title: Multilevel and kin selection in a connected world.
abstract: Wild et al. argue that the evolution of reduced virulence can be understood from the perspective of inclusive fitness, obviating the need to evoke group selection as a contributing causal factor. Although they acknowledge the mathematical equivalence of the inclusive fitness and multilevel selection approaches, they conclude that reduced virulence can be viewed entirely as an individual-level adaptation by the parasite. Here we show that their model is a well-known special case of the more general theory of multilevel selection, and that the cause of reduced virulence resides in the opposition of two processes: within-group and among-group selection. This distinction is important in light of the current controversy among evolutionary biologists in which some continue to affirm that natural selection centres only and always at the level of the individual organism or gene, despite mathematical demonstrations that evolutionary dynamics must be described by selection at various levels in the hierarchy of biological organization.
authors.affiliation: Department of Biology, Indiana University, Bloomington, Indiana 47405, USA. mjwade@indiana.edu
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Wade
authors.forename: David S
authors.initials: DS
authors.lastname: Wilson
authors.forename: Charles
authors.initials: C
authors.lastname: Goodnight
authors.forename: Doug
authors.initials: D
authors.lastname: Taylor
authors.forename: Yaneer
authors.initials: Y
authors.lastname: Bar-Yam
authors.forename: Marcus A M
authors.initials: MA
authors.lastname: de Aguiar
authors.forename: Blake
authors.initials: B
authors.lastname: Stacey
authors.forename: Justin
authors.initials: J
authors.lastname: Werfel
authors.forename: Guy A
authors.initials: GA
authors.lastname: Hoelzer
authors.forename: Edmund D
authors.initials: ED
authors.lastname: Brodie
authors.forename: Peter
authors.initials: P
authors.lastname: Fields
authors.forename: Felix
authors.initials: F
authors.lastname: Breden
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Linksvayer
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Fletcher
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Richerson
authors.forename: James D
authors.initials: JD
authors.lastname: Bever
authors.forename: J David
authors.initials: JD
authors.lastname: Van Dyken
authors.forename: Peter
authors.initials: P
authors.lastname: Zee
mesh_terms: D000818:Animals; D056084:Genetic Fitness / Q000502:physiology*; D008954:Models, Biological; D010271:Parasites / Q000235:genetics* / Q000472:pathogenicity*; D012641:Selection, Genetic / Q000502:physiology*; D014774:Virulence / Q000235:genetics / Q000502:physiology