We aim at understanding the origin and evolution of different types of embryo sacs in flowering plants (varying in anatomy, number and cell-types), with special consideration to the apomeiotic (non-reduced) embryo sacs, their phylogenetic links to meiotic (reduced) ones, and functional roles of certain cell types within the female gametophyte. By using ovule ontogeny, developmental patterns and character states comparisons based on the APGIII phylogenetic tree we analyse the modularity of the female gametophyte in angiosperms and interpret its significance in the frame of current evolutionary theories. We look at resolving main patterns and tendencies originating apomeiotic embryo sacs (four-celled, four nucleate Panicum-type, and seven-celled, eight-nucleate Hieracium-type) and how they are interrelated to meiotic embryo sacs (four-celled, four nucleate Oenothera-type, and seven-celled, eight nucleate reduced Polygonum-type) to recognize clues promoting key evolutionary transitions.
Collaborative project with William (Ned) Friedman from Harvard University, USA.
The project is funded by the German Research Foundation (DFG).
Extensive grazing systems are widely distributed in the world, being one of the more degraded land types. Many factors are involved in land degradation, but the most common is livestock grazing. Alteration of spatial structure of vegetation has measurable consequences on biodiversity and ecosystems functioning. We plan a comprehensive analysis of animals´ grazing behavior, interaction with abiotic factors (water availability, weather, topography) and physical disturbances (fires, drought, flooding), and the response of vegetation communities (resource allocation and reproductive efficiency). We aim at understanding the consequences of grazing on vegetation dynamic and heterogeneity in order to improve management and/or conservation strategies in degraded areas and halt biodiversity losses as final ambition.
Collaborative project with Liliana Inés Allegretti and Eugenia Vazquez Novoa from the National University of Cuyo, Argentina.
Project funded by the National Scientific and Technical Research Council (CONICET, Argentina).
Polyploidy in flowering plants is one of the most significant spontaneous evolutionary processes, promoting diversification via genome duplication and gene pool fragmentation. Standing genetic variation and population structure in diploid and polyploids is primarily shaped by reproductive traits. On the other hand, hybridization and polyploidization events are associated to “genomic shock” and thus such events are prone to shifts in reproductive systems such as self-fertility (autogamy) or apomixis (asexually formed seeds). Breeding system character transitions not only affect the amount and structure of genetic variation within species, it may also affect colonizing abilities and geographic distributions by enabling uniparental reproduction (Baker's law). Reproductive assurance can promote range expansion (and appearance of patterns like geographical parthenogenesis), however their benefit might be outweighed by seed discounting, loss of genetic diversity and inbreeding depression. Apomictic plants may benefit of a more efficient partition of the ecological niche and use of the resource space by broad arrays of clones (The Frozen Niche Variation Model), or may promote dispersal of clones with broad ecological capacity (General Purpose Genotypes). To investigate the complex dynamics determining geographic distributions and cytotype associations in natural populations, we take advantages of the model system Paspalum (ie. presence of sexual self-sterile / self-fertile diploids, sexual self-sterile / self-fertile tetraploids, apomictic self-fertile tetraploids), and analyse consequences of autogamy vs. allogamy, diploid vs. polyploid, sexual vs. apomictic state characters on genetic variation and cytotype diversity at population level. We expect to gain knowledge into the importance of these factors for plant evolution and biogeography
Collaborative project with Eric Martínez, Verena Reutemann, Mara Schedler, Ana Honfi, Fabiana Eckers (National University of Misiones, Argentina), and Piyal Karunarathne (University of Goettingen).
Project funded by the German Research Foundation (DFG, Germany), the Ministry of Science and Technology (MINCyT, Argentina), the National Scientific and Technical Research Council (CONICET, Argentina).
Collaborative project with Eric Martínez and Adriana Gluecksberg from the National University of the Northeast, Argentina.
Project funded by the National Agency for the Promotion of Science and Technology (ANPCYT-FONCyT, Argentina)
I am fascinated by the origin of apomixis and its evolutionary consequences at individual and population levels. The molecular basis for the emergence of apomixis in plants is a long-standing mystery and a complex developmental process that coordinates the circumvention of mechanisms phylogenetically conserved in plants and eukaryotes. Ovules of apomictic plants skip meiosis and egg-cell fertilization and develop plant embryos by parthenogenesis. Thus, apomictic plants are able to produce clonal seeds, a feature that shapes genomic and ecological attributes, and has an immense potential in agriscience. Clonal propagation by seeds provides plants with superior dispersal abilities compared to sexual counterparts, and allow multiplication of fitter genotypes. My group investigates the genetic nature and effects of apomixis on plant reproductive abilities, population genetics, ecological adaptation, and diversification.
