Genetic lineages of the invasive Aegilops triuncialis differ in competitive response to neighboring grassland species

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 population differentiation for invasion characteristics. Here we use two invasive lineages of the exotic grass, Aegilops triuncialis L., to determine if these lineages differ in their response to competitors and in 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 that the two lineages were introduced at different times and are each capable of replacing the other as the most abundant lineage of a given county. Our results demonstrate that genetic lineage is a more important determinant of competitive response than neighbor identity, and that the two lineages may employ alternate invasion mechanisms. Because management techniques are decided upon based on traits that confer invasiveness, our results highlight the importance of considering intraspecific variation in the invaded range.

Within‐species trade‐offs in plant‐stimulated soil enzyme activity and growth, flowering, and seed size

“…In contrast, the East lineage was larger but stimulated less N ‐degrading enzyme activity (although the activity was sustained throughout the development stages), which also correlated with later flowering and production of fewer and larger seeds. Our results support previous work on this invasive species, which found that the East lineage is less affected by interspecific plant competition than the West (Gomola et al, ). We argue that these two lineages follow distinct strategies whereby the West lineage is successful spreading and establishing in open biotope space (i.e., bare soil gaps with fewer competitive neighbors and serpentine sites; Meimberg et al, ) while the East has a more competitive strategy to establish and persist within plant communities with more competitors (Gomola et al, ).…”

“…Our results support previous work on this invasive species, which found that the East lineage is less affected by interspecific plant competition than the West (Gomola et al, ). We argue that these two lineages follow distinct strategies whereby the West lineage is successful spreading and establishing in open biotope space (i.e., bare soil gaps with fewer competitive neighbors and serpentine sites; Meimberg et al, ) while the East has a more competitive strategy to establish and persist within plant communities with more competitors (Gomola et al, ). The ability to stimulate soil enzyme activity has a functional role that mediates these different strategies.…”

“…In addition, these patterns are exhibited with relatively small differences in seed size and within species, whereas most trade‐offs are shown among species (Turnbull et al, ). Gomola et al () showed that these lineages differ in their response to competition with the East being more resistant to the effects of competitive neighbors. Similar to the growth and seed size trade‐off with plant‐stimulated enzyme activity, seed families with delayed flowering had lower initial soil enzyme activity.…”

Intraspecific variation in indirect plant–soil feedbacks influences a wetland plant invasion

“…, Gomola et al. ) on plant fitness, and to influence community composition of soil biota (Schweitzer et al. , Nelson and Karp , Lamit et al.…”

“…Because many studies of invasive species assume that no intraspecific variation exists in their interactions with the environment and resident community, this can result in misleading insights and management recommendations, particularly if different genotypes employ different mechanisms of invasion (Meyerson and Cronin , Gomola et al. ).…”