Community Disease Ecology


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Detailed Description

Unlike our other research programs where we study aspects of primate biology and ecology at the level of the individual and social group, here we take one large step back to view the entire community. There are few places better suited for a community-wide  research program than Los Amigos, boasting 11 different primate species (check them out here), over 500 species of bird, and elevated bat, rodent, and marsupial diversity that is as yet unconfirmed (a indirect goal of this project). Some of them are rare, some are extremely abundant, some compete for food while others have found a special dietary niche (e.g., the howler monkeys are the only folivores or leaf eaters in this forest, while the saki monkeys the only seed-predators).

There are some major limitations, however, to conducting field research at the community level.  For one, it’s hard to find the time to observe many different species to the same extent.  It’s not as simple as hanging out with one social group from each species, because a) not all species are social and b) how could one know that a single group or individual fits the norm?

Instead of launching a massive behavioral research program, we are counting on another method to obtain large amounts of data from each species. Our special method has everything to do with fecal and blood samples.  We can identify an individual primate, determine its sex, tell if it is sexually mature, if it is experiencing high stress, and describe its health status (particularly in terms of parasites and disease): that’s all from a single sample.  If we collect from them consistently over time, we can eventually follow parasites and diseases as they spread through populations and maybe even jump between species (an exceedingly important consideration for humans).

Our task in the field is pretty straight forward, though not easy.  One: find primate  species.  Two: follow social groups as they go about their daily routines, carrying a handheld GPS that tracks their movement, a notebook to record interesting observations, and a whole bunch of collection supplies. Three: collect fecal samples in a variety of ways that preserves DNA, parasite, and dietary data. As far as non-primate sample collection goes, this is achieved by the wildlife handling program

As of July 2018, and for the first time in the history of this program, we will now screen samples directly in the field. Samples collected at the Los Amigos field station are taken to the Green Lab, which is hosted by another research station nearby. Here you will learn to screen samples using both microscopy and molecular techniques.

We welcome enthusiastic, reasonably fit, and self-motivated students and young scientists to join this project.  We require a minimum 4-week time commitment from research assistants that join this project, or 5-weeks if you intend on participating in both sample collection and field diagnostics. If you want to experience first-hand all the primate species at our field site in one training program, and learn to work with biological samples from start to finish, then we encourage you to apply.

At the end of the program, research assistants will be able to:

  • Track primates by movement and vocalizations
  • Work off trail systems, and conduct full-day follows
  • Conduct behavioral observations
  • Record data on feeding ecology
  • Collect GPS data on species movements, create, and maintain a large digital movement map.
  • Demonstrate proficiency in collecting and storing biological samples in field conditions, including participating in downstream applications such as microscopic and molecular diagnostic analyses.
  • Work with an Access database


We are currently recruiting participants with the following requirements.  If you are uncertain if you are eligible, contact us to confirm.

  • Must be at least 18 years of age by the time the training program begins
  • Demonstrate a grounding or strong interest in zoology, biology, or anthropology
  • Previous field experience is not required, but previous research experience (either outdoors or in the laboratory) will be a plus
  • Must be able to justify why this program is important to them and what they hope to gain from it
  • Able to provide a letter of recommendation from a source that can substantiate the participant’s experience and skills
  • Unafraid of insects, reptiles and the jungle in general
  • Must be in good physical condition, with the capability to walk 4 miles a day while carrying field equipment
  • Participants will not be discriminated against for medical conditions they might have if we determine that being on this project will not pose an immediate risk to their health.
  • Willingness to adjust your schedule to primate daily activity patterns. This can require waking up early, sometimes by 5 am, and going to bed early.
  • Due to the nature of the work and weather constraints, participants MUST be willing to be flexible about their days off. Assistants will typically have one day off per week; however we cannot guarantee a set schedule each week.
  • Participants must sign waivers of liability for this project and for the field station before their participation in the project is finalized
  • Participants must be willing to maintain long hours in the field, but also return to complete data entry in the evenings
  • Assistants will have the opportunity during days off to explore various attractions at the field site, such as searching for the resident anaconda at Pozo Don Pedro or looking for endangered giant river otters at Cocha Lobo.

