Mutualism and Inbreeding Depression – Some Surprising Findings

During our stay in Gamboa we were treated with a talk by Allen Herre on figs and their mutualistic wasp species.  In Panama, and elsewhere around the globe, fig tree pollination is wholly dependent on specialized wasp species.  Fig fruits are unique in that their flowering structures are encased inside a fruit-like syconium. The female wasps burrow into the flowering syconium and deposit their eggs into a number of the flowers, which in turn form gall-like structures that encase the developing wasp rather than forming a seed.  During the process of the female wasp entering and laying her eggs in the syconium pollination of the fig’s flowers occurs.

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This process can be active or passive on the part of the wasp.  In active pollination, the newly formed female wasp covers herself in the pollen while exiting the fruit in search for another syconium for her to complete her life cycle in.  When she finds her destination, she will actively take pollen from her body and pollinate many of the flowers before laying her eggs.  In passive pollination, it seems that pollination occurs merely through the consequence of the female burrowing in and laying her eggs; pollen on her body will brush against flowers without any intentional activity by the female.

Some fig species can be pollinated by multiple species of wasps whereas many others are pollinated by only one.  Among the wasps species of figs with a single foundress, Allen produced results that show that individuals of these species have very low heterozygosity.  This may not necessarily be a surprising result considering the high level of linkage disequilibrium fond in these species, but Allen went on to explain that those individuals with lower heterozygosity (and thus higher inbreeding) actually have higher fecundity.  This blew my mind! Traditionally, organisms with high occurrence of inbreeding have lower fecundity due to the accumulation of deleterious alleles, so his results went against everything I have learned about inbreeding and low heterozygosity.

Even more interesting, Allen found that wasps of figs with multiple foundresses have lower genetic linkage and thus higher heterozygosity than their counterparts.  These wasps follow the traditional mechanism of having higher fecundity with higher outbreeding.  As someone who is interested in perusing Conservation Genetics and studying the effects of inbreeding and outbreeding depression these results were very provocative and intriguing.  Why do these wasps have such high linkage disequilibrium?  How could an entire set of species benefit from high inbreeding?  Was it just pure change that these species accumulated a set of genes that are so beneficial they have to be maintained with very little change?  I feel like this is a concept that I could look into deeper for a short term project in Panama.  I’ve enjoyed a lot of talks here but this was one of the few that really spoke to my research interests.  Hopefully I can transform this inquisitiveness into something tangible.

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Sea to Land to Sea

          It’s estimated that the first land plants evolved 450 million years ago. 20 million years later, plants began to diversify and built most of the recognizable characteristics (roots, leaves, wood) we associate with modern plants. This evolutionary radiation on to land is arguably one of the most important niche expansions of all time, as it set the stage, for the diversification of many other life forms that would arise and fall in the coming millennium.
          In summary, plants have been kicking ass in terrestrial systems for millions of years, and it doesn’t look like their complete dominance will let up anything soon (Side-note: but humans are pretty good at making impossible things happen. Like chemically changing the climate. So who knows?).
          Since most plants are terrestrial, and owe much of their dominance to land and air. Plants that have undergone the transition from land to sea provide a fascinating example of retro-niche colonization. 
         Of course, if you’ve talked to me in the past week, you know that this is the point that I transition into talking about mangroves.
(above: Here you see a mangrove forest. If you look closely you can see coral, sponges, and mollusks growing on their submerged aerial roots.)
         Mangroves are awesome. They can be found land, sea, air making  them plant equivalent of all terrain vehicles.  Besides dealing with physiological hurdles they also are important members of the aquatic ecosystem as they provide a niche for all sorts of organisms.
         I want to know what the red mangrove has done to deal with increase salinity, decreased air, and radically different soil type (nutrient availability). With the suspension that it has made new microbial symbioses to deal with it’s new environment. Also how do mangrove forest effect ecosystem level processes in the ocean and shallow soil there found in?  How do they effect the algal community in surrounding water, and the surrounding soil type? I have too many questions and no answers so I should end it here.

What came first, the study system or the research question?

Disclaimer: In this post, I write about research approaches of other scientists based on my (fallible) memory.  My apologies if I accidentally misunderstood or have misrepresented any conversations/presentations, etc.   Take everything in this post with a grain or two of salt.

Last year, when my supervisor asked me what I would be doing during my first term at McGill (before I had ever even seen a coral reef in real life), I replied that I would be reading and planning my project.  What was his response?

“Just remember, we study ecosystems, not books.”

