Abstract Detail


Anneberg, Thomas [1], O'Neill, Elizabeth M. [1], Ashman, Tia-Lynn [2], Turcotte, Martin [1].

Multigenerational population experiments highlight the importance of nutrients, genotype, and future growth potential on polyploid-diploid competitive dynamics.

Whole-genome duplication is a common macromutation that gives rise to nascent polyploid lineages (hereafter neopolyploids) and causes strong reproductive isolation from their diploid ancestors. At the population level, neopolyploids are expected to be extirpated from their progenitor diploid populations due in part to being the minority cytotype in an otherwise diploid community. However, at the individual level, neopolyploidy often causes increased body size, suggesting that neopolyploid individuals should be stronger competitors to diploids for limited niche space, however, increased nutritional needs of polyploidy may levy population-level costs. We argue that empirical studies of neopolyploid population dynamics are a crucial piece of missing information, since neopolyploid establishment is intrinsically a population process. To address this gap, we compared diploid and neopolyploid Spirodela polyrhiza population dynamics in monoculture under any of nine nitrogen and phosphorus treatments. We evaluated whether results were consistent among four independently generated neopolyploid lineages. We show that synthetic neopolyploidy causes populations of S. polyrhiza to have reduced growth rates and achieve 28% lower population sizes of actively growing individuals, regardless of nutrient treatment. Compared to current growth dynamics, neopolyploid populations increased their investment to potential future growth by producing 19% more dormant propagules than diploids when grown in higher resource environments. We thus found that neopolyploidy shifts population growth strategies from current to future growth potential (dormant propagules). We then asked how direct competition between diploid progenitors and neopolyploid descendants affects current and future growth potential investment. We conducted an additive competition experiment with three nutrient treatment levels, growing diploid or neopolyploid S. polyrhiza populations either alone or together in competition. Neopolyploid populations had a stronger competitive effect on diploids, but never outpaced diploids in total abundance. However, we found that neopolyploid populations produced more dormant propagules overall, despite diploid future growth investment responding more to competition than neopolyploids. Furthermore, we found a strong ploidy-by-genotype interaction both current and future population growth across nutrient treatments, suggesting that the effect of polyploidy on competition not simply an effect of genome doubling per se, but rather a higher-order interaction with their background genotype. We thus conclude that based on current growth alone, neopolyploid populations should almost always go extinct, but they may yet persist and establish when considering that they have a greater investment into future growth potential.

1 - University of Pittsburgh, Biological Sciences, 4249 Fifth Ave, Pittsburgh, PA, 15260, United States
2 - Department Of Biological Sciences, 1252 Bellerock Street, Pittsburgh, PA, 15217, United States

nutrient limitation
Abiotic stress.

Presentation Type: Oral Paper
Number: EC07002
Abstract ID:382
Candidate for Awards:None

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