Mucor nidicola sp. nov., a fungal species isolated from an invasive paper wasp nest.

A strain of a novel mucoralean fungus was isolated from a nest of the invasive paper wasp, Polistes dominulus. Phylogenetic analysis based on the internal transcribed spacer (ITS) regions and 5.8S rRNA gene sequences, along with physiological tests, revealed that this strain represents a novel species within the genus Mucor. The novel species also includes a representative that had previously been characterized as part of the Mucor hiemalis complex. Unlike the type strain of M. hiemalis, these two strains can grow at 37 °C and sporulate at 35 °C. Here, we present a partial resolution of the M. hiemalis species complex and propose the novel species Mucor nidicola sp. nov. to accommodate the isolate; the type strain of M. nidicola is F53(T) (=NRRL 54520(T)=UAMH 11442(T)=CBS 130359(T)).

The relationship between serial monogamy and rape in the United States (1960-1995).

In mating systems where individuals pair, separate and re-pair repeatedly (i.e. serial monogamy), some males monopolize more than one female's reproductive life span and thus leave other males effectively mateless. Males who cannot secure females through traditional methods may seek alternatives, such as rape, to ensure gene passage into future generations. Analysis of US government records shows that (i) divorce and remarriage patterns in the United States are likely to increase the variance in male reproductive success, and (ii) rates of divorce and rape correlate positively. The former result suggests that serial monogamy increases the variance in male, relative to female, reproductive success and the latter result suggests that this variance influences the frequency of rape in American society. Because raped females sometimes become pregnant and take these pregnancies to term, our results indicate that rape has current adaptive significance.

Fever in honeybee colonies.

Honeybees, Apis spp., maintain elevated temperatures inside their nests to accelerate brood development and to facilitate defense against predators. We present an additional defensive function of elevating nest temperature: honeybees generate a brood-comb fever in response to colonial infection by the heat-sensitive pathogen Ascosphaera apis. This response occurs before larvae are killed, suggesting that either honeybee workers detect the infection before symptoms are visible, or that larvae communicate the ingestion of the pathogen. This response is a striking example of convergent evolution between this "superorganism" and other fever-producing animals.

Genetic support for the evolutionary theory of reproductive transactions in social wasps.

Recent evolutionary models of reproductive partitioning within animal societies (known as 'optimal skew', 'concessions' or 'transactional' models) predict that a dominant individual will often yield some fraction of the group's reproduction to a subordinate as an incentive to stay in the group and help rear the dominant's offspring. These models quantitatively predict how the magnitude of the subordinate's 'staying incentive' will vary with the genetic relatedness between dominant and subordinate, the overall expected group output and the subordinate's expected output if it breeds solitarily. We report that these predictions accord remarkably well with the observed reproductive partitioning between conesting dominant and subordinate queens in the social paper wasp Polistes fuscatus. In particular, the theory correctly predicts that (i) the dominant's share of reproduction, i.e. the skew, increases as the colony cycle progresses and (ii) the skew is positively associated both with the colony's productivity and with the relatedness between dominant and subordinate. Moreover, aggression between foundresses positively correlated with the skew, as predicted by transactional but not alternative tug-of-war models of societal evolution. Thus, our results provide the strongest (quantitative support yet for a unifying model of social evolution.

Heat shielding: A novel method of colonial thermoregulation in honey bees.

Honey bees, Apis mellifera, maintain constant colony temperatures throughout the year. Honey bees fan their wings to cool the colony, and often spread fluid in conjunction with this behavior to induce evaporative cooling. We present an additional, previously undescribed mechanism used by the honey bee to maintain constant colony temperature in response to localized temperature increases. Worker bees shield the comb from external heat sources by positioning themselves on hot interior regions of the hive's walls. Although honey comb and brood comb were both shielded, the temperature-sensitive brood received a greater number of heat shielders and was thus better protected from overheating. Heat shielding appears to be a context-dependent adaptive behavior performed by worker bees who would previously have been considered "unemployed.

Dispersal of first "workers" in social wasps: causes and implications of an alternative reproductive strategy.

Many "workers" in north temperate colonies of the eusocial paper wasp Polistes fuscatus disappear within a few days of eclosion. We provide evidence that these females are pursuing an alternative reproductive strategy, i.e., dispersing to overwinter and become nest foundresses the following spring, instead of helping to rear brood on their natal nests. A female is most likely to stay and help at the natal nest (i.e., least likely to disperse) when it is among the first workers to emerge and when it emerges on a nest with more pupae (even though worker-brood relatedness tends to be lower in such colonies). The latter cause may result from the fact that pupae-laden nests are especially likely to survive, and thus any direct or indirect reproductive payoffs for staying and working are less likely to be lost. Disappearing females are significantly smaller than predicted if dispersal tendency was independent of body size (emergence order-controlled), suggesting that the females likely to be most effective at challenging for reproductive rights within the natal colony (i.e., the largest females) are also most likely to stay. Thus, early dispersal is conditional on a female's emergence order, the maturity of its natal nest, and its body size. Finally, we present evidence that foundresses may actively limit the sizes of first-emerging females, perhaps to decrease the probability that the latter can effectively challenge foundresses for reproductive rights. The degree to which foundresses limit the size of first-emerging females accords well with the predictions of the theory of staying incentives.