Evolutionary gain and loss of a pathological immune response to parasitism

• DOI: 10.1126/science.abo3411
• Publication Date: 2022-09-08T17:57:40Z
• Authors: Jesse N. Weber; Natalie C. Steinel; Foen Peng; Kum Chuan Shim; Brian K. Lohman; Lauren E. Fuess; Swapna Subramanian; Stephen P. De Lisle; Daniel I. Bolnick
• Keywords: 0301 basic medicine; Fish Diseases; Lakes; 03 medical and health sciences; Immunity; Animals; Cestoda; Smegmamorpha; Host-Parasite Interactions; 3. Good health

Parasites impose fitness costs on their hosts. Biologists often assume that natural selection favors infection-resistant Yet, when the immune response itself is costly, theory suggests may sometimes favor loss of resistance, which result in alternative stable states where some populations are resistant and others tolerant. Intraspecific variation rarely surveyed a manner tests evolutionary patterns, there few examples adaptive resistance. Here, we show marine threespine stickleback colonized freshwater lakes, they gained resistance to freshwater-associated cestode Schistocephalus solidus. Extensive peritoneal fibrosis inflammation commonly observed phenotype contributes suppression growth viability but also imposes substantial cost fecundity. Combining genetic mapping population genomics, find opposing generates system differences between tolerant populations, consistent with divergent optimization.