Genetic effects in interacting species jointly determine ecological outcomes

The greatest diversity of life is not counted in the number of species, explains Zachariah Gompert, an evolutionary geneticist at Utah State University, but in the diversity of interactions between them.

“It is often unclear whether the outcome of an interaction, such as whether a microbe can infect a host, is the same for all members of a species or depends on the genetic makeup of the specific individuals involved,” says Gompert. , associate professor at USU. Department of Biology and Center of Ecology.

For example, he says, one might wonder why a particular butterfly can or cannot feed on a particular plant.

“Is this affected by the specific genetic makeup of the butterfly or is it the specific genetic makeup of the individual plant?” Gompert asks. “Or is it affected by genetic interactions between butterfly and plant species?”

Gompert and his colleagues at the University of Nevada, Rice University, University of Wyoming, University of Tennessee, Texas State University, and Michigan State University fill this knowledge gap with a series of experiments using a recent host range expansion of alfalfa by the blue butterfly Melissa (lemon balm Lycaeides). The team reports its findings in the August 29, 2022 issue of Proceedings of the National Academy of Sciences. The research was supported by the National Science Foundation.

“We show that genetic differences between Melissa blue caterpillars and alfalfa plants account for nearly half of the variability in caterpillar growth and survival,” says 2019 NSF CAREER Award winner Gompert. suggest that individual variation is important, and the outcome of this plant-insect interaction is affected by many genes with mostly independent – ​​or additive – effects.Moreover, genetic differences between alfalfa plants have consistent effects on caterpillar growth in multiple butterfly populations and species, making these effects predictable.”

Collecting detailed data over several years from field plots in Utah and Nevada, the team’s results support the hypothesis that plant and insect genotypes are important, and about equally for the growth and survival of caterpillars.

Beyond problems specific to insects and their host plants, genetic variation within species could also be important for other host-parasite interactions, Gompert says. “Including, for example, susceptibility to parasitic diseases in humans and other animals being a function of both genetic variation in hosts and among pathogenic strains. But the generality of this hypothesis remains to be tested.”

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Materials provided by Utah State University. Original written by Mary-Ann Muffoletto. Note: Content may be edited for style and length.