title: Developmental and genetic origins of murine long bone length variation.
abstract: If we wish to understand whether development influences the rate or direction of morphological evolution, we must first understand the developmental bases of morphological variation within species. However, quantitative variation in adult morphology is the product of molecular and cellular processes unfolding from embryonic development through juvenile growth to maturity. The Atchley-Hall model provides a useful framework for dissecting complex morphologies into their component parts as a way of determining which developmental processes contribute to variation in adult form. We have examined differences in postnatal allometry and the patterns of genetic correlation between age-specific traits for ten recombinant inbred strains of mice generated from an intercross of LG/J and SM/J. Long bone length is closely tied to body size, but variation in adult morphology is more closely tied to differences in growth rate between 3 and 5 weeks of age. These analyses show that variation generated during early development is overridden by variation generated later in life. To more precisely determine the cellular processes generating this variation we then examined the cellular dynamics of long bone growth plates at the time of maximum elongation rate differences in the parent strains. Our analyses revealed that variation in long bone length is the result of faster elongation rates of the LG/J stain. The developmental bases for these differences in growth rate involve the rate of cell division and chondrocyte hypertrophy in the growth plate.
authors.affiliation: Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts 02138, USA. tsanger@oeb.harvard.edu
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Sanger
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Norgard
authors.forename: L Susan
authors.initials: LS
authors.lastname: Pletscher
authors.forename: Michael
authors.initials: M
authors.lastname: Bevilacqua
authors.forename: Victoria R
authors.initials: VR
authors.lastname: Brooks
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Sandell
authors.forename: James M
authors.initials: JM
authors.lastname: Cheverud
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001846:Bone Development / Q000235:genetics*; D001842:Bone and Bones / Q000033:anatomy & histology*; D015331:Cohort Studies; D003433:Crosses, Genetic; D005260:Female; D014644:Genetic Variation; D006132:Growth Plate / Q000502:physiology*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development*; D018709:Statistics, Nonparametric