Molecular detection of Bartonella spp. in deer ked pupae, adult keds and moose blood in Finland.

The deer ked (Lipoptena cervi) is a haematophagous ectoparasite of cervids that harbours haemotrophic Bartonella. A prerequisite for the vector competence of the deer ked is the vertical transmission of the pathogen from the mother to its progeny and transstadial transmission from pupa to winged adult. We screened 1154 pupae and 59 pools of winged adult deer keds from different areas in Finland for Bartonella DNA using PCR. Altogether 13 pupa samples and one winged adult deer ked were positive for the presence of Bartonella DNA. The amplified sequences were closely related to either B. schoenbuchensis or B. bovis. The same lineages were identified in eight blood samples collected from free-ranging moose. This is the first demonstration of Bartonella spp. DNA in a winged adult deer ked and, thus, evidence for potential transstadial transmission of Bartonella spp. in the species.

Polyandrous females produce sons that are successful at post-copulatory competition.

Some of the genetic benefit hypotheses put forward to explain multiple male mating (polyandry) predict that sons of polyandrous females will have an increased competitive ability under precopulatory or post-copulatory competition via paternally inherited traits, such as attractiveness or fertilization efficiency. Here, we tested these predictions by comparing the competitive ability of sons of experimentally monandrous and polyandrous female bank voles (Myodes glareolus), while controlling for potential material and maternal effects. In female choice experiments, we found no clear preference for sons of either monandrous or polyandrous mothers. Moreover, neither male type was dominant over the other, indicating no advantage in precopulatory male contest competition. However, in competitive matings, sons of polyandrous mothers significantly increased their mating efforts (mating duration, intromission number). In line with this, paternity success was biased towards sons of polyandrous mothers. Because there was no evidence for maternal effects, our results suggest that female bank voles gain genetic benefits from polyandry.

Experiments on the ectoparasitic deer ked that often attacks humans; preferences for body parts, colour and temperature.

The deer ked (Lipoptena cervi) can fail in its host search. Host search fails when an individual deer ked irreversibly accepts a host unsuitable for its reproduction (e.g. a human) and drops its wings. In northern Europe, the main host of the deer ked is the moose (Alces alces). The deer ked is increasingly causing serious problems for humans (for example, causing deer ked dermatitis) and is considered a threat for the recreational use of forests. The adult deer ked flies in early and mid-autumn to search for a host. Our aims were: (i) to study whether there are ways to avoid deer ked attacks by wearing particular clothing, and (ii) to evaluate deer ked host choice. Using human targets, we explored the cues the deer ked uses for host selection. We studied which part of the host body deer keds target and if body colour and temperature affect their choice. In our experiments, deer keds landed more on dark and red clothing than on white clothing. Moreover, deer keds mostly attacked the upper body parts and preferred the back side of the body over the front side. Finally, deer keds preferred the warmest areas of the host.

Horn growth rate and longevity: implications for natural and artificial selection in thinhorn sheep (Ovis dalli).

We used horn measurements from natural and hunted mortalities of male thinhorn sheep Ovis dalli from Yukon Territory, Canada, to examine the relationship between rapid growth early in life and longevity. We found that rapid growth was associated with reduced longevity for sheep aged 5 years and older for both the hunted and natural mortality data sets. The negative relationship between growth rate and longevity in hunted sheep can at least partially be explained by morphologically biased hunting regulations. The same trend was evident from natural mortalities from populations that were not hunted or underwent very limited hunting, suggesting a naturally imposed mortality cost directly or indirectly associated with rapid growth. Age and growth rate were both positively associated with horn size at death for both data sets, however of the two growth rate appeared to be a better predictor. Large horn size can be achieved both by individuals that grow horns rapidly and by those that have greater longevity, and the trade-off between growth rate and longevity could limit horn size evolution in this species. The similarity in the relationship between growth rate and longevity for hunted and natural mortalities suggests that horn growth rate should not respond to artificial selection. Our study highlights the need for the existence and study of protected populations to properly assess the impacts of selective harvesting.

Heart rate responses to real and simulated BA Hawk MK 51 flight.

