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Thesis Defense | Delaney Gibbs on 'The secondary dispersal of perennial forest herb seeds by scatter hoarding rodents,' July 23
The Environmental & Plant Biology Department hosts Delaney Gibbs' oral presentation for her M.S. thesis defense on “The secondary dispersal of perennial forest herb seeds by scatter hoarding rodents” is July 23 at 1 p.m. via Teams.
Contact Dr. Rebecca Snell for the Teams link.
Abstract: Seed dispersal is typically thought of as a simple, one-step process in which a seed is moved from point A to point B by some outside force. However, researchers have found in recent years that a seed’s journey is often much more complex and can involve several consecutive agents. For example, rodents have been found to add an extra step to the seed dispersal process for many plant species when they remove seeds from frugivore feces and store them in small hoards for later consumption. In many cases, there is a higher likelihood of germination in scatter hoards, meaning these occasional seed predators can also serve as effective secondary seed dispersal agents. Little is known about the multi-phase dispersal process for the seeds of fleshy-fruited perennial herbs native to temperate deciduous forests. Thus, my overall research question is, “Are scatter hoarding rodents effective secondary seed dispersal agents for perennial forest herbs”? We answered this question with three experiments that explored rodent seed preference, germination requirements for forest herbs, and the movement and fate of seeds that have been foraged by Peromyscus leucopus (white-footed mice).
Our research demonstrated the occurrence of secondary seed movement by scatter-hoarding rodents and the differences among species. Our findings showed variation in seed preference, and therefore the frequency of seed removal, depended on seed characteristics. Using seeds labeled with a radioactive isotope, we also tracked and monitored the fate of foraged seeds, showing that mice store a portion of their foraged seeds in scatter hoards where seeds are placed under a layer of leaf litter. With a multi-year germination experiment, we demonstrated a nearly 100% overlap between microsites selected by rodents for scatter hoards and microsites suitable for successful germination. In conclusion, rodents can provide additional dispersal benefits to the seeds of forest herbs, however the effectiveness of these mice as secondary dispersal agents is variable depending on the plant species.
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