Background
The authors write that "corals in naturally warm environments can have high resistance to bleaching temperatures and can survive heat exposure that would bleach conspecifics in cooler microclimates," citing Oliver and Palumbi (2009, 2011), while further noting that the "recent discovery of populations of acidification-resistant corals show that physiological or evolutionary mechanisms of environmental accommodation exist," citing the findings of Fabricius et al. (2011) and Shamberger et al. (2014).

What was done
In further exploring this intriguing subject, and "to determine the mechanisms of temperature tolerance," Palumbi et al. describe how they "reciprocally transplanted corals between reef sites experiencing distinct temperature regimes and tested subsequent physiological and gene expression profiles."

What was learned
The four U.S. scientists determined that "local acclimatization and fixed effects, such as adaptation, contributed about equally to heat tolerance and are reflected in patterns of gene expression," adding that "in less than two years, acclimatization achieves the same heat tolerance that we would expect from strong natural selection over many generations for these long-lived organisms."

What it means
Once again quoting the researchers who did the work, "our results show both short-term acclamatory and longer-term adaptive acquisition of climate resistance." And they thus conclude that "adding these adaptive abilities to ecosystem models is likely to slow predictions of demise for coral reef ecosystems.'

References
Fabricius, K.E., Langdon, C., Uthicke, S., Humphrey, C., Noonan, S., De'ath, G., Okazaki, R., Muehllehner, N., Glas, M.S. and Lough, J.M. 2011. Nature Climate Change 1: 165-169.

Oliver, T.A. and Palumbi, S.R. 2009. Distributions of stress-resistant coral symbionts match environmental patterns at local but not regional scales. Marine Ecology Progress Series 378: 93-103.

Oliver, T.A. and Palumbi, S.R. 2011. Do fluctuating temperature environments elevate coral thermal tolerance? Coral Reefs 30: 429-440.

Shamberger, K.E.F., Cohen, A.L., Golbuu,Y., McCorkle, D.C., Lentz, S.J. and Barkley, H.C. 2014. Diverse coral communities in naturally acidified waters of a Western Pacific reef. Geophysical Research Letters 41: 499-504.