Data from: Frequency dependence limits divergent evolution by favouring rare immigrants over residents
Bolnick, Daniel I., The University of Texas at Austin
Stutz, William E., The University of Texas at Austin
Published Apr 01, 2018 on Dryad.
Cite this dataset
Bolnick, Daniel I.; Stutz, William E. (2018). Data from: Frequency dependence limits divergent evolution by favouring rare immigrants over residents [Dataset]. Dryad. https://doi.org/10.5061/dryad.61kr4
Two distinct forms of natural selection promote adaptive biological diversity. Divergent selection occurs when different environments favour different phenotypes, leading to increased differences between populations. Negative frequency-dependent selection occurs when rare variants within a population are favoured over common ones, increasing diversity within populations. These two diversifying forces promote genetic variation at different spatial scales, and may act in opposition, but their relative effects remain unclear because they are rarely measured concurrently. Here we show that negative frequency-dependent selection within populations can favor rare immigrants over locally adapted residents. We reciprocally transplanted lake and stream ecotypes of threespine stickleback into lake and stream habitats, while manipulating the relative abundance of residents versus immigrants. We found negative frequency-dependence: survival was highest for the locally rare ecotype, rather than natives. Also, individuals with locally rare major histocompatibility complex (MHC) class IIb genotypes were infected by fewer parasites. This negative frequency-dependent selection will tend to favour rare immigrants over common residents, amplifying the effect of migration and undermining the efficacy of divergent natural selection to drive population differences. The only signal of divergent selection was a tendency for foreign fish to have higher parasite loads than residents, after controlling for MHC genotype rarity. Frequency-dependent ecological interactions have long been thought to promote speciation. Our results suggest a more nuanced view in which negative frequency dependence alters the fate of migrants to promote or constrain evolutionary divergence between populations.
Data on stickleback origin, destination, treatment, phenotype, sex, growth, and survival
Parasite load data on control and recaptured caged stickleback.
MHC class IIb exon 2 genotype data from released and recaptured stickleback.
Converts MHC DNA sequence haplotype identifiers into amino acid sequence identifiers
FASTA file of MHC sequence reads
Aligned sequences of inferred alleles of MHC IIb exon 2.