Biological communities may be assembled by both niche-based and dispersal-based (= historic) proc... more Biological communities may be assembled by both niche-based and dispersal-based (= historic) processes with the relative importance of these processes in community assembly being scale- and context-dependent. To infer whether (a) niche-based or dispersal-based processes play the main role in the assembly of flea communities parasitic on small mammals and whether (b) the main processes of flea community assembly are scale-dependent, we applied a novel permutation-based algorithm (PER-SIMPER) and the dispersal-niche continuum index (DNCI), to data on the species incidence of fleas and their hosts at two spatial scales. At the larger (continental) scale, we analysed flea communities in four biogeographic realms across adjacent continental sections. At the smaller (local) scale, we considered flea communities across two main regions (lowlands and mountains) and seven habitat types within Slovakia. Our analyses demonstrated that species composition of fleas and their small mammalian hosts depended predominantly on historical processes (dispersal) at both scale. This was true for the majority of biogeographic realms at continental scale (except the Nearctic) and both regions at local scale. Nevertheless, strong niche-based assembly mechanism was found in the Nearctic assemblages. At local scale, the intensity of dispersal processes was weaker and niche-driven processes were stronger between habitats within a region than between mountain and lowland regions. We provide historical and ecological explanations for these patterns. We conclude that the assembly of compound flea communities is governed, to a great extent, by the dispersal processes acting on their hosts and, to a lesser extent, by the niche-based processes.
SummaryReproduction is an energy-demanding activity in mammalian females, with increased energy r... more SummaryReproduction is an energy-demanding activity in mammalian females, with increased energy requirements during pregnancy and, especially, during lactation. To better understand the interactions between parasitism and host reproduction, we investigated feeding and reproductive performance of fleas (Xenopsylla ramesis) parasitizing non-reproducing, pregnant, or lactating gerbilline rodents (Meriones crassus). Based on energetic considerations, we predicted that feeding and reproductive performance of fleas would be lowest on non-breeding females, moderate on pregnant females, and highest on lactating females. We estimated feeding performance of the fleas via absolute and mass-specific bloodmeal size and reproductive performance via egg production and latency to peak oviposition. Host reproductive status had no effect on either absolute or mass-specific bloodmeal size or the day of peak oviposition, but significantly affected the daily number of eggs produced by a female flea. Sur...
SUMMARY Fleas can increase the metabolic rate of their hosts. It has been suggested that a consti... more SUMMARY Fleas can increase the metabolic rate of their hosts. It has been suggested that a constitutive response, in which the host constantly maintains a relatively high level of energy metabolism to combat the parasite, is advantageous for hosts with high parasite infestation, while an induced response, in which the host increases energy metabolism in response to a parasite attack, is advantageous with low parasite infestation. As free-living Gerbillus nanus show a relatively low flea infestation, we hypothesized that this host uses an induced strategy and, consequently, flea infestation would not impose a long-term effect on energy metabolism. In a previous study in spring, higher field metabolic rate (FMR) was found in free-living parasitized than in non-parasitized G. nanus. In this study, G. nanus were captured at Hazeva in spring; some had fleas (N=14) and some did not (N=10). We brought them to the laboratory, removed the fleas from those that were infested and, after 3 week...
SUMMARY Fleas consume and digest blood from their hosts. We hypothesized that the energy costs of... more SUMMARY Fleas consume and digest blood from their hosts. We hypothesized that the energy costs of digestion of blood by fleas is dependent on the host species. To test this hypothesis, we studied CO2 emission, a measure of energy expenditure, during digestion of a blood meal taken by Parapulex chephrenis from a preferred (Acomys cahirinus) and a non-preferred (Gerbillus dasyurus) host. We predicted that the energy cost of digestion would be lower for A. cahirinus blood than that for G. dasyurus. Male and female fleas consumed similar amounts of blood per unit body mass, independent of host species. Our prediction was supported in that fleas expended significantly more energy digesting blood of G. dasyurus than blood of A. cahirinus. We also found CO2 emission rates of fed fleas were higher than those of unfed fleas and differed significantly among stages of blood digestion when a flea fed on G. dasyurus but not when it fed on A. cahirinus. When fed on G. dasyurus, fleas spent less e...
