Pinpointing the PRDM9-PRDM7 Gene Duplication Event During Primate Divergence

Area of Science:

• Evolutionary genetics
• Primate genomics
• Reproductive biology

Background:

• PRDM9 is crucial for hybrid sterility and vertebrate evolution, but its homolog PRDM7 and strepsirrhine PRDM9 evolution are poorly understood.
• Understanding PRDM7's origin is key to investigating reproductive incompatibilities in primates.

Purpose of the Study:

• To pinpoint the duplication event of PRDM7 in primate evolution.
• To reconstruct the evolutionary history of PRDM9 zinc finger arrays in primates, including strepsirrhines.

Main Methods:

• Phylogenetic tree reconstruction of PRDM orthologs and paralogs in primates.
• Analysis of database sequences to confirm PRDM7 paralogization patterns.
• Extension of PRDM9 zinc finger phylogeny to include strepsirrhine species.

Main Results:

• PRDM7 originated on the lineage leading to the most recent common ancestor of catarrhines, indicating a more recent emergence than previously thought.
• PRDM9 zinc finger phylogeny was completed by incorporating strepsirrhine data, revealing distinct clusters for strepsirrhine, tarsier, and anthropoid zinc fingers.
• PRDM7 exhibits differential evolution, lacking specific exons in Old World monkeys (Cercopithecoidea) compared to apes (Hominoidea).

Conclusions:

• The origin of PRDM7 is dated to the early catarrhine radiation, providing a crucial temporal marker.
• Differential gene structure evolution of PRDM7 in major primate groups suggests lineage-specific adaptations.
• This study provides essential evolutionary context for future research on PRDM7's role in primate reproductive biology.