The brown treesnake (Boiga irregularis), native to northern coastal Australia, eastern Indonesia, Papua New Guinea and islands in northwestern Melanesia, has been decimating native bird and reptile populations on the island of Guam since the 1940s where it is an invasive species.
The rear-fanged, mildly venomous snake that grows to up to two meters in length, appears to have thrived on Guam despite only a handful of specimens making up the founding stock of this species. The snake, rather than succumbing to the lack of genetic diversity, has adapted quite well given its genetic limitations on the island, according to a study published in the journal Science Advances.
The researchers determined that while the brown treesnake has endured an extreme bottleneck in its genetics, they found “extensive diversity in the form of nearly 19,000 genomic structural variants.” This is enough DNA, the researchers say to “provide material for “rescuing” the population from inbreeding-drive declines.”
Invasive Brown Tree Snakes On Guam Killing Birds Too Large To Swallow
This essentially means that despite the limited genetics of this species on the island in which they are invasive, they have found a way to thrive, “providing a mechanism for rapid evolution of gene-linked diversity,” in spite of the genetic bottleneck from the fact that the snake is on an island in which they are not native and there are no diverse populations of the species.
This throws into question the notion that animals, or in this case, reptiles, lacking genetic diversity within a population, would cause reduced capability of that population to thrive in an environment in which they are not exposed to a wider array of genetics. Though there are documented cases in which populations that lack genetic diversity do not suffer any less than a population with a wider genetic variation and there are also documented instances in which highly inbred populations of fish and Tasmanian devils exhibit rapid and adaptive evolution.
In reptiles, the lack of genetic diversity yet still offering a thriving population can be seen in the Brahminy blindsnake (Indotyphlops braminus), the Burmese python (Python bivittatus) in Florida, island reptiles such as the Seychelles giant tortoise (Aldabrachelys gigantea hololissa) and island bound skinks and geckos.
The complete paper, “Genomic structural variation rescues a classic biological invader from a population bottleneck” can be read on the Science Advances website.
Brown Tree Snake Information
The brown tree snake has caused all sorts of problems on Guam. In addition to effectively changing that island’s ecology, the snake has caused power failures and efforts to eradicate it have cost millions of dollars. The snake is responsible for the extinction of nine native forest birds on Guam and three lizard species. Other bird species on the island have been significantly impacted by this snake and certain sea bird species no longer nest there. With these birds removed from the ecosystem, the island’s spider populations have gone largely unchecked, according to a study published in the journal PLoS One.
Prior to the introduction of the brown tree snake on Guam, there were ten native birds that were known to eat insects: Bridled White-eye (Zosterops conspicillatus), Rufous Fantail (Rhipidura rufifrons), Micronesian Starling (Aplonis opaca), Mariana Swiftlet (Aerodramus bartschi), Cardinal Honeyeater (Myzomela rubratra), Nightingale Reed-Warbler (Acrocephalus luscinia), Mariana Crow (Corvus kubaryi), Micronesian Kingfisher (Todiramphus cinnamominus), Guam Flycatcher (Myiagra freycineti), and the Guam Rail (Gallirallus owstoni).
The snake is a nocturnal, rear fanged venomous species of the family Colubridae. It is native to northern Australia, New Guinea, and the Solomon Islands. It averages two to four feet in length, with the largest specimen captured on Guam measuring 10 feet. It feeds on lizards, rats, birds, shrews, and other small animals.
