Archives: Ecology

Now that we’ve found Nemo, it’s time to save his friends.

Nemo! Picture by Peter E. Lee, used under a CC license.

There’s many things that we don’t know about the ocean, and most people won’t find that too surprising, but what might be surprising is the extent of our ignorance in some areas.  This is the subject of a recent paper by McClenachan et al. in the journal Conservation Letters, entitled “Extinction risk and bottlenecks in the conservation of charismatic marine species.”  The problem, they contend, is that while the oceans are currently undergoing a massive loss of biodiversity, the full picture of that loss cannot be seen because we’re not even close to knowing how many species have been lost or how many are currently threatened with extinction.

As a small first step to dealing with that issue, the authors of this paper examine marine charismatic species as a way of estimating the threat to some of those species and identifying possible impediments to their conservation.  What are charismatic species, you ask?  They’re species with widespread appeal that receive more attention and funding for conservation (some might say too much attention and funding);  it’s suggested that charismatic species can raise awareness and drive conservation goals.  In this paper, the authors leverage the fame and fortune of marine charismatic species by arguing that because they receive special attention and are – theoretically – at the least risk of extinction even when threatened, charismatic species can serve as an estimate of the lower boundary of the probability of extinction.

The paper takes an unusual and amusing tack to do so.  In their own words: “we summarize the extinction risk of 1,568 species within 16 families of well-known marine animals represented in the 2003 Academy Award-winning movie, Finding Nemo“.  It’s not many papers in which you get to start “with all major characters, as defined by those with credited speaking parts”, including all species in their taxonomic families which included invertebrates, bony fishes, elasmobranchs (sharks and rays), birds, and turtles.  You can follow through the paper for the exact details of how they constructed the lists, but they then took that list of species and evaluated their risk of extinction.  Following that, they evaluated the potential bottlenecks to conservation among the various families. There’s a lot of fascinating detail in this paper, but I’ll skip to the punchline and let you read the rest for yourself.  For me, the most interesting aspect of this paper is captured by Figure 3:

Here we see that many species, especially in the invertebrates and fishes, are almost entirely ignored either in terms of scientific effort (here the number of papers published on the species), status evaluation (are they endangered?), or conservation assignment (listed by CITES, the species-protection for threatened species).  The authors point out that the charismatic species like turtles and birds receive the bulk of the attention at every level, while conservation bottlenecks arise in the other families.

The focus on Finding Nemo is an amusing hook, but though the paper deliberately trades-off rigor for rhetorical power, the argument that the authors make is a clear and important one.  In calling for a greater focus on the marine biodiversity being lost before our eyes, McClenachan and her coauthors make a great point and deserve the attention that they received for publishing this paper*.

Having said all that, there’s a lot left that to talk about regarding the issues that this paper raises.  In particular, I’m struck by the elements of economics, social psychology, and sociology that would interact with the conclusions of the authors’ work.  The fact is that conservation is, and probably always will be, a finite resource (limited in part by money, and in part by scientific personnel) that must be spread about the overwhelming number of species that are likely to be threatened.  This isn’t to say that the status quo is right, or that we shouldn’t strive to improve it – quite the contrary.  But even in the best of all possible worlds, the fallible human beings tasked with the goal of saving these species (scientists, polticians, the general public) are going to exhibit biases of cognition and simple attention that may make it difficult to drum up support for, say, many of the invertebrates in the paper’s list of species.

Take another look at Figure 3 and try to imagine reasons why some of these species might be relatively ignored.  Off the top of my head, a few potential hypotheses jump to mind.  Physical features of the species’ in question may play a role;  for instance, simple preference for anthropomorphism could account for some of the attention paid to the charismatic megafauna.  It’s easier to care if you can imagine the animal talking but it’s a lot easier to imagine a talking shark or clownfish than a talking shrimp (and don’t discount preference for neoteny;  this paper by Mark Estren looks like a good read on that subject).  Or, even something as obvious as size could play a role:  it’s a lot harder to find or pay attention to many of these marine invertebrates than the turtles or sharks or birds that they compete with.

Even the sheer number of species involved could be important, in more than one way.  On one hand, the fact that there are 6 species of turtles compared with 536 species of invertebrates in this paper seems relevant, as the sheer effort involved in finding and cataloguing the marine invertebrates is daunting.  On the other hand, I’m also reminded of work in economics by people like Barry Schwartz and Sheena Iyengar on the paradox of choice:  when confronted with too many options, people are unhappy and find making decisions difficult, even though they claim that they prefer to have more choices available to them.  The number of possible targets in marine invertebrates for conservation efforts could drain the will of politicians, the attention of the public, and the interest of new grad students selecting a species to work on.

