Presentation Detail

Evolutionary Genetics and/or Genomics

Lescak, Emily [1], Bassham, Susan [2], Catchen, Julian [2], Sherbick, Mary [1], von Hippel, Frank [1], Cresko, William [2].

Genomic patterns of rapid evolution in 50 year old threespine stickleback populations from seismically uplifted islands in Alaska.

The 1964 Alaska Earthquake was a massive geological event that uplifted marine terraces on islands in Prince William Sound and the Gulf of Alaska. We identified water bodies on newly exposed terraces on Middleton, Montague, and Danger Islands through comparisons of pre- and post-1964 aerial imagery and maps. Resident freshwater and oceanic threespine stickleback (Gasterosteus aculeatus) collected from these new freshwater ponds as well as nearby oceanic sites demonstrate marked phenotypic divergence, suggesting recent and rapid morphological evolution. To characterize the genetic variability underlying morphological change, we examined genome-wide variation through analysis of thousands of SNP genotypes. Using RAD-seq based measures of genetic diversity, STRUCTURE analyses, AMOVA, and principle components analyses, we characterize patterns of genetic variation among stickleback at different geographic scales: these islands, mainland Alaska (Cook Inlet), and coastal Oregon. Pairwise F_ST comparisons are consistent with recent colonization of freshwater by ancestral oceanic stickleback. Supporting the expectation of a recent origin for these populations, most of the genetic variation is partitioned across individuals. Levels of nucleotide diversity and F_IS suggest recurrent gene flow between coastal freshwater and oceanic populations. Our results are consistent with previous findings of low levels of genetic divergence among oceanic populations sampled hundreds to thousands of kilometers from each other. Due to their recent origin and morphological differentiation, these stickleback populations present the rare opportunity to study the early stages of phenotypic and genotypic divergence within a natural ecological context.

1 - University of Alaska Anchorage, Biological Sciences, Ecosystems and Biomedical Laboratory, 3151 Alumni Loop, Anchorage, AK, 99508, USA
2 - University of Oregon, Institute of Ecology and Evolution, 335 Pacific Hall, 5289 University of Oregon, Eugene, OR, 97403, USA

Keywords:
Adaptation
Gasterosteus aculeatus
RAD-seq
phylogeography.

Presentation Type: Regular Oral Presentation
Session: 25
Location: Cotton D/Snowbird Center
Date: Saturday, June 22nd, 2013
Time: 2:30 PM
Number: 25005
Abstract ID:529
Candidate for Awards:W.D. Hamilton Award for Outstanding Student Presentation