Ecology is a Tower of Babel

17 09 2012

The term ‘ecology’ in 16 different languages overlaid on the oil on board ‘The Tower of Babel’ by Flemish Renaissance painter Pieter Bruegel the Elder (1563).

In his song ‘Balada de Babel’, the Spanish artist Luis Eduardo Aute sings several lyrics in unison with the same melody. The effect is a wonderful mess. This is what the scientific literature sounds like when authors generate synonymies (equivalent meaning) and polysemies (multiple meanings), or coin terms to show a point of view. In our recent paper published in Oecologia, we illustrate this problem with regard to ‘density dependence’: a key ecological concept. While the biblical reference is somewhat galling to our atheist dispositions, the analogy is certainly appropriate.

A giant shoal of herring zigzagging in response to a predator; a swarm of social bees tending the multitudinous offspring of their queen; a dense pine forest depriving its own seedlings from light; an over-harvested population of lobsters where individuals can hardly find reproductive mates; pioneering strands of a seaweed colonising a foreign sea after a transoceanic trip attached to the hulk of boat; respiratory parasites spreading in a herd of caribou; or malaria protozoans making their way between mosquitoes and humans – these are all examples of population processes that operate under a density check. The number of individuals within those groups of organisms determines their chances for reproduction, survival or dispersal, which we (ecologists) measure as ‘demographic rates’ (e.g., number of births per mother, number of deaths between consecutive years, or number of immigrants per hectare).

In ecology, the causal relationship between the size of a population and a demographic rate is known as ‘density dependence’ (DD hereafter). This relationship captures the pace at which a demographic rate changes as population size varies in time and/or space. We use DD measurements to infer the operation of social and trophic interactions (cannibalism, competition, cooperation, disease, herbivory, mutualism, parasitism, parasitoidism, predation, reproductive behaviour and the like) between individuals within a population1,2, because the intensity of these interactions varies with population size. Thus, as a population of caribou expands, respiratory parasites will have an easier job to disperse from one animal to another. As the booming parasites breed, increased infestations will kill the weakest caribou or reduce the fertility of females investing too much energy to counteract the infection (yes, immunity is energetically costly, which is why you get sick when you are run down). In turn, as the caribou population decreases, so does the population of parasites3. In cybernetics, such a toing-and-froing is known as ‘feedback’ (a system that controls itself, like a thermostat controls the temperature of a room) – a ‘density feedback’ (Figure 1) is the kind we are highlighting here. Read the rest of this entry »





Twenty landmark papers in biodiversity conservation

13 10 2011

While I can’t claim that this is the first time one of my peer-reviewed papers has been inspired by ConservationBytes.com, I can claim that this is the first time a peer-reviewed paper is derived from the blog.

After a bit of a sordid history of review (isn’t it more and more like that these days?), I have the pleasure of announcing that our paper ‘Twenty landmark papers in biodiversity conservation‘ has now been published as an open-access chapter in the new book ‘Research in Biodiversity – Models and Applications‘ (InTech).

Perhaps not the most conventional of venues (at least, not for me), but it is at the very least ‘out there’ now and freely available.

The paper itself was taken, modified, elaborated and over-hauled from text written in this very blog – the ‘Classics‘ section of ConservationBytes.com. Now, if you’re an avid follower of CB, then the chapter won’t probably represent anything terribly new; however, I encourage you to read it anyway given that it is a vetted overview of possibly some of the most important papers written in conservation biology.

If you are new to the field, an active student or merely need a ‘refresher’ regarding the big leaps forward in this discipline, then this chapter is for you.

The paper’s outline is as follows: Read the rest of this entry »





The rarity paradox

22 06 2011

© C. Madden

My friend and colleague at the Centre National de Recherche Scientfique (CNRS), Laboratoire d’Ecologie Systématique & Evolution based at the Université Paris-Sud in France, Dr. Franck ‘Allee EffectCourchamp, has asked me to help him out finding a suitable candidate for what sounds like a very cool job. If you’re in the market for a very interesting and highly relevant conservation post-doctoral fellowship, please read on.

And even if you’re not looking for a position, but are interested in the anthropogenic Allee effect, then by all means, please read on as well.

This two-year fellowship is part of a grant focused on demonstrating the novel rarity paradox, either in new wildlife trade markets (i.e., exotic pets, traditional medicine, et cetera) or in newly exploited species (e.g., tibetan antilope, seahorses, et cetera). Read the rest of this entry »