The Glanville fritillary genome retains an ancient karyotype and reveals selective chromosomal fusions in Lepidoptera.

Authors: Ahola, Virpi and Lehtonen, Rainer and Somervuo, Panu and Salmela, Leena and Koskinen, Patrik and Rastas, Pasi and Välimäki, Niko and Paulin, Lars and Kvist, Jouni and Wahlberg, Niklas and Tanskanen, Jaakko and Hornett, Emily A and Ferguson, Laura C and Luo, Shiqi and Cao, Zijuan and de Jong, Maaike A and Duplouy, Anne and Smolander, Olli-Pekka and Vogel, Heiko and McCoy, Rajiv C and Qian, Kui and Chong, Wong Swee and Zhang, Qin and Ahmad, Freed and Haukka, Jani K and Joshi, Aruj and Salojärvi, Jarkko and Wheat, Christopher W and Grosse-Wilde, Ewald and Hughes, Daniel and Katainen, Riku and Pitkänen, Esa and Ylinen, Johannes and Waterhouse, Robert M and Turunen, Mikko and Vähärautio, Anna and Ojanen, Sami P and Schulman, Alan H and Taipale, Minna and Lawson, Daniel and Ukkonen, Esko and Mäkinen, Veli and Goldsmith, Marian R and Holm, Liisa and Auvinen, Petri and Frilander, Mikko J and Hanski, Ilkka

Previous studies have reported that chromosome synteny in Lepidoptera has been well conserved, yet the number of haploid chromosomes varies widely from 5 to 223. Here we report the genome (393?Mb) of the Glanville fritillary butterfly (Melitaea cinxia; Nymphalidae), a widely recognized model species in metapopulation biology and eco-evolutionary research, which has the putative ancestral karyotype of n=31. Using a phylogenetic analyses of Nymphalidae and of other Lepidoptera, combined with orthologue-level comparisons of chromosomes, we conclude that the ancestral lepidopteran karyotype has been n=31 for at least 140?My. We show that fusion chromosomes have retained the ancestral chromosome segments and very few rearrangements have occurred across the fusion sites. The same, shortest ancestral chromosomes have independently participated in fusion events in species with smaller karyotypes. The short chromosomes have higher rearrangement rate than long ones. These characteristics highlight distinctive features of the evolutionary dynamics of butterflies and moths.

Journal: Nature communications
DOI: 10.1038/ncomms5737
Year: 2014

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