Abstract Detail

Population Genetics/Genomics

Duque, Josue [1], Lopez, Alexander Joseph [2], Lum, Romy [3], Waselkov, Katherine [1].

Population Genomics of the Native and Invaded California Range of Palmer Amaranth (Amaranthus palmeri).

Palmer amaranth (Amaranthus palmeri S. Watson), a dioecious, wind-pollinated annual plant native to the Southwestern United States, has become a significant challenge in modern weed management over the last three decades, establishing itself as a weed in agricultural ecosystems within the Californian Central Valley in 2015. Palmer amaranth’s range expansion potential is well-documented in the Eastern United States, where it went from a relatively unknown plant to a weedy species of major concern over a short period of time. This expansion into Central California warrants an examination of where the new weed infestations fit into the population structure of Palmer amaranth in the Western United States and what differences in population genetic statistics may be exhibited by the new California populations versus those in Palmer amaranth’s native range. To this end, we have conducted population-level sampling from both these regions and generated genomic data via genotyping-by-sequencing to identify genetic variants (single-nucleotide polymorphisms) for population genetic analysis. Using these data, we conducted population structure analysis including various hierarchical clustering methods (ADMIXTURE/STRUCTURE). STRUCTURE and ADMIXTURE analyses with an original dataset (n = 113 individuals from 9 native Southwestern U.S. populations and 4 invasive Central California populations) shows weak structure within these populations. ADMIXTURE analysis indicates that a scenario with K= 2 genetic clusters is most likely given the data. STRUCTURE analysis also appears to favor a scenario with K = 2. STRUCTURE ancestry estimates indicate that Californian samples from outside of Palmer’s native range do not possess a pattern of estimated ancestry atypical to the Southwestern US. ADMIXTURE, in contrast, appears to indicate patterns of admixture inconsistent with results estimated by STRUCTURE. Additional analyses, including principal component analyses, a Mantel test for isolation-by-distance, distance matrices (Nei/FST), and diversity statistics (allelic richness, observed heterozygosity, FIS) largely favor STRUCTURE’s results over ADMIXTURE, leading to the overall conclusion that the Southwestern US native range and the invaded California range have very similar genetic diversity and population structure for this weedy species.

1 - California State University, Fresno, Department of Biology, 2555 East San Ramon Ave, M/S SB73 , Fresno, CA, 93740, USA
2 - California State University Fresno, Biology, 2555 East San Ramon Ave M/S SB73, Fresno, Ca, 93740, USA
3 -

Palmer amaranth
population genomics.

Presentation Type: Oral Paper
Number: PGG5002
Abstract ID:263
Candidate for Awards:None

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