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1

Behavioural adaptation of Talitrus saltator populations to beaches with different dynamics and degree of human disturbance along Tunisian coasts

100%
El Gtari M., Charfi-Cheikhrouha F., Marchetti G., Scapini F.
Polskie Archiwum Hydrobiologii
|
2000
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tom 47
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nr 3-4
2
Content available remote

Seasonal changes in cryoprotectants concentrations in Helix pomatia snails

80%
Nowakowska A., Caputa M., Rogalska J.
Journal of Physiology and Pharmacology. Supplement
|
2006
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tom 57
|
nr 8
93-105
Terrestrial snails are often exposed to freezing. Therefore, we investigated seasonal shifts in hemolymph concentrations of cryoprotectants such as glycerol and glucose. We also investigated whether summer acclimation to cold and short-day photoperiod induced synthesis of cryoprotectants in Helix pomatia snails. Concentrations of the both cryoprotectants were elevated in winter and reduced in summer. These changes, however, were not correlated with shifts in liver glycogen content. Summer acclimation to cold (5°C) and short-day photoperiod evoked a selective increase in glycerol concentration. In conclusion, glycerol may play a role in adaptation of the snails to winter cold and glucose is rather unlikely to provide the cryoprotection.
3

Behavioural and spatial adaptation of the Eurasian lynx to a decline in prey availability

80%
Schmidt K.
Acta Theriologica
|
2008
|
tom 53
|
nr 1
The distribution and abundance of food resources is a major factor influencing animal populations. I studied the effect of a roe and red deer population decline on diet composition, home range size and foraging pattern in the Eurasian lynxLynx lynx (Linnaeus, 1758) in the Białowieża Primeval Forest (BPF), eastern Poland. The population of cervids in BPF experienced a nearly two-fold reduction in size from 1991 through 2006 due to severe hunting pressure between 1991 and 1996. Comparison of published data on lynx diet during the high abundance of ungulates with new data obtained for the low abundance period showed that despite a significant decline in their availability, cervids (roe and red deer) continued to form the majority of the diet of lynx, with roe deer being most preferred in both periods. Home range sizes of lynx showed a tendency to increase with declining prey densities, as indicated by relative percentage increases in average yearly home range sizes amongst different sex/age groups. In response to lower availability of their main prey, lynx increased their daily straight-line movement distances by 44% and doubled the ranges covered in 5-day periods. This illustrated that, with declining prey abundance, the lynx increased their hunting efforts by either spending more time actively searching for prey or continuing foraging even after a successful hunt. Spatial analysis of the distribution of ungulates and lynx indicated that deer were evenly distributed throughout lynx ranges in BPF and spatial proximity of the predator to prey sites did not play an important role in the efficiency of hunting. Lynx may adapt to changing prey availability by increasing search effort, but this was not sufficient to prevent the negative influences of the prey decline on the lynx population. Prey depletion has an immediate effect on lynx spatial organization and, in consequence, on their density. This information has to be considered in prioritizing lynx conservation measures and management of ungulates.
4

Adaptations of pupae of Chironomidae [Insecta: Diptera] to oxygen-poor habitats

80%
Marziali L., Lencioni V., Rossaro B.
Polish Journal of Ecology
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2006
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tom 54
|
nr 4
Morphological, behavioural and physiological adaptations of chironomid pupae to oxygen-poor habitats, such as the profundal zone of lakes, are discussed. Lentic and oxy-regulator species possess developed respiratory organs (thoracic horns) and an extensive anal fringe to perform respiratory movements, whereas in rheophilic and oxy-conformer species these structures are reduced or absent. This led to the hypothesis that the number of thoracic horn branches, the number of anal macrosetae and the body size could consititute a measure of a species’ oxygen requirements. These characters were analyzed in 12 species groups collected in 39 Italian lakes. Numbers were correlated to the optimum value of oxygen level, total phosphorus concentration and transparency calculated for each taxon. Taxa with plumose thoracic horns, extensive anal fringe and large body size (Chironomus) inhabited habitats poorer in oxygen than those inhabited by taxa with less extensive respiratory surface and fringe and small body size (Paratendipes, Polypedilum, Microtendipes). Stictochironomus was less tolerant than expected. Further studies are needed into the physiological adaptations of chironomid pupae.
5

Effects of light and temperature on the emergence of Haplorchis pumilio cercariae from the snail host, Thiara tuberculata

70%
Umadevi K., Madhavi R.
Acta Parasitologica
|
1997
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tom 42
|
nr 1
The cercaria of Haplorchis pumilio exhibited diurnal pattern in the emergence from the snail host, with peak between 10 am and 12 noon and limited emergence during night. Continuous light permitted emergence to continue rhythmically while continuous dark has suppressed the emergence. Inversion of photoperiod has resulted in immediate reversal of the emergence pattern. Variation is found in the numbers of cercariae released by different individuals of snails and by the single snail on different days, but consistency is maintained in the emergence pattern. Temperature of 30-35°C is found to be favourable for the cercarial emergence. The results of the study demonstrate that emergence pattern is influenced by both exogenous and endogenous factors.
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