Abstracts (first author)
Evolutionary changes in the sexual reproductive system: the case study of the invasive tristylous Oxalis pes-caprae
The establishment and spread of invasive species depends on different evolutionary and ecological pressures, with reproduction being a key factor for success. Among other strategies, vegetative propagation has been correlated with invasion potential. Because clonality affects the spatial distribution of genets and its flowers, clonal species are expected to have increased rates of self-pollination. However, selfing might be advantageous as it enables to overcome the lack of compatible mates or scarcity of pollinators during invasion. Under this scenario, in self-incompatible species, selection may favor the breakdown of the incompatibility system, as plants with some levels of compatibility would have advantage in low density conditions and be able to establish new populations after dispersal (Baker’s law). Oxalis pes-caprae is a tristylous species with heteromorphic incompatibility; in most invaded areas, strong founder events lead to the introduction of the 5x short-styled morph only, leading to an exclusively asexual mode of reproduction. Yet, recent studies have shown scattered sexual reproduction and the emergence of new floral morphs in the western Mediterranean basin. Our objective was to evaluate the rates of self- and morph-incompatibility across this invaded area, and compare it with the native range, in order to assess changes in the reproductive system. Controlled hand-pollinations were made in invasive and native populations and plant reproductive success was quantified. The incompatibility system varied among invasive populations and floral morphs; overall a breakdown in several populations across the invaded range was observed, mostly through a partial breakdown in morph-incompatibility of S-morph, but also in self-incompatibility system of M- and L-morphs. Because reproductive strategies determine the demography and genetics of invasive populations, the results obtained are important to understand the evolutionary dynamics operating during invasion.
New ploidy levels and genome size estimates in wild Beta taxa using flow cytometryPDF
It is widely recognized that the conservation of the Crop Wild Relatives (CWR) in their wild habitats, where they can continue to adapt and evolve along with their natural surroundings, is fundamental to ensure the continuous supply of the novel genetic material critical for future crop improvement. The genus Beta L. (Amaranthaceae) is an important source of crops, primarily for sugar production. Within a broader research project aiming to select appropriate wild accessions and identify priority localities in which to establish genetic reserves of the wild Beta species occurring in Portugal, the aim of this study was to assess the cytogenetic diversity of wild Beta populations. For this, a large scale sampling of natural populations of B. vulgaris subsp. maritima and B. macrocarpa was performed across Portugal (including also the archipelagos of the Azores and Madeira) and genome size and ploidy level estimated using flow cytometry. The analysed populations were mostly diploid, except for one population of B. vulgaris subsp. maritima that presented both diploid and tetraploid individuals, and for two populations of B. macrocarpa where two or three cytotypes (diploids, tetraploids and/or hexaploids) were found. Leaves of both species presented variable levels of endopolyploidy. The obtained results will be discussed within the context of interspecific hybridization and cryptic diversity, and constitute significant data for the conservation of these wild Beta crop relatives.