Molecular phylogeny and divergence time of the water penny genus Eubrianax (Coleoptera: Psephenidae) in Japan

The phylogenetic relationships among the Japanese members of the genus Eubrianax (Coleoptera: Psephenidae) were examined using the mitochondrial cytochrome oxidase subunit I (COI) gene and nuclear 28S rRNA gene sequences. Based on the molecular phylogeny as well as morphological features, the species status of Eubrianax brunneicornis Nakane, 1952 was proposed. The phylogenetic analyses recovered monophyly of the previously proposed pellucidus species group with four Japanese species, whereas a single Japanese species of the granicollis group was included in the lineage of the ramicornis group with five Japanese species. The divergence times of the species were estimated by dating the phylogenetic tree against the fossil record and a molecular clock based on the COI gene. The divergence of the Japanese species was inferred to have occurred during the Pliocene epoch.     

The feeding behaviour of juvenile Atlantic salmon in relation to turbulent flow

The feeding behaviour of juvenile Atlantic salmon Salmo salar in the Sainte‐Marguerite River, Quebec, Canada, varied with the characteristics of turbulent flow. Simulations indicated that juveniles would decrease their swimming costs during attacks by 19·8% in low and by 31·1% in high turbulent conditions by initiating movements in low‐speed flow events. The real swimming costs did not differ from the swimming costs estimated for a situation where fish initiate their movements at randomly selected flow velocities. The juvenile Atlantic salmon did not seem to prefer low‐speed flow events when initiating their movements. The proportion of time used for movements by fish decreased with an increase in the mean and the s . d . of the flow velocity.     

Cod in hot water: observations of behaviour in relation to temperature

Fish behaviour varies considerably in response to changes in environmental and biological conditions. Cod ( Gadus morhua ) is not a homeothermic species and recent research has suggested that the recruitment and distribution of cod stocks may be influenced by temperature. Concerns have therefore been raised about the potential effect of climate change on stocks that are already at the southern limits of their range. We used data storage tags (DSTs) to observe the behaviour of cod in relation to temperature between 1999 and 2002. Over 3500 days of data were collected from 17 individuals tagged in the North and Irish Seas. We describe how the patterns in the temperature experience of cod are related to behavioural mechanisms, such as horizontal and vertical migration, that match habitat choice to physiological preferences. The results are discussed in the context of this behavioural response to short‐ and long‐term shifts in thermal regime and the potential consequences on the overall behaviour and distribution of cod stocks.     

Feeding behaviour of cod (Gadus morhua) in relation to spawning

The food consumption and egg production of 26 adult (13 female and 13 male) Atlantic cod ( Gadus morhua ) were monitored during prespawning, spawning and postspawning periods. Females spawned from late January to mid-April. Feeding activity occurred from December to early January and ceased for females, on average, 36 days (15–54 days) before the onset of spawning. The duration of spawning by females was, on average, 42 days (10–61 days) and feeding was suppressed by both sexes during the first three-quarters of each female's spawning period. Mature females went, on average, 70 days or 19% of the year without eating. An abrupt increase in feeding activity, particularly by females, occurred during the last quarter of spawning or shortly after the release of the last egg batch (on average, feeding started again after 91% of a female's eggs had been released or 82% of egg batches). Females consumed greater quantities of food than males during both winter and postspawning feeding periods. During spawning, females lost, on average, 29% of their body weight and males 14%. Fecundity ranged from 0.75 to 3.97 million eggs per female. The volume of eggs produced by four individual females (range = 1285–5995 ml in four to 11 batches) ranged from 99 to 195% (mean 150%) of a female's postspawning body volume. Six immature cod fed throughout the experimental period and gained, on average, 8% of initial body weight. Laboratory results were supported by stomach fullness index values of Georges Bank cod exhibiting different maturity states.     

