Abstracts (first author)

Poster 

Do native and invasive populations of Oxalis pes-caprae differ in reproductive traits?

Author(s): Castro M, Ferrero V, Costa J, Roiloa S, Loureiro J, Navarro L, Castro S

Summary:

Biological invasions offer the opportunity to study evolutionary transitions in current timescales. Because reproductive strategies determine demographic and genetic characters of invasive populations, variations on reproductive characters have the potential to influence evolutionary processes during invasion, and the invasion process itself. Thus, comparative studies of reproductive systems between native and invaded ranges are crucial for understanding the mechanisms of plant invasion and for predicting microevolutionary changes in anthropogenic environments. Oxalis pes-caprae is a tristylous species native from South Africa and an invasive weed in Mediterranean climate regions worldwide. In its native habitat, the species presents three floral morphs, reproduces sexually and asexually, and has different cytotypes (2x, 4x, 5x). 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. However, in the Mediterranean basin, new floral morphs and cytotypes with the ability to reproduce sexually were recently found. The aim of the present study was to assess evolutionary shifts in asexual and sexual reproduction traits between floral morphs and cytotypes, and between native and invasive populations of O. pes-caprae. For this, phenotypic characters directly linked with reproduction were assessed in plants from native and invasive populations growing in a common garden. The results of the sexual and asexual reproductive traits among floral morphs, cytotypes and invaded vs. native range are presented. The information gathered adds significant background information on the evolutionary biology and ecology of biological invasions. The knowledge of the probability and speed at which local adaptation evolves in invasive plants is particularly important for management practices, especially when evolutionary changes enhance ecological opportunities and invasive spread.



Abstracts (coauthor)

Summary:

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.

Summary:

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.

Contacts

Chairman: Octávio S. Paulo
Tel: 00 351 217500614 direct
Tel: 00 351 217500000 ext22359
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email: mail@eseb2013.com

Address

XIV Congress of the European Society for Evolutionary Biology

Organization Team
Department of Animal Biology (DBA)
Faculty of Sciences of the University of Lisbon
P-1749-016 Lisbon
Portugal

Website

Computational Biology & Population Genomics Group 
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