Evolutionary changes to reproductive systems during the invasion process of the polyploid Oxalis pes-caprae
Coordinator - João Loureiro
Execution dates - 2011-02-15 - 2014-08-14 (42 Months)
Funding Entity - Fundação para a Ciência e Tecnologia
Total Funding - 163 349 €
Proponent Institution -
Participating Institutions
Centre for Functional Ecology, Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra
Departamento Biología Vegetal y Ciencias del Suelo, Facultad de Ciencias, Universidad de Vigo (Luis Navarro)
Estación Biológica de Doñana (Montserrat Vilà)

Biological invasions have long been recognized to comprise significant ecological and evolutionary consequences, both for the species and communities being invaded, as well as for the invasive species themselves (e.g. [1]). Facing the growing evidence on the negative ecological and economic effects of invasive species [2] and the possibility that rapid evolutionary changes in colonizing populations contribute to invasion success [1,3], it became fundamental not only to identify invasive plants and the features related with their invasive character, but also to understand the evolutionary processes operating during invasion.
A major challenge to understand biological invasions is to determine why a species becomes problematic following introduction into a novel environment. The establishment and spread of an invasive species in a new place depends on different evolutionary and ecological pressures [4,5]. In particular, traits linked with production, dispersal and genetic composition of propagules play a special role [6]. Because reproductive strategies determine demographic and genetic characters of the invasive populations, variations on reproductive characters (e.g., relative importance of sexual vs. asexual reproduction or self-fertilization vs. cross-pollination) have the potential to influence evolutionary processes during invasion and the invasion process itself. Therefore, comparative studies of reproductive systems in native vs. invaded ranges are crucial for understanding the biology and mechanisms of plant invasions, for predicting microevolutionary changes in anthropogenic environments, and ultimately, for designing effective control measures for invasive species [4]. However, the roles played by reproductive modes in the successful invasion of exotic species are largely unknown (but see [4]).
Our model species, Oxalis pes-caprae L. (Oxalidaceae), offers an excellent opportunity to study how evolutionary changes in the new range may trigger invasion (hypothesis of Evolution of Increased Competitive Ability, [7]), in particular, the evolutionary shifts in reproductive systems. O. pes-caprae is a heterostylous species native from South Africa that was introduced as an ornamental plant in several areas of the world, particularly in Mediterranean climate regions, where it is currently a noxious and widespread invasive weed. This species has a complex reproductive system, as besides presenting 3 floral morphs (Fig. 1), each plant may have one of three cytotypes (2x, 4x and 5x), with sexual reproduction being possible only after legitimate crosses between floral morphs with compatible ploidy levels. In the invasive area, a shift to obligate asexuality through clonal propagations has been observed as a result of founder events which lead to the introduction of the pentaploid short-styled morphotype, only. The introduced form not only lost the mating partners but it is also an apparently sterile form from a cytological point of view. However, researchers of our team have recently found, for the first time, the presence of new floral morphs and cytotypes in the western Mediterranean basin (Fig. 2 and 3 [8,9]). The occurrence of these new forms opened the possibility for sexual reproduction (we observed, for the first time, seeds in this area) and constitutes a new mean of dispersal and source of genetic diversity [9].
Facing these new findings, the main goals of the current project are: to assess the evolution and contribution of both asexual and sexual reproduction components in the dynamics of the invasion of O. pes-caprae in the Iberian Peninsula, in comparison with the processes acting in the native area; to determine the origin of new cytotypes and floral morphs in invasive populations; to study the impact of the newly established mutualistic interactions (i.e., plant-pollinator interactions) in the reproductive success of invasive populations in comparison with native interactions, and to assess the possible effects of O. pes-caprae in the receptive ecosystem, namely on the native plant-pollinator networks; to raise public awareness about the ecological (and economical) impact of invasive species.
A team of young researchers, with multidisciplinary scientific background, will develop an original approach including observations and data collection in the field, common garden experiments and innovative cytological and molecular tools, in both the native and invaded regions, that, altogether, will enable the successful accomplishment of the proposed objectives. The results of the present project will add important background information on the ecologic and evolutionary processes of biologic invasions. The knowledge of the probability and speed at which local adaptation evolves in invasive plants is particularly important for management practices when evolutionary changes enhance ecological opportunities and invasive spread.

Members on this project
Helena Freitas
Team Member
Joana Costa
Team Member
João Loureiro
Principal Investigator
Sergio Roiloa
Team Member
Sílvia Castro
Team Member
Victoria Ferrero
Team Member