Evidence for social role in a dolphin social network

Social animals have to take into consideration the behaviour of conspecifics when making decisions to go by their daily lives. These decisions affect their fitness and there is therefore an evolutionary pressure to try making the right choices. In many instances individuals will make their own choices and the behaviour of the group will be a democratic integration of everyone’s decision. However, in some instances it can be advantageous to follow the choice of a few individuals in the group if they have more information regarding the situation that has arisen. Here I provide early evidence that decisions about shifts in activity states in a population of bottlenose dolphin follow such a decision-making process. This unshared consensus is mediated by a non-vocal signal, which can be communicated globally within the dolphin school. These signals are emitted by individuals that tend to have more information about the behaviour of potential competitors because of their position in the social network. I hypothesise that this decision-making process emerged from the social structure of the population and the need to maintain mixed-sex schools.     

The influence of social status on the rate of growth, eye color pattern and insulin-like growth factor-I gene expression in Nile tilapia, Oreochromis niloticus

Many aspects of teleost physiology are subject to regulation by social interactions. To evaluate the relationship of social status with growth, eye color pattern and hepatic Insulin-like Growth Factor-I (IGF-I) mRNA expression, 30 Oreochromis niloticus were isolated for 10 days and were used in a social pair study. Results revealed that growth of both dominant (except 1 day after social interaction) and subordinate individuals was suppressed, but growth suppression was greater in the subordinates. The dominant fish completely inhibited the feeding of the subordinate individuals during and 1 day after they were introduced into the aquaria together. After that, a pattern of highly aggressive attacks by dominant fish only partially inhibited feeding by the subordinates. Differential alterations in growth rate between dominants and subordinates were attributed more to behavioral changes (i.e., feeding) as transduced by physiological regulators (i.e., IGF-I level and possibly serotonin and/or neuropeptide Y) but may also be due to changes in metabolism. The fish's relative position in the social hierarchy consistently influenced the levels of IGF-I mRNA in the liver and the eye color pattern. Lower social status depressed hepatic IGF-I levels while dominant status stimulated hepatic IGF-I production, possibly in response to inhibition of somatostatin release in the hypothalamus, leading to greater secretion of pituitary growth hormone (GH). A significant positive association was detected between the IGF-I mRNA expression of the dominant fish and the level of aggression (number of attacks) during the encounter. Social status also influenced the eye color pattern of the fish. During aggressive interactions, most of the fish (22 out of 24) displayed decreased eye darkening. At the later part of the encounter, all subsequent subordinates displayed eye-darkening patterns which acted as a social signal announcing social submission. After the encounter dominant fish had paler eye color pattern than subordinates.     

Regulation of protogynous sex change by competition between corticosteroids and androgens: an experimental test using sandperch, Parapercis cylindrica

Cortisol, the dominant corticosteroid in fish, and 11-ketotestosterone (11KT), the most potent androgen in fish, are both synthesized and (or) deactivated by the same two enzymes, 11beta-hydroxylase and 11beta-hydroxysteroid dehydrogenase. Cortisol is synthesized in response to stress (such as that caused by interaction with a dominant conspecific), whereas 11KT is synthesized during protogynous sex change. It has been hypothesized that corticosteroids (such as cortisol) inhibit 11KT synthesis via substrate competition, thereby providing a mechanism for the regulation of socially mediated, protogynous sex change. We tested this hypothesis by administering cortisol (50 microg g(-1) body weight) to female sandperch (Parapercis cylindrica) under social conditions that were permissive to sex change (i.e. in the absence of suppressive male dominance). Twenty-one days later, mean physiological cortisol concentration in cortisol-treated fish was 4.2-fold greater than that in 'socially stressed' female fish maintained in a semi-natural system. Although the dosage of cortisol was therefore considered to be favorable for engendering competitive inhibition of 11KT synthesis, all cortisol-treated fish changed sex, as did all sham-treated and control fish (n=7 fish per treatment). In addition, there was no effect of cortisol treatment on the rate of sex change or on the pattern of steroidogenesis. Thus, our results refute the hypothesis that protogynous sex change is regulated by substrate competition between corticosteroids and androgens.     

