Sofia Vilaça Nora, University of Seville. Supervisors: A. Aparicio and RG. Albaladejo. January 2019.
Summary:
Important questions to understand the impacts of
population fragmentation are related to the genetic connectivity of
populations and the key influence of pollen (and seed) dispersal of
different species. Some studies have shown that the spatial distribution
of populations in fragmented landscapes does not preclude incoming
pollen flow even in small and isolated patches, but the low number of
effective pollen sources may lead to reduced fitness in progenies.
Moreover, breeding (self-compatible vs. incompatible) and pollination
(wind vs. animal-pollination) systems are regarded to be very
influential as well for the levels of species’ pollen flow. The thesis
study system consists in populations of two common shrub species with
contrasting breeding and pollination systems (Pistacia lentiscus and
Myrtus communis) co-occuring in a diverse regional mosaic of
mediterranean forest patches in the Guadalquivir river valley (where
continuous vs. fragmented and connected vs. isolated populations can be
found).
By assessing naturally produced progenies of both species in contrasting
conditions of local neighbourhood conspecifics and landscape context
this thesis aims to evaluate reproductive female success by performing
path analysis and compare contemporary patterns of pollen flow and
mating systems of Pistacia lentiscus and Myrtus communis by using
indirect analysis (Twogener and Kindist), to illustrate the pollen cloud
structure within and between mothers; estimate the effective distances
of pollen dispersal, the effective number of pollinators and mating
systems rates (selfing, outcrossing and biparental inbreeding). It also
attempts to disentangle the influence of local landscapes attributes,
the spatial configuration of populations itself, the blooming synchrony
and the reproductive effort on the pollen flow parameters, through GLM
and simulation modelling. Finally, aims to assess the importance of the
pollen cloud diversity in offspring performance of both species,
analysing correlations between pollen diversity and measures of fitness
and survival of seedlings both under field and greenhouse conditions.