Maternal rank affects reproductive success of male Barbary macaques (Macaca sylvanus): evidence from DNA fingerprinting

Summary Paternity determination by oligonucleotide fingerprinting confirms that maternal rank affects the reproductive success of male Barbary macaques (Macaca sylvanus). High-born males began to reproduce significantly earlier and sired significantly more infants surviving to at least 1 year of age during the first 4 years of their reproductive career than low-born males. This relation was independent of the natal/non-natal status of the males, and was not affected by external conditions such as the level of intrasexual competition or the number of fertilizable females. Since high-ranking females in this population produced significantly more male offspring than low-ranking females, the data on sex ratio adjustment and comparative breeding success of sons and daughters are consistent with the predictions of the Trivers-Willard hypothesis. Offprint requests to: A. Paul     

Are naked and common mole-rats eusocial and if so, why?

Eusociality in mammals is defined in the present paper by the following criteria: reproductive altruism (which involves reproductive division of labor and cooperative alloparental brood care), overlap of adult generations, and permanent (lifelong) philopatry. We argue that additional criteria such as the existence of castes, colony size, reproductive skew, and social cohesion are not pertinent to the definition of eusociality in mammals. According to our definition of mammalian eusociality, several rodent species of the African family Bathyergidae can be considered eusocial, including the naked mole-rat (Heterocephalus glaber), Damaraland mole-rat (Cryptomys damarensis), and several additional, if not all, species in the genus Cryptomys. Furthermore, some species of social voles (like Microtus ochrogaster) may also fulfill criteria of mammalian eusociality. Understanding the evolution of eusociality in mole-rats requires answers to two primary questions: (1) What are the preconditions for the development of their eusocial systems? (2) Why do offspring remain in the natal group rather than dispersing and reproducing? Eusociality in mammals is by definition a special case of monogamy (more specifically: monogyny one female breeding), involving prolonged pair bonding for more than one breeding period. We argue that eusociality in mole-rats evolved from a monogamous mating system where cooperative brood care was already established. A tendency for group living is considered to be an ancestral (plesiomorph) trait among African bathyergid mole-rats, linking them to other hystricognath rodents. A solitary lifestyle seen in some genera, such as Bathyergus, Georychus, and Heliophobius, is assumed to be a derived trait that arose independently in different lineages of bathyergids, possibly as a consequence of selective constraints associated with the subterranean environment. In proximate terms, in eusocial mole-rats either puberty is assumed to be developmentally delayed so that under natural conditions most animals die before dispersal is triggered (e.g., in the case of Heterocephalus) or dispersal is induced only by an incidental encounter with an unfamiliar, yet adequate sexual partner (e.g., in the case of Cryptomys). Ultimately, a combination of strategies involving either dispersal and/or philopatry can be beneficial, especially in a highly unpredictable environment. If genetic relatedness among siblings is high (e.g., a coefficient of relatedness of 0.5 or more), then philopatry would not invoke an appreciable loss of fitness, especially if the cost of dispersing is higher than staying within the natal group. High genetic relatedness is more likely in a monogamous mating system or a highly inbred population. In this paper, we argue that the preconditions for eusociality in bathyergid mole-rats were a monogamous mating system and high genetic relatedness among individuals. We argue against the aridity food-distribution hypothesis (AFDH) that suggests a causal relationship between cooperative foraging for patchily distributed resources and the origin of eusociality. The AFDH may explain group size dynamics of social mole-rats as a function of the distribution and availability of resources but it is inadequate to explain the formation of eusocial societies of mole-rats, especially with respect to providing preconditions conducive for the emergence of eusociality.     

Effects of fertilization and elevated CO<Subscript>2</Subscript> on larval food and butterfly nectar amino acid preference in<Emphasis Type="Italic"> Coenonympha pamphilus</Emphasis> L.

The effects of larval diet on the nutritional preferences of butterflies has rarely been examined. This study investigates whether alterations in the larval diet result in changes in adult preferences for nectar amino acids. Larvae of Coenonympha pamphilus were raised on fertilized or unfertilized Festuca rubra, grown under ambient (350 ppm) or elevated (750 ppm) atmospheric CO ₂environments. Fertilization led to marked increases in leaf nitrogen concentration. In plants grown under elevated CO ₂conditions, leaf water and nitrogen concentrations were significantly lower, and the C/N-ratio increased significantly. Fertilization of the host plant shortened the development time of C. pamphilus larvae, and pupal weight increased. In contrast, larvae of C. pamphilus developed significantly slower on F. rubra grown under elevated CO ₂, but adult emergence weight was not affected by CO ₂treatment of the plant. C. pamphilus females showed a clear preference for nectar mimics containing amino acids, whereas males, regardless of treatment, either preferred the nectar mimic void of amino acids or showed no preference for the different solutions. Female butterflies raised on fertilized plants showed a significant decline in their preference for nectar mimics containing amino acids. A slight, but not significant, trend towards increased nectar amino acid preference was found in females raised on plants grown under elevated CO ₂. We clearly demonstrate that alterations in larval host quality led to changes in butterfly nectar preferences. The ability of the butterfly to either rely less on nectar uptake or compensate for poor larval conditions represents a trade-off between larval and adult butterfly feeding.     

Verteilung verkehrsbedingter Edelmetallimmissionen in Böden

Contents and distribution of platinum-group-elements (PGE) in soils caused by automobile emissions were investigated at three transects perpendicular to the road at various depths. Concentrations of platinum, rhodium and palladium were determined by ICP-MS after separation and preconcentration by nickel-sulphide fire-assay. Platinum contents in roadside soils range from 250 μg/kg to the local background values which are below 0.5–0.8 μg/kg. Ratios of platinum and rhodium (about 6∶1) are similar to the ratios in catalytic converters. There is evidence for a significant correlation of PGE input and local parameters such as traffic-conditions, distance from the trafficlane, prevailing wind direction, and barriers such as vegetation or morphology.