Helper response to experimentally manipulated predation risk in the cooperatively breeding cichlid Neolamprologus pulcher

Background We manipulated predation risk in a field experiment with the cooperatively breeding cichlid Neolamprologus pulcher by releasing no predator, a medium- or a large-sized fish predator inside underwater cages enclosing two to three natural groups. We assessed whether helpers changed their helping behaviour, and whether within-group conflict changed, depending on these treatments, testing three hypotheses: ‘pay-to-stay’ PS, ‘risk avoidance’ RA, or (future) reproductive benefits RB. We also assessed whether helper food intake was reduced under risk, because this might reduce investments in other behaviours to save energy. Methodology/Principal Findings Medium and large helpers fed less under predation risk. Despite this effect helpers invested more in territory defence, but not territory maintenance, under the risk of predation (supporting PS). Experimentally covering only the breeding shelter with sand induced more helper digging under predation risk compared to the control treatment (supporting PS). Aggression towards the introduced predator did not differ between the two predator treatments and increased with group member size and group size (supporting PS and RA). Large helpers increased their help ratio (helping effort/breeder aggression received, ‘punishment’ by the dominant pair in the group) in the predation treatments compared to the control treatment, suggesting they were more willing to PS. Medium helpers did not show such effects. Large helpers also showed a higher submission ratio (submission/ breeder aggression received) in all treatments, compared to the medium helpers (supporting PS). Conclusions/Significance We conclude that predation risk reduces helper food intake, but despite this effect, helpers were more willing to support the breeders, supporting PS. Effects of breeder punishment suggests that PS might be more important for large compared to the medium helpers. Evidence for RA was also detected. Finally, the results were inconsistent with RB.

Paternity of subordinates raises cooperative effort in cichlids

Background In cooperative breeders, subordinates generally help a dominant breeding pair to raise offspring. Parentage studies have shown that in several species subordinates can participate in reproduction. This suggests an important role of direct fitness benefits for cooperation, particularly where groups contain unrelated subordinates. In this situation parentage should influence levels of cooperation. Here we combine parentage analyses and detailed behavioural observations in the field to study whether in the highly social cichlid Neolamprologus pulcher subordinates participate in reproduction and if so, whether and how this affects their cooperative care, controlling for the effect of kinship. Methodology/Principal Findings We show that: (i) male subordinates gained paternity in 27.8% of all clutches and (ii) if they participated in reproduction, they sired on average 11.8% of young. Subordinate males sharing in reproduction showed more defence against experimentally presented egg predators compared to subordinates not participating in reproduction, and they tended to stay closer to the breeding shelter. No effects of relatedness between subordinates and dominants (to mid-parent, dominant female or dominant male) were detected on parentage and on helping behaviour. Conclusions/Significance This is the first evidence in a cooperatively breeding fish species that the helping effort of male subordinates may depend on obtained paternity, which stresses the need to consider direct fitness benefits in evolutionary studies of helping behaviour.

[Reproductive performance in Herens cows from 2003 to 2007]

Herens cows have been treated at the Clinic for Ruminants, University of Berne, more frequently for fertility problems than other breeds. The aim of the study was to overview the reproductive performance of the Herens breed by analyzing data sets of the Herens Breeding Book and of the Animal Traffic Database of Switzerland. In addition, a questionnaire was sent to the breeders concerning aspects of management and care to identify a possible influence on the reproductive performance of the animals. Based on 4988 lactations starting in 2003, an average interval of calving to first insemination of 86 days a calving to conception interval of 146 days and an inter calving period of 431 days could be calculated. Conception rate resulted in 39.1%, the fertility index was 1.87 and 6.5% of all cows were culled because of fertility problems. Half of the breeders owned 4 or less cows. The most important reason for keeping Herens cows was cow fighting. Traditional alpine pasturing and cow fight rules resulted in a seasonal calving with 80% of the births taking place between October and December. The calving month and seasonal calving were the most important reasons for a prolonged calving to conception interval.

