Locomotion is important across mammals, and how body size and limb length correlate to locomotor performance can be critical to survival. However, we know little about the genetic architecture of limbs in mammals. Our goals were: 1) quantitatively characterize variation in limb lengths across inbred strains of house mice; 2) characterize the genetic architecture of phenotypic variation in limb elements; and 3) relate phenotypic variation in limb elements to measures of locomotor performance. We analyzed, using the SYSTAT program, limb dimensions of 435 females from 42 inbred mouse strains commonly used in laboratory research and compared them to body size. We found that fore- and hind-limb length were significantly different among strains demonstrating genetic contributions to limb lengths. Broad-sense genetic heritability (G2), or the ratio of total genetic to phenotypic variance, ranged from 0.80 (fore- and hindlimb length) to 0.27 (toe length) suggesting that a modest to considerable percentage of limb length is genetically determined in these mice. All limb dimensions exhibited strong genetic correlations with body weight, while limb shapes demonstrated negative correlations with body weight suggesting a size-correlated decrease in relative limb length across house mice. Among limb elements, we saw the highest genetic correlations in the hindlimb and between homologous elements of the limbs. Finally, we observed few correlations between limb elements and performance measures suggesting size plays a more significant role in performance than limb proportions. Overall, our results suggest that mice represent a strong model for studying the genetic architecture of limb elements in mammals.
Dr. Chris Vinyard
Locomotion is important across mammals; however, little is known about the genetic architecture of limbs in mammals. This project was threefold: 1) quantitatively characterize variation in limb lengths across inbred strains of house mice; 2) characterize the genetic architecture of phenotypic variation in limb elements; and 3) relate phenotypic variation in limb elements to measures of locomotor performance. We analyzed 435 female mice of 42 inbred strains commonly used in laboratories and compared them to body size, looked at broad-sense heritability, and analyzed various performance measurements in different studies previously done with these mice strains. We found many interesting aspects of genetic and phenotypic variability in and throughout the mice strains.