Archive for the ‘La Selva REU’ Category

ADLs

August 24, 2009

In the hospital where I work at home, patients are often evaluated on how well they are able to complete Activities of Daily Living or ADLs.  ADLs include the ability to do household chores, personal hygiene, and mobility.  I wanted to include a post on one of my typical days at Las Selva Biological Research Station, and believe that this is an appropriate title.  This post will give you a glimpse into the majority of the days of my two months of research.

All meals are served cafeteria-style in ‘el comedor’, the cafeteria.  Breakfast is served from 6-7:30, with clean-up promptly at 7:30.  Most mornings, I try to be at breakfast by 7.  Though when in the States, I typically shower in the morning, being in the tropics means sweating pretty much all the time and going into the  field just after taking a shower is counter-productive.  So, typically I just get up, change into field clothes and go to breakfast.

After breakfast, it’s time to organize the materials I need for that day, and we (Grace and I go to the field together) are usually leaving for the field (meaning forest) by 8.  Depending on how far we have to walk/bike/hike, we are usually setting up transects with frogs by 8:30 or 9.  Each of my transects have 20 frogs, and we set up 6 in one day.  Each transect takes about 1/2 hour to set up, unless the terrain is especially hilly or there is a lot of undergrowth.  

At La Selva, we divided the forest into two different types: primary and secondary.  Primary forest is also called old-growth, and is considered to have ‘never’ been cut down.  Secondary forest, on the other hand, may have been affected as recently as 5-10 years ago.  After navigating through the forest, one becomes quite good at identifying the forest type.  Primary forest has many large, old trees, with little undergrowth (smaller trees and plants that aren’t much taller than a person).  Secondary forest has less large trees and therefore much more sunlight for the undergrowth to be quite unruly.  Secondary forest is difficult to lay a transect in, and is sometimes frustrating.  We want to have approximately half of the transects in secondary forest and half in primary to account for any differences that may occur in predation, so walking through the secondary forest was necessary, though at times undesirable.

 

This is the beginning of one of my transects in secondary forest.

This is the beginning of one of my transects in secondary forest.

 

 

Depending on how far we have gone, we may make it back to home base for lunch, or may have had to get a bag lunch.  Lunch is served at the comedor from 11:30-1, but the Station realizes that many researchers need to spend the whole day in the field and it is impossible for them to return for lunch.  If we are going to be in the field all day, we can request field lunches, and take them with us.  Field lunches include two sandwiches, fruit, crackers or cookies, and a drink.  The nice thing about taking a field lunch is that you can pick a picturesque place in which to eat your lunch: one day Grace and I ate lunch while sitting on rocks in the middle of a small river, looking at the water tumble around rocks while we ate our PB&J.

 

Ate lunch overlooking this, no reservations needed.

Ate lunch overlooking this, no reservations needed.

 

 

After being the field and eating lunch, we would typically return to the forest to work on Grace’s research.  Grace is studying digit-ratios in amphibians and reptiles, two types of frogs (including the species that I am researching) and two types of anoles (small lizards).  Brief explanation: if you hold up your hand, with your fingers together instead of spread, you will probably notice that your 2nd finger is either a little longer or a little shorter than your 4th finger.  The ratio of lengths is a sexual dimorphic trait in humans, meaning that ratio is different in males than in females.  In this case, typically males have a longer 4th finger and females typically have a longer 2nd finger (don’t be dismayed if the opposite is true for you, it’s just been shown to be a trend).  This has something to do with the levels of hormones we are exposed to while in the womb.  Grace’s study is to determine if the amphibians and reptiles have a similar sexual dimorphism.

 

These are some of the frogs that we caught for Grace's research.

These are some of the frogs that we caught for Grace's research.

 

 

In order to complete her study, Grace has to collect 70 individuals of each of the four species.  This means that almost every afternoon, we go out to the forest to catch frogs and lizards.  The Oophaga pumilio are by far the easiest to catch, because they hop short distances and relatively slowly.  Because they warn predators of their toxicity with their bright coloration they don’t frequently have to escape predators and can take their time leisurely hopping through the forest.  The other frogs we catch are brown frogs that do not contain toxins.  Because they have no other defense, they have evolved into little hopping machines.  They can hop two or three feet in a single jump!  They blend in to the leaf litter, too, so they are much more difficult to catch.  The lizards are very speedy, but often depend upon remaining completely still to blend into the background and avoid being seen and eaten by predators.  Non-moving lizards, though hard to spot, are generally easy to catch because their eyes are on the sides of their heads.  If you approach them from behind, they never see you coming!  

After spending a few hours catching frogs and anoles, we head back to the station where it’s time to take much needed shower.  I then head to the lab to work on making frogs.  Dinner is at 6 in the comedor, and it’s nice to catch up with what everyone else did for the day.  After dinner there may be some socializing, but I generally go back to the lab to make frogs (hopefully with some helpers!).  Frog-making is a HUGE part of my research, and I’m often up until 12 or 1 making frogs.  It takes several hours to make even only enough frogs for one day in the field!  After making enough frogs for the next day, and setting up the materials I will need to take into the field, it’s time for bed.  And the next day, it’s pretty much all the same thing, though I may have to pick up frogs on some days instead o set them out.  Also, every third day, I have no transects to work.  On those days, I try to make as many frogs as possible, go out to catch small things with Grace, and help Grace photograph the feet of her catches (after loading the photos on the computer, she uses a special program to measure the length of the toes).

 

This is an example photo of how the toes were measured for Grace's research.

This is an example photo of how the toes were measured for Grace's research.

 

 

That’s pretty much it.  ADLs of research at La Selva Biological Station!

