BALANCING SELECTION, RANDOM GENETIC DRIFT, AND GENETIC VARIATION AT THE MAJOR HISTOCOMPATIBILITY COMPLEX IN TWO WILD POPULATIONS OF GUPPIES (POECILIA RETICULATA)

Evolution ◽  
2006 ◽  
Vol 60 (12) ◽  
pp. 2562 ◽  
Author(s):  
Cock van Oosterhout ◽  
Domino A. Joyce ◽  
Stephen M. Cummings ◽  
Jonatan Blais ◽  
Nicola J. Barson ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Major Histocompatibility Complex ◽  
Genetic Drift ◽  
Poecilia Reticulata ◽  
Balancing Selection ◽  
Random Genetic Drift ◽  
Major Histocompatibility ◽  
Wild Populations ◽  
Histocompatibility Complex

scholarly journals Major histocompatibility complex selection dynamics in pathogen-infected túngara frog ( Physalaemus pustulosus ) populations

2016 ◽  
Vol 12 (8) ◽  
pp. 20160345 ◽  
Author(s):  
Tiffany A. Kosch ◽  
Arnaud Bataille ◽  
Chelsea Didinger ◽  
John A. Eimes ◽  
Sofia Rodríguez-Brenes ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Balancing Selection ◽  
Directional Selection ◽  
Major Histocompatibility ◽  
Physalaemus Pustulosus ◽  
Mhc Ii ◽  
Histocompatibility Complex ◽  
Selection Dynamics

Pathogen-driven selection can favour major histocompatibility complex (MHC) alleles that confer immunological resistance to specific diseases. However, strong directional selection should deplete genetic variation necessary for robust immune function in the absence of balancing selection or challenges presented by other pathogens. We examined selection dynamics at one MHC class II (MHC-II) locus across Panamanian populations of the túngara frog, Physalaemus pustulosus , infected by the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd). We compared MHC-II diversity in highland túngara frog populations, where amphibian communities have experienced declines owing to Bd, with those in the lowland region that have shown no evidence of decline. Highland region frogs had MHC variants that confer resistance to Bd. Variant fixation appeared to occur by directional selection rather than inbreeding, as overall genetic variation persisted in populations. In Bd-infected lowland sites, however, selective advantage may accrue to individuals with only one Bd-resistance allele, which were more frequent. Environmental conditions in lowlands should be less favourable for Bd infection, which may reduce selection for specific Bd resistance in hosts. Our results suggest that MHC selection dynamics fluctuate in túngara frog populations as a function of the favourability of habitat to pathogen spread and the vulnerability of hosts to infection.

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