VARIACIÓN ESPACIAL EN LA POLINIZACIÓN Y EL ÉXITO REPRODUCTIVO DE UNA HERBÁCEA ENDÉMICA: IMPLICACIONES PARA SU CONSERVACIÓN.

Abstract

The study of plant population dynamics and the effects of biotic and abiotic factors on reproductive success is essential to understand plant reproductive biology. This is especially relevant from the standpoint of conservation of endemic and/or endangered species._x000D_ In this PhD thesis we have studied the reproductive success of Erysimum popovii, a "near-threatened" endemic herb from SE Spain. We selected 28 study sites throughout the entire distribution area of the species. At each site we measured several Erysimum popovii populational variables, as well as variables related to pollinator composition, habitat and climate. Because our study encompasses the entire distribution range of the species, we have been able to analyze our results and establish the status of the species both at the local and regional levels._x000D_ Chapter 1 addresses the effect of pollinator composition and other biotic and abiotic factors on the reproductive success of Erysimum popovii. To do this, we conducted a demographic study covering the different phases of the life cycle. In Chapter 2 we study pollen limitation. We conducted a pollen supplementation experiment and analyzed the spatial distribution and the factors affecting pollen limitation. In addition to pollen limitation, plant populations may be limited by their ability to recruit. We address this issue in Chapter 3, in which a seed supplementation experiment was conducted. Finally, Chapter 4 analyses the conservation status of Erysimum popovii populations in protected versus unprotected areas._x000D_ Erysimum popovii shows dramatic differences across its distribution range in the reproductive variables measured. These differences are accompanied by differences in pollinator composition and habitat factors. Therefore, different populations encounter different local conditions, thus generating a geographic mosaic and suggesting a metapopulation structure. One of the main variables associated to reproductive success in Erysimum popovii is visitation by Beeflies. This result suggests that these dipterans are highly effective pollinators of this species. On the other hand, high densities of co-flowering plants have a negative effect on Erysimum popovii fruit set, indicating possible interspecific competition effects. Seed production is pollen-limited in most of the Erysimum popovii populations. In addition, some populations are limited by the availability of microsites, seed production and/or seed dispersal. We found an important reproductive bottleneck in the seedling to adult transition. The spatial variability of these various types of limitation is very high and does not show any clear geographical pattern._x000D_ The main recommendation to improve the conservation status of the species is the establishment of areas of exclusion of herbivores. These areas may act as sources of propagules enhancing the metapopulational dynamics of the species. We also recommend the search of new populations, seed supplementation of certain populations and the phylogeographic study of the species.

Date of Award	10 Oct 2014
Original language	Spanish
Supervisor	Jordi Bosch Gras (Director) & José María Gómez Reyes (Director)