PgmNr P2102: Genetics of skeletal evolution in unusually large mice from Gough Island.

Authors:
Michelle Parmenter 1 ; Melissa Gray 1 ; Caley Hogan 1 ; Irene Ford 1 ; Richard Cuthbert 2 ; Peter Ryan 3 ; Karl Broman 1 ; Christopher Vinyard 4


Institutes
1) University of Wisconsin-Madison, Madison, WI, USA; 2) The Royal Society for the Protection of Birds, The Lodge, Bedfordshire, UK; 3) University of Cape Town, Cape Town, South Africa; 4) Northeast Ohio Medical University, Rootstown, OH, USA.


Abstract:

Organisms on islands often undergo rapid morphological evolution, providing a platform for understanding mechanisms of phenotypic change. One example is the skeleton, which shows unusual patterns in island populations and forms an integral part of the vertebrate body plan. Although the genetic basis of skeletal variation has been studied extensively in laboratory strains, particularly in the house mouse Mus musculus domesticus, the genetic determinants of skeletal evolution in natural populations remain poorly understood. We used house mice living on the remote Gough Island, the heaviest wild house mice on record, to understand the genetics of rapid skeletal evolution in nature. Compared to a mainland reference strain from the same subspecies (WSB/EiJ), the skeleton of Gough Island mice has enlarged considerably. We used X-ray images to measure 16 skeletal dimensions (at 5, 10, and 16 weeks of age) that are designed to capture major changes in skeletal anatomy. Quantitative trait locus (QTL) mapping in a large F2 intercross between Gough Island mice and WSB/EiJ reveals a total of 198 QTL that control skeletal dimensions. QTL exhibit modest, mostly additive effects and Gough Island alleles are associated with larger skeletal size at most QTL. A large proportion of QTL co-localize across skeletal traits and body weight, an observation that may be explained by a high degree of pleiotropy. Our results provide a rare portrait of the genetic basis of skeletal evolution in an island population, and position the Gough Island mice as a model system for understanding the mechanisms of rapid evolution in nature.