News from IBE
Since long ago, scientists believe that different organisms subject to the same environmental selective pressure can evolve independently and reach a similar result. This is what is known as a convergent or parallel evolution. Although many possible examples have been exposed, there was genetic evidence of only a few cases.
This week, in an investigation leaded by Iñaki Ruiz Trillo, an ICREA research professor at the Institute of Evolutionary Biology (CSIC-UPF) and published in Current Biology, a journal of CellPress, scientists provide the first genetic evidence of convergent evolution in organisms close to animals and fungi. The microorganisms studied belong to the opisthokonts, one of the major lineages of eukaryotes, which includes animals, fungi and some unicellular forms.
Scientists have sequenced and analyzed the transcriptome (messenger RNA) of several of these unicellular organisms (protists), which are poorly known and difficult to find in nature. The results show that the flagellum (organelle used to move) was independently lost several times along the opisthokont evolution that ultimately lead to fungi and animals. The authors infer the presence of genes associated with the flagellum in relatives of non-flagellates ones, an evidence that the flagellum was secondarily lost.
In addition, Iñaki Ruiz-Trillo says, these genes have been found in two organisms that were previously thought to be non flagellated like, Ministeria Vibrans and Chorallochytrium limacisporum. After the genetic evidence, scientists observed Ministeria Vibrans under confocal microscopy and saw that it has a structure that had been overlooked until then. It is, explains Ruiz-Trillo, "the structure of an appendix composed by tubulin and with the classic form of a flagellum, which confirms, beyond doubt and contrary to what was previously believed, that these organisms are flagellate, although only in specific moments of their life cycle".
Phylogenomics reveals convergent evolution of lifestyles in close relatives of animals and fungui. G. Torruella, A. de Mendoza, X. Grau-Bové, M. Antó, M.A. Chaplin, J. del Campo, L. Eme, G. Pérez-Cordón, C.M. Whipps, K.M. Nichols, R. Paley, A.J. Roger, A. Sitja-Bobadilla, S. Donachie, and I. Ruiz-Trillo. Current Biology (10 September)