Red-necked keelback snakes possess a potent toxin derived from the toads they consume, which can cause severe harm to predators like mongooses. The snakes store these toxins in specialized nuchal glands.
An unnamed tourist saw it and told Aidan Moore, who works for Alcatraz City Cruises. Moore told SFGATE that he was initially skeptical, but the guest's iPhone footage left little room for doubt. The video shows, not a sea lion or an otter, but an actual Canis latrans, doggedly dogpaddling, then clambering out of the water, noticeably shaky and struggling to settle tired paws on the craggy rocks.
The work suggested that resistance arises from a relatively large number of sites, each with relatively minor effects. For example, the sites in the genome identified by quantitative trait analysis typically boosted resistance by about 10 points on the researchers' 100-point scale. In the genome-wide analysis, 17 individual genetic differences were associated with about a quarter of the heritable resistance traits.