Polyploidy, or whole genome duplication, is a common phenomenon in plants, but the establishment and persistence of mixed-ploidy populations remains a paradox. This dissertation explores factors that contribute to the persistence and establishment of mixed-ploidy populations in nature. The first chapter investigates the role of unreduced gametes in neopolyploid establishment and finds that variability in their formation rate can have a significant impact on polyploid establishment and persistence. The second chapter searches for evidence of soil microbes exhibiting ploidy-specificity, a pre-condition for microbe-mediated niche differentiation, a possible stabilizing mechanism contributing to ploidy coexistence. Finally, the third chapter tests for microbe-mediated niche differentiation in a mixed-ploidy population of Larrea tridentata. Using a plant-soil feedback experiment this chapter demonstrates that microbe-mediated niche differentiation can facilitate the coexistence of different ploidy levels. Overall, this dissertation demonstrates there are complex and interrelated factors that contribute to the persistence and establishment of mixed-ploidy populations in nature.
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Data from: Plant-soil microbe feedbacks depend on distance and ploidy in a mixed cytotype population of Larrea tridentata
Premise of the study Theory predicts that mixed ploidy populations should
be short-lived due to strong fitness disadvantages for the rare ploidy.
However, mixed ploidy populations are common, suggesting that the fitness
costs for rare ploidies are counterbalanced by ecological benefits that
emerge when rare. We investigated whether differences in ecological
interactions with soil microbes help to maintain a tetraploid-hexaploid
population of Larrea tridentata (creosote bush) in the Sonoran Desert,
California, USA, where prior work documented ploidy-specific
root-associated microbes. Methods We used a plant-soil feedback (PSF)
experiment to test whether host-specific soil microbes can alter the
outcomes of intra-ploidy vs. inter-ploidy competition. Host-specific soil
microbes can build up over time; thus, distance from a host plant can
affect the fitness of nearby plants. Key results Seedlings grown in soils
from near plants of a different ploidy produced greater biomass relative
to seedlings grown in soils from near plants of the same ploidy. Moreover,
seedlings grown in soils from near plants of a different ploidy produced
greater biomass than those grown in soils from further away from plants of
a different ploidy. This suggests the ecological consequences of PSF may
facilitate the persistence of mixed ploidy populations. Conclusions This
is the first evidence, to our knowledge, consistent with plant-soil
microbe feedback as a viable mechanism to maintain the coexistence of
multiple ploidy levels in a single population.
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- Award ID(s):
- 1655499
- NSF-PAR ID:
- 10506701
- Publisher / Repository:
- Dryad
- Date Published:
- Subject(s) / Keyword(s):
- FOS: Biological sciences plant-soil feedback Janzen-Connell Distance-dependent Polyploidy microbe-mediated mixed-ploidy
- Format(s):
- Medium: X Size: 233432 bytes
- Size(s):
- 233432 bytes
- Sponsoring Org:
- National Science Foundation
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