In researching the walking stick insect, SFU biology professor Bernard Crespi is able to analyze how new species evolve in new environments and become genetically diverse from their original species. This type of evolution is called speciation.
According to Crespi, “[Speciation] is the origin of new species, when you go from one species to two species. It is the evolution of new biological diversity. People may not have an appreciation for what a species is, except maybe an intuitive one.”
He continued, “A species is a group of organisms that only breed amongst themselves. They don’t breed with other groups. What is evolving is a new breed or group of species that is isolated reproductively, that means it can evolve independently on its own.”
The main finding of the work has to do with natural selection in facilitating speciation, explained Crespi.
It is important to understand, as Crespi explained, that “natural selection is special because it is the only process that specifically gives rise to adaptation to a fit between organisms and their environments [. . .] Natural selection is only one of the mechanisms of evolution,” he continued, “There is a variety of mechanisms including mutation, migration, and genetic drift.”
Crespi’s research is unique in that he used 160 whole genomes, fully sequenced, whereas previous research has dealt with incomplete sequences. He explained the significance of this: “This is the first study to use whole genomes in combination with experimental analysis to understand the causes of speciation.”
The research involved an experiment that placed walking stick insects into different environments, each with its own host plant. Crespi elaborated, “This work showed a role for natural selection in speciation in these walking sticks in terms of their adaptation to different host plant environments.” Insects with certain characteristics will thrive in their respective environments, this is how natural selection plays a role in organisms genetically diverging through reproductive isolation.
In other words, “Natural selection, in terms of the host plant, pulls them apart genetically and phenotypically,” said Crespi.
