Habitat-dependent differences in architecture and microclimate of the burrows of Sundevall's jird (Meriones crassus) (Rodentia: Gerbillinae) in the Negev Desert, Israel

Flea fitness is reduced by high fractional concentrations of CO2 that simulate levels found in their hosts' burrows

“…Indeed, this behavior is expected if there are costs associated with high F CO2 , because burrows are the product of natural selection acting on the builder (Turner, 2000). Some animals, however, live in burrows with high F CO2 , particularly those with sealed entrances (Maclean, 1981b;Kuhnen, 1986;Mendelssohn and Yom-Tov, 1999;Shenbrot et al, 2002;Burda et al, 2007). This leads to the question, do rodents build burrows designed so they do not to completely eliminate the elevated F CO2 ?…”

“…For example, the microclimate within the burrow is more stable than that outside the burrow (Kenagy, 1973;Reichman and Smith, 1990;Shenbrot et al, 2002). However, the air in some rodent burrows contains high fractional concentrations of CO 2 (F CO2 ), and this is particularly true for burrows of fossorial rodents and those that have blocked entrances (Maclean, 1981b;Kuhnen, 1986;Burda et al, 2007).…”

“…In addition, X. ramesis has been recorded on a rodent species that often seals its burrow entrances, namely Wagner's gerbils (Gerbillus dasyurus) (Harrison, 1956). Furthermore, the tunnels of burrows of these rodents can be long (up to 10 m for Sundevall's jirds; Shenbrot et al, 2002) and deep (up to 80 cm for fat sand rats; Mendelssohn and YomTov, 1999). In general, long burrows and burrows with plugged entrances have elevated F CO2 (Kay and Whitford, 1978;Maclean, 1981b;Kuhnen, 1986;Burda et al, 2007), thus X. ramesis are likely to encounter high F CO2 often.…”

“…First, in the Negev desert, X. ramesis is the most abundant flea of Sundevall's jird, Tristram's jird (Meriones tristrami) and fat sand rats (Psammomys obesus) (Krasnov et al, 1997;Krasnov et al, 1998Krasnov et al, , 1999 and it spends most of its time in the burrow of the host (Krasnov et al, 2004). Both jird species occasionally plug the entrances to their burrows (Mendelssohn and Yom-Tov, 1999;Shenbrot et al, 2002); this happens particularly often in habitats where these species harbor X. ramesis (Krasnov et al, 1996;Shenbrot et al, 2002). In addition, X. ramesis has been recorded on a rodent species that often seals its burrow entrances, namely Wagner's gerbils (Gerbillus dasyurus) (Harrison, 1956).…”

An automated temperature-based option for estimating surface activity and refuge use patterns in free-ranging animals

“…The general dichotomy that exists in temperate-zone climates between highly fluctuating T air and milder, more stable temperatures in thermally insulated refugia-like sub-terranean burrows (Bulova, 2002;Rezende et al, 2003;Shenbrot et al, 2002) and water (Grayson and Dorcas, 2004) led us to test the hypothesis that environmental thermal heterogeneity can be used to predict animal surface activity. We predicted that the thermal dichotomy between air and sub-surface temperatures influences the T b of free-ranging reptiles in a predictable manner such that T b can be used to distinguish surface activity from refuge occupation.…”