Summer of fieldwork: Costa Rica

In July, Jeff Riffell, David Villalobos and I went to La Selva Biological Station in Costa Rica to work on our NSF-funded project “Chance or necessity? Adaptive vs. non adaptive evolution in plant-frugivore interactions”. Going in the middle of the rainy season during an El Niño year made for a very stormy, wet, muddy and soggy couple of weeks. In what I’d like to call “the field season triathlon” (hiking, trawling, and reaching up), we were able to collect Volatile Organic Compounds (VOC) from the fruits of over a dozen species of Piper and other bat-dispersed plants, and fecal and tissue samples from nearly 100 bats. While mapping the VOC profiles onto phylogenies will enable us to investigate how fruit scent evolves in this system, analyses of the bat fecal samples will allow us to expand our current understanding of how much the bats rely on the different Piper species for food.

This autumn, Leith Miller and Ada Kaliszewska are continuing sample collection and analysis for this project in La Selva. Meanwhile, Laurel Yohe (a PhD student at our collaborating lab) gave a talk at the North American Symposium for Bat Research in which she presented preliminary results  on the olfactory receptors of short-tailed fruit bats.

Summer of fieldwork: The Philippines

Time flies when you’re having fun, or if you are catching bats around the world, which is basically the same thing. This is the first post reporting our fieldwork trips this summer, which included four countries across four ecogeographic regions!

It all started with a trip to the Philippines with a team composed by the Sears, Dávalos, Dumont and Santana labs, Dr. Susan Tsang, and colleagues from the National Museum of the Philippines. Our main goal was to collect Old World fruit bats (Pteropodidae) for a study that will contribute to understanding why these bats have much lower cranial diversity than their New World counterparts (Phyllostomidae). Answering this question involves integrating studies on cranial development, bite force and feeding behavior across a range of pteropodid and phyllostomid species.

What impressed me the most upon arriving to the Philippines was the overwhelming population density (Luzon is the 4th most populated island in the world). Our field sites were near, Liliw, a highland town in the southern portion of the Laguna province. Even several hours away from the capital, there were no apparent sights of the kind of habitats that I would expect could sustain bats. Yet, despite the loss of habitat and the pollution, some bat species still seem to fly through this landscape and take advantage of fruiting trees during their nightly foraging activities. Using mist nets suspended a few dozen meters above the ground, and skipping on any form of night sleep, we were able to collect five of these bat species: Cynopterus brachyotis, Eonycteris spelaea, Macroglossus minimus, Ptenochirus jagori, and Rousettus amplexicaudatus. Though this was a considerably lower diversity than what I’m used to experiencing in the Neotropics, it was astonishing to see these species live for the first time.

From the beginning, it was quite evident that pteropodids are a different ballgame than phyllostomids when it comes to recording performance and feeding behavior. Although both Cynopterus and Ptenochirus were reminiscent of Neotropical Artibeus species in their extravagant use of distress calls in the mist net, their approach towards scary things (like a bite force meter) seemed quite different. These species, as well as the rest of the pteropodids we caught, tended to rely more on their flight response when faced with experimental situations – cue adorable bat covering its face with its wings. With much patience and creativity, however, we were able to get bite force data for new species to complement previous datasets for our study. Likewise, Karen Sears and Dan Urban set up a lab in the field that allowed them to conduct unprecedented experiments and observations on the skull development of several pteropodid species.

My favorite catch of this trip was Rousettus, despite the fact that their activity peaked between 2-4 AM, sending the sleep-deprived team into panic mode to quickly release dozens of bats from the nets before sunrise. Rousettus were extremely gentle bats, and it was a treat to hear their tongue clicks (a form of echolocation) as they flew about and while we handled them. The young of at least one species of Rousettus may learn vocalizations in similar ways to the way human babies do. What’s not to love?

The data and samples collected during this trip will serve for dozens of studies that will expand the understanding of this diverse and still obscure group of bats. As it often happens, I came back with many more research questions than when I left. Here’s to hoping there will be more pteropodids in our future.

New NSF grant to study bat-plant coevolution!

We are thrilled to announce that our NSF collaborative proposal has been awarded! Together with the Dávalos lab at SUNY Stony Brook and the Riffell lab at UW, we will be working on the project “Chance or necessity? Adaptive vs. non adaptive evolution in plant-frugivore interactions”. We will investigate the coevolution between fruit scents and the olfactory ability and behavioral preferences of fruit-eating bats by integrating advanced tools from analytical chemistry, genomics, and behavioral ecology. Our work will focus on two ecologically important groups of tropical plants and mammals, Piper plants and Carollia bats, and will be based at La Selva Biological Station in Costa Rica. We are currently looking for a postdoc and recruiting a Ph.D. student for this project.

Photo © Merlin Tuttle, BCI

Meet the Mammals 2013

Thanks to the combined efforts of faculty, students, volunteers and staff, we had a very successful Meet the Mammals day. We received 1,092 visitors, and over 260 children were certified as “Junior Mammalogists” by learning about the adaptations and diversity of extinct and living mammals. Below are some candid photos of this wonderful event.

Meet the Mammals is coming Nov. 16!

