Chromosomal rearrangements as a source of local adaptation in island Drosophila
Authors: Brandon Turner 1; Theresa Miorin 2; Nick Stewart 3; Cathy Moore 1; Robert Reid 1; Rebekah Rogers 1
Affiliations: 1) University of North Carolina at Charlotte; 2) University of Georgia; 3) Fort Hayes State University
Keywords: c. chromosome structural variation; m. adaptation
Chromosomal rearrangements act as a source of genetic novelty by shuffling DNA throughout
the genome. These mutations can produce chimeric genes, induce de novo gene formation,
or alter gene expression changes for existing genes. Here, we explore how these mutations
may serve as agents of evolutionary change as populations adapt to new environments during
habitat shifts. We identify 16,480 rearrangements in mainland D. yakuba and two locally
adapted populations of D. santomea and D. yakuba on Sao Tome. Three loci that are associated
with signals of strong differentiation in D. santomea lie adjacent to UV resistance or
DNA repair genes, suggesting that these rearrangements confer selective advantages in high
altitude environments with greater UV stressors. Some 55% of these mutations are facilitated
by TE insertions, and 28% are TE facilitated ectopic recombination. In D. santomea
468 mutations are associated with strong signals of differentiation from the mainland while
in island D. yakuba we identify 383 candidates of local adaptation. A total of 49.4% of mutations
associated with signals of local adaptation also show signi cant changes in transcript
levels, suggesting that the adaptive value of rearrangements is related to effects on gene
expression. Together, this survey of structural variation identifies key modes of evolutionary
innovation that would be missed in SNP-based screens. This work offers a portrait of how
these mutations appear and help organisms to survive during habitat shifts, furthering our
understanding of evolutionary processes.