Tradeoffs, correlated traits, and functional diversity

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

Tradeoffs are everywhere, and never has this been more apparent to me, than in graduate school. With only so many hours in a day, and an ever-growing to-do list, how I choose to allocate my time becomes an increasingly important decision. Do I work in the greenhouse, resample my field experiment, analyze data, catch up on reading…? Every day, when I wake up, I’m faced with these decisions.  And every day, these decisions are constrained by the same two major factors: What can I do? e.g., how much time do I have in the day; and what have I already done?

Well, I’m glad to say that I know I’m not alone. In fact, most organisms face nearly the exact same constraints. And these two constraints don’t just occur within a single organism’s lifetime. They can often be reflected over evolutionary time, too. In this case, “what can I do?” becomes a question of physiological constraints on phenotypes (some combinations of traits are physiologically impossible), and “what have I done?” becomes a question of evolutionary history, or natural selection (some combinations of traits would confer fitness disadvantages).

As studies of diversity move from descriptions of species numbers (e.g., taxonomic diversity) to descriptions of species physiology (e.g., functional diversity) or evolutionary history (e.g., phylogenetic diversity), it’s becoming more important that we pay attention to the tradeoffs that underlie those patterns. Although not the first to suggest this, Wright et. al’s description of the worldwide leaf economics spectrum demonstrated the universality of tradeoffs between natural selection and physiological constraints, and argued that plants tend to fall on a continuum between two fundamental strategies for dealing with these tradeoffs, termed the slow- to quick-return continuum.

This spectrum runs from species with potential for quick returns on investments of nutrients and dry mass in leaves to species with a slower potential rate of return. At the quick-return end are species with high leaf nutrient concentrations, high rates of photosynthesis and respiration, short leaf lifetimes and low dry-mass investment per leaf area. At the slow-return end are species with long leaf lifetimes, expensive high-LMA leaf construction, low nutrient concentrations, and low rates of photosynthesis and respiration.

For example, imagine you are a small grass seedling, your goal in life is reproduction, and you only have a finite number of resources to allocate in order to reach that goal. Do you allocate them to growth and additional resource acquisition, or do you conserve the resources that you have so that you can allocate them all to reproduction? What Wright et al. suggest is that you are fundamentally asking, “Should I be a quick-return plant or a slow return plant?” Physiologically, it is not possible to exhibit both high rates of photosynthesis (future resource acquisition) as well as low leaf nitrogen concentrations and long lived leaves (resource conservation). In addition, if you choose to allocate few resources to photosynthesis, jack up your leaf nitrogen concentrations, and rapidly shed leaves, you are unlikely to successfully reproduce. As a result, your phenotype is constrained physiologically and evolutionarily, and Wright et al. argue that this tradeoff is fundamental across all plants and results in a predictable spectrum of phenotypes.

I was introduced to this paper very early in my graduate career, long before I had a flicker of an inkling of a speck of a thought about the multiple dimensions of biodiversity. But when I start to think about patterns of functional diversity through the lens of the leaf economics spectrum, I start to wonder. If groups of physiological traits covary and are constrained by physiological processes and evolutionary history, how might this influence the inferences that we draw from patterns of functional diversity? When measuring functional diversity, how important are the specific traits that we consider? And if groups of physiological traits are strongly correlated along a phylogeny, how useful are measures of phylogenetic diversity at inferring patterns of functional diversity?

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 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.


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”?


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 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:


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


Fletcher Halliday

And 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, but I was surprised to find that the top-five most-cited articles on ISI have never been written about on 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 isn’t a representative sample of science blogs on the web.  But then, if 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. 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 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 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?