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Updated: Apr 27, 2026
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Competitive Genomic Screens of Barcoded Yeast Libraries
Published on: August 11, 2011
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DNA barcoding works in practice but not in (neutral) theory.
Mark Y Stoeckle1, David S Thaler2
1Program for the Human Environment, The Rockefeller University, New York, New York, United States of America.
Plos One
|July 3, 2014
Summary
Intraspecific DNA barcode variation in birds is uniformly low, contradicting neutral evolution theories. Extreme purifying selection, not neutral processes, likely limits mitochondrial diversity within species.
Area of Science:
- Evolutionary Biology
- Genetics
- Ornithology
Background:
- DNA barcoding relies on greater interspecific than intraspecific variation.
- Neutral theory predicts intraspecific variation relates to population size (2Nµ).
- Avian species offer robust data due to known limits and census sizes.
Purpose of the Study:
- Investigate evolutionary mechanisms behind the DNA barcode gap.
- Test neutral theory's prediction of intraspecific variation (2Nµ) in birds.
- Examine if avian mitochondrial molecular clock rates align with neutral theory (µ).
Main Methods:
- Analyzed avian mitochondrial COI barcode data from 142 species.
- Re-analyzed avian cytochrome b data from 93 species.
- Correlated intraspecific variation with census population sizes.
Main Results:
- Intraspecific variation was uniformly low across diverse bird species and families.
- Low variation persisted irrespective of population size.
- Hybridization and gene flow were identified as limitations to DNA barcoding.
Conclusions:
- Universally low intraspecific variation contradicts neutral theory predictions.
- Neutral evolution appears to play a minor role in mitochondrial sequence evolution.
- Extreme purifying and adaptive selection may better explain observed patterns.
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