Primate Speciation Links to Massive and Directional Shrinkage of the Dinucleotide Short Tandem Repeat Compartment.

Abstract

The evolutionary trend of short tandem repeats (STRs) at the crossroads of speciation remains largely elusive and attributed to random evolution for the most part. Here we investigated the dinucleotide STR compartment in primate speciation. We selected six species, which shared sequential chronological ancestors, including mouse, macaque, gorilla, chimpanzee, bonobo, and human, and collected three sets of data on the abundance of all classes of dinucleotide STRs (≥6-repeats) for three regions of every chromosome, each region spanning 10 Mb of DNA. In all three datasets, we found consistent directional shrinkage of the dinucleotide STR compartment in all the primate species selected vs. mouse, as follows: mouse>macaque>great apes. The >20-repeat STRs were the most significantly affected as a result of this shrinkage. We propose that massive and directional shrinkage of the dinucleotide STR compartment had a decisive link with primate speciation. This is a prime instane of massive directional STR trend in multiple speciation.

Novel crossover and recombination hotspots massively spread across human genome

“…The AT-TTU colonies were signi cantly larger and more complex than the CG-rich colonies that we reported previously [20,21]. These ndings support a more signi cant role of AT-rich sequences in comparison with CG-rich sequences, as crossover and recombination hotspots.…”

“…We previously reported that CG-rich trinucleotide two-repeat units (CG-TTUs) form colonies of exceeding signi cance across the human genome, based on Poisson distribution [20,21]. Several of the large and medium size colonies that were further analyzed in other species, unveiled crossover and recombination hotspots, shared across primates, and in some instances, even in mouse.…”