May 17, 2012
Researchers Find That Some Butterflies Share DNA
Brett Smith for RedOrbit.com
Geneticists have made a startling breakthrough while sequencing the genome of a South American butterfly, according to a study published in the May 16 edition of Nature.
More than 70 scientists from 9 different institutions were involved in the Heliconius Genome Consortium, which sequenced the entire genome of the Postman butterfly (Heliconius melpomene). They found that the insect and two other related species, Heliconius timareta and Heliconius elevatus, share similar color patterns on their wings because they share related sequences of DNA.
Researchers said the genetic sharing between these species is the result of hybridization, or inter-species breeding. The resulting hybrid offspring inherit traits of both the mother and father. Though often considered evolutionary dead-end in other animals like the mule, the Heliconius hybrids occasionally interbreed with a parent species, in the process introducing new genes that can help populations adapt to new or changing environments.
“This project really changes how we think about adaptation in general,” said Marcus Kronforst, a Bauer Fellow at Harvard, who participated in the sequencing. “Evolutionary biologists often wonder whether different species use the same genes to generate similar traits, like the mimetic wing patterns of Heliconius butterflies. This study shows us that sometimes different species not only use the same genes, but the exact same stretches of DNA, which they pass around by hybridization.”
Heliconius species have long been a favorite organism of study for evolutionary biologists. This is because of their abundance and ease of breeding in the laboratory. Scientists also prefer studying these butterflies because of their mimicry. Some species of Heliconius are noxious to predators that avoid the insects´ brightly colored wings after an initial encounter. Other non-poisonous species of Heliconius have adapted the ability to resemble their distasteful relatives, thus avoiding these same predators.
"What we discovered is that one butterfly species can gain its protective color pattern genes ready-made from a different species by hybridizing with it--a much faster process than having to evolve one's color patterns from scratch,” noted Kanchon Dasmahapatra, a postdoctoral researcher at the University College London´s Department of Genetics, Evolution, and Environment, and a co-author of the study.
The researchers also found a large number of genes in the Heliconius are dedicated to smell and taste. This runs counter to the researchers´ presumption that the butterflies, which are most active in the daytime, rely primarily on vision for feeding and breeding.
"Instead, we learned that they have a rich repertoire of genes for olfaction [smell] and chemosensation [in this case taste]," said University of California at Irvine biologist and article co-author Adriana Briscoe.
The genetic capacity for butterflies to receive chemical information is even greater than that of moths, which depend on chemical signals for finding mates and host plants. The Heliconius receive this information through their delicate antennae, which contain smell receptors. The butterflies' tiny feet hold the chemosensation receptors or taste buds, according to researchers.
Briscoe said additional findings by the consortium could help scientists better understand trait sharing in other species, such as Homo sapiens and Neanderthals. In 2011, an article in Science said these species probably interbred during ancient times and strengthened the genetic pool of modern man.