Advancements in our understanding of the genetic makeup of invasive rats point to gene drives as novel mitigation techniques for the future.
Invasive rat species like R. rattus (ship rats) and R. norvegicus (Norway rats) have been hitching a ride alongside sea travelers and adventurers from diverse locations for many generations. The adverse effects they have had on native wildlife and plants have been numerous and impactful. That is why New Zealand researchers from Auckland University sought to better understand the geographic origins and mitochondrial diversity of these invasive species. In a new study, scientists James Russell, Judith Robins, and Rachel Fewster attempted to track rat genes and their physical characteristics.
The study was conducted by collecting tissue samples from 425 R. rattus and 130 R. norvegicus throughout the New Zealand archipelago and nearby islands from 2001-2015. From here, researchers performed mitochondrial DNA sequencing. This helped them to create a “phylogeography”—using genetic information, they were able to determine the locations each of these species originated from.
This groundbreaking research could assist in a novel wildlife management technique known as gene editing or a gene drive. The GBIRd partnership is one of just a few groups in the world seeking to investigate the use of gene drives in invasive rodents for conservation purposes.
Gene drives are a naturally occurring phenomenon where a gene has a greater than 50% chance of being passed to offspring. Researchers believe using mitochondrial DNA is the best way to facilitate gene editing because mDNA is passed exclusively from mother to offspring and is consistently passed down generation to generation. Gene editing could alter the genetic information housed within mitochondrial DNA so that over time, a dominant gene is created; leading to either an all-male or all-female population. Ultimately, the invasive population would be rendered infertile and the remaining population would be far easier to remove utilizing existing methods.
This research is a beacon of hope for the future. As we learn more about the genetic makeup of invasive species and their origins, we are more prepared to implement gene editing mitigation approaches in the future in order to restore island ecosystems and prevent extinctions of threatened wildlife.