Parasite biodiversity – a missing dimension?

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

Here are a few statistics:

  • Forty-percent of all species are parasites, and more than 75% of links in natural food webs are likely to involve them.
  • As many as 10,000 parasitic helminth species are threatened with extinction.
  • Decreases in avian diversity due to habitat loss and climate change will contribute to even greater parasite species loss in the future.

Parasites are everywhere and outnumber what we can see by a huge margin. So what does this mean when we start losing all these parasite species?

In their 2008 paper in PNAS, Dobson et al. had three objectives: 1) show exactly how abundant parasites are compared to other organisms, 2) estimate how many parasites are threatened with extinction, and 3) evaluate the potential impacts of parasite extinction.

They started by looking at previous estimates of parasite diversity, concluding that there could be over 300,000 parasitic helminth species that use vertebrates as hosts. They then took an alternate approach – evaluating all organisms in single habitat – and asked, how many parasites are there here? Their conclusion: at least 40% of all species in marshes along the California Coast are parasites. Not only that, but the structure of food webs changes dramatically depending on whether or not you include parasites in it.

Next, they looked at expected host extinction rates, and asked at what rate are parasites going to go extinct? Then they used theory on host-parasite interactions to ask, what can we expect as consequences of parasite extinctions?

This paper is a really cool example of what a talented group of researchers* can do when they really dig in to three simple questions about biodiversity and biodiversity loss, but here’s the reason that this paper should be considered a frontier in biodiversity research:

The authors fundamentally and meaningfully argued for a change in the way scientists describe biodiversity by showing that including parasites dramatically changes our understanding of global patterns of diversity, food-web structure, and the consequences of environmental change.  And in doing so, they challenged my notions about generality in ecological research.

What does it mean that 90% of biodiversity research addresses about half of biodiversity? Maybe nothing – Hechinger et al. (2011) argue that parasites obey similar ecological rules as free-living organisms when it comes to abundance, energetics, and production. And if parasites obey the same ecological rules as their free-living counterparts, then maybe it’s not that big of a deal that most ecological research ignores them. However, a recent meta-analysis by Kamiya et al. from the University of Otago in New Zealand suggests that parasite biodiversity may be structured by entirely different processes than those controlling the diversity of free-living organisms. If this is the case, then maybe we do have a problem.

I am aware of ongoing debates on the value of model systems vs. purely empirical, system-specific work in gleaning ecologically relevant information. Generally, I’m of the opinion that there is value in all of these approaches. Yes, while many specific ecological systems can be context dependent, theoretical models and microcosm experiments can tell us a lot about generality despite context dependence. But what if it’s not the context-dependence that we’re getting wrong. What if general biodiversity research is only targeting half of biodiversity? How general are even the most general of theories then?

Ok, so parasites are a diverse group, and much of biodiversity research has historically failed to address them. Are there other systems that biodiversity research has failed to do justice to?

*And a courteous airline staff? A note from the acknowledgements of this paper: ”The first draft of the article was written in Kilimanjaro, Nairobi, and Heathrow Airports; A.D. thanks British Airways and Precision Air for the patience, care, and attention of their ground staff.”

Is blogging effective at communicating biodiversity research?

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

My original intent in writing this post was to compare the 5 most-cited papers on biodiversity to the 5 most blogged-about papers on biodiversity to address the differences between what we value as researchers versus what we value as general science communicators. However, I was shocked by the results of my search.  Over 49,000 papers have been published containing the word “biodiversity”.  In contrast, only 448 blog entries on researchblogging.org contain the word “biodiversity”, citing just 427 papers. What does this mean about the state of biodiversity research versus the state of biodiversity-research communication? Do bloggers and their readers value fundamentally different research than that being conducted and cited? Or are researchers simply falling short of effectively communicating the most important research in biodiversity science? Here at biodiverse perspectives, we aim to bridge the gap between research blogging and scientific research, by focusing on the research that we consider to be truly transformative in the field of biodiversity regardless of publication date.

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In this blog, we present the papers that we think are the foundational and frontier papers in biodiversity science. But we are just a subset of a vast scientific community. I recently began to wonder, if I were able to poll all biodiversity researchers, what would they say are the five most important papers for biodiversity science?