There’s never a dull moment at the Burke. Today we moved the skulls of a sperm whale and gray whale from the mammalogy collection into the lobby to prepare for our Meet the Mammals event on Saturday, 11/16: http://bit.ly/burkemam. You can see the skulls in our lobby during the month of November.

More photos of the skull move in this Post by the Burke Museum on Facebook.

484781_10152037060188064_218322464_n

 

Notes from the field: Ectophylla alba

Ectophylla alba, the Honduran white bat, is a unique species of Neotropical leaf-nosed bat. Not only they are among the very few species of bats that are almost completely white, but they are extremely specialized in their diets and roosting ecology. Males and females of the species skillfully construct delicate tents from the leaves of Heliconia plants, and their diet is restricted to fruits of Ficus colubrinae plants. During our most recent trip to Costa Rica, we had the opportunity to record and measure these bats as they frantically fed from a F. colubrinae fruiting tree (below). Fruiting events in Ficus plants occur in short bursts and are scattered throughout the landscape, and E. alba likely choose places to “camp out” according to the potential for food availability.

 

Integration of bat skulls

Previous research in vertebrates has demonstrated that selection can cause rapid evolutionary changes in cranial modularity, that is, how many and which parts of the skull vary and evolve together. Mammals, however, seem to have maintained a simple pattern of cranial modularity throughout their evolutionary history and across tremendous ecological and morphological diversity. All mammals studied to date have two cranial modules, the braincase and rostrum. But what happens when parts of the skull acquire novel functions? Does cranial integration remain the same? We just published a study in which we test whether skull modularity has been remodeled in rhinolophid bats due to the novel and critical function of their nasal cavity in echolocation. Rhinolophids have greatly enlarged nasal cavities that vary in shape across species, thus we predicted that nasal echolocation resulted in the evolution of a third cranial module, the ‘nasal dome’, in addition to the braincase and rostrum modules. Remarkably, despite large variation in the shape of the nasal dome, we found that the integration of the rhinolophid skull still follows the two-module pattern found in other mammals. In other words, the shape of the nasal cavity changes together with the shape of the snout across species. We also found distinct trends in the evolution of skull shape across these bats’ geographic distribution. Our findings highlight that broad morphological and functional diversity can still be achieved in spite of a relatively simple modular template.

Does nasal echolocation influence the modularity of the mammal skull? – Santana & Lofgren (2013) – Journal of Evolutionary Biology 

Costa Rica 2013

After the Belize warm up, I went to Costa Rica to work at two main sites, the Tirimbina Forest Reserve and OTS La Selva research station. The major goal of this trip was to collect fecal samples for molecular dietary analyses in foliage-gleaning bats, along with performance data across bats and other mammals. These data will allow us to understand patterns and mechanisms of food resource partitioning within and across dietary guilds. With the help of collaborator Dr. Bernal Rodríguez Herrera and his students at the Universidad de Costa Rica, we were able to collect data for a total of 24 species of bats, plus several kinkajous.

One of the trip highlights included catching Honduran white bats (Ectophylla alba), a very small frugivore that builds tents in the vegetation. Findings about Ectophylla’s tent construction behavior have changed the paradigm that only male bats build these roosts as part of a resource-defense polygynous system; female Ectophylla also contribute to building tents. A second high point was collecting a wrinkle-faced bat (Centurio senex), a very rare and morphologically derived stenodermatine that is built to bite. Just as impressive, the second largest bat in the Neotropics (Phyllostomus hastatus) made its appearance in our nets and contributed to our dataset. With such stunning biodiversity, we are very much looking forward to continue work and collaborations in Costa Rica. Pura vida!

Belize 2013

The field season 2013 started with a bang! This May, I joined an international team of over 40 bat biologists in an expedition to Lamanai, Belize. The trip was led by Dr. Brock Fenton, a bat expert from the University of Western Ontario who has been visiting the site for over 20 years. Lamanai is impressive with biodiversity and archeological remains;  jaguar faces not only decorate the Mayan temples, but these animals can be seen around the area as well.

With a few dozen bat researchers in the group, projects were as diverse as the bats: morphology of wings, muscles, skulls and reproductive tracts, echolocation, feeding behavior, diet, flight aerodynamics, radio tracking, viruses, and more. We caught around 500 bats from 28 species, the great majority of which were released unharmed. The voucher specimens that were kept will serve as the basis of studies in labs across five institutions, which is an impressive use of field-collected specimens. These will continue to be available to researchers at the American Museum of Natural History’s Mammal Collection.

Primate faces on Discover

uakariWhy do primates have such colorful and distinct faces? We have been trying to answer this question in a broad comparative context by integrating data on the two most likely drivers of primate facial diversity: sociality and ecology. A major challenge during this research has been to quantify the facial patterns in a way that is comparable across hundreds of primates species. So, we devised  a metric, “facial complexity”, which represents how many colors there are in a primate’s face. Much to my own surprise, the evolution of facial complexity seems to be tightly linked to social group size and species sympatry. This is usually a positive relationship (Neotropical primates are the oddball), indicating that differences in the number of colors in primate faces provide cues that might be used for species and/or individual recognition.

This research has been getting a lot of media coverage (I guess everyone likes monkeys!), and a new article in Discover magazine does an excellent job at decribing our complexity scale. Check it out:

http://discovermagazine.com/2013/march/7-monkey-face#.UTAFVPkS5sJ