Winged or Wingless Aphids: it all Depends on a Virus Co-opting in the Organism of the Insect

A large number of an organism’s features are affected by signals from the organism’s environment. These traits are called ‘phenotypically plastic trait​s,’ and are crucial in enabling an organism to handle uncertain habitats.

Jennifer Brisson, an associate professor of biology at the University of Rochester, explains what the genetic mechanisms underlying there features are. Brisson and her former postdoctoral student Benjamin Parker, now an assistant professor of microbiology at the University of Tennessee, examined phenotypically plastic traits​ in pea aphids, and unveiled, for the first time, genes that impact whether aphids create winged or wingless progeny as a reaction to their environment.

In a new study published in the journal Current Biology, the scientists showed off how phenotypically plastic traits​ develop and respond to crucial questions regarding the evolution of environmentally delicate features.

Pea aphids are insects that duplicate quickly and usually give birth to wingless progeny. Many gardeners know that aphids can rapidly submerge and kill the host plants on which they feed and live. When the habitat turns out too jammed with other aphids, the females begin giving birth to progeny that have wings, instead of the usual wingless offspring. The winged progeny is then able to fly and occupy not such crowded plants.

Brisson explains that finding why some of the aphids doing this trick for millions of years are more sensitive to jammed places than others is the key to understanding how the phenotypic plasticity functions.

The biologists utilized a simple method from evolutionary genetics and molecular biology to discover genes that decide the ratio to which aphids react to crowding. To the scientists’ surprise, the genes they unveiled are from a virus that became included in the aphids genome. The virus, coming from a group of insect viruses known as ‘densoviruses,’ makes its host create progeny with wings.

Scientists think the virus appeals to this tactic, so it facilitates its own dispersal. Brisson and Parker discovered that the gene from the virus maintained the same function of generating winged progeny even after it was moved and integrated into the aphid genome.

The majority of laterally transferred DNA, DNA that is taken from other organisms, such as viruses, is not supported by the host because it is rapidly disabled or eradicated. But, there are instances in most organisms, even humans, where genomes actually embrace genes. In humans, for example, the gene that produces a membrane between the placenta and the fetus was adopted from a retrovirus.

Brisson and Parker discovered a specific case in which genes from other organism were co-opted by the organism’s genome to alter the power of a plastic reaction to environmental signals. Microbial genes similar to those from viruses are, thus, able to play a crucial part in insect and animal evolution, Brisson says.

She also explained that even in ancient features like the one examined in this study, new genes are able to start to play a part in forming plastic traits and can aid organisms to handle an uncertain world.

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Benjamin Diaz

About the Author: Benjamin Diaz

Benjamin Diaz started working for Debate Report in 2017. Ben grew up in a small town in northern Ontario. He studied chemistry in college, graduated, and married his wife a year later. Benhas been a proud Torontonian for the past 10 years. He covers politics and the economy. Previously he wrote for CTV News and the Huffington Post Canada.

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