The fact that the rate of climate warming is lower in tropics than at higher latitudes has fed the thinking that also the impacts of climate warming on organisms will be of less concern in low as compared to high latitudes. Logical, but think again. It has been known for a quite while that tropical ectotherms have narrower thermal tolerance limits than temperate zone ectotherms. In other words, tropical species are often thermal specialists, whereas temperate zone species are typically thermal generalists.
In a ‘Perspective’ published in Science 6 June, Teweskbury et al. (2008) point out an obvious, but so far largely overlooked, lesson to be learned from this: for a given raise in mean temperature, the tropical species are more likely to be displaced from their thermal optimum than the temperate zone species. Hence, although the rate of climate warming is faster at high high latitudes, ectotherms at low latitudes are likely to suffer more (and faster) about climate warming as their tolerance ranges are narrower than those of temperate zone ectotherms. Adding compounding effects of habitat loss and fragmentation on this, it should be clear the worries concerning the climate change are not restricted – perhaps even misplaced – at higher latitudes.
Tewksbury JJ, RB Huey, CA Deutsch (2008) Putting the Heat on Tropical Animals. Science 320:1296-1297.