As far as I can tell, inspiration for research projects can arrive by two major paths.  The first, as espoused to me by my supervisor, is to spend time in an ecosystem or with a study animal that interests you, make observations, and try to see if there are patterns or phenomena that can be explored and explained.  We’ve seen over the duration of this course that this can lead to some beautiful, fascinating research projects- for example, why do capuchins have such big brains when maintaining brain tissue is so energetically costly?  Why are there so many near-identical plants in a tropical forest?  Why do vampire bats feed one another?

Alternatively, you can take the opposite tack: find a research question that interests you, and then decide which study system is logistically amenable to answering that question.  Dr. Ehab Abouheif, a scientist who studies phenotypic plasticity in ants, described to us a meeting with his supervisor which illustrates this method perfectly: he sat down, told his supervisor what he was interested in, and together they came up with a list of requirements.  His research organisms had to be small enough to raise in a lab, had to exhibit certain behaviours, etc. etc.  After producing what sounds like a rather long list of conditions, they brainstormed until they came up with their ideal study organism: ants.  This approach led to decades of innovative and exciting research, which we were lucky enough to hear about when Dr. Abouheif visited our little schoolhouse and blew our collective minds.

When thinking about this dichotomy, I asked myself how I came up with my research projects so far.  I remembered my first night ever doing real ecological research (in intertidal seagrass meadows at the 3 AM low tide), when the grad student I was assisting told me to pay attention to what I saw and think about research I could do myself.  I think my (silent) thoughts were something along the lines of

“I’m looking at a bunch of wet grass in the pitch fucking dark, what exactly is there to think about?”

Four years later, here I am.  I believe my thought process has become significantly more sophisticated since that night at Crescent Beach.

 

P.S. I sure hope we’re allowed to curse in these blog posts.  Sorry Owen.

 

Crabs with Javier Luque and Kecia Kerr

Jan 28th

While working on terrestrial models, reference and metaphors often get biased towards them. For instance if I said, “Javier, are crabs are the insects of the sea?”, he would reply with something along the lines of, “NO! Insects are the crabs of the land!” For as we know, due to past taxonomic and molecular work, insects are seen to be derived from crustaceous origins. While I enjoy insects as model organisms (and simply just organisms) I come to be interested in their relatives in Pancrustacea (and chelicerata). Crabs (Brachyura), while especially charismatic and successful, captured my attention during the talks and I suddenly realized that I love crabs for all the same reasons I like insects. I will not provide that list here but I will say that I have broadened my horizon on research interests. To further pique our interests (not Gerard Piqué) Kecia talked about fiddler crabs which have quite advanced social behavior in terms of crabs. With the great radiation and success of crabs, they are without a doubt full of interesting questions. For example, in Fortuna some of us were able to see a forest crab – what was it doing there!? I had never seen a crab in a forest and I had not expected to see one. This is a great example of a sea going invertebrate that has successfully inhabited places much farther inland. With the ability to obtain moisture from the wet Fortuna environment it starts to make sense how this crab made it up to the mountains. But what is life like for a forest crab compared to a ocean going crabs or frog crabs? Life histories of crabs can tell us a lot about their successful evolution and can bring to light new questions regarding molecular techniques. Of course, I think molecular work is very interesting and crabs could be a great candidate. For now, I will continue to work on insects but I will have other arthropods on my mind.

Project idea: Does different nesting locations affect ant aggression?

Over the past few weeks I’ve been bitten by ants in the genus Azteca several times. Once when we cut down the Cecropia, a couple of times when I was absently mindless chasing ants on a tree, and in Bocas after standing on ground nesting colony. While their sting is only mildly painful their power lies in their aggressive swarming behavior. Azteca is facultatively symbiotic with plants (like with Cecropia) where they defend it against herbivores in exchange for housing and food. However they can also create nests on/in other trees and (although I don’t see it recorded in the literature anywhere) in the ground. I expect that this high plasticity in nesting behavior would affect a number of other important individual and colony-level traits.

Agression

Many ants are aggressive when it comes to defending their nests although not al of them will be so aggressive to large vertebrate intruders. When living in Cecropia the ants will not only defend the stem, where they colony is located, but also the leaves from herbivores. While there are clear benefits to the colony I would guess that this comes at a high cost of worker mortality. If nesting in other places will worker aggression be lower?. The high levels of aggression needed to properly defend the host plant may be needlessly reckless if nesting in another location.  Using a transcriptomics approach we could find differentially expressed genes among the locations. While there are genes that are linked to aggression, they may not be the only ones involved with such a response. The colony can also exhibit this aggressive response if individuals are more finely tuned to alarm pheromones, vibrations, CO2 or any number of stimuli.

