Does an individual’s response to environmental conditions within its lifetime predict evolutionary changes in future generations? In a recent study by Colorado State University researchers, the answer to this long-standing question is yes, but not for the reason many scientists have historically assumed.
Cameron Ghalambor, professor of biology at CSU, and his colleagues transplanted guppies from waters rife with natural predators to streams with few enemies. Previous research had shown guppies could rapidly evolve genetically based differences in their appearance, behavior and physiology to adapt to the presence or absence of predators. The new research demonstrates that how guppies initially respond to a new environment influences which set of genes evolve first.
“These results have implications for not only predicting how plants and animals might respond to changing environmental conditions such as those associated with climate change, emerging diseases and habitat modification, but also for how bacteria or pathogens will respond to an antibiotic or other drug,” said Ghalambor.
The results, which were published this week in the journal Nature, show that guppies from the transplanted population initially respond to a lack of predators with coping mechanisms that include changes in the expression of genes in the brain; some of the changes were beneficial, while others were disadvantageous.
When the researchers compared how the brains of the introduced guppies evolved to incorporate the initial coping responses, they found that the genes that exhibited the initially maladaptive responses evolved rapidly to allow future generations to thrive better in the new environment.
The study, which is funded by the National Science Foundation, is being hailed as groundbreaking.
“In the presence of predators, animals spend more time looking around and hiding instead of foraging for food and reproducing,” says George Gilchrist, program director in the National Science Foundation’s Division of Environmental Biology, which funded the research along with NSF’s Division of Integrative Organismal Systems. “These scientists have shown that guppies from high-predation environments rapidly evolve both genetic and non-genetic changes when moved to low-predation environments. Surprisingly, the non-genetic changes apparently increase natural selection on the genetic adaptations.”
The findings counter the common assumption that plasticity, or the ability of an individual to respond and cope with changes in the environment, is always beneficial. The study is noteworthy, Ghalambor said, because the inappropriate initial response to a new environment actually caused more rapid evolution.
The full study can be found at http://dx.doi.org/10.1038/nature15256.