Study Uncovers New Evidence on Species Evolution
Walking stick insects illustrate new evidence of "parallel evolution"
A study involving Simon Fraser University researchers and published in the journal Science has found evidence for the genomic basis of how new species evolve in adapting to different environments.
Researchers studying an insect known as the walking stick (genus Timema) determined that the process of “speciation” happened in association with the use of different host plants. They also determined that across many populations of the insect, those on one host plant are diverging, genetically, from the populations on another host plant, a process they call “parallel speciation.”
“Parallel speciation is important because it is like replication in a scientific study—it tells you whether a pattern and process are repeatable, which lends credence and statistical rigor to the causes,” says SFU biology professor Bernard Crespi, whose former PhD student, Patrik Nosil, led the research. Nosil is now a professor at the U.K.’s University of Sheffield.
“From this we can learn, more effectively than in systems where speciation processes happen only once, how new species arise.”
The work involved experiments in combination with genome sequencing of populations from two host plants. The sets of individual walking sticks were put on different host plants to test directly for natural selection's role in speciation.
Whole-genome data was obtained, which allowed inference of which genes were associated with speciation processes. “This tells you about the roles of natural selection, and how many genes are involved, in speciation,” Crespi notes.
The team’s work extends numerous earlier studies by using whole genomes on a large scale, and conducting experiments to validate the roles of natural selection in speciation.
“The combination of whole genomes, and experiments, is unprecedented in speciation studies,” says Crespi, adding that future work will involve determining what specific genes are involved in speciation, and how natural selection works upon them.