A team of scientists has tracked the invasion history of monk parakeets and discovered some interesting findings.

Thanks to the pet trade, thousands of monk parakeets (Myiopsitta monachus) began appearing in the United States in the 1960s and in Europe in the 1980s. Now it appears that these two separate invasions actually originated from the same small area in South America, likely located in Uruguay, according to the study.

The study, published in the journal Molecular Ecology, also found that the North American and European monk parakeets have lower genetic diversity in their invasive populations compared to the genetic diversity in native populations. That's particularly interesting to scientists, given that invasive species are more likely to survive with greater genetic diversity. A more diverse gene pool means more variety in traits of individuals for natural selection to act upon and allow the species to survive and thrive in a new area.

Until now, researchers knew very little about how genetics play a role in the establishment of invasive species like monk parakeets. But this latest research could help shed light on the ingredients required for a successful invasion.

During the study, an international team of researchers based at institutions in Spain, the United States, Canada and Australia used mitochondrial DNA and microsatellite genotypic data to investigate the levels of genetic variation and to reconstruct the history of parakeet invasions.

Based on the results, scientists speculated as to why these bright green birds boasted such similar genetic patterns in both the US and European invasions.

"One possibility is that these invasive populations may be under similar selection pressures. Most of the invasive populations are restricted to urban and suburban habitats, which may be selecting for some key traits that increase fitness of individuals in those environments," co-author Elizabeth Hobson explained in a statement.

"It could make it easier for a species to invade a new area and survive, or it could inhibit invasions in other circumstances," she added.

Starting in the late 1960s, tens of thousands of parakeets were imported to the United States as pets. Many birds have been released either deliberately or by accident by their owners, and some may have also escaped during transport. The monk parakeet has now been documented in at least 14 US states with the highest concentrations in Florida and Texas. They can also be found in nests atop utility poles in many urban areas such as New York City and Chicago, where they form large, noisy flocks that can be heard for great distances.

And like in their native South America, these parakeets could become crop pests in the United States as well, especially in Florida. Although so far these non-native birds have had minimal impacts, they could eat cereal grain and citrus fruits important to the agriculture industry and cause problems for electrical companies with their massive nests.

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