Current research: What is the influence of agriculture on the geographic mosaic of selection in Helianthus (sunflower)? The GMT framework has been increasingly used to examine spatial variation in selection on one or both species in an interaction. However, only very little work has been done to incorporate the influence of any anthropogenic landscape factors into the GMT framework. This is despite the fact that most species probably occur in close proximity to human disturbance of some kind, whether development, pollution, habitat fragmentation, or agriculture. I am using wild and cultivated Helianthus annuus to explore how agriculture plays into the GMT framework. I am taking a broad geographic approach within Texas, with clusters of sites near Corpus Christi, Houston, Austin, and Lubbock (see map to right). I am examining geographic variation in selection on flower traits in H. annuus, and hopefully a bee species or two if methods present themselves. Experiments will manipulate proximity of wild sunflowers to agricultural sunflowers, replicated throughout Texas. I will also examine how sunflower seed predators are linked to geographic variation in patterns of selection on flower traits. Conditionality in competition, predation, and mutualism Species interaction outcomes are often examined, and compared among studies, in terms of their mean outcome, ignoring variation in those outcomes. We are conducting a meta-analysis to ask if species interaction outcomes are more variable in competition, predation, and mutualism, and whether outcomes are more variable in time or space, or with body size, developmental stage, nutrient level, etc. This research will hopefully give us a very broad look at the most important axes along which species interaction outcomes vary, with implications for predicting the most important variables in little explored systems, and to better inform models. Trade-offs or synergies among floral and extrafloral nectar traits in Gossypium (cotton)?  Production of defense traits are often costly to plants. Thus, researchers have often predicted a negative relationship between two defense traits that deter plant enemies. However, little research has explored whether traits to attract two mutualist guilds, such as pollinators and ant bodyguards, are positively or negatively correlated. Using the cotton genus, comprised of ~50 species worldwide, Jenn Rudgers and I are asking whether there are positive or negative correlations among floral and extrafloral nectar traits. See the poster presented at ESA 2009 here. And see more details here. Past research: Ant-plant networks: examining structure and mutualisms Some past research examined networks of species interactions between extrafloral nectar bearing plants and ants that (presumably) protect plants against herbivores. We examined network properties in relation to ant body size, and examining if biological attributes of plants and ants contribute to explaining network structures. --Poster of previous work (see attachments below) How context-dependent are ant-plant protection mutualisms? Interaction outcomes in mutualism are often thought to be context dependent, especially more so relative to competition and predation. However, this has largely not been explored outside of single species studies. We explored this question using meta-anlaytic techniques and a database of ant-plant protection studies. Natural history and pollination biology of a California native geophyte. Natural history is the foundation of ecology and evolution. Dr. Rob Schlising and I documented many aspects of the natural history of a the California native geophyte, Triteleia laxa. In addition, we explored the role of non-native honey bees (Apis mellifera) in the pollination of this native geophyte. It turns out that honey bees are quite important for T. laxa pollination. It remains to be seen how important honey bees are for other native plants. Apparently mutualistic ant-plant protection interactions in the Sonoran Desert. Extra-floral nectaries (EFN) occur in more than 20% of flowering plant families, and they have evolved independently in unrelated groups, suggesting an adaptive significance. EFN bearing plants have largely been studied in the tropics, and have been neglected in deserts where almost all species of cacti have EFN. Senita cacti (Pachycereus schottii) in the Sonoran Desert have EFN on buds, flowers, and fruits. At least ten ant species facultatively interact with senita as a result of gathering these extra-floral nectar rewards. We studied the ecology and evolution of the interactions between senita cacti and the associated guild of EFN feeding ants. We found that ant interactions with senita cacti are largely driven by EFN production, and ants do have the potential to disrupt pollination processes. |