40.5 Thursday, Jan. 5 From a Seed Predator to a High-Quality Seed Disperser: The tale of Acomys cahirinus and Ochradenus baccatus SAMUNI-BLANK, M.*; IZHAKI, I.; DEARING, M.D.; ARAD, Z.; Technion, Haifa, Israel; Univ. of Haifa, Haifa, Israel; Univ. of Utah, Salt Lake City; Technion, Haifa, Israel email@example.com
The ripe fruits of many plants contain plant secondary metabolites (PSMs) in concentrations that could be toxic to vertebrates. The directed-deterrence hypothesis (DDH) states that PSMs in ripe fruit are deterrents for seed predators, but have no or little toxic effect on seed dispersers. Acomys cahirinus is a murid rodent usually described as a predominantly seed predator, sharing its habitat with the Ochradenus baccatus bush in the Israeli desert. In this study, observations on captive individuals, backed by field observations, revealed A. cahirinus as a high-quality seed disperser that: (1) carries the whole fruit cluster away from the parent plant, (2) consumes an average of six fruits per minute, (3) eats only pulp and expectorates the majority (73.8%) of the seeds undamaged, (4) expectorates seeds that have a germination success (74.4%) similar to that of seeds manually separated from the pulp, (5) consumes the fruits mainly between the rocks, a location that may provide favorable conditions for seedling establishment. We suggest that this unique behavior is the result of the presence of PSMs in O. baccatus fruits. Glucosinolates (GLSs) located mainly in the pulp of O. baccatus are activated upon mechanical injury to the seeds by the enzyme myrosinase. These activated GLSs are known to generate considerable physiological effects on mammals. The compartmentalization of the GLSs and myrosinase in O. baccatus fruits may shape the interaction between O. baccatus and A. cahirinus. Thus, in agreement with the DDH, the PSMs in O. baccatus may have transformed the role of A. cahirinus from a seed predator to a high-quality seed disperser by modifying its feeding behavior.