Evidence of long-distance clonal spreading and low genomic diversity of Kikuyu grass from highland livestock farms after a century of intentional introduction in Colombia

Abstract

Kikuyu grass was introduced to Colombia in 1928 as livestock forage at high altitudes. Despite its low genetic diversity, it exhibits substantial phenotypic variation in Colombia, the United States, and Australia. Therefore, it remains unclear whether improvements in livestock productivity in the Colombian highlands should include selection programs. To address this gap, we analyzed diversity using a reduced-representation genome library of 146 samples from livestock farms across six localities at three distinct altitudes. We identified 514 and 41 single nucleotide polymorphisms (SNPs) through SNP calling based on the tetraploid whole genome using a de novo strategy and the haploid reference genome of the chloroplast, respectively. The data indicated long-distance clonality, nonsignificant genomic diversity within groups, and low genetic differentiation among groups unrelated to the sampling locations, which ranged from one to five clusters, depending on the SNP calling strategy and missing data thresholds. We concluded that this low diversity pattern aligns with the reported history of farmers progressively dispersing Kikuyu grass samples over long distances, preventing local isolation 96 years after arrival and masking the effects of sexual reproduction. As Colombian law prohibits importing foreign varieties, selection programs should focus on broadening genetic diversity based on a deeper understanding of reproductive strategies using modern omics techniques and developing optimized management strategies.