title: The red death meets the abdominal bristle: polygenic mutation for susceptibility to a bacterial pathogen in Caenorhabditis elegans.
abstract: Understanding the genetic basis of susceptibility to pathogens is an important goal of medicine and of evolutionary biology. A key first step toward understanding the genetics and evolution of any phenotypic trait is characterizing the role of mutation. However, the rate at which mutation introduces genetic variance for pathogen susceptibility in any organism is essentially unknown. Here, we quantify the per-generation input of genetic variance by mutation (VM) for susceptibility of Caenorhabditis elegans to the pathogenic bacterium Pseudomonas aeruginosa (defined as the median time of death, LT50). VM for LT50 is slightly less than VM for a variety of life-history and morphological traits in this strain of C. elegans, but is well within the range of reported values in a variety of organisms. Mean LT50 did not change significantly over 250 generations of mutation accumulation. Comparison of VM to the standing genetic variance (VG) implies a strength of selection against new mutations of a few tenths of a percent. These results suggest that the substantial standing genetic variation for susceptibility of C. elegans to P. aeruginosa can be explained by polygenic mutation coupled with purifying selection.
authors.affiliation: Department of Biology, University of Florida, P.O. Box 118525, Gainesville, Florida, 32611.
authors.forename: Veronique
authors.initials: V
authors.lastname: Etienne
authors.forename: Erik C
authors.initials: EC
authors.lastname: Andersen
authors.forename: José Miguel
authors.initials: JM
authors.lastname: Ponciano
authors.forename: Dustin
authors.initials: D
authors.lastname: Blanton
authors.forename: Analucia
authors.initials: A
authors.lastname: Cadavid
authors.forename: Joanna
authors.initials: J
authors.lastname: Joyner-Matos
authors.forename: Chikako
authors.initials: C
authors.lastname: Matsuba
authors.forename: Brandon
authors.initials: B
authors.lastname: Tabman
authors.forename: Charles F
authors.initials: CF
authors.lastname: Baer
mesh_terms: D000818:Animals; D005075:Biological Evolution; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000382:microbiology*; D004198:Disease Susceptibility / Q000382:microbiology; D014644:Genetic Variation; D009154:Mutation; D011552:Pseudomonas Infections / Q000235:genetics*; D011550:Pseudomonas aeruginosa
keywords: LT50; Pseudomonas aeruginosa; mutation accumulation; mutational bias; mutational variance; spontaneous mutation