Sexual behaviour in female pigs

This paper reviews the influence of social mechanisms on oestrus and sexual motivation in pigs. The social relations between the animals and the signals they send out can inhibit as well as encourage their social motivation. Social stimuli from both boars and other sows in oestrus tend to induce and synchronise oestrus and ovulation amongst sows. The courting behaviour of boars is also facilitated by social stimuli from other boars. However, when sows are kept under conditions where the social pressure is high, e.g. due to limited space and/or resources, the social stress experienced by particularly the subordinate individuals may inhibit sexual motivation during oestrus. To a large extent this effect seems to be mediated via specific fear reactions towards dominant individuals of sows that have lost many aggressive encounters. For example, fear reduces the sexual motivation during mating and during sexual interactions amongst sows within a group, and fear may thus inhibit their chances of reproductive success. Similarly, fear of humans caused by innate fearfulness or negative handling procedures reduces sexual motivation in the presence of the human handler even when sows are in standing oestrus.     

Phylogeny and phylogeography of the Mediterranean species of the parasitic ant genus <Emphasis Type="Italic">Chalepoxenus</Emphasis> and its <Emphasis Type="Italic">Temnothorax</Emphasis> hosts

We analysed the phylogenetic and phylogeographic relationships of four Mediterranean species of the rare slave-making ant genus Chalepoxenus and eleven of its about 20 Temnothorax host species by sequencing the mitochondrial Cytochrome Oxidase I and II genes. Neighbour-Joining, Maximum Parsimony and Bayesian analyses based on 1320 bp indicate that the genus Chalepoxenus constitutes a monophylum. In all three analyses, C. kutteri from Southwest Europe and the workerless, “degenerate slavemaker” C. brunneus from North Africa form a monophyletic group. C. muellerianus and C. tauricus, distributed in Southern Europe and Ukraine, respectively, form a monophylum in the Neighbour-Joining and the Maximum Parsimony analysis. In our limited set of only 11 of several hundred Temnothorax species, T. flavicornis forms the sister group of Chalepoxenus. Our study further indicates paraphyly of the genus Temnothorax with respect to Chalepoxenus. Moreover, the results suggest that speciation in this slave-making genus is possibly caused by the formation of host races as different Chalepoxenus species use different hosts, and some samples seem to cluster by host species rather than by geographical distance. Received 5 September 2006; revised 17 March 2007; accepted 23 March 2007.     

Negotiating the Therapeutic Gap: Prenatal Diagnostics and Termination of Pregnancy in Sri Lanka

In Sri Lanka, termination of pregnancy, other than in extreme circumstances, is strictly illegal. Among the public and large sections of the medical community there is widespread support for some degree of liberalization of the law, particularly where this relates to serious genetic conditions which can be identified prenatally. Tension emerges out of a publicly maintained conservatism on issues of abortion on the one hand and a growing disconnection from unregulated practices of termination in the private sector on the other. Social science approaches have much to contribute when understanding the ‘therapeutic gap’ that opens up and, in particular, the way that local ideas of fate, destiny and how suffering might be ameliorated become blended with the predictive power of genetic testing.     

Restoration of Dry Afromontane Forest Using Pioneer Shrubs as Nurse-Plants for Olea europaea ssp. cuspidata

