Nuclear gene variation in wild brown rats

Area of Science:

• Genetics
• Evolutionary Biology
• Mammalian Biology

Background:

• The brown rat (Rattus norvegicus) is a key model organism in scientific research.
• Limited understanding exists regarding genetic variation within wild rat populations and their relationship to laboratory strains.

Purpose of the Study:

• To investigate nucleotide diversity and population structure in wild brown rat populations.
• To compare genetic diversity between the presumed ancestral range in China and a derived population in the UK.
• To estimate the effective population size of brown rats and compare it to wild house mice.

Main Methods:

• Sequencing of 30 autosomal protein-coding loci from wild brown rats.
• Analysis of genetic variation, nucleotide diversity, and population subdivision (using Fst and STRUCTURE).
• Estimation of effective population size based on synonymous diversity and divergence.

Main Results:

• Neutral genetic diversity in wild brown rats was approximately 0.2%, significantly lower than in wild house mice.
• Significant population differentiation was observed between Chinese and UK brown rat populations.
• The estimated recent effective population size for brown rats was approximately 130,000, about fivefold lower than for wild house mice.

Conclusions:

• Wild brown rat populations exhibit low genetic diversity and significant structure.
• Laboratory strains may not fully represent the genetic diversity of wild populations.
• The lower effective population size of brown rats has implications for their evolutionary trajectory and use as a model organism.