A Promiscuous Wallflower: The Rare Zayante Sandhills Endemic Erysimum Teretifolium (Brassicaceae) Benefits From Outcrossing

The Zayante sandhills ecosystem of Santa Cruz County, California, contains a rich mosaic of plants and animals adapted to unusual soils and microclimates. In this environment, local adaptation of populations is expected to lead to greater endemism and outbreeding depression. Anthropogenic fragmentation has further isolated populations, however, which paradoxically could result in inbreeding depression. One of these plants, Erysimum teretifolium (Ben Lomond wallflower) is an endangered endemic herb in the Brassicaceae family. This study assessed genetic mixing across remnant patches of E. teretifolium in order to estimate the effects of fragmentation and the reliance on pollinators. A captive breeding colony was established from seeds collected from four locations across the Zayante sandhills and used in 161 pollinations. Individual allele frequencies were measured using microsatellites, and pollination potential was evaluated through insect camera trapping. Self-pollinations produced 6.5 times fewer seeds than outcrosses. There is no evidence of outbreeding depression. Results suggest that there is a potential for inbreeding depression; however, it is possible that self-incompatibility and reliance on pollinators for outcrosses across geographic divides may be buffering effects. Implications for managers include evidence that geographic origin of individuals may not be critical for reintroduction; however, conservation of the pollinator community should remain a priority