Shrubs are often considered competitive barriers for seedlings planted in reforestation programs, although they can facilitate tree recruitment, especially in ecosystems under high abiotic stress. An alternative reforestation technique using pioneer shrubs as nurse‐plants for Olea europaea ssp. cuspidata was tested in exclosures in northern Ethiopia. Seedlings were planted in three different microhabitats, and their survival was monitored. The microhabitats were bare soil patches between shrubs, patches under the dominant shrub Acacia etbaica, and patches under Euclea racemosa, an evergreen shrub, which supports the majority of naturally established Olea recruits. The ability of shrubs to offer protection against browsing goats was tested experimentally. Controlled shading was used to determine whether solar irradiation causes seedling mortality in environments without water stress. Data were analyzed using Kaplan–Meier survival analysis, Kruskal–Wallis analysis of variance (ANOVA), and one‐way ANOVA. Olea survival was significantly higher and shoot damage by goats was lower when planted under shrub cover compared to bare soil patches, particularly under Euclea canopies, although high shade levels reduced seedling performance. Reduction of solar radiation by shrub canopies and thus control of soil–water evaporation and seedling transpiration most likely controlled the observed facilitation. Planting under shrubs may increase seedling survival and assist regeneration of dry Afromontane vegetation. Preserving pioneers also reduces soil erosion and conserves biodiversity. Excluding livestock is essential for Olea woodland restoration and allows persistent but morphologically modified Olea shrubs to develop vigorous regrowth. Facilitative processes are guiding principles for assisted forest restoration, but above‐average rains may be critical to restore higher biomass levels in semiarid areas.     

The effects of early and adult social environment on zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>) behavior

Because early social experience can have a profound effect on later mate and social choices, the availability of options and decisions made early in development can have major effects on adult behavior. Herein, we use strain differences among zebrafish, Danio rerio, as an experimental tool to test the effects of social experience on behavior. By manipulating the strain composition of groups in which the subject fish are housed at different ages, we tested (1) whether mixing with dissimilar individuals influenced subsequent behavior, (2) whether prolonged mixing during the juvenile stage had a more pronounced effect than a shorter period of mixing during adulthood and (3) whether mixing had a lasting effect after animals were resorted into groups of same strain animals. We found that social experience had a profound impact on social behavior. Both Nadia and TM1 individuals engaged in more frequent biting after having been in mixed strain groups compared to pure strain groups. This was true of groups mixed as juveniles, as well as adults, indicating that this response was not dependent on exposure during a critical developmental period. Also, TM1 fish (but not Nadia) having recently been housed in mixed-strain groups were more willing to leave the immediate vicinity of a shoal than were TM1 fish raised in pure strain groups. This change was more pronounced in groups mixed as juveniles than as adults. In addition, the observed changes persisted after mixed groups were separated into pure strain groups for a month. Other behavioral measures including Activity Level, Predator Response and Stress Recovery were unaffected by previous social experience.     

Pollination of the European food-deceptive Traunsteinera globosa (Orchidaceae): the importance of nectar-producing neighbouring plants

European food-deceptive orchids generally flower early in spring and rely on naïve pollinators for their reproduction. Some species however, flower later in the summer, when many other rewarding plants species are also in bloom. In dense flowering communities, deceptive orchids may suffer from competition for pollinator resources, or might alternatively benefit from higher community attractiveness. We investigated the pollination strategy of the deceptive species Traunsteinera globosa, and more specifically whether it benefited from the presence of coflowering rewarding species. We carried out a population survey to quantify the density and reproductive success of the orchid as well as the density of all coflowering species. Our results suggest that the deceptive orchid not only benefited from the presence of coflowering species, but that interestingly the density of the species Trifolium pratense was significantly positively correlated with the orchid's reproductive success. This species might simply act as a magnet species attracting pollinators near T. globosa, or could influence the orchid reproductive fitness through a more species-specific interaction. We propose that morphological or colour similarities between the two species should be investigated in more detail to decipher this pollination facilitation effect.     

Spatial dynamics,social norms,and the opportunity of the commons

The most important message of Levin (Ecol Res 21:328–333, 2006) is that “Ecologists and economists have much incentive for interaction.” Recent studies that account for evolutionary processes and local interactions support this view by obtaining results that run counter to conventional wisdom within resource economics. A second major message of the article is that to meet environmental challenges, humanity must develop social norms that enhance cooperative responses. Successful examples of resource management systems back up norms with economic incentives: rewards for good behavior and punishments for bad. Economic incentives are especially important if rapid and large changes in human behavior are desired.