SUMMARYThis study set out to determine whether the sex ratio of fleas collected from host bodies ... more SUMMARYThis study set out to determine whether the sex ratio of fleas collected from host bodies is a reliable indicator of sex ratio in the entire flea population. To answer this question, previously published data on 18 flea species was used and it was tested to see whether a correlation exists between the sex ratio of fleas collected from host bodies and the sex ratio of fleas collected from host burrows. Across species, the female:male ratio of fleas on hosts correlated strongly with the female:male ratio of fleas in their burrows, with the slope of the regression overlapping 1. Controlling for flea phylogeny by independent contrasts produced similar results. It was also ascertained whether a host individual is a proportional random sampler of male and female fleas and whether the sex ratio in flea infrapopulations depends on the size of infrapopulations and on the gender and age of a host. Using field data, the sex ratio in infrapopulations of 7 flea species parasitic on 4 rode...
SUMMARYWe investigated spatial variation in the phylogenetic structure of host spectra in fleas p... more SUMMARYWe investigated spatial variation in the phylogenetic structure of host spectra in fleas parasitic on small mammals. Measures of phylogenetic host specificity ((phylogenetic species clustering (PSC) and phylogenetic species variability (PSV)) varied significantly more between than within flea species, but the proportion of variation which accounted for among-species differences was low. In 13 of 18 common flea species, at least one of the indices of the phylogenetic structure of regional host spectra revealed a significantly positive association with the phylogenetic structure of regional host assemblage, while relationships between PSC or PSV of the regional host spectrum and the distance from either the region of a flea's maximal abundance or latitude were not supported. Overall, results of this study demonstrated that although the degree of phylogenetic host specificity in fleas can be considered as a true attribute of a flea species, it is highly spatially variable, w...
Rodents affect soil microbial communities by burrow architecture, diet composition, and foraging ... more Rodents affect soil microbial communities by burrow architecture, diet composition, and foraging behavior. We examined the effect of desert rodents on nitrogen-fixing bacteria (NFB) communities by identifying bacteria colony-forming units (CFU) and measuring nitrogen fixation rates (ARA), denitrification (DA), and CO2 emission in soil from burrows of three gerbil species differing in diets. Psammomys obesus is folivorous, Meriones crassus is omnivorous, consuming green vegetation and seeds, and Dipodillus dasyurus is predominantly granivorous. We also identified NFB in the digestive tract of each rodent species and in Atriplex halimus and Anabasis articulata, dominant plants at the study site. ARA rates of soil from burrows of the rodent species were similar, and substantially lower than control soil, but rates of DA and CO2 emission differed significantly among burrows. Highest rates of DA and CO2 emission were measured in D. dasyurus burrows and lowest in P. obesus. CFU differed among bacteria isolates, which reflected dietary selection. Strains of cellulolytic representatives of the family Myxococcaceae and the genus Cytophaga dominated burrows of P. obesus, while enteric Bacteroides dominated burrows of D. dasyurus. Burrows of M. crassus contained both cellulolytic and enteric bacteria. Using discriminant function analysis, differences were revealed among burrow soils of all rodent species and control soil, and the two axes accounted for 91 % of the variance in bacterial occurrences. Differences in digestive tract bacterial occurrences were found among these rodent species. Bacterial colonies in P. obesus and M. crassus burrows were related to bacteria of A. articulata, the main plant consumed by both species. In contrast, bacteria colonies in the burrow soil of D. dasyurus were related to bacteria in its digestive tract. We concluded that gerbils play an important role as ecosystem engineers within their burrow environment and affect the microbial complex of the nitrogen-fixing organisms in soils.
Abstract This article reviews patterns, causes and consequences of gender-biased infestation of s... more Abstract This article reviews patterns, causes and consequences of gender-biased infestation of small mammalian hosts by macroparasites. We start with a description of gender biases in parasite infestation and discuss variation in these patterns among host and parasite taxa. We also look at temporal and spatial variations in gender-biased parasitism and demonstrate that they can vary seasonally and be mediated by environmental conditions. Then, we present main hypotheses that examine mechanisms of gender- ...
We studied dietary intakes and time budgets in two desert gerbillids, Psammomys obesus, a diurnal... more We studied dietary intakes and time budgets in two desert gerbillids, Psammomys obesus, a diurnal herbivore, and Meriones crassus, a nocturnal granivore. P. obesus was offered fresh leaves of Atriplex halimus while M. crassus was offered millet seeds and Atriplex halimus, mainly as a source of water. We predicted that the (1) nocturnal rodent will feed mainly at night and the diurnal rodent mainly during the day; and (2) the herbivore consuming a relatively low energy diet will spend more time feeding than the granivore consuming a relatively high energy diet. The latter prediction was confirmed in that P. obesus spent more time feeding than M. crassus. Number of feeding sessions in M. crassus was the same as in P. obesus but each feeding session was shorter. However, the former prediction was only partially confirmed. Feeding during the dark phase was significantly longer than the light phase in the nocturnal M. crassus, as predicted; but feeding did not differ between diel phases ...
