title: Frequency-dependent survival in natural guppy populations.
abstract: The maintenance of genetic variation in traits under natural selection is a long-standing paradox in evolutionary biology. Of the processes capable of maintaining variation, negative frequency-dependent selection (where rare types are favoured by selection) is the most powerful, at least in theory; however, few experimental studies have confirmed that this process operates in nature. One of the most extreme, unexplained genetic polymorphisms is seen in the colour patterns of male guppies (Poecilia reticulata). Here we manipulated the frequencies of males with different colour patterns in three natural populations to estimate survival rates, and found that rare phenotypes had a highly significant survival advantage compared to common phenotypes. Evidence from humans and other species implicates frequency-dependent survival in the maintenance of molecular, morphological and health-related polymorphisms. As a controlled manipulation in nature, this study provides unequivocal support for frequency-dependent survival--an evolutionary process capable of maintaining extreme polymorphism.
authors.affiliation: School of Integrative Biology, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Olendorf
authors.forename: F Helen
authors.initials: FH
authors.lastname: Rodd
authors.forename: David
authors.initials: D
authors.lastname: Punzalan
authors.forename: Anne E
authors.initials: AE
authors.lastname: Houde
authors.forename: Carla
authors.initials: C
authors.lastname: Hurt
authors.forename: David N
authors.initials: DN
authors.lastname: Reznick
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Hughes
mesh_terms: D000818:Animals; D000835:Animals, Wild; D003116:Color; D005260:Female; D016013:Likelihood Functions; D008297:Male; D008954:Models, Biological; D010641:Phenotype; D010858:Pigmentation / Q000235:genetics / Q000502:physiology; D011036:Poecilia / Q000235:genetics / Q000502:physiology*; D011110:Polymorphism, Genetic / Q000235:genetics; D011157:Population Dynamics; D045483:Rivers; D015996:Survival Rate; D013997:Time Factors; D014300:Trinidad and Tobago