Meeting Abstract
113.3 Monday, Jan. 7 Divergent Behavioral Strategies in Three Congeneric Rodents for Dealing with Fruit Toxins SAMUNI-BLANK, M*; IZHAKI, I; DEARING, MD; KARASOV, WH; GERCHMAN, Y; KOHL, K; LYMBERAKIS, P; KURNATH , P; ARAD, Z; Technion, Haifa; Univ. of Haifa, Haifa; Univ. of Utah, Salt Lake City; Univ. of Wisconsin, Madison; Haifa Univ. in Oranim, Tivon; Univ. of Utah, Salt Lake City; Natural History Museum of Crete, Crete; Univ. of Utah, Salt Lake City; Technion, Haifa michal.samuni@gmail.com
Fleshy, ripe fruits facilitate seed dispersal by attracting animals that consume the fruits and disperse the seeds. However, many fruits contain secondary compounds (FSCs) that deter potential consumers. Previous studies have demonstrated class-dependent deterrence where frugivorous birds were not affected by the FSCs while granivorous rodents were deterred by them. Here we show divergent behavioral strategies for dealing with FSCs within a single genus of rodents. In a series of field observations, controlled feeding trials and biochemical analysis we investigated the fruit eating strategies of three congeneric rodents for Ochradenus baccatus, a desert plant with unique compartmentalization of FSCs. The fruit pulp has high concentrations of glucosinolates (GSLs) that are hydrolyzed into active toxic compounds upon contact with myrosinase released from the seeds crushed during consumption. We found that the granivorous rodents, Acomys cahirinus and A. minous, circumvent the activation of the GSLs by, respectively, orally expelling vital seeds or by making a hole in the pulp and consuming only the seeds. In contrast, A. russatus activates GSLs by consuming the whole fruit. We propose that A. russatus possesses physiological adaptations to cope with the toxic compounds generated from the GSLs-myrosinase system whereas A. cahirinus and A. minous exhibit behavioral adaptations (seed or pulp spitting) to avoid the activation of these toxins. These findings demonstrate the extreme ecological/evolutionary lability of this plant-animal symbiosis to shift from predation to mutualism.
