Biodiversity Challenge: Biodiversity hidden in plain view

This post was originally published on BioDiverse Perspectives – a research blog aimed at fostering communication about biodiversity.

I’m trapped in a barren wasteland. It smells of PineSol and fast food. There are people milling about all around me. They are coming and going in and out of little hallways, and there are so many iphones! Everyone is looking at their iphone! I am at the Dallas Fort Worth International Airport. There’s nothing here. Everything’s so sterile (which I guess is an improvement over the way it used to be). There can’t possibly be biodiversity here.

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But wait! What’s that, over there by the power outlet? That filth! Those crumbs! There! That’s biodiversity! And there’s more! There’s biodiversity all over that bag of chips, and on the drinking fountain handles. There’s biodiversity on all of those iphones!. And there’s biodiversity on all of the people. All of them are teeming with germs! PineSol, you don’t stand a chance. There’s so much diversity, and it should stay that way!

Traditionally, when people think about biodiversity, they focus on the things that they can see: Tropical rainforests, African savannahs, wildflower meadows, even diversified agriculture systems. For me, it started with mangrove forests and grasslands, but recently, I’ve become more and more interested in the biodiversity that’s all around us that you can’t see. And I’m not the only one thinking about biodiversity hidden in plain view. Researchers are studying biodiversity in our houses, on our bodies, in hospital air, even inside the leaves of plants!

And those researchers are finding incredible things! The microscopic creatures inhabiting houses with dogs differ from houses without dogs, and might even contribute to healthier people in those houses. The microbes on our bodies vary by who we are, where we look, and even how much roller-derby we play.

Ok, Fletcher, so there’s biodiversity all around us, and some of it is pretty cool. But why on earth would you recommend that we conserve biodiversity in an airport? You’re talking about germs! People get sick in airports!

Well, although there’s a lot that we don’t know about the hidden biodiversity around us, we do know a few things. There are microscopic bacteria and fungi everywhere. And they’re important. We know that some of them cause diseases, but it looks like some of them might protect us from diseases, too.  We know that they can interact with each other, that they can form communities, and that those communities can be really different from each other. And I’m not talking apples and oranges different. I’m talking sea cucumber and redwood tree different, all in one square inch! And for the most part, we don’t know how they came to be different, but when we eliminate these communities from the face of the earth with PineSol or antibiotics, the communities that replace them are unlike those that were there before.

So we should conserve biodiversity at the airport because we don’t understand it. We should conserve biodiversity at the airport because it might just protect us from some of the diseases that we’re trying to prevent**. We should conserve biodiversity in the airport for the same reasons that we should conserve biodiversity in the Amazon and in the oceans and in our backyards. We should conserve it because it’s there.

30 October, 2013

*I should confess. I don’t study the microbial ecology of airports. I know virtually nothing about them other than what I’ve inferred from the references above.

**Alright, that might be a bit of a stretch. I am an advocate of sanitation at airports

On biodiversity and disease risk

This post was originally published on BioDiverse Perspectives – a research blog aimed at fostering communication about biodiversity.

Few studies have had as large of an impact on me as Charles Mitchell’s study of the impacts of plant species diversity on fungal diseases at the Cedar Creek grassland in Minnesota, USA.

Ok; quick caveat, Charles Mitchell is my advisor. But I’m not saying this to put my advisor on a pedestal.  This study is in large part the reason that I study what I do, and that I am a graduate student where I am.  By evaluating disease impact in an experiment that directly manipulated host species diversity, Mitchell was able to provide empirical evidence that decreased host diversity should increase the abundance of many diseases. Not only did it key in on the link between biodiversity loss and health risk, but the study showed me that such a complicated question could be approached in a way that was experimentally tractable.

But I don’t want to focus on Mitchell’s research here.  See, although his study provided evidence to support the diversity-disease hypothesis, I am highlighting it here because it led to the search for general mechanisms behind that phenomenon.  Instead I want to focus on a paper that I consider a true frontier in biodiversity science. This is a paper that took an often disjointed and complicated field, grounded it in a very simple theoretical model, and then generated some clear, testable hypotheses to move the field forward.

In their 2006 paper, Effects of species diversity on disease risk, Keesing, Holt, and Ostfeld provided a synthesis that would address the key question that underlies the diversity-disease hypothesis: What is the mechanism by which biodiversity influences disease risk?  By generating 5 discrete mechanisms from a litany of previous research, they provided what would hopefully become a roadmap for future research aiming to understand and possibly mitigate for the relationship between biodiversity loss and increased disease risk.

I’m not going to get into the nitty-gritty details of this paper. Rather, I want to highlight one really cool aspect of it that I think was truly innovative and inspirational: that they take something almost immeasurably complicated (the ecology of plant and animal hosts, and the epidemiology of specialist, generalist, and vector born pathogens) and reduce it to the simplest system possible (a simple epidemiological susceptible-infected model) to identify the specific mechanisms by which diversity can influence disease risk. From this simplified model, they are then able to scale up in complexity to explain patterns observed in far more complicated systems.

So obviously, this paper is important to disease ecologists and conservationists aiming to prevent the spread and emergence of infectious diseases (not a trivial thing in and of itself). But I think this paper has value to all biodiversity researchers.  It’s so easy to get bogged down in our own subfields and forget that we can often look to other disciplines or simple theory to synthesize our own research. Keesing, Holt, and Ostfeld used a simple epidemiological model to decompose nearly 100 years of research into 5 testable hypotheses. Biodiversity, with it’s multiple dimensions, drivers, results, and feedbacks, can often seem immeasurably complicated. Is there a simple, ecological theory that can unify this field as well?

Update: The PEGE Journal Club just posted a review of a recent empirical study of biodiversity and disease risk in a trematode parasite of amphibians that was published in Nature. Pieter Johnson’s lab at CU Boulder is doing a lot of really cool research in disease ecology, and this recent paper is a great example! Here, they argue that there’s an emergent property of host diversity that can decrease disease risk that acts independent of host density.