Trait responses of invasive aquatic macrophyte congeners: colonizing diploid outperforms polyploid

Abstract

Polyploidy (multiple copies of whole genomes) is over-represented in invasive plants and thought to promote their success in novel environments. Understanding functional traits supporting colonization can provide a foundation for development of effective management strategies. We compared how two aquatic invasive congeners differing in ploidy (diploid, decaploid) respond to resource availability (light, nutrients). Counter to our predictions, the diploid congener out-performed the decaploid with nutrient enrichment. Our results suggest the congeners have alternate colonization strategies, and trait responses underlying their success may change with ontogeny. Management strategies for invasive Ludwigia species should therefore be tailored for specific cytotypes and unique characteristics of their life stages.

Impacts of soil nitrogen and phosphorus levels on cytotype performance of the circumboreal herbChamerion angustifolium: implications for polyploid establishment

“…In fact, our results contradict with the recent findings of Grewell et al. (), who found that diploid Ludwigia peploides (floating primrose‐willow) had greater biomass accumulation and growth rates under nutrient‐enriched conditions than the closely related allodecaploid L. hexapetala (water primrose). Because nutrient demands can depend on other physiological and molecular factors, such as RNA quantities and expression patterns, cell sizes, and secondary metabolite concentrations, future studies evaluating cytotype responses to nutrient enrichment would benefit from studying trade‐offs associated with transcriptome size, and cell size versus cell quantity (Sterner and Elser, ; Elser et al., ; Cavalier‐Smith, ; Coate and Doyle, ).…”

“…Theoretical models (Tilman, , ; Goldberg, ; Gioria and Osborne, ; Goldberg et al., ) and field experimentations (Schoener, ; Goldberg and Barton, ; Wilson and Tilman, ; Mason et al., ) both suggest that competitive interactions have the largest negative fitness consequences for individuals when there is greater overlap in required limited resources or resource allocation strategies. WGD can result in differences in physiological processes (Schlaepfer et al., ; Grewell et al., ; Van Drunen and Husband, ), environmental tolerances (Maherali et al., ; Jamieson et al., ; Thompson et al., , ), and resource allocation strategies (Bales and Hersch‐Green, ), such that similar cytotypes may share more resource requirements or resource allocation strategies with each other than they do with dissimilar cytotypes. If cytotypes are ecologically differentiated in terms of their nutrient requirements, as is hypothesized here, it is expected that intra‐cytotype competition would be more intense than inter‐cytotype competition—mirroring the stronger effects of intraspecific competition than of interspecific competition frequently observed in natural populations (Adler et al., ).…”

“…For example, organisms with larger genomes (such as polyploids) contain cells with increased nucleic acid contents and protein demands in comparison to closely related organisms with smaller genomes (such as diploids), and it has been predicted that organisms with larger genomes should be more negatively affected by nutrient limitations than organisms with smaller genomes (Lewis, ; Leitch and Bennett, ; Cavalier‐Smith, ; Hessen et al., ; Guignard et al., ). Several studies involving a wide range of organisms support these predictions (algae: Lewis, ; plants: Šmarda et al., ; Kang et al., ; Guignard et al., ; Bales and Hersch‐Green, ; snails: Neiman et al., ; Neiman et al., ; but see Mable, ; Grewell et al., ), suggesting that nutrient supplies could influence the ecological sorting of plant communities based upon genome size (Šmarda et al., ; Guignard et al., ). However, it is also possible that genome size does not significantly influence nitrogen and phosphorus requirements for synthesis because there is a trade‐off in cell size and cell number per area of tissue such that organisms with larger genomes do not have higher syntheses costs than organisms with smaller genomes (Cavalier‐Smith, ; Coate and Doyle, ).…”

Seed source regions drive fitness differences in invasive macrophytes

“…montevidensis in highly disturbed sites, inferring recruitment from seedbanks. Recent studies also have revealed significant resource allocation to early flowering and seed production (Ruaux et al., 2009; Grewell et al., 2016b; B. J. Grewell, personal observations), suggesting sexual reproduction of L. p . subsp.…”

“…subsp. montevidensis and polyploid congeners (Rejmánková, 1992; Haury et al., 2014; Smida et al., 2015; Thiébaut and Martinez, 2015; Grewell et al., 2016b). However, the taxon has both asexual and sexual reproductive modes and is self‐compatible.…”