I wouldn’t be surprised at all to hear that the people involved in conservation work have thought about some or even all of these issues, but I would not hesitate to recommend a multidisciplinary approach to this problem.  The answer to the call put out by McClenachan and her co-authors has to include a sober analysis that maximizes the efficiency of the resources we have while, perhaps, searching for innovative new ways to increase those resources.  Here’s one thought:  maybe it’s time for a Kickstarter for conservation – a ConservationStarter?  If the idea of a charismatic species is to reach its fullest expression, I can imagine that it might be in the form of directly crowdfunded conservation efforts targeted at particular species.

Whatever we do, the authors of the paper make it clear that we have to do something, and that our actions have to start with knowledge.  There’s simply too much out there that we don’t know;  we may have found Nemo, but we don’t know very much about his friends and we’re in danger of losing them too.

—————

Loren McClenachan, Andrew Cooper,, Kent Carpenter, and Nick Dulvy (2012). Extinction Risk and Bottlenecks in the Conservation of Charismatic Marine Species. Conservation Letters, 5:73-80.

* My post isn’t especially timely when it comes to this paper, as it was published in January, and others have written about it before me;  a good example is the fine folks over at Southern Fried Science or the Scientific American blogs.  However, the paper was only recently brought to my attention by the good folks in Bill Sherwin’s lab, and the discussion we had about it inspired this blog post.

Gay zebra finches, oh my. Oh, wait…

Taeniopygia guttata (Zebra finch)

Image via Wikipedia

I’ve seen this paper about strong homosexual pair bonding in zebra finches pop up in a couple of places around the web, but it only really caught my eye when I read Carin Bondar’s somewhat breathless report on the matter entitled “The astounding strength of homosexual bonds in Zebra Finches: Ladies need not apply…”.  In essence, the researchers discovered that when you manipulate the sex ratio of zebra finch groups to be male-biased, male pair bonds form that display all of the same behaviours that female-male pair bonds do, and that when females are later reintroduced to these homosexual pair bonds, the male pair-bonds don’t break up.

It’s an interesting paper, and the findings are, well, pretty cool.  But I have to disagree – respectfully – with Dr. Bondar’s assessment of the startling nature of these results.  First, given that zebra finches tend to mate for life anyways, the finding that male-male pair bonds are strong shouldn’t come as a surprise if you think mechanistically.  In fact, I think it would have been a lot more surprising if the male-male bonds had been of a different quality;  if you think through the evolutionary implications, having a different mechanism for male-male as opposed to male-female bonds would imply that selective pressures on these types of bonds was different for some reason, and would really beg the question of why.  Instead of a single ‘mating’ mechanism (a combination of hormones and neurobiology among other things, which I’ll touch on again in a moment), this ‘conditional’ pair bonding would require either a single mechanism with an unintended consequence, or two separate mechanisms, one for male-male bonds and one for male-female.  That’s not out of the question, certainly;  many potential explanations for same-sex sexual behaviour in animals imply such mechanisms.  But to me, having a life long pair bond with females and then an entirely separate short-term pair bonding mechanism for male-male interactions would need explanation.  Indeed, as Dr. Bondar’s own blog post notes, “homosexual couples both COURTED and COPULATED with each other”;  even if homosexual pairings are adaptive (as they might well be!), it seems odd to waste even a little energy on copulation and suggests a single mechanism or set of mechanisms at work.

Second, it was already established that there are both hormonal and social / developmental mechanisms affecting same-sex preferences in zebra finches;  in particular, Elizabeth Adkins-Regan did a lot of work from the late 90s onwards on both of these mechanisms (and her student, James Goodson, has done a lot of great follow-up work on mapping the endocrinology and neurobiology of social behaviour in estrildid finches).  The finding in the article by Elie et al. that biased sex ratios promote homosexual pair bonds is interesting, but I wonder how different it is from the social deprivation work by Adkins-Regan and her collaborators.

Don’t get me wrong:  this is a cool article.  It deserved to be published, and it seems to make a couple of important contributions- exploring and quantifying the strength of these bonds was a worthwhile task, and the evidence it provides for the “social partner hypothesis” is worth looking at.  But the media has, as per usual, gotten most of the story wrong here (for instance, the BBC Nature story made it sound like the paper was the first to establish same-sex bonds in zebra finches – <sigh>), and while I share Dr. Bondar’s interest in the results, I don’t think that they’re nearly as shocking as she does.

