|GOMOLA, COURTNEY - Colorado State University
|MCKAY, JOHN - Colorado State University
Submitted to: Biological Invasions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/26/2016
Publication Date: 1/6/2017
Publication URL: http://handle.nal.usda.gov/10113/5742647
Citation: Gomola, C.E., Mckay, J.K., Espeland, E.K. 2017. Genetic lineages of the invasive Aegilops triuncialis differ in competitive response to neighboring grassland species. Biological Invasions. 19(2):469-478. doi:10.1007/s10530-016-1366-0.
Interpretive Summary: The identity of the winner of competitive interaction between native and invasive species determines both invasive spread and the diversity and persistence of native species in the invaded landscape. Here we use the most common two genotypes of the invasive grass, Aegilops triuncialis (barbed goatgrass), to determine if these lineages differ in their competitive ability. We find that one genotype is negatively affected by competitor presence in both its flowering timing and reproductive output, while the other genotype shows no response to competition. Furthermore, we find through historical herbaria specimens that the two genotypes were introduced at different times and each is capable of replacing the other as the most abundant lineage of a given county in California. Our results demonstrate that genotype is a more important determinant of competitive outcomes than the species identity of the competitor, and that the two genotypes may employ different mechanisms of invasion through being responsive or nonresponsive to competition. These results can help inform more effective management techniques for Ae. triuncialis, and highlight the importance of considering variation within invasive species rather than treating them as homogeneous with regard to important invasive traits.
Technical Abstract: Competitive dynamics between native and exotic species can influence both the success of exotics in the novel environment as well as diversity and abundance of native species. Invasive species are often characterized by multiple introductions in the novel range, which can lead to differentiation in invasion characteristics. Here we use two invasive lineages of the exotic grass, Aegilops triuncialis, to determine if these lineages differ in their response to competitor species and their persistence in the invaded range. We find that one lineage is negatively affected by competitor presence in both flowering phenology and reproductive output, while the other lineage shows no response in either trait. Furthermore, we find through herbaria studies that the two lineages were introduced at different times and are both capable of replacing the other as the abundant lineage of a given county. Our results demonstrate that genetic lineage is a more important determinant of competitive response than identity of neighbor for this species, and that the two lineages may employ different mechanisms of invasion. These results can help inform more effective management techniques for Ae. triuncialis, and highlight the importance of considering intraspecific variation in the invaded range.