Strategies for conservation of rare and endemic species: characterization of genetic and epigenetic variation and unusual reproductive biology of coastal species from Limonium ovalifolium and Limonium binervosum complexes (Plumbaginaceae)

Abstract

Doutoramento em Biologia - Instituto Superior de AgronomiaLimonium Mill. (Plumbaginaceae) is among the best represented genus in coastal habitats. In Continental Portugal, two taxonomically complex groups, diploid Limonium ovalifolium and tetraploid Limonium binervosum complexes are present, and species within these complexes present morphological similarities. These species are threatened as a result of negative anthropic impacts in coastal areas. The aims of the study presented in here were to collect information on chorology, karyology, natural population genetic and epigenetic variation, and reproductive biology of those species. A comparison of populations’ chromosome numbers revealed the presence of aneuploid individuals in species of both complexes. Male micro- sporogenesis and gametogenesis analyses showed regular meiosis and viable pollen grains formation in diploids as opposed to tetraploids. Floral heteromorphisms studies, pollination experiments and cytoembryological analyses demonstrated facultative apomixis in diploids and obligate apomixis in tetraploids. Analysis of methylation sensitive amplification polymorphisms revealed modest genetic and epigenetic differentiation among species populations’. Phylogeographic studies using chloroplast DNA marker sequences demonstrated a large amount of haplotype sharing indicating hybridization among species. This thesis offers deeper insights into these taxonomic complexes for better design conservation strategies in situ and ex situ, and a basis for ongoing and future research projects dealing with the expression of apomixis as well as genome evolution in Limonium spp