Wednesday, April 20, 2016

Insects and Amphibians in Monteverde Cloud Forest

Upon my arrival in Monteverde, many changes in the habitat around me were apparent, including a chilly breeze, high humidity, droplets covering all vegetation, and fast-moving clouds that allowed for ephemeral pockets of sunlight shining through. In comparison to Palo Verde, the last biological station I had visited, the dense premontane wet forest offered a completely distinct web of interspecific interactions with organisms possessing traits adapted for this specific ecosystem. Although I could not explore the forest thoroughly during my first day in Monteverde, my first taste of biodiversity occurred at night. After dusk had passed, I was taking notes in class, and a large moth (Rothschildia sp.) flew around a light above me. Eager to catch it after lecture, I ran upstairs to grab my net. To my surprise, the lights on the second floor of the station were covered with large saturniid and sphinx moths, and very few of them appeared to be identical. This small moment impacted me since although I was encompassed by such incredible diversity, the species that were present at the moment represented a negligible amount in comparison to the entire Monteverde area, and this is only considering two moth families, not to mention other insects, each with dozens of families, and vertebrates such as amphibians, reptiles, birds, and mammals.
            One species in particular that impressed me was the hawkmoth Xylophanes zurcheri. It had a green/brown mossy coloration with dark lines that broke up the outline of the body and projections on the side of the abdomen. If it were present on a mossy tree, it would certainly lie undetected in the presence of many predators. The most impressive example of crypsis I found in Monteverde was a phasmid in the genus Prisopus. This spectacular insect measuring about 5.5 inches in length had similar characteristics to the hawkmoth since it also appeared to be a moss-mimic, but in addition it had spines, assorted colorations on its entire body including wing veins and limbs, and a flattened body posture to remain apposed to surfaces with limbs folding together against the body like a puzzle.
            Like insects, amphibians are also very diverse in the Monteverde cloud forest, and this group was the one we studied primarily in class in the context of conservation and the population declines. Because of the nature of high elevation ecosystems, species are more vulnerable than in lower elevations due to factors such as limited home range and suitable habitat, and the facility of lower elevation competitors to move to higher elevations simultaneously with increase in temperature. In particular, this has a large effect on endemic species such as the golden toad (Bufo periglenes), since subpopulations cannot persist away from their original habitat to help prevent complete population collapse and extinction. Mark Wainwright, a guest professor, spoke about the large role of humans in driving the decline and extinctions of amphibians. He explained that the primary drivers of such declines appear to be pathogens (i.e. Chytrid fungus, Ranavirus) and climate change (global warming), which are exacerbated by other factors such as forest fragmentation, UV contamination and pesticide use. Because amphibians have the greatest biomass of any group of organisms in tropical ecosystems, population declines pose a large threat to preserving species interactions in ecosystems. Specifically, the loss of amphibian life can lead to a reduction in vertebrate life that use them as a primary food source (e.g. snakes, mammals, birds), an increase in insect life that would normally be maintained at lower levels through amphibian consumption, and an increase the availability of open niches for competitors to replace them by home range shifts. Conservation biologists and ecologists often try to justify the preservation of ecosystems at risk of degradation and/or collapse through the impacts it will have on humans and nearby communities. However, Mark said the foremost reason for conservation in his mind lies in the importance of the organisms themselves. We should be able to promote conservation with the interest of preserving species and biodiversity as the primary motivating factor, which is something I strongly believe in.
Christian Perez
Harvard University

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