Seed Production and Viability of Golden Paintbrush (Casteilleja Levisecta) in Persisting Native Legacy
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Seed Production and Viability of Golden Paintbrush (Casteilleja Levisecta) in Persisting Native Legacy
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The rare Washington state native plant Castilleja levisecta has faced difficulties in its legacy populations. While restoration populations have climbed in numbers over the past 15 years, the native legacy populations have all but disappeared. They have lost over 90% of their total numbers during this period. This may be due in part to decisions by site managers to genetically isolate native legacy populations, refusing to introduce new genetic material to those sites. This study compares two populations of C. levisecta, one persisting legacy population and one restoration population. Focusing on seed production and viability, this study compares and contrasts the seed count per seedpod, weight per seed, viability of seed, and germination rate of seed taken from a native legacy population and a restoration population. The findings demonstrate that there are differences in seed weight, viability, and germination rates between the native legacy and restored populations. The findings also show that a genetically isolated native legacy population is producing fewer seeds than a restored population of mixed genetic stock. These findings imply that the management driven genetic isolation is likely leading to reduced fecundity in native legacy populations via inbreeding depression. The implication of these findings is that the management strategy of genetic isolation is harmful and must be discarded in favor of genetic mixing if these native populations are to be preserved.
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December 2024
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E. David Heydt
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Thesis-David Heydt-FormattedFinal
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