The Recombination Rate Landscape of the Mississippi Diamond-backed Terrapin (Malaclemys terrapin pileata)

Abstract

Meiotic recombination rates vary between taxa, species, and populations. Across genomes, exchanges can occur in short sequences known as recombination hotspots. The presence of the zinc-finger histone methyltransferase protein PRDM9 has been implicated directing recombination machinery away from functional elements of genomes (e.g., transcription start sites, CpG islands) across vertebrates. This dynamic, however, has been investigated extensively in only a handful of taxa, and recent studies suggest many species exist along a continuum of reliance on PRDM9-directed recombination. We use a linkage disequilibrium-based approach to characterize the recombination rate landscape across both macrochromosomes and microchromosomes in Mississippi diamond-backed terrapins (Malaclemys terrapin pileata), a turtle species of conservation concern. We then show recombination rates are higher in transcription start sites on macrochromosomes and decrease as distance to the nearest predicted PRDM9 binding site increases on microchromosomes.