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Updated: Jun 8, 2026
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Following the Dynamics of Structural Variants in Experimentally Evolved Populations
Published on: February 3, 2023
Genomic patterns of pleiotropy and the evolution of complexity
Zhi Wang1, Ben-Yang Liao, Jianzhi Zhang
1Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA.
Summary
Most genes affect only a few traits, challenging previous models of pleiotropy. This study reveals that higher pleiotropy, or genes affecting many traits, actually enhances adaptation and complexity in organisms.
Area of Science:
- Genetics
- Evolutionary Biology
- Systems Biology
Background:
- Pleiotropy, where one gene influences multiple traits, is fundamental to biology but lacks empirical validation in theoretical models.
- Previous models of pleiotropy have not been extensively tested against real-world genomic data.
Purpose of the Study:
- To empirically investigate the genomic patterns of pleiotropy across different species.
- To analyze the relationship between gene pleiotropy, phenotypic effects, and organismal adaptation.
- To re-evaluate theoretical models of pleiotropy in light of genome-wide data.
Main Methods:
- Analysis of phenotypic data from large mutant collections in yeast, nematodes, and mice.
- Quantification of the fraction of traits affected by gene deletions.
- Statistical analysis of the distribution and scaling properties of gene pleiotropy and phenotypic effects.
Main Results:
- Most genes exhibit low pleiotropy, affecting only a small fraction of traits, and gene-trait relationships are highly modular.
- Genes with higher pleiotropy show larger per-trait phenotypic effects, contrary to expectations.
- A scaling property of pleiotropy counteracts the 'cost of complexity,' favoring intermediate organismal complexity for higher adaptation rates.
Conclusions:
- Genome-wide data necessitate significant revisions to existing theoretical models of pleiotropy.
- Observed patterns suggest pleiotropy has actively promoted, not hindered, the evolution of biological complexity.
- The modular nature and specific scaling of pleiotropy are key to understanding evolutionary trajectories.
Related Concept Videos
01:33Pleiotropy
Pleiotropy is the phenomenon in which a single gene impacts multiple, seemingly unrelated phenotypic traits. For example, defects in the SOX10 gene cause Waardenburg Syndrome Type 4, or WS4, which can cause defects in pigmentation, hearing impairments, and an absence of intestinal contractions necessary for elimination. This diversity of phenotypes results from the expression pattern of SOX10 in early embryonic and fetal development. SOX10 is found in neural crest cells that form melanocytes,...
02:37Gene Duplication and Divergence
The seminal work of Ohno in 1970 popularized the idea of gene duplication and divergence. DNA sequence comparison studies reveal that a large portion of the genes in bacteria, archaebacteria, and eukaryotes was generated by gene duplication and divergence, indicating its critical role in evolution.
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.
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While every living organism has a genome of some kind (be it RNA, or DNA), there is considerable variation in the sizes of these blueprints. One major factor that impacts genome size is whether the organism is prokaryotic or eukaryotic. In prokaryotes, the genome contains little to no non-coding sequence, such that genes are tightly clustered in groups or operons sequentially along the chromosome. Conversely, the genes in eukaryotes are punctuated by long stretches of non-coding sequence.
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02:05Gene Evolution - Fast or Slow?
The genomes of eukaryotes are punctuated by long stretches of sequence which do not code for proteins or RNAs. Although some of these regions do contain crucial regulatory sequences, the vast majority of this DNA serves no known function. Typically, these regions of the genome are the ones in which the fastest change, in evolutionary terms, is observed, because there is typically little to no selection pressure acting on these regions to preserve their sequences.
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