The Frogs

July 15, 2009

I imagine that many people reading this blog may wonder exactly what I am doing for 6 months in Costa Rica.  Though I will be here for 6 months, it is actually through two separate, though related, programs that I am able to be here.  Starting in June, and continuing until mid-August, I am participating in an REU program with OTS, which is funded by NSF.  Now to decipher the acronyms!  REU is Research Experience for Undergraduates that is funded by NSF, the National Science Foundation.  NSF provides funds for selected undergraduates to complete 8 to 10 week research projects throughout the US and throughout the world.  Undergraduate science students can apply to compete for a limited number of paid positions for summer research.  The specific program that I am involved with is through OTS, the Organization for Tropical Studies, which is located at 3 sites throughout Costa Rica.  In Costa Rica, OTS is referred to as OET, La Organización para Estudios Tropicales.

After being accepted to the program, I chose/was assigned to a mentor.  Each student has a mentor that leads him or her through the process of attaining permits, developing a scientific proposal, completing field research, troubleshooting (all science guarantees a certain amount of needed creativity!), running statistics, and completing a publish-worthy research paper.  My mentor is Dr. Ralph Saporito, a post-doc at Old Dominion University in Virginia.  Ralph studies aposematism in the dart-poison frogs of the Neotropics.  An example of a dart-poison frog is the Strawberry Dart-Poison frog, also called “blue-jeans” because of the distinctive coloration.

Strawberry Dart-Poison Frog

Strawberry Dart-Poison Frog

The scientific name of the frog I am studying is Oophaga pumilio, or O. pumilio.  Aposematism is a form of deterring predators.  The frogs sequester toxic alkaloids from the mites and small insects in their diets.  The bright coloration (think of a bright red frog against the browns of leaf litter in the forest) is believed to warn potential predators to avoid the distasteful frog.

Though only one color morph of the species occurs at La Selva, in other locations throughout Central America, there are many morphs of the same species, some orange, green, blue, and other colors.  The question that I am attempting to answer is: Why does only one color morph exist at La Selva?  Maybe predators at La Selva don’t know to avoid the occasional mutant colored morph (such as orange or blue) and eat it before the frog has a chance Four morphs of La Selva frogsto reproduce and pass along its coloration to future generations?  In order to answer the question, I am making small clay frogs of non natural colors to place in the forest.  I am making red/blue frogs similar to the morph that exists at La Selva, brown frogs that represent the non-toxic frogs at La Selva, yellow frogs that represent an actual color that does not occur at La Selva, and hot pink (yes, hot pink) frogs that represent a completely fictional color.

After inspecting the clay frogs for signs of predation, we will be able to determine why more color morphs are not present at La Selva.  This experiment requires the mass production of clay frogs: 1,200 models are needed to complete 60 transects.  Every three days, I need 120 frogs to set out in the forest.  Fortunately, I have had plenty of help, and though I have spent many late nights and early mornings finishing frogs for the next day, many people have generously donated their time to help me make frogs.Frog bodiesEvery frog is handmade from start to finish, starting with a mold.  The basic body shape is created, and completely smoothed so that no marks remain on the body.

Frog bodies with eyesAfter the bodies are completely smooth, each frog gets two eyes using a Sharpie marker.  Then back and front legs are created and pressed onto the body, forming a complete frog!  I’m still unsure of how long it takes to make a frog from start to finish-we generally start a sort of assembly line, with one person completing each step.

The frog army is almost ready to go.

The frog army is almost ready to go.

With the addition of the brown models, the army is ready for the field!

With the addition of the brown models, the army is ready for the field!

The frogs fit nicely on the lids that I found in the supply boxes.

Each frog is approx. 20mm in length

Each frog is approx. 20mm in length

After theHeading out with the tackle box full of frogs army of frogs is assembled, they are place in compartmentalized tackle boxes (no longer just for fishermen!) to keep them from being marked by each other or by rough handling.  I head out to the forest with my lab partner, Grace, where we set up the transects.


Each frog is placed in a specific location along a string transect in the forest.

Each frog is placed in a specific location along a string transect in the forest.

Though clay frogs seem like a very serious matter, we occasionally have time for fun!

Though clay frogs seem like a very serious matter, we occasionally have time for fun!

Rain or shine (remember, this is the rainforest, so more frequently, rain)

Rain or shine (remember, this is the rainforest, so more frequently, rain)

Grace and I go out in all types of weather, and often come back from the field soaked.  Most times, there’s no point to even trying to wear a poncho.  Once you’re wet, you notice it less and less and it continues to rain.  However, once the insides of the rubber boots get wet, it’s really uncomfortable, and time to head home, if possible.

Heading out, until next time!

Heading out, until next time!


Week 1

June 19, 2009

I’ve delayed posting not because there is nothing to write, but because there is so much to write.  The biodiversity of the tropics never ceases to amaze, and since our arrival on Monday, we have been exposed to a wide variety of animals and plants.  We have been on a number of hikes with various guides: a nature guide, botanist, herpetologist, and ornithologist.  Each of these people have offered an insight to their specific tropical knowledge, along with being aware of the details of other disciplines besides their own.  Most of the trails we have explored thus far have looked something like this:

La Selva trailThe trails are mapped and the whole forest contains posts spread 50m and 100m apart.  With a map of the Station, and a bit of knowledge of the post system, it is easy to find your way through the forest (even if you get lost!).

While on the trail, we saw a toucan high in the canopy.  There were three flying throughout the leaves and communicating with each other:

Toucan at La Selva

While many of the sites in the forest are beautiful, there are certainly some things of which to be aware.  The Bara ant is not something you want crawling on you.  

Bara ant

They are found throughout the foliage (you need be aware of them unintentionally dropping on you while walking through the forest), and they can deliver a nasty bite.  In contrast, it is nice to not have to constantly worry about absent-mindedly brushing against an Acacia tree, as we did in Guanacaste last year.


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