Repeated Selection of Alternatively Adapted Haplotypes Creates Sweeping Genomic Remodeling in Stickleback

Genetics: A Periodical Record of Investigations Bearing on Heredity and Variation

article

Susan Bassham¹  Julian Catchen²  Emily Lescak³  Frank A. von Hippel⁵  William A. Cresko¹ 

[1] Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon 97403;Department of Animal Biology, University of Illinois at Urbana–Champaign, Illinois 61801;Department of Biological Sciences, University of Alaska Anchorage, Alaska 99508;College of Fisheries and Ocean Science, University of Alaska Fairbanks, Alaska 99775;Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona 86011;Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, Arizona 86011

关键词: contemporary evolution;    ecological divergence;    population genomics;    Gasterosteus aculeatus;    threespine stickleback;   

DOI  :  10.1534/genetics.117.300610

学科分类：医学（综合）

来源: Genetics Society of America

【 摘 要 】

Heterogeneous genetic divergence can accumulate across the genome when populations adapt to different habitats while still exchanging alleles. How long does diversification take and how much of the genome is affected? When divergence occurs in parallel from standing genetic variation, how often are the same haplotypes involved? We explore these questions using restriction site-associated DNA sequencing genotyping data and show that broad-scale genomic repatterning, fueled by copious standing variation, can emerge in just dozens of generations in replicate natural populations of threespine stickleback fish ( Gasterosteus aculeatus ). After the catastrophic 1964 Alaskan earthquake, marine stickleback colonized newly created ponds on seismically uplifted islands. We find that freshwater fish in these young ponds differ from their marine ancestors across the same genomic segments previously shown to have diverged in much older lake populations. Outside of these core divergent regions the genome shows no population structure across the ocean–freshwater divide, consistent with strong local selection acting in alternative environments on stickleback populations still connected by significant gene flow. Reinforcing this inference, a majority of divergent haplotypes that are at high frequency in ponds are detectable in the sea, even across great geographic distances. Building upon previous population genomics work in this model species, our data suggest that a long history of divergent selection and gene flow among stickleback populations in oceanic and freshwater habitats has maintained polymorphisms of alternatively adapted DNA sequences that facilitate parallel evolution.

【 授权许可】

CC BY