design: Approximately 500 ng of genomic DNA was fragmented using the type II-b restriction enzyme BcgI (New England Biolabs) to generate fragments of 36 bp in length. Illumina adapters were ligated to samples on both ends followed by unique indexed Illumina TruSeq PCR primers. Samples were amplified with 15 PCR cycles. The PCR products were purified using gel purification witha MinElute Gel Extraction Kit (Qiagen) and pooled into a final library at a 10 nM concentration.Samples were sequenced on an Illumina HiSeq 4000 using 50 bp single-end reads at the NUSeq Core facility of Northwestern University. Raw sequence reads were assessed for quality using FastQC and demultiplexed and trimmed using a custom script. Low quality reads were removed withFASTX-Toolkit version 0.0.14 with the following parameters: -Q 33 -q 20 -p 90.