Lund University researchers have uncovered that the hereditary color variation in female bluetail damselflies, including a male-mimicking kind, came from over five million years earlier. This finding deepens our understanding of hereditary variety and evolutionary processes in damselflies and sets the stage for more evolutionary studies.For more than twenty years, scientists at Lund University in Sweden have been studying the common bluetail damselfly, a species where women display three unique color types, consisting of one that resembles males, offering protection from mating harassment. Recently, an international team of researchers found that this hereditary color variation, typical amongst several species, stemmed from changes in a particular genomic area, going back a minimum of five million years.The question of how and why genetic variation arises and is kept over long periods of time is of key importance to evolutionary biology, population genetics, and conservation biology. In all populations of limited size, hereditary variation is lost in time. It is for that reason essential to understand both the systems that trigger new hereditary variation, and the mechanisms that act to preserve variation. This has significance both for saving types and for the future evolutionary capacity of populations to adapt to quickly changing environments. Findings from the New StudyIn the new study released in Nature Ecology and Evolution, a research group mapped the extensive and striking color variation among the women of the bluetail damselfly (Ischnura elegans).” In this damselfly species, there are three genetically identified color kinds in the women, among that makes them appear like males. These male-like females have an advantage because they prevent extreme breeding harassment from the males. Our study clarifies when, how and why this variation developed, and shows that this variation has actually been maintained over long evolutionary time durations through so-called balanced natural selection”, states Erik Svensson, biology teacher at Lund University.By sequencing the DNA of the 3 color kinds of the bluetail damselfly and comparing it to the two color types in its closely associated tropical relative Ischnura senegalensis, the researchers were able to demonstrate that this genetic color variation in females arose a minimum of 5 million years ago; through a number of different mutations in a particular hereditary area on the damselflys thirteenth chromosome.” The excellent color variation in bugs fascinates the public, and raises concerns about the function of color signals and its evolutionary repercussions for partner choice and conflicts between the sexes”, says Erik Svensson.Future Research DirectionsHaving located the gene behind the female color variation, the scientists can now go further and determine various genotypes in the males, and in the marine larval stage of these bugs. The males lack visible color forms, however the scientists plan to examine whether the color gene impacts other attributes of the larvae and males, consisting of survival and behaviors.” We now have a great knowledge base for investigating the color variation over longer evolutionary time scales to name a few species of this damselfly genus, which takes place in Europe, Africa, Asia, Australia, North, and South America. These new hereditary results assist us understand both the evolutionary procedures that take place within a species, and what takes place over longer evolutionary macroevolutionary time scales of 10s of countless years and across several different species”, concludes Erik Svensson.Reference: “The genomics and evolution of inter-sexual mimicry and female-limited polymorphisms in damselflies” by Beatriz Willink, Kalle Tunström, Sofie Nilén, Rayan Chikhi, Téo Lemane, Michihiko Takahashi, Yuma Takahashi, Erik I. Svensson and Christopher West Wheat, 6 November 2023, Nature Ecology & & Evolution.DOI: 10.1038/ s41559-023-02243-1.
