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BMC Evolutionary Biology

, 10:75

First Online: 12 March 2010Received: 12 August 2009Accepted: 12 March 2010


BackgroundWhen introduced to novel environments, the ability for a species to survive and rapidly proliferate corresponds with its adaptive potential. Of the many factors that can yield an environment inhospitable to foreign species, phenotypic response to variation in the thermal climate has been observed within a wide variety of species. Experimental evolution studies using bacteriophage model systems have been able to elucidate mutations, which may correspond with the ability of phage to survive modest increases-decreases in the temperature of their environment.

ResultsPhage ΦX174 was subjected to both elevated 50°C and extreme 70°C+ temperatures for anywhere from a few hours to days. While no decline in the phage-s fitness was detected when it was exposed to 50°C for a few hours, more extreme temperatures significantly impaired the phage; isolates that survived these heat treatments included the acquisition of several mutations within structural genes. As was expected, long-term treatment of elevated and extreme temperatures, ranging from 50-75°C, reduced the survival rate even more. Isolates which survived the initial treatment at 70°C for 24 or 48 hours exhibited a significantly greater tolerance to subsequent heat treatments.

ConclusionsUsing the model organism ΦX174, we have been able to study adaptive evolution on the molecular level under extreme thermal changes in the environment, which to-date had yet to be thoroughly examined. Under both acute and extended thermal selection, we were able to observe mutations that occurred in response to excessive external pressures independent of concurrently evolving hosts. Even though its host cannot tolerate extreme temperatures such as the ones tested here, this study confirms that ΦX174 is capable of survival.

Electronic supplementary materialThe online version of this article doi:10.1186-1471-2148-10-75 contains supplementary material, which is available to authorized users.

Jennifer Cox, Alyxandria M Schubert contributed equally to this work.

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Autor: Jennifer Cox - Alyxandria M Schubert - Michael Travisano - Catherine Putonti


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