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Program dates: June 3 – July 30, 2019

Minimum stay required: 4 weeks (*5 weeks if completing both field collection and field diagnostics components)

Program fee: $450 per week during sample collection phase; $600 per week during field diagnostics phase



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Primary Investigators

This project has been running since 2012, and the primary investigators working on it currently are Gideon Erkenswick, Mrinalini Watsa, and collaborators Krista Banda and Dr. Anne Stone from Arizona State University. These researchers have extensive experience handling wildlife, and have conducted a wildlife capture-and-release program at this site for 9 years (as of 2018). They also have experience in laboratory screening for parasite DNA. The data analyses are presented here by Gideon, and are an offshoot of his doctoral thesis.

Project Background

Parasitism can be defined as any relationship in which one organism consumes the resources of another organism without providing anything in return.  Seems malicious right?  Actually, the question of whether parasites are good or bad is no longer very relevant.  It is purported that parasitism is the most common life strategy on the planet, and moreover that parasites play central roles in regulating plant and animal populations, communities, and even entire ecosystems.  Contrary to popular belief, the removal of parasites (certain bacteria for example) can be detrimental to an individual’s health, or to ecological balance.  Spokes are to a wheel, what parasites are to predator-prey dynamics, nutrient cycles, speciation, extinction, social behavior, and much more.  Parasitism occurs in as many ways as parasites themselves are diverse.  Stealing a neighbor’s hard won meal, entering someone else’s turf for a clandestine mating opportunity, invading the red blood cells of a host, occupying someone else’s nest – these can all be viewed as examples of parasitism.  Studying parasites informs us about how the natural world functions at a fundamental level.

Why monkey parasites in particular?

One of the oldest reasons for studying monkeys is because through them we are driven to understand ourselves.  Monkeys are close evolutionary relatives of humans, and we learn about the evolution of humans by identifying similarities and differences that we share with other primates.  Some of the most interesting comparisons pertain to the parasites that we host in common and those we do not.  More and more we are seeing that parasites defy species boundaries, particularly among primates.  Are parasites adapting to new host environments at greater rates than ever before? Alternatively, perhaps increased parasite sharing is driven by human-caused disturbances to stable ecological relationships that previously obstructed parasite exchange.  Either way, monitoring the parasites of natural primate populations is of importance to all parties involved.

Beyond our vain curiosities and concerns, primates provide a good model for the study of parasite–host relationships and parasite–parasite relationships.  For example, regardless of the host-parasite system you choose, the parasite is unlikely to be distributed evenly across host individuals.  In other words, all individuals in a population do not share an equal burden of parasites. This inequality can frequently be driven in human populations by host age, sex, socioeconomic status, diet or family size.  In this research project, we are interested in determining what factors explain uneven distributions of parasites under the most natural environmental conditions.

In other words, who is most parasitized and why?

At an even finer level, we can think of the host as one environment within which many different parasites interact.  Just like all living organisms, parasites sometimes struggle to survive, compete for resources, and work together for mutual benefit.  In a similar fashion, the loss of top predators in North America such as wolves and large cats has resulted in overpopulation of large herbivores, like deer, which now require coordinated management programs.  Exploring these relationships will help us understand why the removal of some parasites may not be in the best interest of a host.

Sex, Stress and Self-Defense

There is a great deal of interest today in how complex organisms allocate resources (e.g. energy) toward different functions necessary for their survival and ability to reproduce.  For example, how much energy should an animal devote toward searching for food as opposed to courting a mate?  There should be some optimal strategy that maximizes one’s chances of securing mating opportunities and sufficient food resources, but presumably, these strategies vary over time depending on the availability of mates and food.

We are interested in these life history trade-offs, but we are also curious about the mechanisms that mediate them.  One commonly cited trade-off occurs between immune function and reproductive investment.  The strength of one’s immune system, i.e. the humoral or cell-mediated immune response, and the extent of reproductive investment could be pertinent to sexual signaling to attract a mate (e.g. the male peacock’s tail) or parental care investment in offspring.  Previous research has noted that changes in an animal’s reproductive and health status are tightly associated with changes in steroid hormone production (i.e. testosterone, estrogen, progesterone, and cortisol).  For example, male ungulates that experience increases in testosterone levels grow larger horns and become more territorial. Also, animals that experience chronic stress tend to have higher cortisol levels and depressed immune systems.

Thus, we wonder to what extent steroid hormones regulate these life history trade-offs?  If they do, does this differ between sexes, given the differing hormone profiles of males and females.  We can explore these potential relationships by collecting data on levels of parasitism, hormone concentrations, immune status, and sexual signaling in wild primates, as we do at Los Amigos on the wild populations of callitrichid primates.