Colony structure

I expect that colony structure will be highly affected by the location of the nest for because of the differences in availability of food. Cecropia nesting colony have continual access to protein rich food provided by the plant while this may be more varied for colonies nesting in other places. By measuring colony size, size distribution of workers in the field we could see these effects. Then a common garden experiment we could see if any of these traits are heritable.

They went for a hike in Boquete, what they discovered the following day will blow your mind.

It was a windy and cold morning. The sky was covered in light grey clouds and a gentle rain was falling down our coats. The plan of the day was to visit a coffee plantation, and then hike up in the mountains to be able to see the differences in forest composition at different altitudes. I was part of a group of seven explorers (Carlos, Anne-Sophie, Perry, José, Brandon, Kari, and me) that wanted to reach the top of the mountain, and Ceci, who is an IGERT student but who is also working in a plot in those mountains, drove us to a place where we could start our hike.

I would say that the beginning was easy: we walked a trail in the lower forest, and were amazed to see how the bamboo, introduced in Panama, was doing so well. The more we hiked, the more we could see the transformation of the forest composition: less bamboos, more epiphytes, mosses, and lichens.

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Mosses and lichen everywhere! (Photo by Léa Blondel)

The slope was getting very steep, but the feeling of accomplishment and of being above the clouds kept our motivation to go on climbing. We finally reached the altitude of 2800 meters, proud of ourselves, and after a few pictures and some sandwiches, we decided to go back down.

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When we still didn’t know what would happened (Selfie by Léa Blondel)

The story could end here: we found our friends, got back to the bus and drank delicious coffee while looking at the marvelous rainbows that characterize the sky of Boquete. Nonetheless, there is more to add to this adventure. We thought that we made the way back just the seven of us, but in reality, we were probably more than one hundred to go back to the bus. Let me present you the real protagonists of this anecdote, ladies and gentlemen: THE CHIGGERS.

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Meet the devil (MedicineNet.com)

The chiggers are a species of mites belonging to the Trombiculidae family. There is more than 30 genera of chiggers and they are basically everywhere in the world. Their life cycle comprises four stages and in order to complete its development, the parasitic larva attaches itself to a host until it is fully engorged with the tissue fluid. Unfortunately for us, we are part of the vertebrate hosts that the chiggers like to bite. The day after our hike, I woke up with almost twenty bites on my shoulders and around my neck, and discovered later in the day way more on my back, ribs, and bellybutton. Anne-Sophie seemed to have won the contest though, for she had a perfect line of bites running all around her chest. Everyone was red, everyone was itchy.

Why so many bites? The larvae hide mostly in the ground and attach to the boots of hikers. When you hike in chiggers’ high density places, you collect a lot of them, and these little creatures then seek comfy and dark places of your body to start feeding. There are several solutions to avoid the bites. Number one is to wash your clothes directly after the hike and use the dryer at high temperature. Number two is to take a hot shower, and scrub your skin as hard as you can with soap. Number three is to have great friends that will delouse you (like monkeys do), by removing the tiny red larva that you can spot in the middle of the bites.

In the new world, chiggers don’t transmit any diseases, but in Asia chiggers carry a bacterium responsible for a form of Typhus called the Scrub Typhus and a lot of the research is thus focused on this particular region of the world.

Reference

Sasa M (1961) BIOLOGY OF CHIGGERS. Annuv. Rev. Entomol., 6, 221–244.

The inherent “coolness” of insects

Two weeks ago, during on of our few free moments, I was checking my twitter account and stumbled on a great article by Paul Manning, a PhD student at Oxford University (and great science communicator and illustrator). Titled « Why we should learn to love all insects – not just the ones that work for us », this article touched on something pervasive when entomologists talk about their research: the fact that people seem to only care about insects in the light of ecosystem services.

Now, even though my research interest lies primarily in this particular subject, I am also an entomologist in the greater sense of the term and think insects are inherently fascinating. But for most people, this is hard to conceive. Insects, maybe because of their small size and their slightly creepy ways to get around, do not have the benefit of being seen as charismatic animals like mammals and birds. It is therefore harder to get people interested in the incredible adaptations (physiological, morphological, behavioural or ecological) that have arose in the insect world.

In the past few weeks, we have had the chance to meet researchers undeniably passionate about their work, many of whom worked on insects. Here’s only a few examples how fascinating those small creatures can be.

