Salinity and Simulated Herbivory Influence Spartina alterniflora Traits and Defense Strategy

Sea level rise is expected to push saline waters into previously fresher regions of estuaries, and higher salinities may expose oligohaline marshes to invertebrate herbivores typically constrained by salinity. The smooth cordgrass, Spartina alterniflora (syn. Sporobolus alterniflorus), can defend itself against herbivores in polyhaline marshes, however it is not known if S. alterniflora’s defense varies along the mesohaline to oligohaline marsh gradient in estuaries. I found that S. alterniflora from a mesohaline marsh is better defended than plants from an oligohaline marsh, supporting the optimal defense theory. Higher salinity treatments lowered carbon content, C:N, and new stem biomass production, traits associated with a tolerance strategy, suggesting that salinity may mediate the defense response of S. alterniflora. Further, simulated herbivory increased the nitrogen content and decreased C:N of S. alterniflora. This indicates that grazing may increase S. alterniflora susceptibility to future herbivory via improved forage quality. Simulated herbivory also decreased both belowground and new stem biomass production, highlighting a potential pathway in which herbivory can indirectly facilitate marsh loss, as S. alterniflora biomass is critical for vertical accretion and marsh stability under future sea level rise scenarios

Castorid phylogenetics: Implications for the evolution of swimming and tree-exploitation in beavers

Beavers (Castoridae) are semiaquatic rodents that modify forest and aquatic habitats by exploiting trees as a source of food and building material. The capacity of beavers to transform habitats has attracted interest from a variety of researchers, including ecologists, geomorphologists and evolutionary biologists. This study uses morphological and behavioral evidence from the fossil record to investigate the evolutionary history of tree-exploitation and swimming in beavers. The findings suggest that both behaviors appeared within a single castorid lineage by the beginning of the Miocene, roughly 24 million years ago. Biogeographic results support the hypothesis that tree-exploitation evolved at high latitudes, possibly influenced by the development of hard winters

Modelling the Defensive Potential of Plants

Plants use resources, i.e. coarbon, nutrients, water and enery, either for growth or to defend themselves from biotic and abiotic stresses. This volume provides a timely understanding of resource allocation and its regulation in plants, linking the molecular with biochemical and physiological-level processes. Ecological scenarios covered include competitors, pathogends, hervivores, mycorrhizae, soil micorogranisms, carbon dioxide/ozone regimes, nitrogen and light availabilities. The validity of the "Growth-Differentiation Balance Hypothesis is examined and novel theoretical concepts and approaches to modelling plant resource allocation are discussed. The results presented can be applied in plant breeding and engineering, as well in resource-efficient stand management in agriculture and forestry