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BioMed Research International
Volume 2016, Article ID 5761983, 13 pages
Research Article

-Index for Differentiating Complex Dynamic Traits

1School of Information, Beijing Forestry University, Beijing 100083, China
2Center for Computational Biology, Beijing Forestry University, Beijing 100083, China

Received 3 July 2015; Revised 28 October 2015; Accepted 11 February 2016

Academic Editor: Sílvia A. Sousa

Copyright © 2016 Jiandong Qi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


While it is a daunting challenge in current biology to understand how the underlying network of genes regulates complex dynamic traits, functional mapping, a tool for mapping quantitative trait loci (QTLs) and single nucleotide polymorphisms (SNPs), has been applied in a variety of cases to tackle this challenge. Though useful and powerful, functional mapping performs well only when one or more model parameters are clearly responsible for the developmental trajectory, typically being a logistic curve. Moreover, it does not work when the curves are more complex than that, especially when they are not monotonic. To overcome this inadaptability, we therefore propose a mathematical-biological concept and measurement, -index (earliness-index), which cumulatively measures the earliness degree to which a variable (or a dynamic trait) increases or decreases its value. Theoretical proofs and simulation studies show that -index is more general than functional mapping and can be applied to any complex dynamic traits, including those with logistic curves and those with nonmonotonic curves. Meanwhile, -index vector is proposed as well to capture more subtle differences of developmental patterns.