BACKGROUND: The effects of psychological workload on inflight heart rate were studied in five experienced (flight instructors) and five less experienced (cadets) military pilots of the Finnish Air Force (FAF). METHOD: The subjects performed the same flight mission twice; first with the BA Hawk MK 51 simulator with minimal G-forces and after that with the BA Hawk MK 51 jet trainer with Gz-forces below +2. The mission included: a) 2 min rest after seating; b) take-off; c) ILS approach in the minimum weather conditions (initial, intermediate and final approach); d) landing tour (visual approach); and e) landing. The heart rates were continuously measured using a small portable recorder developed at the University of Jyväskylä, Finland. The R-R intervals were stored and analyzed with an accuracy of 1 ms. The different phases of each flight were marked in the data by using codes given beforehand for each critical event. RESULTS: The take-off resulted in a significant increase in the heart rate from the resting levels both in the cadets and the flight instructors in both planes. In the simulator the heart rate decreased during the initial approach and slightly increased after it during the intermediate approach. Thereafter the heart rate decreased during the landing tour which seemed to be the least psychologically demanding phase of the simulated flight. The heart rate increased again during the landing but did not exceed the heart rates measured during the take-off and the ILS-approach. There were no statistical differences between the groups. In the jet trainer no decrease in the heart rate could be observed immediately after the take-off, unlike in the case of the simulated flight. The inflight heart rate increased during the final approach, decreased during the landing tour and finally increased during the landing. According to the heart rate analysis the final approach was the most loaded phase of the real flight. The changes towards the phases of final approach and landing were greater among the flight instructors. CONCLUSION: There were no statistically significant differences between the mean heart rates during the real and the simulated flight. It is suggested that the heart rate changes for most reflected the changes in cognitive workload.

Reproductive costs and litter size in the bank vole.

The potential reproductive costs for free-ranging bank vole (Clethrionomys glareolus) offspring and mothers were assessed by manipulating litter size and by determining the effects of nursing varied numbers of offspring. Litter enlargement did not increase the number of weanlings per mother. The mass of juveniles was significantly lower in the enlarged litters and higher in the reduced litters, compared to the control group. However, the survival of juveniles from weaning aged three months did not depend on their mass at weaning. Data from a previous study (Mappes et al. 1995) indicated that a higher mass at weaning may increase juveniles' abilities to maturate and breed during their summer of birth. Manipulation of litter size did not significantly affect the mass or survival of mothers or the success of subsequent breeding. The size of home ranges did correlate positively with the initial litter size. However, space use by females did not change with the degree of manipulation. Our results indicate that females nursing enlarged litters produce smaller offspring at weaning with no residual effects on future maternal survival or reproduction. Mothers did not seem to compensate the nursing costs with increased parental effort (which should be reflected in the condition of mothers or in the use of resources), for example, in an enlarged size of home range. Probably the possibility of obtaining a larger home range is constrained by the other breeding females, in a saturated breeding population. These results may support the optimal investment hypothesis that a female will produce a particular litter size which gives the best reproductive success in the particular environment where offspring are nursed.

Behaviour of cyclic bank voles under risk of mustelid predation: do females avoid copulations?

Mustelid odours have been shown to suppress breeding in captive bank voles (Clethrionomys glareolus) from cyclic populations (Ylönen 1989; Ylönen and Ronkainen 1994). The mechanism behind the suppression is unknown. Based on a series of behavioural trials and breeding experiments with pairs of bank voles in breeding condition, we suggest that the primary cause for breeding suppression is a change in female mating behaviour. Experimental female-male pairs (n=34) exposed to mustelid odour decreased their general activity compared to control pairs (n=34). When encountering males in behavioural trials, females exposed to stoat odour were more aggressive and actively avoided precopulatory behaviours of males. No copulations were observed in experimental pairs compared to five in control pairs during the behavioural trials. Males actively approached females in general but male behaviour did not change under exposure to mustelid odours. We suggest that females are more vulnerable to mustelid predators than males and therefore actively avoid copulations in the (indirect) presence of mustelids. As well as this behavioural response, internal abortive mechanisms (cf. Bruce 1959) could play a role in the observed breeding suppression.

Vole cycles and antipredatory behaviour.

During recent years the role of predation as a simple mechanism to produce cyclical population fluctuations in microtine rodent populations has gained stronger empirical and theoretical support. Predation by several generalist species produces non-cyclicity, and predation by resident specialists, such as small mustelids, produces a synchronous cyclic pattern of population fluctuations in several vole species. At the same time, behavioural ecological studies have shown that the same group of specialist predators crucial for cyclicity causes the strongest antipredatory responses in vole behaviour. Recently, breeding suppression in cyclic microtines under risk of mustelid predation has been documented both in the laboratory and in the field. This review links the new population ecological studies and modelling of cyclic microtines and their predators with recent findings on antipredatory adaptations of voles.

Different demography of friends and strangers: an experiment on the impact of kinship and familiarity in Clethrionomys glareolus.

We examined demographic effects of familiarity and relatedness in the bank vole Clethrionomys glareolus (Schreber) in four 0.5-ha enclosures in Central Finland. In two enclosures were mature voles which had overwintered together and some of their mature off-spring (hereafter referred to as "Friends"), and in the other two individuals of the same species captured from different localities near the study area ("Strangers"). The experiment lasted from June to September. The populations of Friends reached densities twice as high as those of Strangers with a significantly higher rate of recruitment and survival of the young. This may have been due to mutual familiarity decreasing antagonism towards the juveniles. The conflicting results obtained from studies of Clethrionomys and Microtus are discussed. We believe that these genera represent behavioural adaptations to different habitats and ways of life. Most behavioural population regulation hypotheses are based on studies of Microtus. We conclude that these results should be applied with great caution to other rodent genera.