Whole Genome Sequencing Reveals How Plasticity and Genetic Differentiation Underlie Sympatric Morphs of Arctic Charr.
Unraveling the genetic secrets of Arctic charr's remarkable ability to form distinct morphs in freshwater lakes. Whole genome sequencing reveals a complex interplay of plasticity and genetic differentiation, with inversions playing a key role in driving morph diversification.
This study used whole genome sequencing to investigate the genetic basis of sympatric morph formation in Arctic charr, a salmonid fish. The researchers established a high-quality reference genome and sequenced 283 individuals from four Norwegian and Icelandic lakes, representing a spectrum of genetic differentiation between morphs. They found that up to 12 large inversions contributed significantly to genetic differences between morphs in one lake, while other lakes showed partial haplotype sharing and locus-specific differentiation. These findings support a model where morph differentiation begins with phenotypic plasticity, leading to niche expansion, and is followed by the gradual development of reproductive isolation. The study provides valuable insights into the genomic mechanisms underlying adaptive radiation and speciation in this ecologically important fish species.