Fear of the unknown: local knowledge and perceptions of the Eurasian lynx

The remnant population of Balkan lynx Lynx lynx martinoi is small, isolated and highly threatened. Since 2006 a conservation project has surveyed its status and promoted its recovery in Albania and Macedonia. Eurasian lynx are often associated with conflicts of an economic or social nature, and their conservation requires a focus on the people sharing the landscape with the species. In this study we adopt methods and conceptual frameworks from anthropology to explore the local knowledge and perceptions of lynx among rural hunters and livestock breeders in the western mountains of the Republic of Macedonia in south-east Europe. The main finding was that local people rarely saw or interacted with lynx. As the level of interactions with this species is very low, the lynx doesn?t appear to be a species associated with conflicts in Macedonia. There was also a general lack of both scientific and local knowledge, which has led to somewhat negative attitudes, mainly based on myths and rumours. Poaching of lynx and their prey seem to be the main barriers to lynx conservation.

Reduction in Predator Defense in the Presence of Neighbors in a Colonial Fish

Predation pressure has long been considered a leading explanation of colonies, where close neighbors may reduce predation via dilution, alarming or group predator attacks. Attacking predators may be costly in terms of energy and survival, leading to the question of how neighbors contribute to predator deterrence in relationship to each other. Two hypotheses explaining the relative efforts made by neighbors are byproduct-mutualism, which occurs when breeders inadvertently attack predators by defending their nests, and reciprocity, which occurs when breeders deliberately exchange predator defense efforts with neighbors. Most studies investigating group nest defense have been performed with birds. However, colonial fish may constitute a more practical model system for an experimental approach because of the greater ability of researchers to manipulate their environment. We investigated in the colonial fish, Neolamprologus caudopunctatus, whether prospecting pairs preferred to breed near conspecifics or solitarily, and how breeders invested in anti-predator defense in relation to neighbors. In a simple choice test, prospecting pairs selected breeding sites close to neighbors versus a solitary site. Predators were then sequentially presented to the newly established test pairs, the previously established stimulus pairs or in between the two pairs. Test pairs attacked the predator eight times more frequently when they were presented on their non-neighbor side compared to between the two breeding sites, where stimulus pairs maintained high attack rates. Thus, by joining an established pair, test pairs were able to reduce their anti-predator efforts near neighbors, at no apparent cost to the stimulus pairs. These findings are unlikely to be explained by reciprocity or byproduct-mutualism. Our results instead suggest a commensal relationship in which new pairs exploit the high anti-predator efforts of established pairs, which invest similarly with or without neighbors. Further studies are needed to determine the scope of commensalism as an anti-predator strategy in colonial animals.

[The influence of the socio-economic structure of the breeding farms of Franches-Montagnes horses on the conditions of husbandry]

The socio-economic structure of the breeding farms of Franches-Montagnes horses (FM) in Switzerland is evaluated on the basis of an investigation carried out in 2002 by the Swiss FM breeding federation. Questionnaires were sent to 3500 of its members and the results include data from 968 breeding enterprises, housing a total of 3965 FM. The quality of the husbandry of FM varies according to factors such as the altitude and the geographical situation of the farms and studs. Socio-economic parameters, such as the role of FM in the business, their use (breeding, driving, riding) and the age and level of professional education of the owners may also have an effect on standards of husbandry. The results show that the owners for whom FM represent a source of income more frequently keep their horses in standing stalls, but give them more time to exercise at liberty than the horses belonging to amateur breeders. Younger and better educated breeders are more likely to house their animals in groups.

