In the Dune area of Meijendel, close to Leiden, a population of crested newts occurs. The history of this population is dodgy. While genetic data could not confirm that this population is introduced, the isolated position and apparent rapid expansion speak in favor of such a scenario. Previously we reported on an aberrantly colored newt from this population, with a pattern reminding of a Koi carp. Last spring we caught another odd individual, this time almost completely pale yellow.

Catching two of these weird newts in rapid succession in the same area: surely that cannot be a coincidence? I suspect this high freak-frequency fits with an introduction history for the Meijendel crested newts. The establishment of an introduced population involves similar genetic bottlenecking and inbreeding dynamics as the establishment of island populations and island populations also tend to show a higher incidence of color deviations.

Reference: Elfering, R., Bijlsma, L., Mannix, S., Plomp, S., Theodoropoulos, A., Wielstra, B. (2023). Kamsalamanders met kleurafwijking uit Meijendel. Holland’s Duinen 83: 38-39.