A recent North­eastern Uni­ver­sity study has shown, for the first time, the effect of indi­vidual genes on the fit­ness of a marine species at the ecosystem level. Using his inno­v­a­tive com­puter sim­u­la­tion model, engi­neering pro­fessor Ferdi Hell­weger found that elim­i­nating pho­to­syn­thesis genes from viruses that attack impor­tant marine pho­to­syn­thetic bac­te­rial organ­isms will neg­a­tively impact the fit­ness of these viruses, ulti­mately killing them.

The find­ings, pub­lished in the journal Envi­ron­mental Micro­bi­ology, have led to a new inter­dis­ci­pli­nary field called “sys­tems bioe­cology.” Com­bining sys­tems biology and ecology, sys­tems bioe­cology uses com­puter sim­u­la­tion to better under­stand the role of indi­vidual genes at the ecosystem scale.

With his com­puter sim­u­la­tion model, Hell­weger “knocked out” the pho­to­syn­thesis genes of cyanophages (viruses that attack marine cyanobac­teria species such as Syne­chococcus and Prochloro­coccus) to com­pare the fitness-​​level of these viruses to those con­taining the genes. Sim­u­lating a ten-​​year time span, he found that viruses without the pho­to­syn­thesis genes were dead while the ones with the genes present survive.

The find­ings demon­strate that the fit­ness of cyanophage viruses is pos­i­tively affected by the pres­ence of pho­to­syn­thesis genes.

Syne­chococcus and Prochloro­coccus are known to be the most abun­dant pho­to­syn­thetic organ­isms on Earth and play a major role in our carbon and cli­mate cycles and the ocean ecosystem. Thus, finding out what fac­tors influ­ence the fit­ness and destruc­tive impact of marine viruses on these bac­teria is cru­cial in order to better under­stand the ecosystem.

The inno­v­a­tive com­puter sim­u­la­tion model can be expanded and mod­i­fied using dif­ferent genes and applying it to dif­ferent species of other marine bacteria.

Most of the bio­log­ical sci­ence that comes out today is at the mol­e­c­ular level, but our models have not reached that point,” said Hell­weger. “Sys­tems bioe­cology has the poten­tial for becoming widely used and the ‘method of choice’ for sim­u­la­tion in the post-​​genomic era.”