Invasive monk parakeets come from one small region

Introduced species that are able to successfully establish and become invasive usually come from a very small sample of the native gene pool and so have little genetic variability.  By evaluating the genetic make-up of the introduced population and compare it to samples from the native population, researchers can sometimes define the origin of the introduced species.

monk parakeet (Myiopsitta monachus) by Stephanie Sanchez, Bugwood.org

The monk parakeet (Myiopsitta monachus) is from South America and is now found in North America, Europe, and Africa where it was sold as pets for many years.  Evaluation of the genetic information within mitochondrial DNA and nuclear microsatellites showed that all of the established invasive populations within Europe and North America are from the same haplotype (groups of DNA sequence variations).  This haplotype, called Monarch1, only occurs in two small populations in its native range, Entre Ríos, Argentina and Rio Grande do Sul, Brazil, and it is uncommon even in its native population.  The low genetic diversity doesn't seem to be affecting the invasive populations success in any of the sampled locations.

Source Article: All invasive parakeets come from a small region in South America