THE IMPORTANCE OF BEING LARGER: INTRASPECIFIC COMPETITION FOR PRIME WEB SITES IN ORB-WEB SPIDERS (ARANEAE, ARANEIDAE)

Behaviour ◽  
1999 ◽  
Vol 136 (5) ◽  
pp. 669-677 ◽  
Author(s):  
◽  

AbstractThe effects of two contrasting habitats on the distribution and the body condition of Larinioides sclopetarius (Clerck, 1757) were studied in an urban area. Throughout the season, significantly more spiders of all size classes were found in the prime habitat, which was characterised by the presence of artificial light and, consequently, a superabundance of prey. The higher food intake in the prime habitat also resulted in a better body condition of immature spiders. During periods of high spider density, small immatures were found more frequently than expected in the lower ranked habitat, which contained no artificial light and significantly less prey, while larger conspecifics exclusively foraged in the prime habitat. High females density in the prime habitat coincided with decreasing density and decreasing territory sizes of smaller immatures.

Ethology ◽  
2019 ◽  
Vol 125 (5) ◽  
pp. 289-297 ◽  
Author(s):  
Nikolas J. Willmott ◽  
Jessica Henneken ◽  
Mark A. Elgar ◽  
Therésa M. Jones

1974 ◽  
Vol 25 (5) ◽  
pp. 813 ◽  
Author(s):  
JR Donnelly ◽  
JL Davidson ◽  
M Freer

Mature Merino wethers were changed in liveweight by grazing treatments or by feeding in pens and their intake of food over the next 5 weeks was then measured at two levels of pasture availability or in pens. Of nine groups of six sheep with mean initial fleece-free liveweight of 33 kg, three groups were increased to 37 kg (389 MJ energy) in 6 weeks by grazing abundant pasture, another three were reduced to 28 kg (220 MJ) on sparse pasture, and those remaining were reduced to 30 kg (268 MJ) by restricted feeding in pens. The three groups from each treatment were then moved to abundant pasture, to sparse pasture or to pens where food was offered ad lib. Energy status, within the range imposed here, had no effect on the intake of pasture or on the time spent grazing; both of these variables depended solely on the herbage currently available. Nor did energy status affect food intake when sheep were removed from pasture and compared in pens with a standard food. Sheep moved from sparse pasture to abundant pasture gained at least as much liveweight, but only 20% as much energy as sheep in better condition because more of their gain was water. These results suggest that short-term changes in the body condition of mature grazing sheep will have no effect on their intake of food and that their subsequent changes in fasted liveweight may give a misleading impression of changes in energy status.


Author(s):  
V A Baranov ◽  
N M Lugovaya ◽  
A S Mikhalev ◽  
V I Kudymov ◽  
T V Strekaleva

2021 ◽  
Vol 17 (11) ◽  
Author(s):  
Leonardo Ferreira-Sousa ◽  
Pedro N. Rocha ◽  
Paulo C. Motta ◽  
Felipe M. Gawryszewski

Body temperature can strongly influence fitness. Some Sun-exposed ectotherms thermoregulate by adjusting body posture according to the Sun's position. In these species, body elongation should reduce the risk of heat stress by allowing the exposure of a smaller body area to sunlight. Therefore, selection should favour more elongated bodies in Sun-exposed than in Sun-protected species. Diurnal orb-web spider species that sit on their webs are more likely to be Sun-exposed, on average, than nocturnal or diurnal shelter-building species. We measured the body elongation of orb-web spiders (Araneae, Araneidae) across 1024 species and classified them as Sun-protected or exposed based on the literature. We found that Sun-exposed species evolved more elongate bodies than Sun-protected ones. Further, we built a model combining traditional heat transfer models with models of thermoregulatory postures in orb-web spiders and meteorological data. The model indicates that body elongation in large orb-web spiders decreases the risk of high body temperatures. Overall, our results suggest that Sun exposure influenced the evolution of body shapes of orb-web spiders.


2007 ◽  
Vol 55 (1) ◽  
pp. 1 ◽  
Author(s):  
Sean J. Blamires ◽  
Dieter F. Hochuli ◽  
Michael B. Thompson

Antipredator strategies adopted by animals need to compensate for temporal changes. Many orb-web spiders add silk decorations to their webs, which principally attract prey but may attract some predators. To identify their influence on antipredator behaviour in adult female St Andrew’s cross spiders (Argiope keyserlingi) we measured: spider body condition, web characteristics (area, spiral length and decoration building), environmental variables (air temperature, humidity, wind speed, relative prey abundance) and antipredator responses (remaining at the hub, dropping, shifting to the web periphery, or pumping the web) at three distinct periods (July–August, September–October and January–February) in the field. We developed path models from multiple regression analyses to distinguish between factors having direct and indirect effects. We found that even though both antipredator responses and decoration building change over time, antipredator responses and decoration investment are independent. Body condition and wind speed are directly positively associated with pumping frequency, and decoration building is negatively associated with the frequency of remaining at the hub because the likelihood that an object approaching the web is a predator increases if decorations are added. Wind speed is positively associated with antipredator behaviour and decoration building, due to an increased rate of feeding affecting body condition.


