Using laboratory selection for desiccation resistance to examine the relationship between respiratory pattern and water loss in insects.

1998 ◽  
Vol 201 (21) ◽  
pp. 2945-2952 ◽  
Author(s):  
A E Williams ◽  
M R Rose ◽  
T J Bradley

We conducted concurrent measurements of rates of CO2 and H2O release from individual fruit flies Drosophila melanogaster taken from populations subjected to three different selective regimes: (1) populations selected for resistance to desiccation (D flies); (2) populations maintained as their controls (C flies); and (3) the ancestral populations of the D and C populations (O flies). In the D flies, water loss rates were significantly reduced, the standard error of the regression (SER) of the CO2 release pattern measured over the survival period of the flies was increased, and the ratio of CO2 loss to H2O loss (VCO2/VH2O) was increased. Correlations across all 15 populations from the three selection treatments indicate that survival time was negatively correlated with water loss rate, positively correlated with the SER of CO2 release and positively correlated with the VCO2/VH2O ratio. We did not, however, find a significant correlation between the SER of CO2 release and rates of water loss or the VCO2/VH2O ratio.

1998 ◽  
Vol 201 (21) ◽  
pp. 2953-2959 ◽  
Author(s):  
A E Williams ◽  
T J Bradley

We measured CO2 and H2O release from individual fruit flies from five populations of Drosophila melanogaster selected for resistance to desiccation (D flies). Our previous work found that these flies survive for an extended period in dry air, have an increase in the peak height and frequency of CO2 release, as measured by the standard error of a linear regression (SER) of CO2 release for the entire survival period, and have reduced water loss rates (VH2O) compared with their control or ancestor populations. In the present study, we examined the following respiratory characteristics: VCO2, VH2O, the SER of CO2 release and the ratio of VCO2 to VH2O in the D flies. Correlations between these characters were calculated in order to determine the effect of respiratory pattern on water loss. We found that, within the D flies, neither periodic release of CO2 nor an increased SER for CO2 release was associated with reduced water loss. In addition, an increased SER was positively correlated with both an increased water loss rate and a decreased survival time. Therefore, although selection for desiccation resistance leads to both an increased SER and a decreased rate of water loss in the D flies, the increased SER does not significantly reduce respiratory water loss.


1997 ◽  
Vol 200 (3) ◽  
pp. 615-624 ◽  
Author(s):  
A E Williams ◽  
M R Rose ◽  
T J Bradley

We used laboratory natural selection on insects as a means of investigating the role of patterns of gas exchange in desiccation resistance. We used 15 populations of Drosophila melanogaster: five selected for desiccation resistance, five control populations and five ancestral populations. Using flow-through respirometry, we found that D. melanogaster from all populations produced irregular peaks of CO2 release. To quantify the height and frequency of these peaks, we used the standard error of a linear regression (SER) through the recordings of CO2 release. The values for the SER were significantly larger in the populations selected for desiccation resistance than in the control and ancestral populations. Occasionally, highly periodic peaks of CO2 release were observed in the desiccation-resistant populations only. Maximum SER was found to be strongly correlated with survival time in dry air among selection treatments, but not among individuals within a population. Access to dietary water resulted in lower SER values. These data demonstrate that gas exchange is physiologically controlled in Drosophila melanogaster and that the pattern of gas exchange can change under selection. The relationship between these CO2 release patterns and classic discontinuous ventilation is discussed.


BMC Zoology ◽  
2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Beatrice Nervo ◽  
Angela Roggero ◽  
Dan Chamberlain ◽  
Enrico Caprio ◽  
Antonio Rolando ◽  
...  

Abstract Background Increasing temperatures and changes in precipitation patterns threaten the existence of many organisms. It is therefore informative to identify the functional traits that underlie differences in desiccation resistance to understand the response of different species to changes in water availability resulting from climate change. We used adult dung beetles as model species due to their importance to ecosystem services. We investigated: (i) the effect of physiological (water loss rate, water loss tolerance, body water content), morphological (body mass) and ecological (nesting behaviour) traits on desiccation resistance; (ii) the role of phylogenetic relatedness in the above associations; and, (iii) whether relatively large or small individuals within a species have similar desiccation resistance and whether these responses are consistent across species. Results Desiccation resistance decreased with increasing water loss rate and increased with increasing water loss tolerance (i.e. proportion of initial water content lost at the time of death). A lack of consistent correlation between these traits due to phylogenetic relatedness suggests that the relationship is not determined by a shared evolutionary history. The advantage of a large body size in favouring desiccation resistance depended on the nesting behaviour of the dung beetles. In rollers (one species), large body sizes increased desiccation resistance, while in tunnelers and dwellers, desiccation resistance seemed not to be dependent on body mass. The phylogenetic correlation between desiccation resistance and nesting strategies was significant. Within each species, large individuals showed greater resistance to desiccation, and these responses were consistent across species. Conclusions Resistance to desiccation was explained mainly by the dung beetles’ ability to reduce water loss rate (avoidance) and to tolerate water loss (tolerance). A reduction in water availability may impose a selection pressure on body size that varies based on nesting strategies, even though these responses may be phylogenetically constrained. Changes in water availability are more likely to affect dweller species, and hence the ecosystem services they provide.


PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2382 ◽  
Author(s):  
Susana Pallarés ◽  
Josefa Velasco ◽  
Andrés Millán ◽  
David T. Bilton ◽  
Paula Arribas

BackgroundDesiccation resistance shapes the distribution of terrestrial insects at multiple spatial scales. However, responses to drying stress have been poorly studied in aquatic groups, despite their potential role in constraining their distribution and diversification, particularly in arid and semi-arid regions.MethodsWe examined desiccation resistance in adults of four congeneric water beetle species (Enochrus, family Hydrophilidae) with contrasting habitat specificity (lenticvs.lotic systems and different salinity optima from fresh- to hypersaline waters). We measured survival, recovery capacity and key traits related to desiccation resistance (fresh mass, % water content, % cuticle content and water loss rate) under controlled exposure to desiccation, and explored their variability within and between species.ResultsMeso- and hypersaline species were more resistant to desiccation than freshwater and hyposaline ones, showing significantly lower water loss rates and higher water content. No clear patterns in desiccation resistance traits were observed between lotic and lentic species. Intraspecifically, water loss rate was positively related to specimens’ initial % water content, but not to fresh mass or % cuticle content, suggesting that the dynamic mechanism controlling water loss is mainly regulated by the amount of body water available.DiscussionOur results support previous hypotheses suggesting that the evolution of desiccation resistance is associated with the colonization of saline habitats by aquatic beetles. The interespecific patterns observed inEnochrusalso suggest that freshwater species may be more vulnerable than saline ones to drought intensification expected under climate change in semi-arid regions such as the Mediterranean Basin.


2016 ◽  
Author(s):  
Susana Pallarés ◽  
Josefa Velasco ◽  
Andrés Millán ◽  
David T. Bilton ◽  
Paula Arribas

Background. Desiccation resistance shapes the distribution of terrestrial insects at multiple spatial scales. However, responses to desiccation stress have been poorly studied in aquatic groups, despite their potential role in constraining their distribution and diversification, particularly in arid and semi-arid regions. Methods. We examined desiccation resistance in adults of four congeneric water beetle species (Enochrus, family Hydrophilidae) with contrasting habitat specificity (lentic vs lotic systems and different salinity optima from fresh- to hypersaline waters).We measured survival, recovery capacity and key traits related to desiccation resistance (fresh mass, % water content, % cuticle content and water loss rate) under controlled exposure to desiccation, and explored their variability within and between species. Results. Meso- and hypersaline species were more resistant to desiccation than freshwater and hyposaline ones, showing significantly lower water loss rates and higher water content. No clear patterns in desiccation resistance traits were observed between lotic and lentic species. Intraspecifically, water loss rate was positively related to specimens’ initial % water content, but not to fresh mass or % cuticle content, suggesting that the dynamic mechanism controlling water loss is mainly regulated by the amount of body water available. Discussion. Our results support previous hypotheses suggesting that the evolution of desiccation resistance is associated with the colonization of saline habitats by aquatic beetles. The interespecific patterns observed in Enochrus also suggest that freshwater species may be more vulnerable than saline ones to drought intensification expected under climate change in semi-arid regions such as the Mediterranean Basin.