Let’s begin how they influence their ecosystem. Because of their small size, it is hard to imagine that insect herbivores can drive the evolution of chemical defense in organisms way bigger than they are, such as in the plant genus Inga. Those trees had to have the possibility to turn genes on and off to produce different compounds if they wanted to be able to keep up with the insects in an evolutionary arm’s race.

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An Atta colombica queen covered by her workers (Photo by Anne-Sophie Caron)

But insects are also interesting at the scale of their genome and its expression. Ehab Abouheif, from McGill University, gave an amazing talk on phenotypic plasticity in ants. He showed us how vestigial structures have controlling effects on size in ant colonies, enlightening the mechanisms behind the huge amount of phenotypic variation within an individual species.

Finally, Don Windsor, staff scientist at STRI (and my co-supervisor!) shared with us his knowledge of leaf beetles. Because of familiarity with the beetles’ natural history, he is able to discover unusual patterns that would go unnoticed by the untrained eye. That way, he saw a species of the genus Doryphora who’s offspring practice cannibalism during their first meal, some species where there are high levels of maternal care (Platyphora microspina only lays 4 live offsprings!) and high polymorphism within species, with some species having 6 different morphs. This also echoes some of the research done in Heliconius butterflies, where wings patterns vary within species across geographically scales.

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A leaf beetle (Chrysomelidae) in its rightful place (Photo by Anne-Sophie Caron)

I have, hopefully, succeeded in convincing you of the coolness of insects (and also suggest you to check out Paul’s blog for more examples!)

Taxonomy and Systematics: why do they matter?

    During the last weeks we had the incredible opportunity to explore different approaches in biology research. We learned about birds, monkeys, bats, butterflies, plants, fungi… and one fact that caught my attention was that all the researches were driven by evolutionary, ecological and/or conservation general questions. I even wrote a post about how we should not be afraid to think “big” and this is definitely a thinking I want to carry during my entire academic career.

    But what is “to think big”? Do we need to have a general question driven our research to be worth it? What about taxonomy, life history and systematics’ studies? All these questions arose after some talks and were the cause of interesting discussions in our group of students.

    While we were in Bocas del Toro, we explored different aspects of marine biology. During a talk about the “Comparative Development and Life History Diversity in Sipuncula” we were awarded with wonderful pictures, videos and we learned about some hypotheses of the evolutionary history of Sipuncula. Another interesting talk about the evolution of crab eyes gave us a broad perception about this highly diverse group. But, why is this important? Why should we care about characters, morphology, phylogenies and taxonomy of a specific group? What is the point?

    As a former taxonomy and systematics’ student and as a passionate and curious biologist I can’t understand why these two important areas are so neglected. Since the beginning of 1900, biologists gradually have gotten away from taxonomy and systematics and these approaches are often associated with pejorative implications. However, this “phenomenon” has a dangerous outcome. How can we infer general statements if we don’t know with what we are dealing with? How can one propose conservation measures if we can’t identify the organisms of an area? How can one understand the ecological relationships of organisms if they can’t be identified? How can we trace the evolutionary history of important traits if we don’t have a hypothesis of phylogenetic relationships? How can one propose evolutionary patterns without studying different specific cases?

    Taxonomy and systematics studies, as I see, are fundamental in Biology and they should be treated with the respect they deserve. We need to realize that there is no hierarchy inside Biology and different areas need to integrate so we can have a broader and more complete view of life.

There is more than one way to think “big”.

More information:

Bortolus, A. Error cascades in the Biological Sciences: The unwanted consequences of Using Bad Taxonomy in Ecology. Ambio 37, 114-118, 2008.

Disney, H. Hands-on taxonomy. Nature 405: 619, 2000.

Feldman, R.M. and Manning, R.B. Crisis in systematic biology in the ‘‘Age of Biodiversity.’’ J. Paleontol. 66, 157–158.

Godfray, H.C.J. Challenges for taxonomy. Nature 417, 17–19, 2002.

Food sovereignty in Changuinola: A certain hope from a cacao farm

Food is something I think about a lot on a regular basis. Of course, I love eating and cooking, but I am also interested in where my food comes from, how it was grown and what are the politics/social issues surrounding its production.

