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Researchers at the Insti­tute of Biotech­nol­ogy at the Helsinki Uni­ver­sity and the Uni­ver­si­tat Autònoma de Barcelona (UAB) have devel­oped the first three-​dimensional sim­u­la­tion of the evo­lu­tion of mor­phol­ogy by inte­grat­ing the mech­a­nisms of genetic reg­u­la­tion that take place dur­ing embryo devel­op­ment. The study, pub­lished online on 1 May in Nature, high­lights the real com­plex­ity of the genetic inter­ac­tions that lead to adult organ­isms’ phe­no­types (phys­i­cal forms), helps to explain how nat­ural selec­tion influ­ences body form and leads towards much more real­is­tic vir­tual exper­i­ments on evo­lu­tion.

explains Isaac Salazar, a researcher at the Uni­ver­sity of Helsinki and in the Depart­ment of Genet­ics and Micro­bi­ol­ogy of the UAB, and lead author of the arti­cle. In nature this is deter­mined by embryo devel­op­ment, dur­ing the life of each organ­ism, and by evo­lu­tion through nat­ural selec­tion, for each pop­u­la­tion and species.

But in the field of evo­lu­tion of organ­isms it is prac­ti­cally impos­si­ble to set up exper­i­ments, given the long timescale these phe­nom­ena oper­ate on. This means that there are still open debates, with hypothe­ses that are hard to prove exper­i­men­tally. This dif­fi­culty is com­pen­sated for by the use of the­o­ret­i­cal mod­els to inte­grate in detail the exist­ing exper­i­men­tal data, thus cre­at­ing a vir­tual sim­u­la­tion of evolution.

The researchers used a the­o­ret­i­cal model based on exper­i­ments on embryo devel­op­ment, on a pre­vi­ous study by the same authors, also pub­lished in Nature (Salazar-​Ciudad and Jern­vall, 2010), and on three dif­fer­ent math­e­mat­i­cal mod­els of vir­tual evo­lu­tion by nat­ural selec­tion of form. Evo­lu­tion takes place vir­tu­ally on the com­puter in pop­u­la­tions of indi­vid­u­als in which each indi­vid­ual can mutate its genes, just as this works in nature. Through the devel­op­ment model, these pro­duce new mor­pholo­gies and nat­ural selec­tion decides which ones pass on to the next gen­er­a­tion. By repeat­ing the process in each gen­er­a­tion, we can see evo­lu­tion in action on the computer.

This sim­u­la­tion enables a com­par­i­son of the dif­fer­ent hypothe­ses in the field of evo­lu­tion regard­ing which aspects of mor­phol­ogy evolve most eas­ily. The first vision is that all met­ric aspects of form con­tribute to adap­ta­tion and that, con­se­quently, all are fine-​tuned by evo­lu­tion over time. The sec­ond vision is that some aspects of form have greater adap­tive value and that the remain­der evolve col­lat­er­ally from changes in these. The third is that no aspect of form is intrin­si­cally more impor­tant, but what is impor­tant adap­tively is a com­plex mea­sure­ment of the form’s roughness.

“What we have found is that the first hypoth­e­sis is not pos­si­ble and that the sec­ond is pos­si­ble in some cases. Even if ecol­ogy favoured this type of selec­tion (the first vision), embryo devel­op­ment and the rela­tion­ship between genetic and mor­pho­log­i­cal vari­a­tion imposed by this is too com­plex for every aspect of mor­phol­ogy to have been fine-​tuned. In one way, what we are see­ing is that nat­ural selec­tion is con­stantly mod­el­ling body forms, but these are still a long way from per­fec­tion in many ways”, points out Salazar.

(Source: Uni­ver­si­tat Autònoma de Barcelona lat­est news, 02.05.2013)