Demystifying the RAD fad.

Area of Science:

• Molecular Ecology
• Population Genomics
• Bioinformatics

Background:

• Restriction-site-associated DNA (RAD) sequencing is a widely used method in molecular ecology for population genomics.
• A recent review suggested the original RAD protocol minimizes PCR artifacts, a claim this study addresses.
• Several RAD sequencing variants exist, each with unique strengths and weaknesses.

Purpose of the Study:

• To challenge the assertion that the original RAD protocol is superior in minimizing PCR artifacts.
• To identify and discuss other significant biases in RAD sequencing protocols.
• To compare the strengths and weaknesses of four representative RADseq approaches.

Main Methods:

• Comparative analysis of four RAD sequencing protocols: original RAD (mbRAD), double digest RAD (ddRAD), ezRAD, and 2bRAD.
• Evaluation of PCR duplicate identification and other potential biases impacting allele frequency estimates.
• Literature review and critical assessment of published RADseq methodologies.

Main Results:

• The original RAD protocol is not necessarily superior in minimizing PCR artifacts compared to other variants.
• RADseq protocols are subject to various biases beyond PCR duplicates, including those affecting allele frequency estimation.
• Each RADseq method (mbRAD, ddRAD, ezRAD, 2bRAD) presents a distinct profile of advantages and limitations.

Conclusions:

• Researchers must consider multiple biases, not just PCR artifacts, when selecting a RAD sequencing protocol.
• A nuanced understanding of different RADseq methods is crucial for informed decision-making in population genomics studies.
• The choice of RADseq protocol should be tailored to specific research questions and data requirements.