Can forest fragmentation disrupt a conditional mutualism? A case from central Amazon.
This is the first study to investigate whether scatter-hoarding behavior, a conditional mutualism, can be disrupted by forest fragmentation. We examined whether acouchies (Myoprocta acouchy, Rodentia) and agoutis (Dasyprocta leporina, Rodentia) changed scatter-hoarding behavior toward seeds of Astrocaryum aculeatum (Arecaceae) as a consequence of a decrease in forest-patch area. Our study was conducted at the 30-year-old Biological Dynamics of Forest Fragments Project, in central Amazon, Brazil. We tested whether forest size affected the number of Astrocaryum seeds removed and scatter-hoarded (and likely dispersed) by acouchies and agoutis, as well as the distance that the seeds were hoarded. The study extended over three seasons: the peak of the rainy season (March-April), the transition between the rainy and the dry season (May-June), and the peak of the dry season (August-September). Our results revealed that the number of seeds removed was larger in smaller fragments, but that the percentage of seeds hoarded was much lower, and seeds eaten much higher, in 1-ha fragments. Moreover, fewer seeds were taken longer distances in fragments than in the continuous forest. Site affected the number of seeds removed and season affected the percentage of seeds hoarded: more seeds were removed from stations in one site than in two others, and hoarding was more important in April and September than in June. Our study reveals that scatter-hoarding behavior is affected by forest fragmentation, with the most important disruption in very small fragments. Fragmentation converts a largely mutualistic relationship between the rodents and this palm in large forest patches into seed predation in small fragments.
Jorge
Maria Luisa S P
ML
Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA. malu.jorge@vanderbilt.edu
Howe
Henry F
HF
D000704:Analysis of Variance; D000818:Animals; D028023:Arecaceae / Q000502:physiology*; D001938:Brazil; D017753:Ecosystem; D005247:Feeding Behavior / Q000502:physiology*; D005843:Geography; D011157:Population Dynamics; D012377:Rodentia / Q000502:physiology*; D012621:Seasons; D012639:Seeds / Q000502:physiology*; D014197:Trees / Q000502:physiology*