title: Impacts of genetic correlation on the independent evolution of body mass and skeletal size in mammals.
abstract: BACKGROUND
  Mammals show a predictable scaling relationship between limb bone size and body mass. This relationship has a genetic basis which likely evolved via natural selection, but it is unclear how much the genetic correlation between these traits in turn impacts their capacity to evolve independently. We selectively bred laboratory mice for increases in tibia length independent of body mass, to test the hypothesis that a genetic correlation with body mass constrains evolutionary change in tibia length.
  
  
  RESULTS
  Over 14 generations, we produced mean tibia length increases of 9-13%, while mean body mass was unchanged, in selectively bred mice and random-bred controls. Using evolutionary scenarios with different selection and quantitative genetic parameters, we also found that this genetic correlation impedes the rate of evolutionary change in both traits, slowing increases in tibia length while preventing decreases in body mass, despite the latter's negative effect on fitness.
  
  
  CONCLUSIONS
  Overall, results from this ongoing selection experiment suggest that parallel evolution of relatively longer hind limbs among rodents, for example in the context of strong competition for resources and niche partitioning in heterogeneous environments, may have occurred very rapidly on geological timescales, in spite of a moderately strong genetic correlation between tibia length and body mass.
authors.affiliation: Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N4N1, Canada. mmarchin@ucalgary.ca.
authors.forename: Marta
authors.initials: M
authors.lastname: Marchini
authors.affiliation: Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N4N1, Canada. lmsparro@ucalgary.ca.
authors.forename: Leah M
authors.initials: LM
authors.lastname: Sparrow
authors.affiliation: Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N4N1, Canada. mncosman@ucalgary.ca.
authors.forename: Miranda N
authors.initials: MN
authors.lastname: Cosman
authors.affiliation: Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N4N1, Canada. dowhanik@ualberta.ca.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Dowhanik
authors.affiliation: Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N4N1, Canada. cbkruege@ucalgary.ca.
authors.forename: Carsten B
authors.initials: CB
authors.lastname: Krueger
authors.affiliation: Department of Anatomy and Cell Biology, Faculty of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N4N1, Canada. bhallgri@ucalgary.ca.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Hallgrimsson
authors.affiliation: Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N4N1, Canada. cprolian@ucalgary.ca.
authors.forename: Campbell
authors.initials: C
authors.lastname: Rolian
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001835:Body Weight; D051379:Mice / Q000033:anatomy & histology* / Q000145:classification / Q000235:genetics* / Q000502:physiology; D012641:Selection, Genetic; D013977:Tibia / Q000033:anatomy & histology