Shell form,behaviour, and tolerance to water movement in the limpet Patina pellucida (L.) (Gastropoda: Prosobranchia)

The diotocardian gastropod Patina pellucida (L.) is a macro-herbivore common upon the fronds of laminarian algae. Considerations of shell shape, adhesive tenacity, and current tolerance, together with calculations of expected hydrodynamic drag, indicate that this limpet is effectively streamlined. Smaller individuals are relatively more resistant to dislodgement than are larger ones. Experimental animals of 6.0–13.5 mm shell length resisted constant flows of up to 0.9-1.3 m s^?1. An orientation, in which the longitudinal axis of a limpet is aligned parallel to the direction of the prevailing flow, is induced by currents faster than ≈ 0.5 m s^?1, and is an adaptation to conditions of directional water streaming. P. pellucida appears to show a seasonal change in orientatory preference, individuals tending to point distally with respect to the algal lamina in spring and proximally in autumn: this change may be associated with the annual growth cycle of the host plant.     

Diving behaviour in relation to water temperature in the southern elephant seal: foraging implications

Summary A time-depth-temperature recorder provided a continuous record of diving by a female southern elephant seal in relation to water temperature for 27 days (1939 dives) after completion of moult. Mean maximum dive depth was 391±2.6 m and the overall maximum was 775 m. Dives lasted on average 17.5±0.09 min. Most dives showed a rapid descent to the discontinuity between the cold surface water and warmer deep water. Consequently the seal spent 57% of its time while diving at a depth of 200–400 m when it may have been foraging. This strongly suggests that the seal was exploiting a food source at the discontinuity between vertically stratified water masses. The water temperature data also indicated that the seal was diving in waters south of the Antarctic Polar Front and at some distance from the northern edge of the pack ice. The seal spent 88% of its time under water. Normal surface intervals between dives lasted an average of 2.1 ± 0.1 min whereas 16 extended surface intervals (>10 min duration) lasted 32.7±4.6 min. Dives were deeper during the day than at night and all but one extended surface interval occurred at night. The pattern of dives was similar to records from northern elephant seals but this is the first study to show how diving behaviour relates to water temperature.     

Development of colour patterns in relation to behaviour in Tilapia mossambica (Peters)

The development of chromatophores and the formation of colour patterns in Tilapia mossambica are described. A number of colour patterns are associated with certain aspects of behaviour. Four different melanophore systems are involved in the colour pattern formation. There appear to be 14 patterns which, in various combinations, produce a series of colour patterns. Each of these may convey a different message to different species of Tilapia .     

The searching behaviour of Anthocoris confusus (Reuter) in relation to prey density and plant surface topography

• 1 The searching behaviour of A.confusus females was investigated in an artificial arena.
• 2 Females showed an increase in the frequency of turning movements following feeding and this concentrated search in a small area. As a result more prey were found in areas where prey distribution was clumped.
• 3 If no prey was encountered within 5–8 min the search track straightened out.
• 4 First and second instar nymphs searching on broad bean plants moved faster on the undersides of leaves which were the sites most likely to support aphid populations. A considerable proportion of available time was wasted in periods of inactivity.
• 5 It was concluded that while plant topography strongly influences search pattern, the underlying trend demonstrated in these experiments was of advantage to predators searching for colonial prey.

     

Body temperature and foraging behaviour of the Eurasian otter (Lutra lutra), in relation to water temperature

The effects of water temperature (T_w) on core body temperature (T_b) and foraging behaviour were studied in four free-ranging and one captive otter Lutra lutra in NE Scotland. The free-ranging animals were observed in and around two freshwater lochs, and measurements were made of T_w (2–16°C), T_b at the beginning and end of swimming bouts, lengths of swimming bouts, and dive times and intervals. T_b ranged from 35.9 to 40.4°C (mean 38.1°C). At the beginning of a period of activity and of a swimming bout. T_b rose significantly; during swimming it fell at a rate of 2.3°C/h, independent of T_w. Dive intervals were longer in colder waters, but this was probably due to other, seasonal environmental changes (perhaps water level). T_w had no significant effect on length of swimming bouts or on T_b. Although otters entered water with increased T_b, they exited when T_b was not significantly different from the mean resting T_b. The data suggest that otters maintain T_b irrespective of T_w, by increasing it before entering water, then either exiting at a given T_b, or at an earlier time determined by other environmental conditions.     

