Effects of distance between pollen donor and pollen recipient on fitness components in Espeletia schultzii

• Published in: American journal of botany 1988-05, Vol.75 (5), p.701-724
• Main Author: Sobrevila, C
• Format: Article
• Language: English
• Subjects: Achenes; Biological and medical sciences; COMPOSITAE; Espeletia schultzii; Flowering; Flowering seasons; Fundamental and applied biological sciences. Psychology; Genetics of eukaryotes. Biological and molecular evolution; Inbreeding depression; Plants; POLINIZACION; Pollen; POLLINATION; POLLINISATION; Population genetics; Population genetics, reproduction patterns; Pteridophyta, spermatophyta; Seed production; Seed set; Seedlings; Vegetals; VENEZUELA
• ISSN: 0002-9122; 1537-2197
• DOI: 10.1002/j.1537-2197.1988.tb13492.x

The effect of flowering time and of distance between pollen donor and pollen recipient on the proportion of filled achenes, aborted seeds, and seedling survivorship was studied in populations of Espeletia schultzii in the Venezuelan Andes. Hand-pollinations were performed in two different years and at different times during the flowering season. Pollinations within-population included crosses between plants within a few meters to a maximum of 500 m apart and between-population pollinations included crosses between plants more than 10 km and up to 78 km away. Late in the flowering season, plants suffered a reduction in the proportion of filled achenes and an increase in aborted seeds. The proportion of filled achenes and aborted seeds did not vary significantly between the distances between pollen and ovules in crosses done early in the flowering season. However, the proportion of filled achenes in crosses between individuals within 30 m distance were very variable, either very successful or not successful. Beyond 30 m, for some of the populations, the frequency of unsuccessful crosses was almost 0. This pattern was observed at three elevation sites in two consecutive years. When crosses were done late in the flowering season, the proportion of filled achenes was lower in crosses between close individuals and between very distant ones. Seedling survivorship varied significantly between the crossing distances at the higher elevation only. The results show that a clear effect of the incompatibility alleles on the crossing success of the plants is present in the different populations examined, while they suggest that the effect of inbreeding or outcrossing depression is less clear but might still be present only under certain conditions. Late in the season, when plants might have fewer resources available for reproduction and at the high and intermediate site where cold and dry environmental conditions are less favorable for the plants, the discrimination among distances was stronger.