Mouse (Mus musculus) stocks derived from tropical islands: new models for genetic analysis of life-history traits

Abstract

Founder effects, together with access to unoccupied ecological niches, may allow rodent populations on isolated islands to evolve constellations of life-history traits that distinguish them from their mainland relatives, for example in body size, litter size, and longevity. In particular, low intrinsic mortality risks on islands with reduced predator numbers and not subject to harsh winter climates may in principle support the development of stocks with extended longevity. Conversely, the conditions under which laboratory rodents are typically bred are thought to select for genotypes that produce large, rapidly maturing races with high early reproductive rates but diminished longevity. To test these ideas, and to generate new mouse stocks suitable for genetic and molecular analysis of the processes that time life-history events, we have developed speci®c pathogen-free stocks from mice trapped from three distinct populations: the U.S. mainland (Idaho) and the tropical Paci®c islands Majuro and Pohnpei. Mice from all three locations were found to be shorter and lighter, to have smaller litters, and to have higher faecal corticosterone levels than mice of a genetically heterogeneous stock derived from four common laboratory inbred strains. Among the wild-derived stocks, mice from Pohnpei and Majuro were signi®cantly lighter and shorter than Idahoderived animals, even in populations kept from birth under identical housing conditions. Litter size and reproductive success rates did not differ signi®cantly among the three wild-derived stocks. Although further work will be needed to see if, as predicted, the wild-derived stocks differ from one another and from laboratory mice in longevity, these stocks provide useful tools for genetic dissection of factors that regulate body size and reproductive success.

Methionine‐deficient diet extends mouse lifespan, slows immune and lens aging, alters glucose, T4, IGF‐I and insulin levels, and increases hepatocyte MIF levels and stress resistance

“…(2) Are mice of other strains, and genetically heterogeneous mice, also susceptible to lifespan extension by Meth-R? (3) Is the longevity effect seen only in mice whose genes have been selected for laboratory confinement, or would it be demonstrable as well in wild-derived mouse stocks, which are longer-lived than laboratory-adapted strains (Miller et al ., 2000(Miller et al ., , 2002b? (4) What is the optimal regimen for lifespan extension by Meth-R diets?…”

Big mice die young: early life body weight predicts longevity in genetically heterogeneous mice

“…Our new data suggest that this relationship may be a general one, not restricted to the products of artificial selection for extremes in growth rate or body size. It is noteworthy that laboratory-adapted mouse stocks, such as the progenitors of the inbred lines from which our UM-HET3 mice are derived, are larger in body weight (Miller et al ., 2000b) and body dimensions (Harper et al , unpublished observations) than laboratory-raised stocks derived from recently wild-trapped progenitors. Furthermore, the small size of wild-derived mice is associated with an increase of 24% in mean life span and a 16% increase in maximum life span of the longest lived animals (Miller et al ., unpublished observations).…”

Genetic engineering to eradicate invasive mice on islands: modeling the efficiency and ecological impacts

“…In most situations, GE organisms would be expected to have a lower survival rate than their wild counterparts. This is because engineered genes tend to impose a fitness cost on individuals that carry them (Catteruccia et al 2003, Marrelli et al 2006) and because the t-Sry construct would be engineered in laboratory mice that would not be adapted to surviving in island ecosystems (Miller et al 2000). Some of these costs could be reduced by backcrossing laboratory-derived t-Sry mice with wild-derived varieties.…”

“…Alternatively, we also consider the theoretical possibility that the t-Sry construct could be selfsustaining, in the sense that the GE construct would remain in the population without additional releases. There are a wide variety of wild M. musculus populations throughout the world, each with unique genetic traits (Miller et al 2000, Chalfin et al 2014, including differences in lifespan, maturation rates (Miller et al 2002), and competitive ability (Cunningham et al 2013). Additionally, some M. musculus populations could be theoretically less susceptible to climate stress, predators, or pathogens.…”