title: High mitochondrial mutation rates estimated from deep-rooting Costa Rican pedigrees.
abstract: Estimates of mutation rates for the noncoding hypervariable Region I (HVR-I) of mitochondrial DNA vary widely, depending on whether they are inferred from phylogenies (assuming that molecular evolution is clock-like) or directly from pedigrees. All pedigree-based studies so far were conducted on populations of European origin. In this article, we analyzed 19 deep-rooting pedigrees in a population of mixed origin in Costa Rica. We calculated two estimates of the HVR-I mutation rate, one considering all apparent mutations, and one disregarding changes at sites known to be mutational hot spots and eliminating genealogy branches which might be suspected to include errors, or unrecognized adoptions along the female lines. At the end of this procedure, we still observed a mutation rate equal to 1.24 × 10(-6) , per site per year, i.e., at least threefold as high as estimates derived from phylogenies. Our results confirm that mutation rates observed in pedigrees are much higher than estimated assuming a neutral model of long-term HVRI evolution. We argue that until the cause of these discrepancies will be fully understood, both lower estimates (i.e., those derived from phylogenetic comparisons) and higher, direct estimates such as those obtained in this study, should be considered when modeling evolutionary and demographic processes.
authors.affiliation: Department of Anthropology, University of South Florida, Tampa, FL 3360, USA.
authors.forename: Lorena
authors.initials: L
authors.lastname: Madrigal
authors.forename: Loredana Castrì
authors.initials: LC
authors.lastname: Posthumously
authors.forename: Mauricio
authors.initials: M
authors.lastname: Melendez-Obando
authors.forename: Ramon
authors.initials: R
authors.lastname: Villegas-Palma
authors.forename: Ramiro
authors.initials: R
authors.lastname: Barrantes
authors.forename: Henrieta
authors.initials: H
authors.lastname: Raventos
authors.forename: Reynaldo
authors.initials: R
authors.lastname: Pereira
authors.forename: Donata
authors.initials: D
authors.lastname: Luiselli
authors.forename: Davide
authors.initials: D
authors.lastname: Pettener
authors.forename: Guido
authors.initials: G
authors.lastname: Barbujani
mesh_terms: D000328:Adult; D003364:Costa Rica; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D014644:Genetic Variation / Q000235:genetics; D005828:Genetics, Population; D006801:Humans; D009035:Mothers; D059645:Mutation Rate; D010375:Pedigree
chemical_list: D004272:DNA, Mitochondrial