Guest essay by Eric Worrall
PLOS ONE has published a study which suggests two thirds of rabbit species will be severely affected by climate change. The authors of the study think climate change will force rabbits to migrate towards the poles, or to higher altitudes, and that some species will suffer significant range declines.
Climate change during the past five decades has impacted significantly on natural ecosystems, and the rate of current climate change is of great concern among conservation biologists. Species Distribution Models (SDMs) have been used widely to project changes in species’ bioclimatic envelopes under future climate scenarios. Here, we aimed to advance this technique by assessing future changes in the bioclimatic envelopes of an entire mammalian order, the Lagomorpha, using a novel framework for model validation based jointly on subjective expert evaluation and objective model evaluation statistics. SDMs were built using climatic, topographical, and habitat variables for all 87 lagomorph species under past and current climate scenarios. Expert evaluation and Kappa values were used to validate past and current models and only those deemed ‘modellable’ within our framework were projected under future climate scenarios (58 species).
Phylogenetically-controlled regressions were used to test whether species traits correlated with predicted responses to climate change. Climate change is likely to impact more than two-thirds of lagomorph species, with leporids (rabbits, hares, and jackrabbits) likely to undertake poleward shifts with little overall change in range extent, whilst pikas are likely to show extreme shifts to higher altitudes associated with marked range declines, including the likely extinction of Kozlov’s Pika (Ochotona koslowi). Smaller-bodied species were more likely to exhibit range contractions and elevational increases, but showing little poleward movement, and fecund species were more likely to shift latitudinally and elevationally. Our results suggest that species traits may be important indicators of future climate change and we believe multi-species approaches, as demonstrated here, are likely to lead to more effective mitigation measures and conservation management. We strongly advocate studies minimising data gaps in our knowledge of the Order, specifically collecting more specimens for biodiversity archives and targeting data deficient geographic regions.
The biggest issue I have with this study is, it doesn’t appear to make any serious allowance for adaption.
The main study includes an acknowledgement that adaptability might play a role – … If species can broaden their occupied bioclimatic niche through trait plasticity, for example, altering their diel patterns of activity, then they may be less susceptible to future change ….
However, it is futile, in my opinion, to attempt to draw conclusions about future range, from a model which appears to treat highly adaptable species as static entities. Even if the global climate changes as radically as alarmists predict, rabbits which are subject to environmental stress won’t stay within their current ecological niches, they will adapt to take advantage of new opportunities.
In less than a century, rabbits introduced from temperate England infested the blistering hot Australian outback, to the point that they became a major economic threat to Australian farmers.
Even biological warfare has failed to contain the rabbit plague. Australia runs one of the most advanced biological warfare laboratories in the world, dedicated to finding new rabbit specific plagues, to control numbers. The research is ongoing, because nothing works for long. When a virulent new disease, or a genetically modified version of an old disease is released, the rabbit population crashes, but within a few years it bounces back, as adaptions for resistance to the new disease spread rapidly through the population.
The reason for this adaptability is that rabbits breed like, er rabbits. Any advantageous mutation can reach the entire population within a few generations. Even when subject to extreme stress, such as artificially weaponised diseases, the entire population is reconstituted from a handful of survivors, faster than Australian scientists can find new ways to kill them. The suggestion that a few degrees of warming would have a significant impact on rabbit populations is ridiculous, in the face of the Australian experience.