That suggested that evolution might be occurring in the same repeatable fashion at each location. To further test this, the team devised an experiment to gather genomic data from individuals that were actively under selection.
"We took individuals from a mixed population of the striped versus the no-striped ecotype, and we transplanted them back into nature onto the two host plants in five different sets," Egan said. "We allowed them to go an entire generation, and then we resampled those populations, resequenced the genome of the survivors and compared those to the ancestors that we started with a year before. We tried to match up the allele frequency shifts in this experiment with the genome-level differentiation that we observed in our genome-resequencing populations. And what we found was that many of the regions that were highly differentiated in nature were the exact same regions that were responding to our selection experiment."
Egan said it was previously impossible to conduct this kind of study because of the expense of genomic tests. Though the genomes of many plant, animal and microbial species have been sequenced over the past decade, most of those are model organisms. Scientists use model organisms to study critical biological processes, but Egan said the study of nonmodel organisms is often the key to ecological questions, including those related to how the environment influences natural selection and speciation.
"The world of genomics is beginning to open up for people like me who don't study model organisms," Egan said. "This is allowing us to address, in new ways, questions that Darwin posed over 150 years ago."
|Contact: Jade Boyd|