Genetic characterization of invasive house mouse populations on small islands

Abstract

House mice (Mus musculus) have dispersed to nearly every major landmass around the globe as a result of human activity. They are a highly successful invasive species, but their presence can be devastating for native ecosystems. This is particularly true on small offshore islands where mouse populations may grow unchecked by predators. Here we use genome-wide SNP genotypes to examine ancestry and population structure on two islands of ecological interest - Southeast Farallon Island, near San Francisco, CA; and Floreana Island in the Galápagos - in the context of a total cohort of 520 mice with diverse geographic origins, as a first step towards genetically-based eradication campaigns. We show that Farallon and Floreana mice, like those from previously-studied islands in both the Atlantic and Pacific Oceans, are of admixed European ancestry. We find that these populations are on average more inbred than mainland ones and passed through a strong colonization bottleneck with little subsequent genetic exchange. Finally we show that rodenticide resistance alleles present in parts of Europe are absent from all island populations studied. Our results add nuance to previous studies of island populations based on mitochondrial sequences or small numbers of microsatellites and will be useful for future eradication and monitoring efforts.

Genetic tools in the management of invasive mammals: recent trends and future perspectives

“…Although these types of data (microsatellites and SNPs) and analyses (population structure and gene flow) are useful for planning and assessing the success of management and eradication programmes, an important consideration is the likely response of the invader to control or eradication measures, whether these be chemical or biological. For example, using a genome‐wide SNPs, Morgan et al () demonstrated that invasive house mice on islands off North and South America did not possess rodenticide resistance alleles that are present in parts of Europe (even though the study also found that these house mice were of European ancestry). This has important implications for subsequent eradication and control measures.…”

Invasive Species Control and Resolution of Wildlife Damage Conflicts: A Framework for Chemical and Genetically Based Management Methods

“…As gene drive effectiveness will be diminished by the influx of resistant individuals, relatively isolated populations with low levels of gene flow to nontarget populations, such as oceanic islands, would provide ideal settings. Small populations of introduced species, which are often founded by a small number of individuals, are also expected to harbor reduced allelic diversity, thereby providing a greater number of potential locally fixed allele targets (Morgan et al 2018). Overall, it is clear that the success of the LFA approach will depend on rigorous population genetic survey of allelic variation within the target population prior to any action.…”

Rodent gene drives for conservation: opportunities and data needs

“…The very limited results available so far suggest mice from commensal habitat backgrounds may be more competitive than mice from invasive island populations [83,84], but this needs more investigation and seems likely to vary depending on the specific island population considered. Additionally, any competitive advantage based on a different genetic background may need to be balanced against the potential negative consequences of introducing new alleles to island populations that show reduced genetic diversity [70] and potentially enhanced invasiveness elsewhere should gene drive carriers escape the target island. Runge & Lindholm [91] found that t-haplotype carriers showed increased migratory propensity within and from their naturalistic barn colony.…”

“…Island populations are often derived from few initial colonizers and genetic diversity is therefore typically reduced relative to mainland populations (e.g. [70]). This reduced diversity means there may be drive recognition sequences that are fixed in a target population, but absent in nearby non-target populations.…”