Biological communities may be assembled by both niche-based and dispersal-based (= historic) proc... more Biological communities may be assembled by both niche-based and dispersal-based (= historic) processes with the relative importance of these processes in community assembly being scale- and context-dependent. To infer whether (a) niche-based or dispersal-based processes play the main role in the assembly of flea communities parasitic on small mammals and whether (b) the main processes of flea community assembly are scale-dependent, we applied a novel permutation-based algorithm (PER-SIMPER) and the dispersal-niche continuum index (DNCI), to data on the species incidence of fleas and their hosts at two spatial scales. At the larger (continental) scale, we analysed flea communities in four biogeographic realms across adjacent continental sections. At the smaller (local) scale, we considered flea communities across two main regions (lowlands and mountains) and seven habitat types within Slovakia. Our analyses demonstrated that species composition of fleas and their small mammalian hosts depended predominantly on historical processes (dispersal) at both scale. This was true for the majority of biogeographic realms at continental scale (except the Nearctic) and both regions at local scale. Nevertheless, strong niche-based assembly mechanism was found in the Nearctic assemblages. At local scale, the intensity of dispersal processes was weaker and niche-driven processes were stronger between habitats within a region than between mountain and lowland regions. We provide historical and ecological explanations for these patterns. We conclude that the assembly of compound flea communities is governed, to a great extent, by the dispersal processes acting on their hosts and, to a lesser extent, by the niche-based processes.
SummaryReproduction is an energy-demanding activity in mammalian females, with increased energy r... more SummaryReproduction is an energy-demanding activity in mammalian females, with increased energy requirements during pregnancy and, especially, during lactation. To better understand the interactions between parasitism and host reproduction, we investigated feeding and reproductive performance of fleas (Xenopsylla ramesis) parasitizing non-reproducing, pregnant, or lactating gerbilline rodents (Meriones crassus). Based on energetic considerations, we predicted that feeding and reproductive performance of fleas would be lowest on non-breeding females, moderate on pregnant females, and highest on lactating females. We estimated feeding performance of the fleas via absolute and mass-specific bloodmeal size and reproductive performance via egg production and latency to peak oviposition. Host reproductive status had no effect on either absolute or mass-specific bloodmeal size or the day of peak oviposition, but significantly affected the daily number of eggs produced by a female flea. Sur...
SUMMARY Fleas can increase the metabolic rate of their hosts. It has been suggested that a consti... more SUMMARY Fleas can increase the metabolic rate of their hosts. It has been suggested that a constitutive response, in which the host constantly maintains a relatively high level of energy metabolism to combat the parasite, is advantageous for hosts with high parasite infestation, while an induced response, in which the host increases energy metabolism in response to a parasite attack, is advantageous with low parasite infestation. As free-living Gerbillus nanus show a relatively low flea infestation, we hypothesized that this host uses an induced strategy and, consequently, flea infestation would not impose a long-term effect on energy metabolism. In a previous study in spring, higher field metabolic rate (FMR) was found in free-living parasitized than in non-parasitized G. nanus. In this study, G. nanus were captured at Hazeva in spring; some had fleas (N=14) and some did not (N=10). We brought them to the laboratory, removed the fleas from those that were infested and, after 3 week...
SUMMARY Fleas consume and digest blood from their hosts. We hypothesized that the energy costs of... more SUMMARY Fleas consume and digest blood from their hosts. We hypothesized that the energy costs of digestion of blood by fleas is dependent on the host species. To test this hypothesis, we studied CO2 emission, a measure of energy expenditure, during digestion of a blood meal taken by Parapulex chephrenis from a preferred (Acomys cahirinus) and a non-preferred (Gerbillus dasyurus) host. We predicted that the energy cost of digestion would be lower for A. cahirinus blood than that for G. dasyurus. Male and female fleas consumed similar amounts of blood per unit body mass, independent of host species. Our prediction was supported in that fleas expended significantly more energy digesting blood of G. dasyurus than blood of A. cahirinus. We also found CO2 emission rates of fed fleas were higher than those of unfed fleas and differed significantly among stages of blood digestion when a flea fed on G. dasyurus but not when it fed on A. cahirinus. When fed on G. dasyurus, fleas spent less e...
