1 / 21

Evolution of Plant Size in the Common Morning Glory, Ipomoea purpurea

Evolution of Plant Size in the Common Morning Glory, Ipomoea purpurea. Rick E. Miller Southeastern Louisiana Univ and Mark D. Rausher Duke University. Ipomoea purpurea source population in soybean field in North Carolina.

bozica
Download Presentation

Evolution of Plant Size in the Common Morning Glory, Ipomoea purpurea

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Evolution of Plant Size in the Common Morning Glory, Ipomoea purpurea Rick E. Miller Southeastern Louisiana Univ and Mark D. Rausher Duke University Ipomoea purpurea source population in soybean field in North Carolina

  2. Plant size as an ecological trait -- arguably most important trait influencing population biology of plants • Universally correlated with fecundity • Influences survival • Determinant in intra- and interspecific competition • Susceptibility to natural enemies -- apparency • Ability to tolerate stressful environments Insect herbivore damage on Ipomoea purpurea Photograph by John Stinchcombe

  3. Investigated the evolution of plant size Challenging -- size often differs among individuals due to environmental influences Phenotypic plasticity Ipomoea violacea grown from seed -- same accession Difference in pot size reflects availability of resources larger pot small pot

  4. Research Objectives • Additive genetic variation for size? • Additive genetic variation for fitness? • Pattern of selection acting on size? • Genetic correlations between traits • tradeoffs/constraints

  5. Established experimental population of the common morning glory, Ipomoea purpurea, obtaining measures of plant size and fitness

  6. Main results • Genetic variation for seed mass and cotyledon size • Genetic variation for male fitness (flower production and survival) • Positive directional selection acting on seed mass and cotyledon area

  7. Ipomoea purpurea twining vine, common agricultural weed in s.e. US Collected seeds from a large source population in North Carolina soybean field

  8. Created experimental population using half-sib breeding design 90 sires 270 dams 12 offspring/dam 3,240 seeds Sires (males) Dams (females) Offspring

  9. Planted seeds in ploughed field and allowed plants to twine up 2m stakes

  10. Measured size throughout the growing season, including initial mass of each seed. Counted flowers and collected seeds, as well as monitored survival. Chris Nacci counting flowers

  11. Pattern of survival through the growing season for the experimental population of Ipomoea purpurea

  12. Analysis of genetic variation for measures of plant size. Used likelihood-based statistics with explicit spatial models of the fine-scale environmental heterogeneity within the experiment. Likelihoods Trait Sire varianceFull modelWithout sireΩP/2 Initial seed 13.102 14869.6 16474.7 1605.1 <0.0001 mass Cotyledon 0.0067 -1955.7 -1897.5 58.2 <0.0001 area Leaf area 0.0084 2032.8 20033.9 1.1 0.1471 in August Leaf area 0.0089 2514.4 2515.7 1.3 0.1271 in September Leaf area 0.0117 2722.2 2722.9 0.7 0.2014 in October Maternal 0.0084 289.5 290.0 0.5 0.2398 seed mass

  13. seed production

  14. Analysis of genetic variation for reproduction and fitness. Likelihoods Trait Sire varianceFull modelWithout sireΩP/2 Flower 0.0 2106.2 -- -- -- production Male 0.0134 9902.3 9906.6 4.3 0.01906 fitness Seed 0.0039 649.3 649.3 0.0 -- production Female 0.0 18409.8 -- -- -- fitness

  15. Genetic correlations among measures of size are positive and significant. No evidence of a seed size versus seed number tradeoff. Values are based on Best Linear Unbiased Predictors (BLUPs) from models used to estimate variance components. Cotyledon Leaf area Leaf area Leaf area Flower Seed Maternal area in August in Sept in Oct production production seed mass Initial seed 0.91 0.52 0.34 0.40 0.00 0.10 0.06 mass P < 0.0001 P < 0.0001 P < 0.01 P < 0.0001 -- n.s. n.s. Cotyledon 0.58 0.38 0.42 0.00 0.21 0.01 area P < 0.0001 P < 0.001 P < 0.0001 -- n.s. n.s. Leaf area 0.57 0.51 0.00 0.28 -0.08 in August P < 0.0001 P < 0.0001 -- P < 0.0001 n.s Leaf area 0.87 0.00 0.13 0.10 in Sept P < 0.0001 -- n.s. n.s. Leaf area 0.00 0.08 0.15 in Oct -- n.s. n.s. Flower 0.00 0.00 production -- -- Seed 0.06 production n.s.

  16. Pattern of selection acting on initial seed mass involving male fitness (flower production and survival) Genetical analysis of selection using BLUPs ≈ family means.

  17. Large seeds Large plants Lots of flowers • Genetical analysis of selection • Explicit models of fine-scale spatial heterogeneity Ipomoea pedicellaris Oaxaca, Mexico

  18. Positive directional selection Initial seed mass β = 0.2448 Cotyledon area β = 0.2639 Frequency distribution of estimated linear selection gradients for quantitative traits in natural populations, compiled from 63 studies. Hoekstra et al. 2001. PNAS 98: 9157-9160.

  19. Is this population of Ipomoea purpurea evolving in the direction of larger seeds?

  20. John Harper (1977) in Population Biology of Plants provided comprehensive review of demographic studies. Emphasized special attention be paid to the early fate of individuals in life cycle of plants, especially for annual species. This study supports this view -- finding significant selection acting on initial seed mass and cotyledon size, but not on size later in the growing season

  21. Acknowledgements • Chris Nacci • fantastic research assistant • National Science Foundation • Louisiana Board of Regents

More Related