Will the same ex situ protocols give similar results for closely related species?

Conservation of imperiled plant species often requires ex situ (offsite) living collections. Protocols for developing these collections most often emphasize sampling depth, but little is known about the genetics of such collections. This study compares how well a single collecting protocol can capture the diversity in wild populations of two closely related species. We selected two exemplar species, bay rush (Zamia lucayana) and sinkhole cycad (Zamia decumbens), based on similarities and differences that allow for rigorous comparison, including geographic isolation and reproductive factors. For each species, we compared in situ plants to ex situ plants via the same panel of 10 microsatellite markers. Genetic distance analysis shows high fidelity of the ex situ collections to their in situ source populations and sub-populations. Structured resampling of allele capture from the in situ populations by the ex situ collections shows that allele capture increases as number of ex situ plants maintained increases, but with a diminishing rate of increase. Difference in the rate of allele capture between the two species was significant at the alpha = 0.1 level, (p = 0.097) but not at the alpha = 0.05 level. At larger collection sizes, the difference in rate of allele capture showed a high practical significance (d = 5.41). These data illustrate that a unified collecting protocol can achieve similar allele capture among related species, but also that geographic and reproductive factors can influence the rate of allele capture.