Inbreeding and reintroduction: Progeny success in rare Silene populations of varied density

ISSN： 1566-0621

Source： Conservation Genetics, Vol.5, Iss.1, 2004-01, pp. : 49-61

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Abstract

Genetic factors influence the population viability of rare species, yet the fitness consequences of inbred and outbred progeny are seldom tested empirically in reintroduction strategies designed for species recovery or habitat restoration. Rare and endangered plants of Silene (Caryophyllaceae) occur on four continents, including North America. In Oregon, inbred and outbred progeny were monitored for three years after experimental reintroduction of a narrow endemic, S. douglasii var. oraria, into formerly grazed habitat within its presumed historical range. Survival and reproduction were compared for progeny that were derived from the seeds of self- versus cross-pollinated flowers produced in situ at Cascade Head, a UNESCO Biosphere Reserve where the largest of three extant populations occurs. Progeny of cross-pollinated flowers had significantly greater field survival in all years than did offspring of selfed or open-pollinated flowers (P < 0.01). Outbred progeny also significantly exceeded other treatment cohorts in canopy area, and produced more reproductive stems and flowers than other progeny types of the same maternity. For plots varying in plant density, mortality was greatest in the high-density competitive regime but the survivors reached significantly larger sizes and reproductive capacities than in low density plots (P < 0.05). In all, successful conservation plans involving reintroduction may require genetically diverse progeny to offset inbreeding depression as well as suitable planting densities and source populations.