Hereditary hydrocephalus in laboratory-reared golden hamsters (Mesocricetus auratus)

A colony of golden hamsters had an ongoing problem with hydrocephalus. In an attempt to clear the colony of the problem, new breeders from another supplier had been purchased. At termination of a behavioral study, the brain was collected from 35 animals (four of which had died with hydrocephalus during the study) and was examined macroscopically and by light microscopy. Although no animals manifested obvious behavioral changes, 31 of 35 (88.6%, 13/15 males and 18/20 females in control and manipulated groups) had hydrocephalus. Twenty-five animals had macroscopically identifiable hydrocephalus, and six had hydrocephalus identified microscopically. Neither teratogenic concentrations of metals nor mycotoxins were detected in tissues or food, and sera from breeders tested negative for antibodies to Sendai virus, reovirus 3, and lymphocytic choriomeningitis virus. Trial matings of breeders expected to produce hydrocephalic offspring resulted in affected offspring, and mating of breeders expected to produce normal offspring resulted in normal or less-affected offspring. Hydrocephalus was confirmed retrospectively in some breeders. Hereditary hydrocephalus appears to be widespread in hamster stocks in Central Europe. Affected animals do not manifest signs of disease and usually die without obvious premonitory signs. Despite severe hydrocephalus, the animals can breed, and animal handlers do not identify motor deficits or abnormal behavioral activity. This entity is unlike the previously described, hereditary hydrocephalus of hamsters that is phenotypically identifiable and usually is lethal before they attain breeding age.

Adaptive behavioural syndromes due to strategic niche specialization

BACKGROUND: Behavioural syndromes, i.e. consistent individual differences in behaviours that are correlated across different functional contexts, are a challenge to evolutionary reasoning because individuals should adapt their behaviour to the requirements of each situation. Behavioural syndromes are often interpreted as a result of constraints resulting in limited plasticity and inflexible behaviour. Alternatively, they may be adaptive if correlated ecological or social challenges functionally integrate apparently independent behaviours. To test the latter hypothesis we repeatedly tested helpers in the cooperative breeder Neolamprologus pulcher for exploration and two types of helping behaviour. In case of adaptive behavioural syndromes we predicted a positive relationship between exploration and aggressive helping (territory defence) and a negative relationship between these behaviours and non-aggressive helping (territory maintenance). RESULTS: As expected, helpers engaging more in territory defence were consistently more explorative and engaged less in territory maintenance, the latter only when dominant breeders were present. Contrary to our prediction, there was no negative relationship between exploration and territory maintenance. CONCLUSION: Our results suggest that the three behaviours we measured are part of behavioural syndromes. These may be adaptive, in that they reflect strategic specialization of helpers into one of two different life history strategies, namely (a) to stay and help in the home territory in order to inherit the breeding position or (b) to disperse early in order to breed independently.

Mothers adjust egg size to helper number in a cooperatively breeding cichlid

Mothers should adjust the size of propagules to the selective forces to which these offspring will be exposed. Usually, a larger propagule size is favored when young are exposed to high mortality risk or conspecific competition. Here we test 2 predictions on how egg size should vary with these selective agents. When offspring are cared for by parents and/or alloparents, protection may reduce the predation risk to young, which may allow mothers to invest less per single offspring. In the cooperatively breeding cichlid Neolamprologus pulcher, brood care helpers protect group offspring and reduce the latters' mortality rate. Therefore, females are expected to reduce their investment per egg when more helpers are present. In a first experiment, we tested this prediction by manipulating the helper number. In N. pulcher, helpers compete for dispersal opportunities with similar-sized individuals of neighboring groups. If the expected future competition pressure on young is high, females should increase their investment per offspring to give them a head start. In a second experiment, we tested whether females produce larger eggs when perceived neighbor density is high. Females indeed reduced egg size with increasing helper number. However, we did not detect an effect of local density on egg size, although females took longer to produce the next clutch when local density was high. We argue that females can use the energy saved by adjusting egg size to reduced predation risk to enhance future reproductive output. Adaptive adjustment of offspring size to helper number may be an important, as yet unrecognized, strategy of cooperative breeders.