As a postscript to this:  at the end of her article, Dr. Bondar says:

 However, long term studies will shed light on whether males will seek out females for the sole purpose of genetic propagation outside of their homosexual partnerships.  For the sake of their evolutionary future I hope they do :)

I’m not aware of anyone having tested this specifically.  But it’s been known for a long time that zebra finches engage in a fair amount of extra-pair copulating (i.e. they’re socially monogamous, but not sexually monogamous), so I would expect that the males are stepping out to enhance their reproductive fitness.

Bees going, going, gone? Maybe so, but…

Honey Bee Colony Collapse Disorder, In Context – MYRMECOS.
Drove through a series of posts on colony collapse disorder today as linked to cell phones today following the hoopla over a report on the matter a couple of weeks ago and ended up at this awesome post with a truly eye-opening graphic.  It turns out that maybe the bees aren’t suddenly dying off like the news stories would have us believe.  It turns out that the western honey bee population has been declining since World War II!  Who knew?  It’s definitely worth reading, so have a click.

Oh, and cell phones?  Seems unlikely that they’re killing bees or giving us brain cancer.

Review of “Exploring Animal Social Networks”

A segment of a social network

Image via Wikipedia

As promised in this post, I said that I would review “Exploring Animal Social Networks”, by Croft, James, and Krause. I finished the book a while ago, but I’ve been stuck in the hell of my examen de synthèse and haven’t had time to do a proper review.

Having said that, I’m not going to do a proper review anyways. Why? Well, as full disclosure, I’ve spoken with Dr. Krause about the possibility of joining his lab as a postdoctoral researcher when I’ve finished my Ph.D; while it’s only a preliminary discussion at this point, any review I would make of this book would probably be tinged in a way I don’t feel like trying to control. So, I’ll just mention a few points of interest about the book, and I’d be happy to answer questions in the comments.

The book’s publication, two years ago, came at a perfect time. Social network analysis (SNA), the study of relationships among individuals by encoding them as a mathematical object known as a graph, has been a topic of some interest in fields such as sociology for decades, but has only recently attracted widespread interest in biology. In animal behavior, the use of SNA is even more recent. Its usefulness has been hampered by a lack of statistical tools to accommodate sampling, and it is only in the past fear years that methods from mathematics, statistical physics, and nonparametric statistics have converged to enhance the usefulness of SNA for behavioral biologists.

Exploring Animal Social Networks synthesizes recent advances in the field and provides an extremely accessible introduction to the methods and applications of SNA to animal behaviour. They discuss issues of interest to practicing researchers: sampling, coding, and descriptive and inferential analysis; their statistical test of choice is randomization tests, and the authors discuss the applications of these tests using real data. The tests they discuss are not a cure-all (and recent papers are engaged in a lively debate over the best applications of these methods), but they are careful to point out where researchers might go astray.

In reading it, I found the book quite engaging and well-written. Don’t be fooled by the mentions I made above of the various mathematical fields which inform SNA;  this is not a mathematical text, and though there are a few equations sprinkled through the text, readers of all ability should be able to read it with ease.  If I have one criticism, it’s that it’s too short by half and I felt that they were too quick to pass off the details to other texts, like Wasserman and Faust. It would have been nice to see them dedicate more time to integrating the older methods of SNA into a context that behavioral biologists can understand.

The other problem – which is not within their control – is that the book is going to be outdated within five years of its publication. The consensus on how to apply these methods to biological question is still emerging, and it seems likely that the pace of publication won’t slow down any time soon. An updated version would be a good idea within the next few years.

My own experience with the text is in light of the fact that I’ve been following SNA methods for years (including the work of the authors), and have done a bit of work applying it to my own research;  from that perspective I can say that aside from some of the discussion on statistical methods, there was little in the book that I hadn’t seen in other places.  However, I still greatly enjoyed the book’s presentation, and I can imagine that naive readers will find it one of the better introductions to the area that they are likely to find.

My verdict? If you’re a researcher or student looking to explore the application of SNA to biological questions and have no previous experience with the topic, this is a no-brainer:  buy the book.  And though the material is deeply mathematical at its core the authors present it with a minimum of mathematical formalism, which should be accessible to even the most math-phobic of readers.

If you’re more experienced then you won’t find much new here, but the book manages to combine a great introduction with a good round-up of recent research;  the combination will be of value even to researchers well-familiar with the field.

Exploring Animal Social Networks, by Darren P. Croft, Richard James, and Jens Krause (2008). Princeton University Press: Princeton, New Jersey.