Long-read sequencing found nearly 19,000 structural variants in Guam's brown tree snakes after an extreme population bottleneck, with roughly half the genome showing runs of homozygosity even as larger duplications, deletions and rearrangements affected almost eight times more sequence than single-nucleotide variants. [1][2]

The variants clustered around gene promoters and were enriched in genes associated with adaptive immunity and smell, supplying plausible material on which selection could act while showing how genomes that look similar letter by letter may still contain whole passages that moved or were copied. [1][2]

The primary Science Advances paper appeared July 24, while July 26 brought a University at Buffalo explainer distributed by ScienceDaily, so the later date marks institutional publicity rather than a new experiment. [1][2]

That publicity moves faster than the causal evidence because the study cannot establish whether the variants arrived with the founding snakes or arose later, and the researchers said comparisons with native-range populations would be needed to investigate timing. [1]

The record also does not prove that structural variants caused invasion success, changed behavior or created resistance to control, and reports of as many as 30,000 snakes per square mile apply only to some parts of Guam; functional tests, comparison populations and management outcomes must still show what the recovered diversity did. [1]

-- KENJI NAKAMURA, Tokyo