This stability exists despite the incredible diversity seen today in wing patterns, sizes, and caterpillar forms across over 160,000 species globally, according to a new paper published in the journal Nature Ecology and Evolution.
Butterflies and moths (order Lepidoptera) represent 10% of all described animal species and are hugely important pollinators and herbivores in many ecosystems.
In a new study, Wellcome Sanger Institute’s Professor Mark Blaxter and his colleagues set out to understand the processes that drive the evolution of chromosomes of this highly diverse group.
They analyzed and compared over 200 high-quality chromosome-level genomes of butterflies and moths.
They identified 32 ancestral chromosome building blocks, named Merian elements after the pioneering 17th century entomologist Maria Sibylla Merian, that have stayed intact across most butterfly and moth species since their last common ancestor over 250 million years ago.
With the exception of a single ancient fusion event between two chromosomes that led to the 31 chromosomes seen in most species today, chromosomes of most current species directly correspond to these ancestral Merian elements.
The researchers found not only were chromosomes incredibly stable, but the order of genes within them was too.
They found some species with minor changes, mainly involving fusions of small autosomes and the sex chromosome. This highlights the role of chromosome length as a driver of evolutionary change.
However, the scientists uncovered a rare subset of species such as the blue butterflies (Lysandra) and the group containing cabbage white butterflies (Pieris) that have defied these genome structure constraints.
These groups underwent extensive chromosome reshuffling, including breakage of chromosomes, and large scale reshuffling through fission and fusion.
The work increases understanding of factors that lead to genetic diversity within these insects. This can guide efforts to protect and preserve…
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