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Additional Information

Competing Interests

Leon G. Higley is an Academic Editor for PeerJ.

Author Contributions

Robert K Peterson analyzed the data, wrote the paper, prepared figures and/or tables, reviewed drafts of the paper.

Andrea C Varella analyzed the data, wrote the paper, reviewed drafts of the paper.

Leon G Higley wrote the paper.

Data Deposition

The following information was supplied regarding data availability:

The submitted manuscript is a review article.


The authors received no funding for this work.

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