Where you’ve been and where you’re going: Seed source and reintroduction success

Background/Question/Methods

Genetic background of seed source can have a major impact on reintroduction success due to breeding system, genetic variation and local adaptation. Use of multiple versus single seed sources for restoration is of concern due to the potential for outbreeding depression. Low genetic diversity of the source population may reduce reintroduction success.  Also, local adaptation can result in a mismatch between the source plant material and the reintroduction site. We address these issues using four herbaceous perennials from a variety of genetic backgrounds, including inbred and outbred planned crosses in an orchid (Platanthera leucophaea), between population crosses of a prairie forb with self-incompatibility (Asclepias meadii), naturally low and high genetic variability of a monocarpic dune plant (Cirsium pitcheri), and intense edaphic differentiation in populations of a local endemic (Lomatium cookii).

Results/Conclusions

Crossing experiments using P. leucophaea, revealed that progeny from flowers that were selfed had significantly lower seed viability and germination compared to outcrossed seeds.  Lack of evidence for outbreeding depression was indicated by no difference between intrapopulation and interpopulation outcrossing.  Potential hybrid vigor was revealed by seedlings from  interpopulation crosses having greater growth than those from intrapopulation crosses for A. meadii.  For C. pitcheri, plants from a source population with low genetic diversity were smaller and had lower survival compared to other source populations with higher genetic diversity.  However, reintroduction success projected using population viability analysis did not differ among seed sources, apparently because lower survival of plants from the low genetic diversity population was compensated for by higher growth and fecundity in later stages.  Populations of L. cookii occur in widely different habitat types, including wetland and upland sites and serpentine and non-serpentine soils.   When seeds from a non-serpentine source were planted with seeds from a local source on serpentine soils, germination was similar for both seed types (~15%) but seedlings from local seed had much lower mortality than those from nonlocal seeds (4% vs. 32%), as did small juvenile plants (12% vs. 22%).  Local adaptation may have strong effects on reintroduction success if habitats differ between the seed source and the reintroduction site.   Genetic background, whether from manipulated crosses or population history, can have strong effects on reintroduced population vital rates and overall performance.