SUMMARYThis study set out to determine whether the sex ratio of fleas collected from host bodies ... more SUMMARYThis study set out to determine whether the sex ratio of fleas collected from host bodies is a reliable indicator of sex ratio in the entire flea population. To answer this question, previously published data on 18 flea species was used and it was tested to see whether a correlation exists between the sex ratio of fleas collected from host bodies and the sex ratio of fleas collected from host burrows. Across species, the female:male ratio of fleas on hosts correlated strongly with the female:male ratio of fleas in their burrows, with the slope of the regression overlapping 1. Controlling for flea phylogeny by independent contrasts produced similar results. It was also ascertained whether a host individual is a proportional random sampler of male and female fleas and whether the sex ratio in flea infrapopulations depends on the size of infrapopulations and on the gender and age of a host. Using field data, the sex ratio in infrapopulations of 7 flea species parasitic on 4 rode...
SUMMARYWe investigated spatial variation in the phylogenetic structure of host spectra in fleas p... more SUMMARYWe investigated spatial variation in the phylogenetic structure of host spectra in fleas parasitic on small mammals. Measures of phylogenetic host specificity ((phylogenetic species clustering (PSC) and phylogenetic species variability (PSV)) varied significantly more between than within flea species, but the proportion of variation which accounted for among-species differences was low. In 13 of 18 common flea species, at least one of the indices of the phylogenetic structure of regional host spectra revealed a significantly positive association with the phylogenetic structure of regional host assemblage, while relationships between PSC or PSV of the regional host spectrum and the distance from either the region of a flea's maximal abundance or latitude were not supported. Overall, results of this study demonstrated that although the degree of phylogenetic host specificity in fleas can be considered as a true attribute of a flea species, it is highly spatially variable, w...
Rodents affect soil microbial communities by burrow architecture, diet composition, and foraging ... more Rodents affect soil microbial communities by burrow architecture, diet composition, and foraging behavior. We examined the effect of desert rodents on nitrogen-fixing bacteria (NFB) communities by identifying bacteria colony-forming units (CFU) and measuring nitrogen fixation rates (ARA), denitrification (DA), and CO2 emission in soil from burrows of three gerbil species differing in diets. Psammomys obesus is folivorous, Meriones crassus is omnivorous, consuming green vegetation and seeds, and Dipodillus dasyurus is predominantly granivorous. We also identified NFB in the digestive tract of each rodent species and in Atriplex halimus and Anabasis articulata, dominant plants at the study site. ARA rates of soil from burrows of the rodent species were similar, and substantially lower than control soil, but rates of DA and CO2 emission differed significantly among burrows. Highest rates of DA and CO2 emission were measured in D. dasyurus burrows and lowest in P. obesus. CFU differed among bacteria isolates, which reflected dietary selection. Strains of cellulolytic representatives of the family Myxococcaceae and the genus Cytophaga dominated burrows of P. obesus, while enteric Bacteroides dominated burrows of D. dasyurus. Burrows of M. crassus contained both cellulolytic and enteric bacteria. Using discriminant function analysis, differences were revealed among burrow soils of all rodent species and control soil, and the two axes accounted for 91 % of the variance in bacterial occurrences. Differences in digestive tract bacterial occurrences were found among these rodent species. Bacterial colonies in P. obesus and M. crassus burrows were related to bacteria of A. articulata, the main plant consumed by both species. In contrast, bacteria colonies in the burrow soil of D. dasyurus were related to bacteria in its digestive tract. We concluded that gerbils play an important role as ecosystem engineers within their burrow environment and affect the microbial complex of the nitrogen-fixing organisms in soils.
Abstract This article reviews patterns, causes and consequences of gender-biased infestation of s... more Abstract This article reviews patterns, causes and consequences of gender-biased infestation of small mammalian hosts by macroparasites. We start with a description of gender biases in parasite infestation and discuss variation in these patterns among host and parasite taxa. We also look at temporal and spatial variations in gender-biased parasitism and demonstrate that they can vary seasonally and be mediated by environmental conditions. Then, we present main hypotheses that examine mechanisms of gender- ...
We studied dietary intakes and time budgets in two desert gerbillids, Psammomys obesus, a diurnal... more We studied dietary intakes and time budgets in two desert gerbillids, Psammomys obesus, a diurnal herbivore, and Meriones crassus, a nocturnal granivore. P. obesus was offered fresh leaves of Atriplex halimus while M. crassus was offered millet seeds and Atriplex halimus, mainly as a source of water. We predicted that the (1) nocturnal rodent will feed mainly at night and the diurnal rodent mainly during the day; and (2) the herbivore consuming a relatively low energy diet will spend more time feeding than the granivore consuming a relatively high energy diet. The latter prediction was confirmed in that P. obesus spent more time feeding than M. crassus. Number of feeding sessions in M. crassus was the same as in P. obesus but each feeding session was shorter. However, the former prediction was only partially confirmed. Feeding during the dark phase was significantly longer than the light phase in the nocturnal M. crassus, as predicted; but feeding did not differ between diel phases ...
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