Researchers have been working to understand the balance of how genetics and environment affect organisms since the term "nature versus nurture" was first put into play in the mid-1800s, a Virginia Tech news release reported.
A research team observed that fruit flies that live on opposite sides of a unique environment, dubbed the "Evolution Canyon," are primarily genetically affected by their surroundings even in extreme situations such as cross-breeding, migration, and even extinction.
"Despite complicating factors, such as likely gene flow between the two populations and changing demographics, the difference in the microclimate in this canyon apparently is so pervasive that it is sufficient to drive the genetic differences," said Pawel Michalak, an associate professor at the Virginia Bioinformatics Institute said. "We don't have many examples of rapid environmental adaptation to stressful conditions from the field. We can simulate such conditions in a lab, but it is valuable to observe this actually happening in a natural system."
The "canyon" can be found in Mount Carmel, Israel. The regions are surprisingly close to each other (about the distance of two football fields). One side of the canyon faces north and gets about eight times as much sun as the south -facing side. The south side has been described as "tropical" while the other is more comparable to a European forest.
The drastically different environments seem to affect the fruit flies' genomes despite other factors such as migration.
The fruit fly (Drosophila melanogaster) has been rigorously studied in the past in order to help scientists understand how "genetic information is packaged in chromosomes." About 65 percent of all genomes relating to disease in humans are believed to be present in these fruit flies as well.
The team used a technique called whole genome sequencing to understand the DNA of the entire local fruit fly population.
The researchers were able to pinpoint 572 genes that were significantly different in frequency between the two populations; these led to differences in a number of areas including heat tolerance and mating behavior. The team also noticed the genetic changes were accumulating in chromosomal "islands" in the north facing population, which suggests the potential for gene mutations to spread in the future.
"Although we were not correlating genetic change with climate change, we were looking at heat-stress effects, which gives us an indirect understanding relevant to global climate changes," Michalak said. "We need some good indicators of genomic changes induced by climate changes. People have ways to cope unlike those of other organisms, but stress-resistance mechanisms are well-conserved in nature. The basic question of how organisms adapt to stressful environments is going to be more important in the years ahead. It affects us as a whole."
The team concluded with the idea that natural selection is a powerful process in terms of influencing genomes.
"It is nice to see the molecular work finally completed, and that the molecular signal confirms the phenotypic data: There is divergence between the two slopes," Marta L. Wayne, a professor of biology at the University of Florida and a member of the UF Genetics Institute, who was not involved in the research, said. "This is interesting because the slopes are close enough that we know animals travel between them, yet selection is so strong that there are differences between animals on the two slopes. This is really strong natural selection."