2016 ◽  
Author(s):  
Susana Pallarés ◽  
Josefa Velasco ◽  
Andrés Millán ◽  
David T. Bilton ◽  
Paula Arribas

Background. Desiccation resistance shapes the distribution of terrestrial insects at multiple spatial scales. However, responses to desiccation stress have been poorly studied in aquatic groups, despite their potential role in constraining their distribution and diversification, particularly in arid and semi-arid regions. Methods. We examined desiccation resistance in adults of four congeneric water beetle species (Enochrus, family Hydrophilidae) with contrasting habitat specificity (lentic vs lotic systems and different salinity optima from fresh- to hypersaline waters).We measured survival, recovery capacity and key traits related to desiccation resistance (fresh mass, % water content, % cuticle content and water loss rate) under controlled exposure to desiccation, and explored their variability within and between species. Results. Meso- and hypersaline species were more resistant to desiccation than freshwater and hyposaline ones, showing significantly lower water loss rates and higher water content. No clear patterns in desiccation resistance traits were observed between lotic and lentic species. Intraspecifically, water loss rate was positively related to specimens’ initial % water content, but not to fresh mass or % cuticle content, suggesting that the dynamic mechanism controlling water loss is mainly regulated by the amount of body water available. Discussion. Our results support previous hypotheses suggesting that the evolution of desiccation resistance is associated with the colonization of saline habitats by aquatic beetles. The interespecific patterns observed in Enochrus also suggest that freshwater species may be more vulnerable than saline ones to drought intensification expected under climate change in semi-arid regions such as the Mediterranean Basin.


2019 ◽  
Vol 2 ◽  
Author(s):  
Eliška Baranovská ◽  
Petr Chajma ◽  
Michal Knapp

Water is the limiting factor for all organisms. Due to global climate change, prolonged drought periods are predicted and the importance of drought-related research is increasing. Water, together with temperature, determines the abundance and spatial distribution of animals. In this study, we investigated the effects of body size and habitat preference on desiccation resistance of carabid beetles under controlled laboratory condition. Firstly, we measured the longevity of 641 carabid individuals belonging to 18 species. These beetles were exposed to extremely low relative humidity (ca. 15-20%) using silica gel bags within experimental Petri dishes. Secondly, the rate of water loss was measured for 236 individuals belonging to eight carabid species. Rate of water loss was measured using exposition to the same extremely dry conditions, but only for 12 hours. Body size was represented by elytron length and live weight was also measured to analyse effects of body condition (weight corrected for structural size). Experimental beetles were collected in different habitats ranging from extremely dry to very wet conditions. Carabids were provided with food and water ad libitum for at least 7 days prior to the experiments. All experiments were performed using a climatic chamber set to a long day (16L:8D) and the constant temperature of 20°C. The preliminary results show that species from wet habitats were more sensitive to desiccation and larger species were more resistant (survived for a longer time) compared to smaller species. Species from wet habitats had higher water loss rate compared to species originating from dry habitats. At the intraspecific level, individuals with larger body size (elytron length) survived longer than smaller individuals. Interestingly, the rate of water loss was affected by initial body condition and sex but not by structural body size at the intraspecific level. The most resistant species was Pseudoophonus rufipes. This species was not superior to other species with respect to water loss rate but it had the highest relative water content. It is also possible that P. rufipes has some other physiological or behavioural adaptation enabling a better survival under stressful, dry condition. This issue could be investigated in a future study.


2017 ◽  
Vol 12 (1) ◽  
pp. 12-20 ◽  
Author(s):  
Zhijun Liu ◽  
Dongquan Wang ◽  
Xiaobi Wei ◽  
Liangliang Wang

Cement-stabilized macadam is the most widely used road base material in road engineering. The current study investigated the impact of fiber diameter on its performance. The authors prepared polyester fibers with diameters of 20, 35, 70, and 105 μm and added them to cement-stabilized macadam. Then, the indoor shrinkage tests and mechanical property tests at different ages were conducted. Then, the property changes of the polyester-reinforced cement-stabilized macadam were analysed. The water loss rate of the polyester-reinforced cement-stabilized macadam is subject to the combined influence of the “water loss surface effect” and “water loss porthole effect.” With increasing fiber diameter, the water loss surface effect becomes stronger, and the water loss porthole effect gradually decreases; thus, the overall effect transitions from the latter to the former. Moreover, the water loss rate shows an increasing trend of decreasing to its minimum. Therefore, with increasing fiber diameter, the average dry shrinkage coefficient of the polyester-reinforced cement-stabilized macadam first increases and then decreases, while the temperature shrinkage coefficients increase. The change in the fiber diameter does not significantly affect the compressive resilient modulus of the polyester-reinforced cement-stabilized macadam if the fiber content remains constant. These findings demonstrate the functional mechanism of the fiber diameter on the road performance of cement-stabilized macadam, thus improving our understanding of the road performance of the polyester-reinforced cement-stabilized macadam and laying a solid theoretical foundation for its many applications.


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