The citrus leaf cuticle in relation to measurement of leaf water potential using thermocouple psychrometers*

Abstract. Cuticular resistance to water vapour diffusion is an important aspect of thermocouple psychrometry and may introduce significant error in the measurement of leaf water potential (Ψ). The effect of the citrus (Citrus mitis Blanco) leaf cuticle on water vapour movement was studied using the times required for vapour pressure equilibration during thermocouple psychrometric measurement of Ψ. Cuticular abrasion with various carborundum powders was used to reduce the diffusive resistance of both the adaxial and abaxial leaf surfaces, and the extent of the disruption to the leaf was investigated with light and electron microscopy. Cuticular abrasion resulted in reduced equilibration times due to decreased cuticular resistance and greater water vapour movement between the leaf and the psychrometer chamber. Equilibration times were reduced from over 5 h in the unabraded control leaves to 1 h with cuticle abrasion. This was associated with the decrease in diffusive resistance with cuticular abrasion from over 55 s cm^?1 to less than 8 s cm^?1 for both the adaxial and abaxial leaf surfaces. Scanning electron micrographs of the abraded leaf tissue revealed considerable disruption of the stomatal ledge and of the guard cells, surface smoothing and displacement of waxes into the stomatal aperture, and damage to veins. Observations with the transmission electron microscope revealed frequent disruption of epidermal cell walls, and damage to both the cytoplasmic and vacuolar membranes.     

Diel patterns of activity of Thymelicus lineola adults (Lepidoptera: Hesperiidae) in relation to weather *

ABSTRACT. 1. Daily patterns of activity, thoracic temperature (T_th) and thermoregulatory behaviour in relation to environmental conditions were studied in the European skipper Thymelicus lineola (Ochsenheimer) adults. 2. Daily activity was limited mainly by T_th, which in turn was dependent on air temperature (T_a) and sunlight. However, when light intensity fell to < 100 W m^?2, skippers also became inactive. 3. T_th was sometimes as much as 12°C above T_a, and this was most pronounced under cool conditions when basking activity predominated. 4. Black globe temperature (T_bg) which, in the absence of wind, is influenced by both T^a, and radiant heat load in a manner similar to a basking butterfly, was used to approximate the maximum T_th attained by T.lineola through basking. 5. Both males and females basked at T_bg >20°C, and if this temperature was not attained, skippers remained inactive. As T_bg increased, basking activity declined more rapidly in males than in females. Basking bouts were also shorter in males. 6. Males also flew, fed and courted females at T_bg >20°C, while females only fed and flew at T_bg >22°C. The percentage of both sexes feeding and flying, and courting in the case of males, were positively correlated with T_bg. 7. In warm weather, males divided their time equally between flying and feeding, while females spent the majority of their time feeding. Feeding bouts were shorter and flying bouts were longer in males than in females. Flight duration in males was positively correlated with T_bg. 8. Skippers avoided, and, consequently laid fewer eggs in, shady areas. 9. Sexual differences in activity patterns in relation to weather reflect differences in the reproductive requirements of the two sexes.     

Food hoarding behaviour of black-capped chickadees (Poecile atricapillus ) in relation to forest edges

In temperate forests, small birds avoid the use of forest edges in adverse winter weather suggesting high foraging costs in terms of energetic requirements. Since hoarding species will often retrieve caches during adverse winter weather, they may perceive forest edges, especially exposed ones, as low quality hoarding sites. We tested whether black-capped chickadees ( Poecile atricapillus) inhabiting fragmented forests modify and reduce hoarding activity near forest edges. We also tested whether hoarding behaviour will be most affected in sites with forest edges more exposed to extreme weather. Black-capped chickadees taking food from a feeder 30 m from the nearest forest edges hoarded items mostly towards the forest interior, whereas no preference in hoarding location was observed with birds taking food from a feeder placed >100 m from the edge. Furthermore, birds avoided direct flights towards forest edges and, at sites exposed to prevailing winds, hoarding trips were shorter than at other locations. These results suggest that individuals avoid hoarding near forest edges and there, they lower their investment in terms of hoarding effort. The observed difference in hoarding behaviour was more evident near forest edges delimiting wide unforested areas than in edges delimiting narrower unforested areas. Edge exposure to prevailing winds influenced hoarding behaviour much less. We suggest that hoarding birds may partially overcome the ecological costs of habitat loss and fragmentation due to abiotic edge effects. By hoarding food away from forest edges in good weather, they may use forest interiors as low-cost retrieval sites under adverse weather.