CONICET | Buscador de Institutos y Recursos Humanos

Amphitropical species have disjunct distributions south and north of the equator. That is thecase of Leptochloa crinita, a perennial grass found in dry and warm regions of South and North America,and recommended for rangeland restoration. We analyzed to what degree the distribution of the species inboth subcontinents shaped its genetic differentiation and population variability. We collected seeds from 15populations from South America and 7 from North America, and grew them in a common garden to evaluateadaptive variation. Three microsatellite markers and DNA sequences from one nuclear (ITS1-5.8S-ITS2) andone chloroplast region (rpl32-trnL) were used to analyze recent and historical gene flow, respectively. We usedclimatic niche models to infer past suitable habitats. We found significant genetic variability among populationswithin each subcontinent, but low genetic differences between populations from South vs. North America;these were detected only with microsatellites and not with DNA sequences. Results show that the species hasdiverged from a common gene pool in the recent past (~500-3300 generations ago [estimate: ~3000-20000 years]).Populations from South America had plants with more and taller inflorescences, more tillers and heavier seedsthan the North American ones, which could represent adaptations to the less stressful environments that thespecies inhabits in South America. Climatic niche models indicate few potential habitats for the species inNorth America during the Last Glacial Maximum and Middle Holocene, in contrast to South America, wherepotential habitats seemed to be comparable or more extensive than at present. This and previous studiesprovide a view of the genetic resources of the species. Results suggest that if necessary, and taking properprecautions the admixture of L. crinita populations or the germplasm translocation between subcontinentsare alternatives to consider in restoration practices.

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