Well, I don’t have the eyes and ears of all biodiversity researchers, but I do have some tools for garnering their opinions. If journals are the primary method for sharing scientific material, then to some extent, the number of citations should tell us something about how we value research.

So, I sent a letter to every published biodiversity researcher:

 Dear ISI Web of Science,

What are the five most-cited papers that contain the word “biodiversity”?

Sincerely,

Fletcher Halliday

And, believe it or not, I got a reply! Here’s a list of the top five cited articles from Web of Science:

Myers et al. (2000) Biodiversity hotspots for conservation priorities. Nature. 4,790 citations

Vitousek et al. (1997) Human domination of Earth’s ecosystems. Science. 2,410 citations

Sala et al. (2000) Biodiversity – Global biodiversity scenarios for the year 2100. Science. 1,764 citation

Thomas et a.l (2004) Extinction risk from climate change. Nature. 1,690 citations

Hewitt, GM (1996) Some genetic consequences of ice ages, and their role in divergence and speciation. Biological Journal of the Linnean Society. 1,667 citations

But this website wasn’t designed just to be a compendium of articles that may or may-not be well cited in the literature. As the name suggests, the purpose of this website is to present the perspectives of a diverse community of graduate students. In many ways, this blog is unique. We have over 15 contributing authors, representing 5 countries, and we focus primarily on sharing our opinions on primary literature in biodiversity science. However, in many ways we aren’t so unique. In fact, there are over 2,500 blogs on the web registered as “research blogs” with the website researchblogging.org. And it seems to me that my letter to every published biodiversity researcher may have missed a large segment of the scientific community.

So I sent out another letter:

Dear Researchblogging.org,

What are the 5 most blogged-about papers containing the word “biodiversity”?

Sincerely,

Fletcher Halliday

And researchblogging.org replied too- and what a surprising reply it was! Of 448 blog posts, only 19 papers were written about more than once and only 2 papers were written about more than twice:

Evans, et al. (2011) The spatial distribution of threats to species in Australia. BioScience. 3 blog posts

Strassburg et al. (2010) Global congruence of carbon storage and biodiversity in terrestrial ecosystems. Conservation Letters. 3 blog posts

17 papers tied for the remaining three slots in the top 5, each with 2 posts apiece. They ranged in subject from the use of DNA barcoding to infer patterns of avian diversification all the way to role of the Chicxulub Asteroid in mass extinctions.

I wasn’t surprised that the top-five papers were different between ISI and researchblogging.org, but I was surprised to find that the top-five most-cited articles on ISI have never been written about on researchblogging.org. What does it mean that the 5 most important papers to biodiversity researchers don’t even register with biodiversity bloggers?

I’ll pose 3 possible explanations and then leave it up to you to decide what we need to do.

First, perhaps researchblogging.org isn’t a representative sample of science blogs on the web.  But then, if researchblogging.org is not, then what is? If blogs about research aren’t easy to find, then are they really doing their job?

Second, by focusing on very recently published articles, researchbloggers are missing some of the more foundational research in the field. Researchblogging.org launched in 2008 and consequently, the vast majority of papers that have been blogged about were published after that time. Maybe the purpose of researchblogging isn’t to share the most important research, but rather the new and exciting research. However, by only focusing on recent publications, do we run the risk of perpetuating the trend in ecology to reinvent the wheel?

Finally, perhaps not enough researchers are contributing to researchblogging. There are WAY more publications than there are blogs about them! In fact, ISI gave me more than 49,000 results for my query of papers using the word “biodiversity”, whereas researchblogging.org gave me 448 blog entries, citing 427 papers. Just to put this in perspective, the most cited paper containing the word “biodiversity” has been cited 10 times more than the total number of blogs on researchblogging.org that contain the word “biodiversity”. Maybe research blogging and the literature don’t agree because not enough scientists write in blogs.

If science blogging is intended to disseminate science to the public, then it seems important that science blogs aren’t limited to presenting just the newest and most exciting research out there. Here at Biodiverse Perspectives, we are trying to put biodiversity research into some kind of context by writing about papers that are new and exciting as well as papers that have contributed to our foundational knowledge of the field. We hope that this endeavor will allow us to share our excitement about the future direction of biodiversity research in light of its past. What do you think?