The role of site, habitat, seasonality and competition in determining the nightly activity patterns of psammophilic gerbils in a centrifugally organized community

Abstract

Z. 2006. The role of site, habitat, seasonality and competition in determining the nightly activity patterns of psammophilic gerbils in a centrifugally organized community. Á/ Oikos 112: 573 Á/579.Major ecological forces affecting diel activity patterns include predation, competition, resource dynamics, and ambient conditions. In this work we studied if, how, and why the nocturnal activity patterns of two gerbil species differed with respect to site, habitat, season, and inter-specific competition. The study system included two gerbil speciesGerbillus pyramidum and G. andersoni allenbyi in a sandy landscape composed of three habitats-shifting, semi-stabilized, and stabilized sand habitats. Conforming to previous studies, in the semi-stabilized sand habitat clear temporal partitioning in activity times occurred, with G. pyramidum being active earlier in the night and G. a. allenbyi being active in the later part of the night. As shown in previous studies in a different, more xeric site, removal of G. pyramidum demonstrated that this activity pattern is the result of interference competition by the latter on the former. Nocturnal activity pattern differed between habitats and seasons. Temporal partitioning occurred in the semistabilized sand habitat where both gerbil species were common. In the shifting sand habitat, G. pyramidum activity pattern was similar to that in the semi-stabilized sand habitat, but at a lower level. In the stabilized sand habitat where G. a. allenbyi occurred alone, its activity was the highest among the three habitats and was fairly constant throughout the night. Temporal partitioning occurred in the fall and early summer, but not in the early spring. The roles of predation risk, competition and resource dynamics in determining the gerbils' temporal activity together with their implications for community structure, are discussed.

Multiple effects of host‐species diversity on coexisting host‐specific and host‐opportunistic microbes

“…Differences in host‐species composition of plots in relative close proximity to one another were attributed to microhabitat heterogeneity in the western Negev sand dune ecosystem and the related habitat preference of the rodents. In particular, G. andersoni and G. pyramidum prefer semistabilized microhabitats but when the preferred habitat is occupied, the secondary preference of the two species differs, with G. andersoni preferring more stabilized sandy microhabitats and G. pyramidum preferring the drifting sandy microhabitats where G. gerbillus is mostly found (Shanas et al 2006, Wasserberg et al 2006). The observed species composition of 31 plots was in agreement with previous surveys.…”

“…1). These communities have been well studied for over more than 30 years (e.g., Abramsky et al 1985, Wasserberg et al 2006), giving us the advantage of focusing on the most common species assemblages rather than on ephemeral species compositions. In the study area, all rodent species are infested by the same flea species, Synosternus cleopatrae , which is likely to transmit bacteria from one host species to another via blood feeding.…”

Invasive lionfish increase activity and foraging movements at greater local densities

“…For example, if it takes longer to find and consume prey due to increased resource depletion or interference while foraging at higher densities, some individuals may increase the amount of time spent foraging (Clark & Mangel 1986, Shaw et al 1995, Anholt & Werner 1995, Grand & Dill 1999, Bohlin & Johnsson 2004, White & Warner 2007, which may also be accom panied by an in crease in conspecific aggressive encounters (Pintor et al 2009, Kaspersson et al 2010. Species that differentially forage over a diel cycle can expand their foraging time by hunting for longer during their typical hunting hours and/or by hunting at more periods of the day (Lawton 1987, Kronfeld-Schor & Dayan 2003, Wasserberg et al 2006. Hunting at more periods of the day could in turn cause prey species with various diurnal patterns to be differentially susceptible to predation.…”

Out of the ground: two coexisting fossorial toad species differ in their emergence and movement patterns

“…Diel activity patterns are the evolutionary result of interactions between physiological constraints and ecological selective forces (Rubal et al, 1992;Fraser et al, 1993;Winandy et al, 2016). Temporal partitioning was shown to exist between syntopic species (Cotton, 1998;Wasserberg et al, 2006;Gerber et al, 2012), or even between members of the same species: juveniles vs. adults (Gries et al, 1997), males vs. females (Woolbright, 1985), or subordinate vs. dominant individuals (Craig and Douglas, 1984;Alanärä et al, 2001).…”