Parts a whole do not make

17 02 2012

I’m particularly proud of our latest paper for three main reasons:  (1) Salva Herrando-Pérez, lead author and contributor-extraordinaire to CB, has worked extremely hard to get this one out; (2) it is published in a really good journal; and most importantly, (3) it’s the very first empirical demonstration over hundreds of species that just because you have a density effect on some vital rate (e.g., survival, fertility, dispersal), this in no way means you have any evidence at all for density dependence at the population level. Let us explain.

Quantifying variation in population size is an important element for explaining and predicting population dynamics. In models where a vital (demographic) rate responds to change in population size, those ‘density-dependent’ relationships are ecologically understood as being demographic signals of trophic and social interactions, such as parasitism, predation or competition for shelter, because the intensity of those interactions varies with population size.

In fact, density-dependent effects reflect the theoretical capacity of populations to adjust growth and rebound from low or high numbers – and so this concept has become an important metric in population management and conservation  (Eberhardt et al. 2008). Read the rest of this entry »





One billion people still hungry

12 11 2010

 

overpopulationA few days ago, that printed mouthpiece of Murdoch’s News Corporation in Australia – The Australiani, attacked Paul Ehrlich with a spectacular piece of uninformed gibberish (‘Population bomb still a fizzer 40 years on‘) that we both feel compelled to contest.

The Australian, well-known for its ‘War on Science’, refused to give us the opportunity to respond officially in an Opinion Editorial, so we are compelled to fight back using the blogosphere and our collective networks (which, we might add, probably exceed the distribution of said newspaper). Frankly, it was no surprise that The Australian chose to ignore us.

The article in question was written by Oliver Marc Hartwich of the so-called ‘Centre for Independent Studies’, the hyper-conservative Australian propaganda machine reminiscent of the ultra-right wing American Enterprise Institute, made up of some of Australia’s most powerful business magnates and with no academic affiliation whatsoever. Anything vaguely left-of-centre and even remotely promoting environmental responsibility is considered a viable target.

Recently, we blew the whistle on an equally dangerous man and the institutes he represents – climate-denier Alan Oxley; he and the business interests he represents are responsible for more deforestation, biodiversity loss and financial inequity in South East Asia over the last few decades than almost any single group.

Now we turn our attention to expose the true colours of the Centre for Independent Studies and Mr. Hartwich. Read the rest of this entry »