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Piyal´s research interests are mainly in evolutionary ecology and plant evolution. He is interested in understanding how the current complex plant communities evolved from primitive life forms over millions of years. Piyal´ specific research topics involve ecological consequences of polyploidization, apomixis and cytotype co-existence. During his Master project at the Institute of Science (University of Peradeniya, Sri Lanka) he focused on identifying evolutionary groups in the Zingiberaceae family in Sri Lanka and the relationships of Sri Lankan gingers to neighboring African groups and east and north Asian ginger groups base on fruit morphology. Piyal is currently holding a Ph.D. scholarship from the DFG (Germany) to explore the ecological consequences of polyploidization and how polyploidization operates at ground level. Using the South American grass species Paspalum intermedium as a model plant, he is looking into how cytotypes deal with different reproductive strategies, dissimilar habitat availability, and coexistence after polyploidization events. The study focuses on understanding initial mechanisms that lead to speciation events in closely related taxa.
Trained as an Agricultural Engineer at the National University of the Northeast (FCA – UNNE), Mara is currently holding a Doctoral scholarship from CONICET (Argentina) to study patterns of genetic diversity in natural populations of five different Paspalum species. Analysing morphological variability, ploidy levels, reproductive strategies and genetic variability, she plans to disentangle the dynamic formation and distribution of genetic diversity that promotes species range shifts and adaptation.
Verena´s interest has focussed on sexual reproduction, one of the most studied puzzling paradigms in evolution. Why? well, in spite of the high costs derived from generating sexual progeny, it remains the most widespread reproductive strategy in nature. One of the most common reasons is that without genetic recombination and reshuffling of variability organisms will become extinct in long-term evolutionary times. With a Bachelor in Genetics, Verena holds a scholarship from CONICET (Argentina) to study facultative asexual plant systems and evaluate how small rates of sexuality contributes to shape paired patterns of genetic diversity in natural populations. I use several grass species ( Paspalum L.) that differ in modes of reproduction (sex vs. apomixis), pollination systems (self- vs. out-crossers), ploidy levels (diploids vs. polyploids) and geographic distribution patterns (narrow vs. wide-ranging).
Fabiana received a Bachelor degree in Genetics at the National University of Misiones (Argentina), and she is currently holding a Doctoral scholarship from CONICET (Argentina) at the Institute of Subtropical Biology (CONICET – IBS, Argentina). Her research aims at characterizing the reproductive biology of four different species within genus Paspalum which exhibit different ploidy levels and geographic distributions. Fabiana got a DAAD scholarship to visit our lab and carry out part of her research project on the analysis of the sexual and asexual reproductive strategies.
With a strong interest in Ecology and Animal Production, Eugenia has focused her research on describing the effect of grazing of Criolla goat on the biodiversity and resilience of the “algarrobal abierto”(Prosopis flexuosa) plant community, in the Central Monte (Argentina). For achieving her goals, she carries out fieldwork studies to detect changes in taxonomic, functional and phylogenetic plant diversity as well as in specific plant traits related to reproductive fitness. The project will contribute to evaluate the best strategies to maintain small farmers´ returns while limiting land-use intensification and preserving the diversity of native plants and animals. Eugenia holds a Doctoral scholarship from CONICET (Argentina) and her project is further supported by the Instituto Argentino de Investigaciones de Zonas Áridas (IADIZA).
Advisors: Dr. Juan Carlos Guevara; Dr. Diego Hojsgaard
Borja is close to finishing his Master Science in Molecular Medicine and will soon move to Heidelberg where he will be working in R&D activities for BiomedX. He was a research assistant in our group and worked on Flow Cytometry, helping us to elucidate patterns of variation in ploidies and reproductive methods on several species of interest.
Adriana graduated in Genetics at the National University of Misiones (Argentina) and moved to Salamanca (Spain) to obtain a Master's degree in Agrobiotecnology at the University of Salamanca. Currently Adriana holds a Doctoral scholarship at the Institute of Botany of the Northeast (CONICET – IBONE, Argentina) to study how cytogeography and alternative reproductive strategies shape the distribution of standing genetic and morphological variability contributing to adaptiveness in a wide spread South American species. Adriana is further interested in the causality of epigenetics to adaptation and evolution.