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<\/a><\/p>\nBen Chehida et al. studied convergent evolution in multiple mimetic Neotropical lepidopteran lineages that diverged between 1 and 120 million years ago, including seven species of Ithomiini and Heliconius butterflies and a day-flying Chetone moth. Image credit: Ben Chehida et al., doi: 10.1371\/journal.pbio.3003742.<\/p>\n
\u201cConvergent or parallel evolution is a natural experiment where unrelated species independently evolve similar traits in response to similar selective pressures,\u201d said University of York\u2019s Professor Kanchon Dasmahapatra and colleagues.<\/p>\n
\u201cIt informs us about the extent to which evolution is repeatable and thus predictable.\u201d<\/p>\n
\u201cHighly divergent lineages can show strong trait convergence, for example, associated with the repeated colonization of land, water, or air or the repeated evolution of resistance to challenges like insecticides or drought and heat stress.\u201d<\/p>\n
\u201cTrait convergence in different species can be caused by genetic changes at different genes or the same gene (gene reuse),\u201d they added.<\/p>\n
\u201cGene reuse is predicted to be more common among closely related lineages or when developmental pathways towards shared fitness optima are constrained.\u201d<\/p>\n
\u201cWhere genes are reused, convergence may result from independent mutations at the same gene or because the same alleles are reused (allele sharing), either from ancestral standing variation or as a result of introgression between species.\u201d<\/p>\n
In new research, the authors studied several distantly related South American rainforest butterfly and moth species that sport similar wing color patterns that warn away predators, a phenomenon known as mimicry.<\/p>\n
The aimed to discover the genes controlling these similar mimicry color patterns among seven distantly related species.<\/p>\n
They found that despite being very distantly related to each other, the various butterfly and moth species reused the same two genes \u2014 ivory and optix \u2014 to evolve near identical color patterns.<\/p>\n
The genetic changes in the different butterfly species did not happen in the genes themselves, but in similar \u2018switches\u2019 that turn the genes on or off.<\/p>\n
The moth species surprisingly used an inversion mechanism \u2014 a large chunk of DNA flipped backwards \u2014 a near identical genetic trick used by one of the butterflies.<\/p>\n
\u201cConvergent evolution, where many unrelated species independently evolve the same trait, is common across the tree of life,\u201d Professor Dasmahapatra said.<\/p>\n
\u201cBut we rarely have the opportunity to investigate the genetic basis of this phenomenon.\u201d<\/p>\n
\u201cInvestigating seven butterfly lineages and a day-flying moth, we show that evolution can be surprisingly predictable, and that butterflies and moths have been using the exact same genetic tricks repeatedly to achieve similar color patterns since the age of the dinosaurs.\u201d<\/p>\n
The findings show that evolution isn\u2019t always a roll-of-the-dice, but can be more predictable than previously thought.<\/p>\n
\u201cThese distantly related butterflies and the moth are all toxic and distasteful to birds trying to eat them,\u201d said Wellcome Sanger Institute\u2019s Professor Joana Meier.<\/p>\n
\u201cThey look very much alike because if birds have already learned that a specific color pattern means \u2018do not eat, we are toxic,\u2019 it is beneficial for other species to display the same warning colors.\u201d<\/p>\n
\u201cHere, we show that these warning colors are particularly ideal as it seems quite easy to evolve these same color patterns due to the highly conserved genetic basis over 120 million years.\u201d<\/p>\n