Current Projects:
 
  • Research project 1: The evolution of rewards in a mutualistic interaction: the cross‑systems transferability of hypotheses in the study of seed dispersal by ants. 
     
    Recent theoretical developments concerning the evolution of species interactions in general and mutualism in particular, have emphasized the need to consider the geographical, environmental and spatial contexts within which species interactions occur and evolve.  Myrmecochory, seed dispersal by ants, is a mutalistic animal-plant interaction whose ecology and evolution have been thoroughly studied in several ecosystems around the world.  However, although many plant species in Mediterranean and desert ecosystems exhibit morphological adaptations that characterize dispersal by ants our knowledge of that type of interactions in these ecosystems is very poor.
    The main goal of this project is to test whether ideas and hypotheses that were generated in regions where myrmecochory is well studied, are valid and gain support in other ecosystems where the payoffs for the participants (plants and ants) are context-dependent and less certain.
     
    Seed dispersal of Sternbergia clusiana
    We are looking at the ecological significance and selection for seed dispersal by ants along a sharp environmental gradient.  Our model system is the plant Sternbergia clusiana and the ants with which it interacts. This rare plant, which is of conservation, cultural and aesthetic value, has a very patchy distribution that may reflect strict availability of suitable habitat and/or very limited seed dispersal capabilities. This plant has many characteristics and adaptations that make it a very good candidate for being dispersed by ants. We hypothesize that the plant adaptations for dispersal by ants evolved in a different ecological and evolutionary context. We plan to use a combination of observations, field experiments, chemical analyses and introduction experiments to test: a) whether the plant distribution is limited by the same factors along the climatic gradient, b) whether there is a geographical gradient in the investment of the plant in dispersal adaptations and c) whether dispersal limitations can be overcome by planned introduction, a question with direct implications for the conservation of this plant. This plant is a representative of a small group of plants in the Israeli flora, most of which are rare, that share similar adaptation for dispersal by ants. We plan to expand our research to other species.

  • Research project 2: The role of harvester ants in structuring plant communities and ecosystem functioning in arid environments:                                                                                                                                                                                                                             This research project concerns the interaction between plants, ants and the soil biota in a desert ecosystem. In this project we mapped the location of the main seed-eating ants and we investigate how the production of seeds by the annual and the perennial vegetation affect the choice location of the establishment of ant colonies. We then study how nest location and foraging behavior of the ants affect their impact on plant population and community dynamics.  As part of this project we investigate the effect of ant activity (around the nesting site) and desert shrubs on biodiversity above (annual plants) and below (soil microbial and fungal communities) ground and the consequences of these on ecosystem processes and the recruitment and success of plants in the vicinity of ant nests.                                                                                                                             

  • Research project 3: The evolution of seed dispersal distances

     

      The third research project is on the evolution of seed dispersal traits in relation to selection pressures by the physical, biological and genetical environment.  In one part of the project I plan to test the hypothesis that position along environmental gradient interacts with landscape configuration in shaping the distribution of seed dispersal distances.  I will study dispersal phenotypes of three annual plants (Catananche lutea, Geropogon hispida and Crepis sancta) and conduct controlled experiments to tease apart the contribution of genetics and phenotypic plasticity to the observed dispersal phenotypes.
    In a second part of this project, we test whether the genetic relatedness of a mother plant and her offspring affect the dispersal phenotype of the offspring (seeds).  This research involves sampling of a model plant, Crepis sancta from mapped populations, experimental pollination that controls for the genetic relatedness of the seeds and genetic analysis (in collaboration with Prof. Victoria Sork from UCLA).                                                                                                                                                                                                                                                                  
                        
  • Research project 4: The conservation of endangered plant species in agricultural landscapes:                                                                                                                                                                                                                                                          The realization that huge areas on the surface of earth are affected by human activity led many ecologists to direct significant conservation efforts to anthropogenic landscapes. Agricultural landscapes in particular are a good candidate for biodiversity conservation, if properly managed. Within such landscapes, suitable habitats of many organisms are limited to fragments of natural and semi-natural patches embedded in an agricultural matrix. We (a collaborative with Yaron Ziv, Anat Zafrir) investigate how the patchy structure and the nature of agricultural practices affect the maintenance of viable populations (and metapopulation) of endangered plant species in a unique habitat in the southern Judea lowland. A first step, where the environmental determinants of the distribution of two endangered plant species (Teucrium spinosum and Onosma gigantea) were investigated, will be followed by a long-term monitoring program combined with manipulative experiments that will help to characterize the spatial dynamics of these (and other) rare species. The identification of the most applicable model of spatial dynamics of these plant species will help in designing informed conservation programs and effective management.