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Abstract Detail


Ramsey, Justin [1], Ramsey, Tara [2].

Divergence of growth and phenology traits in tetraploid populations of wild yarrow (Achillea millefolium complex, Asteraceae) spanning an elevational gradient in the Black Hills and Great Plains.

The unusual genetic features of autopolyploids may underlie their ecological success in many plant groups. Based on multisomic inheritance and increased number of alleles per locus, autopolyploids may have high mean fitness (masking of deleterious alleles), maintain genetic diversity in small populations, and exhibit rapid responses to selection. Due to their genetic complexities, autopolyploids are traditionally eschewed in population studies. However, autopolyploids often have desirable research features – wide geographic distributions, clonal growth, cross-ability of populations and varieties – and empirical work is needed to evaluate factors affecting their ecological success. As a first step towards studying their ecological genetics, we investigated the character and spatial scale of ecological divergence in North American wild yarrow (A. borealis) along a 250 km transect in the Black Hills and Great Plains. This region represents the eastern range boundary for many western plant communities and taxa, including tetraploid A. borealis vars. lanulosa, pacifica, and alpicola. Our 25 study sites included shortgrass prairies, sagebrush flats, sand dunes, pine and aspen forest, montane grassland and mountain summits (770-2,200 m elevation); vegetation ordinations suggest a sharp transition in community composition of these sites at ~1,500 m elevation. Yarrows along the transect differed markedly in size and architecture, with diminutive plants found in low-elevation prairies and exposed rocky summits, and large plants found in mid- to high-elevation forest and meadows. In a baseline survey (2015), populations showed 10-fold leaf-size variation (population means 12.7 to 131.1 cm2) while stem length and flower head number showed 5- and 3-fold variation, respectively. In follow-up surveys (2016-2020) that included wet and dry years, relative plant size of populations ranked consistently. Garden experiments (2016-2020) suggest a strong genetic component for studied traits. Correlation in size-related traits of populations measured in the field vs. garden was highly significant (P<0.001, R2>0.800) through the duration of the grow-out. Irrespective of size at maturity, plants of low-elevation sites initiated stem elongation and leaf growth before plants of mid and high-elevation sites, and on average flowered ~3-6 weeks earlier. Large-statured plants of wet meadows and forests produced substantially more flower heads than short-statured plants of dry prairie and mountain summits – both in terms of counts per stem and lifetime totals – but also exhibited much greater whole-plant transpiration. These findings point to differentiation of autotetraploid yarrows for growth-related traits, in a spatial pattern that mirrors climate factors and reflects tradeoffs in drought tolerance vs. competitive ability.

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1 - Black Hills State University, School Of Natural Sciences, 1200 University Street, Unit 9095, Spearfish, SD, 57799, United States
2 - Black Hills State University, School of Natural Sciences, 1200 University Street, Unit 9095, Spearfish, SD, 57799, USA


Presentation Type: Oral Paper
Location: Virtual/Virtual
Date: Wednesday, July 21st, 2021
Time: 4:00 PM(EDT)
Number: BIOGIII005
Abstract ID:1039
Candidate for Awards:None

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