(However, I do not pretend to be an expert on the subject and what is written in this blog post represents only a small fraction of this complicated issue)

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The cacao fruit (Photo by Anne-Sophie Caron)

A few days ago, we had the opportunity to visit a cacao farm in Changuinola. This farm contrasted strongly with the coffee farm we visited the previous day which was mostly a monoculture, continued to use pesticides and marketed its production strongly to the international market. The cacao farm, on the other, was an agroforestry system, with the land being divided in three parts:

  1. Crops (mostly aim as a way to increase food security in the community and protecting the farmers against the rapid changes in the market)
  2. Agroforesty (where cacao, plantain and timber species are grown simultaneously)
  3. Parcel of protected forest (which helps regulate the microclimate of the farm

Agroforesty systems have shown to be an important tool of rural development since they provide a range of ecosystem services (soil protection, biodiversity conservation, carbon sequestration, …) as well as providing an additional mean of livelihood for the producers since they can also harvest the wood. This type of system also promotes a certain resilience of the land to both climatic events and crop diseases.

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An example of the tree diversity within the cacao plantation (Photo by Anne-Sophie Caron)

However, the system is not perfect, especially since there is no difference in price on the market between products grown without pesticides and in a way that provides ecosystem services and products grown “traditionally”. But the farmers are aware of this and are trying to change this unfortunate situation and make this choice more appealing than the alternative for fellow farmers.

Additionally, the farmer refused to be part of the cooperative in place in the region, which he did not think respected the producers enough and instead started a group with other cacao farmers of the region. Farms like this one are an important example of the possibilities of self-governance, even in a region like Changuinola where the agricultural landscape seems to be dominated bigger farms (like banana farms) owned by American companies. These farms have been found to have huge impacts on both social and environmental aspects of the region, so it is important to provide an alternative.

However, it seems that times are slowly changing. In fact, multiple countries from Central America and the FAO have discussing public policies that aim to promote family farming as a tool of social development for rural areas and to ensure food security and sovereignty to the farmers and their communities. Such policies are also framed to protect natural resources and manage risk and adaptations to climate change. It is unknown if the social policies will be put in place soon, but this still shows a slight shift in mentalities which cannot be ignored.

 

References

http://www.fao.org/panama/noticias/detail-events/en/c/372983/

Rodriguez, T. (2012). Dynamiques de coopération transfrontalière sur la façade caraïbe du Costa Rica et du Panama : le cas du bassin du fleuve Sixaola. Études caribéennes [Online] URL : http://etudescaribeennes.revues.org/5747

Kapp, G., & Manning, D. B. (2014). Land Management Systems at the Interface Between Forestry and Agriculture. In Forests and Rural Development (pp. 85-110). Springer Berlin Heidelberg.

Rossi, D. (2013). Los Agroquímicos usados en Las Plantaciones Bananeras y sus Efectos en el Agua, la Gente, y el Ambiente en la Comunidad de Changuinola, Bocas del Toro, Panamá.

Mist Netting on Pipeline and in Gamboa

One of my favorite aspects about field biology is observing animals up close, so I was really looking forward to mist netting.  During the first week of the course we were able to visit mist nets set up on Pipeline Road and see the distribution of mid-story birds present in the surrounding forest.  We caught ant birds, manikins, and even a humming bird!  It was amazing being able to see these beautiful animals so close.  We were even able to hold a release some of the birds we caught, which really excited me; actually being able to handle some wild animals was phenomenal.  It was also a great relief that none of the birds were injured while we were netting, which is apparently common given that birds are so delicate and prone to stress.

Along with mist netting, we also walked up and down the road to do some birding.  We observed many of the same species we caught and even some we didn’t like toucans!  While we were closing up the nets we had the privilege to see several army ant swarms.  We watched as the swarm front covered the forest floor, causing other insects and invertebrates to run for cover.

The following week we had a “bat night” where we did some evening mist netting along with observing echolocation and learning about food sharing behaviors in vampire bats.  The mist netting, like that we did for the birds, was my favorite part.  Although we were not able to touch the bats, we got to see some amazing species very close up.  While learning about echolocation we utilized some instruments that allowed us to hear and visualize the various calls the bats made while hunting for insects.  Lastly, I really enjoyed learning about peculiar behaviors in vampire bats.  Vampire bats depend entirely on blood meals for all their nutrition, so they are very vulnerable to starvation.  If a vampire bat goes more than two nights without a meal they can easily starve.  However, vampire bats have developed a behavior in which mostly females will regurgitate and share part of their blood meal with a conspecific.  Some bats will beg for a blood meal by licking the other bat’s mouth, but often bats will offer blood meals to emaciated bats.  Bats that share blood meals are not necessarily related either, which I found fascinating.  The basis behind this behavior is still being studied, but it is a creative way for the bats to sustain their colony.