2020 ◽  
Vol 20 (8) ◽  
pp. 1262-1267
Author(s):  
Haojun Yang ◽  
Hanyang Liu ◽  
YuWen Jiao ◽  
Jun Qian

Background: G protein-coupled bile acid receptor (TGR5) is involved in a number of metabolic diseases. The aim of this study was to identify the role of TGR5 after Roux-en-Y gastric bypass (GBP). Methods: Wild type and TGR5 knockout mice (tgr5-/-) were fed a high-fat diet (HFD) to establish the obesity model. GBP was performed. The changes in body weight and food intake were measured. The levels of TGR5 and peptide YY (PYY) were evaluated by RT-PCR, Western blot, and ELISA. Moreover, the L-cells were separated from wild type and tgr5-/- mice. The levels of PYY in L-cells were evaluated by ELISA. Results: The body weights were significantly decreased after GBP in wild type mice (p<0.05), but not tgr5-/- mice (p>0.05). Food intake was reduced after GBP in wild type mice, but also not significantly affected in tgr5-/- mice (p>0.05). The levels of PYY were significantly increased after GBP compared with the sham group (p<0.05); however, in tgr5-/- mice the expression of PYY was not significantly affected (p>0.05). After INT-777 stimulation in L-cells obtained from murine intestines, the levels of PYY were significantly increased in L-cells tgr5+/+ (p<0.05). Conclusion: Our study suggests that GBP up-regulated the expression of TGR5 in murine intestines, and increased the levels of PYY, which further reduced food intake and decreased the body weight.


2020 ◽  
Vol 20 (3) ◽  
pp. 446-452
Author(s):  
Seyed S. Mortazavi-Jahromi ◽  
Shahab Alizadeh ◽  
Mohammad H. Javanbakht ◽  
Abbas Mirshafiey

Background: This study aimed to investigate the effects of guluronic acid (G2013) on blood sugar, insulin, and gene expression profile of oxLDL receptors (SR-A, CD36, LOX-1, and CD68) in the experimental model of diabetes. Methods: 18 Sprague Dawley rats were randomly assigned to three groups of healthy control, diabetic control, and G2013 group. Diabetes was induced through intraperitoneal (IP) injection of 60 mg/kg streptozotocin. The subjects were IP treated with 25 mg/kg of G2013 per day for 28 days. The body weight, food intake, fasting blood glucose and insulin were measured. In addition, the expression of mentioned genes was investigated through quantitative real-time PCR. Results: The data showed that the final weight increased significantly in the G2013-treated subjects compared to the diabetic control (p < 0.05). The results indicated that final food intake significantly reduced in the G2013-treated subjects compared to the diabetic control (p < 0.05). The study findings also suggested that the final fasting blood glucose significantly reduced in the G2013-treated group, whereas the final fasting serum insulin level significantly increased in this group compared to the diabetic control (p < 0.05). Moreover, the gene expression levels of SR-A, CD36, LOX-1, and CD68 in the G2013 group significantly reduced compared to the diabetic control (p < 0.05). Conclusion: This study showed that G2013, could reduce blood glucose and increase insulin levels and reduce the gene expression level of oxLDL receptors. In addition, it may probably play an important role in reducing the severity of diabetes-induced inflammatory symptoms.


Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1414
Author(s):  
Ramūnas Antanaitis ◽  
Vida Juozaitienė ◽  
Dovilė Malašauskienė ◽  
Mindaugas Televičius ◽  
Mingaudas Urbutis ◽  
...  

The aim of the current study was to evaluate the relation of automatically determined body condition score (BCS) and inline biomarkers such as β-hydroxybutyrate (BHB), milk yield (MY), lactate dehydrogenase (LDH), and progesterone (mP4) with the pregnancy success of cows. The cows (n = 281) had 2.1 ± 0.1. lactations on average, were 151.6 ± 0.06 days postpartum, and were once tested with “Easy scan” ultrasound (IMV imaging, Scotland) at 30–35 d post-insemination. According to their reproductive status, cows were grouped into two groups: non-pregnant (n = 194 or 69.0% of cows) and pregnant (n = 87 or 31.0% of cows). Data concerning their BCS, mP4, MY, BHB, and LDH were collected each day from the day of insemination for 7 days. The BCS was collected with body condition score camera (DeLaval Inc., Tumba, Sweden); mP4, MY, BHB, and LDH were collected with the fully automated real-time analyzer Herd Navigator™ (Lattec I/S, Hillerød, Denmark) in combination with a DeLaval milking robot (DeLaval Inc., Tumba, Sweden). Of all the biomarkers, three differences between groups were significant. The body condition score (BCS) of the pregnant cows was higher (+0.49 score), the milk yield (MY) was lower (−4.36 kg), and milk progesterone in pregnant cows was (+6.11 ng/mL) higher compared to the group of non-pregnant cows (p < 0.001). The pregnancy status of the cows was associated with their BCS assessment (p < 0.001). We estimated that cows with BCS > 3.2 were 22 times more likely to have reproductive success than cows with BCS ≤ 3.2.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Takashi Nakamura ◽  
Mai Nampei ◽  
Takayo Murase ◽  
Etsuko Satoh ◽  
Seigo Akari ◽  
...  

AbstractPlasma xanthine oxidoreductase (XOR) activity is high in metabolic disorders such as diabetic mellitus, obesity, or overweight. Thus, this study investigated whether the XOR inhibitor, topiroxostat, affected body weight. Male db/db mice were fed standard diets with or without topiroxostat for 4 weeks. Body weight and food intake were constantly monitored, along with monitoring plasma biochemical markers, including insulin and XOR activity. Additionally, hepatic hypoxanthine and XOR activity were also documented. Single regression analysis was performed to determine the mechanism. Topiroxostat treatment suppressed weight gain relative to the vehicle without any impact on food intake. However, the weight of fat pads and hepatic and muscle triglyceride content did not change. Topiroxostat decreased the plasma uric acid and increased hepatic hypoxanthine in response to the inhibition of XOR activity. Plasma ketone body and free fatty acid were also increased. Moreover, fat weight was weakly associated with plasma XOR activity in the diabetic state and was negatively associated with ketone body by topiroxostat. These results suggested that topiroxostat amplified the burning of lipids and the salvage pathway, resulting in predisposing the body toward catabolism. The inhibition of plasma XOR activity may contribute to weight loss.


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