Effect of cross proximity on progeny fitness in a rare and a common species of Eupatorium (Asteraceae)

Abstract

Offspring from matings between near neighbors may exhibit lower fitness relative to offspring from more distant matings due to spatial structuring of populations resulting from limited dispersal of pollen and seed. This response, which can be interpreted as inbreeding depression, is studied in the rare species, Eupatorium resinosum, and a closely related congener, E. perfoliatum, through the use of hand pollinations representing three distance classes (near-within a population, far-within a population, and between populations) and an assay of the offspring in an experimental plot. Early traits such as seed mass and first-year stem length were not significantly affected by the cross type, although they were affected by maternal parentage. Size and reproduction in the second field season increased with increased pollen donor distance from the maternal plant. Cross type was significant for many traits in the second field season, indicating inbreeding depression in crosses of neighbors (for E. resinosum) and hybrid vigor between populations (both species). This suggests that the rare species, E. resinosum, had a more spatially structured population than E. perfoliatum. The implications of these results for conservation of rare species indicate that protection of habitats sufficient for large populations is necessary to maintain genetic diversity since each population likely consists of many smaller subpopulations.

Distance between pollen donor and recipient influences fruiting success in slickspot peppergrass, Lepidium papilliferum

“…Population structure and reduced fecundity through inbreeding are of critical importance for rare species because their populations tend to be small and opportunities for outcrossing are often limited (Lande 1988;Ellstrand and Elam 1993;Byers 1998;Lande 1995). Studies have shown that the scale of population structure and the extent of its influence on reproduction varies between species.…”

“…Understanding the relationship between outcrossing distance and reproductive performance is of particular importance for rare and endangered species because any decrease in seed production can threaten the species' long-term viability (Ellstrand and Elam 1993;Byers 1998). Because rare plants typically occur in small populations that are vulnerable to local extinction due to a fixation of deleterious alleles (genetic risk of extinction) and to demographic factors (ecological risk of extinction), opportunities for outcrossing may be critical to ensure maintenance of genetic diversity within populations (Lande 1995).…”

Rare Plant Monitoring and Restoration at the Lawrence Livermore National Laboratory Experimental Test Site, Site 300, Project Progress Report 2007 through 2011

“…For effective conservation and management, a thorough understanding of the population dynamics of B. plumosa is necessary. Blepharizonia laxa is also of interest as comparisons of rare and common congeners can provide important information for rare plant management (Bevill and Louda, 1999;Pantone et al, 1995) and can illuminate differences that affect comparative abundance (Byers, 1998). Therefore, between 1996 and 2001 demographic and population biology data on B. plumosa and B. laxa were collected.…”

Biología floral y reproductiva de Escallonia pulverulenta (Ruiz et Pav.) Pers. (Escalloniaceae) y su relación con los visitantes florales

“…Diferentes estudios han encontrado relación entre la proximidad espacial y el nivel de consanguinidad de los individuos, producto de una dispersión a corta distancia de polen y/o semillas, lo que resulta en poblaciones espacialmente estructuradas (Glaettli et al 2006). Como resultado, el apareamiento entre vecinos puede generar una fertilidad reducida en comparación con apareamientos entre individuos más distantes, debido a un incremento de los niveles de homocigosidad (Byers 1998, Hardner et al 1998, Glaettli et al 2006. De este modo, la polinización cruzada entre individuos genéticamente diferentes (i.e.…”