Based on an September 2020 extract of the California Plant Rescue Database, California Botanic Garden holds 5 accessions of Sibara filifolia in orthodox seed collection. There are as many as 192920 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.
Based on an August 2020 extract of the California Plant Rescue Database, California Botanic Garden has collected 4 seed accessions of Sibara filifolia from 2 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass 8 maternal plants
Currently known only from at least 3 sites, located in a small area on 1 of the Channel Islands of southern California; thought to have been widely distributed in this archipelago formerly. A 2002 report describes a population on a second Channel Island in an area protected from feral goats. Extirpated on at least 1 island by intensive browsing by non-native feral goats. Feral herbivores have been removed from San Clemente Island, where the extant plants are located.
Grazing of domesticated animals and introduced non-native plants have been the greatest historical threat. Goats were present on San Clemente Island as early as 1827. Sheep grazing occurred on many of the islands from the late 1800's to the early 1900's w
There are less than 500 individuals remaining on San Clemente Island (USFWS 1995).
Allozyme variation in Sibara filifolia is being studied by Dr. Kaius Helenurm (2001) and his graduate student Sarah Helm at the University of South Dakota. Helenurm's study (2001) obtained electrophoretic data for 29 allozyme loci from individuals collected as seed from the three known populations on San Clemente Island. Overall levels of genetic variation were low. Only two polymorphic loci were observed, resulting in low number of alleles per locus (1.01), average observed heterozygosity (0.006) and average expected heterozygosity (0.009) for populations. Interestingly, all polymorphism occurred in just one of the three populations, in spite of their close proximity. Most variation on San Clemente Island is thus found within rather than among populations (GST = 0.144), and there is significant differentiation among populations (FST = 0.145). Gene flow is estimated as Nm = 0.41 based on private alleles and Nm = 1.49 based on FST. The differentiation of populations and low level of gene flow suggests that genetic drift is a potent force in these small populations and may further reduce genetic variation. RAPD and quantitative genetic studies are recommended to further evaluate these populations and the long-term prospects for this species.
In the 1990's the U.S. Navy removed approximately 20,000 feral goats and pigs from San Clemente Island (USFWS 1995). Developing and implementing a management plan that includes fire protection, population monitoring and the establishment of new populations will be necessary for this species recovery.
Habitat protection and the promotion of self-sustaining populations are primary concerns. Understanding reproductive biology will aid in the establishment of new populations.
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