Researchers at Lund University have discovered that genetic color variations in female blue-tailed damselflies, including a form that mimics males, originated more than five million years ago. This discovery deepens our understanding of damselfly genetic diversity and evolutionary processes and lays the foundation for further evolutionary research.
For more than two decades, scientists at Sweden's Lund University have been studying the common blue-tailed damselfly, a species in which female damselflies display three different color forms, including one that mimics the male to protect themselves from mating harassment. Recently, an international team of researchers discovered that this genetic color variation, common across multiple species, originates from changes in a specific region of the genome that dates back at least 5 million years.
The question of how genetic variation arises and why it persists over time is central to evolutionary biology, population genetics, and conservation biology. In all populations of limited size, genetic variation disappears over time. Therefore, it is important to understand the mechanisms that generate new genetic variants and those that maintain them. This has important implications for protecting the future evolutionary potential of species and populations to adapt to rapidly changing environments.
In new research published in Nature Ecology and Evolution, a team of researchers has mapped the extensive and surprising color variation among females of blue-tailed damselflies (Ischnuraelegans).
"In this damselfly species, females have three genetically determined color forms, one of which makes them look like males. These male-like females have an advantage because they avoid excessive mating harassment by males," said Erik Svensson, professor of biology at Lund University. "Our study clarifies when, how and why this variation arose, and shows that this variation has been maintained over the long process of evolution by so-called balancing natural selection."
By sequencing the DNA of three color forms of the blue-tailed damselfly and comparing it to the two color forms of the closely related tropical damselfly Ischnurasenegalensis, the researchers were able to show that this genetic color variation in female damselflies arose at least 5 million years ago through several different mutations in a specific genetic region on the damselfly's chromosome 13.
Erik Svensson said: "The huge differences in insect color fascinate the public and raise questions about the function of color signals and their evolutionary consequences for mate choice and sexual conflict."
Having found the gene behind color variation in females, researchers can now go a step further and identify different genotypes in males and the aquatic larval stages of these insects. Males lack visible color forms, but the researchers plan to investigate whether color genes affect other characteristics of larvae and males, including survival and behavior.
"We now have a good knowledge base to study color variation in this damselfly genus, which is found in Europe, Africa, Asia, Australia, North and South America, over much longer evolutionary timescales," Erik Svensson concludes: "These new genetic results help us understand what happens within a species, as well as over much longer evolutionary macrotimescales of tens of millions of years, and between multiple different species."
Compiled source: ScitechDaily