On the Order of Gene Distribution on Chromosomes Across the Animal Kingdom

TL;DR

This study reveals that gene distribution on chromosomes across various animal species follows a mathematical pattern, becoming more dispersed as organism complexity increases, indicating an ordered evolutionary process.

Contribution

It demonstrates that gene distribution across animal genomes is non-random and follows a specific inverse relationship with chromosome number, a novel insight into genome organization.

Findings

Gene content increases with genome size.

Gene distribution follows an inverse square root relationship with chromosome number.

Genes become more dispersed as organism complexity increases.

Abstract

Background. The large-scale pattern of distribution of genes on the chromosomes in the known animal genomes is not well characterized. We hypothesized that individual genes will be distributed on chromosomes in a mathematically ordered manner across the animal kingdom. Results. Twenty-one animal genomes reported in the NCBI database were examined. Numerically, there was a trend towards increasing overall gene content with increasing size of the genome as reflected by the chromosomal complement. Gene frequency on individual chromosomes in each animal genome was analyzed and demonstrated uniformity of proportions within each animal with respect to both average gene frequency on individual chromosomes and gene distribution across the unique genomes. Further, average gene distribution across animal species followed a relationship whereby it was, approximately, inversely proportional to the square root of the number of chromosomes in the unique animal genomes, consistent with the notion that there is an ordered increase in gene dispersion as the complexity of the genome increased. To further corroborate these findings a derived measure, termed gene spacing on chromosomes correlated with gene frequency and gene distribution. Conclusion. As animal species have evolved, the distribution of their genes on individual chromosomes and within their genomes, when viewed on a large scale is not random, but follows a mathematically ordered process, such that as the complexity of the organism increases, the genes become less densely distributed on the chromosomes and more dispersed across the genome.