Pollination to Population Structure - How Understanding Reproductive Biology Can Inform Conservation of Rare Plants
Bell, Timothy , Bowles, Marlin .
The impacts of plant life history and reproductive biology on population viability and restoration.
Understanding the life history and reproductive biology of endangered plant species is critical to their management and restoration. We discuss the impacts of life span, time to reproduction, number of reproductive events, breeding system, seed size and number, and genetic diversity, on population viability of three federally threatened plants, including: Pitcherís Thistle (Cirsium pitcheri), Meadís Milkweed (Asclepias meadii), and the Eastern Prairie Fringed Orchid (Platanthera leucophaea). Because C. pitcheri is a short-lived, monocarpic perennial that requires frequent cohort replacement, small populations are more vulnerable to environmental stochasticity than for long-lived polycarpic perennials such as A. meadii and P. leucophaea. Both C. pitcheri and P. leucophaea have mixed mating systems, and can therefore be restored using seeds collected from single natural populations. In contrast, A. meadii is self-incompatible and restorations require multiple genotypes for successful cross-pollination. In the eastern half of its range, natural populations comprise single genotypes, and a nursery population of diverse genotypes was used to produce propagules for restoration. Because P. leucophaea requires mycorrhizae for germination, broadcast seeding has been the only successful restoration strategy. Ex situ propagation followed by outplanting seedlings is a more efficient method for C. pitcheri restoration because of low seed production and high in situ predation of large seeds. Time to reproduction should also be considered during restoration. For example, A. meadii requires 12 or more years to reach reproductive size. Thus, restoration involves establishment of mixed stage classes through planting seeds and transplanting juveniles. Lastly, low genetic diversity and potential inbreeding found in some C. pitcheri populations, presumably due to isolation resulting from habitat fragmentation and restricted seed dispersal, could lead to lower population growth rates for these populations. In contrast, as a consequence of long distance gene flow, populations of P. leucophaea are genetically similar and have high diversity.
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1 - Chicago State University, Biological Sciences, 9501 South King Drive, Chicago, Illinois, 60628, USA
2 - The Morton Arboretum, 4100 Illinois Route 53, Lisle, Illinois, 60532, USA
Presentation Type: Symposium or Colloquium Presentation
Location: Room 3/Woodward
Date: Monday, July 28th, 2008
Time: 10:30 AM