Multilevel and kin selection in a connected world.
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.
Wade
Michael J
MJ
Department of Biology, Indiana University, Bloomington, Indiana 47405, USA. mjwade@indiana.edu
Wilson
David S
DS
Goodnight
Charles
C
Taylor
Doug
D
Bar-Yam
Yaneer
Y
de Aguiar
Marcus A M
MA
Stacey
Blake
B
Werfel
Justin
J
Hoelzer
Guy A
GA
Brodie
Edmund D
ED
Fields
Peter
P
Breden
Felix
F
Linksvayer
Timothy A
TA
Fletcher
Jeffrey A
JA
Richerson
Peter J
PJ
Bever
James D
JD
Van Dyken
J David
JD
Zee
Peter
P
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