolation from all positive organs or blood was unsuccessful. Additionally, viral load analyses in positive blood samples by qRT-PCR showed virus concentrations under the minimal dose required for mosquito infection. Simultaneously, 651 mosquitoes were collected using EVS-CO2 traps and analyzed for DENV and feeding preferences (bat cytochrome b). Only three mosquitoes were found DENV positive and none was positive for bat cytochrome b. Our results suggest an accidental presence of DENV in bats probably caused from oral ingestion of infected mosquitoes. Phylogenetic analyses suggest also a spillover event from humans to bats. Therefore, we conclude that bats in these urban environments do not sustain DENV amplification, they do not have a role as reservoirs, but function as epidemiological dead end hosts for this virus.

Implications of a specialized diet for the foraging behavior of the Honduran white bat, Ectophylla alba (Chiroptera: Phyllostomidae)

Specialist species are defined by their restricted range of tolerated environmental conditions and required resources. For example, in the New World leaf-nosed bats (Phyllostomidae), specialization in diet has been linked to morphological and behavioral innovations (i.e., skull form, foraging behaviors) that facilitate the occupation of new ecological niches by these animals. Here, we use the Honduran white bat, Ectophylla alba, as a model to test the behavioral responses of the species to a narrow diet: one based on figs of Ficus colubrinae (Moraceae). Through the use of radiotelemetry, we demonstrate that the foraging behavior of these bats is highly dependent on their main food resource. In response, behavioral adaptations have evolved to optimize the bats foraging strategies and—at a broad level—the performance and survival of the species in their habitat. Conservation decisions should consider the tight linkage that exists among some species and their habitat characteristics or food resources (as demonstrated herein), in order to protect highly susceptible and unique species that could potentially go extinct with the disturbance or removal of specific features of their ecological interactions.