Evolution of sprouting versus seeding inAspalathus linearis

We have tested the hypothesis that reseeding is a plesiomorphic character state and that sprouting is a derived state inAspalathus linearis, and that the latter is an adaptation to ensure fire-survival in a fireprone environment. Samples of five seeder and four sprouter populations of A.linearis were examined by horizontal starch gel electrophoresis to assess the amount of genetic differentiation within and between sprouting and seeding populations, and to determine the extent of gene flow between the populations. Leaf extracts were surveyed for ten enzymes and gene products revealed genetic variation at 13 (76%) of 17 protein coding loci. Allele frequency differences were found between sprouting and seeding populations and genetic distance values show that the sprouters are grouped separate from the seeders, thus providing support for the morphological data on which the above mentioned hypothesis is based. It is evident that evolution operates at the population level inA. linearis.     

No More Foreigners? The Remaking of German Naturalization and Citizenship Law, 1990–2000

Since the beginning of the 1990s, Germany has been taking controversial policy measures that had been quite unimaginable, even in the 1980s. On the one hand, regulations for asylum seekers and ethnic Germans have gradually become restrictive in nature. On the other hand, changes to the Citizenship and Nationality Law of 1913 (Reichs und Staatsangehörigkeitsgesetz) and the Alien Act of 1965 (Ausländergesetz) have dramatically altered the naturalization process. Before the passage of the new German citizenship law in 1999, the acquisition of citizenship in Germany was solely based on the principle of descent (jus sanguinis). This paper attempts to explain why German government altered its citizenship policy and introduced birthright citizenship. It reviews the post-war contextual factors that have shaped the debate on citizenship and asks whether it is external or internal factors, that is international-level norms and institutions or domestic politics, that led to the change. If domestic politics can fully explain the adoption of the new citizenship law, what domestic forces played an important role? Was state action taken in the name of protecting “the national interest” or was it party politics? What role did societal forces play in the making of new citizenship policy? Did the act seek to mitigate anti-foreigner sentiment growing in Germany since the 1990s? Using archival and documentary research and secondary data on socio-economic and demographic trends in Germany, this paper concludes that domestic politics explain the changes in the citizenship law. I argue that granting and withholding national citizenship, including birthright citizenship, is exclusively in the hands of a nation state. Considering a purely ethnocultural understanding of nation-hood now includes legal and territorial components, the new German citizenship law is a major reform at the both theoretical and conceptual level. However, the practical consequences of the new naturalization process remain to be seen. The main question for the future research agenda is whether the new naturalization and citizenship laws will bring full integration of foreigners living in German society.     

Optimal reproductive phenology under size‐dependent cannibalism

Intra‐cohort cannibalism is an example of a size‐mediated priority effect. If early life stages cannibalize slightly smaller individuals, then parents face a trade‐off between breeding at the best time for larval growth or development and predation risk from offspring born earlier. This game‐theoretic situation among parents may drive adaptive reproductive phenology toward earlier breeding. However, it is not straightforward to quantify how cannibalism affects seasonal egg fitness or to distinguish emergent breeding phenology from alternative adaptive drivers. Here, we devise an age‐structured game‐theoretic mathematical model to find evolutionary stable breeding phenologies. We predict how size‐dependent cannibalism acting on eggs, larvae, or both changes emergent breeding phenology and find that breeding under inter‐cohort cannibalism occurs earlier than the optimal match to environmental conditions. We show that emergent breeding phenology patterns at the level of the population are sensitive to the ontogeny of cannibalism, that is, which life stage is subject to cannibalism. This suggests that the nature of cannibalism among early life stages is a potential driver of the diversity of reproductive phenologies seen across taxa and may be a contributing factor in situations where breeding occurs earlier than expected from environmental conditions.     

Feigning death in the Central American cichlid Parachromis friedrichsthalii

Feigning death, a hunting strategy in which a healthy individual acts as if it was dead to trick prey into its reach, is reported for a population of the Central American cichlid Parachromis friedrichsthalii . Possible mechanisms leading to the evolution of such a behaviour are discussed.     

Confronting the challenges of discovery of novel antibacterial agents

Bacterial resistance is inevitable and is a growing concern. It can be addressed only by discovery and development of new agents. However the discovery and development of new antibacterial agents are at an all time low. This article broadly examines the historical as well as current status of antibacterial discovery and provides some perspective as how to address some of the challenges.     

Evolutionarily stable seasonal timing for insects with competition for renewable resource

Summary I study the evolutionarily stable seasonal patterns of hatching and pupation for herbivorous insects that engage in exploitative competition for a renewable resource. A longer larval feeding period enhances female fecundity, but also causes a higher mortality by predation and parasitism. Previously, it was shown that the evolutionarily stable population exhibits asynchronous starting and ending of the larval feeding period in a model in which larval growth rate decreases with the total larval biomass in the population due presumably to interference competition. Here I study the case in which resource availability changes not only with environmental seasonality but with the depletion by the feeding of larvae. I find that if the impact of the herbivory is strong, both hatching and pupation should occur asynchronously in the evolutionarily stable population. And if the favourable season for the host plant is short the ESS population may include synchronous timing of pupation. If the timing of hatching and pupation occurs asynchronously, in the first day of each interval some fraction of the population hatch or pupate, respectively and the rest do so gradually over the interval. In addition, if the environmental variable changes as a symmetric function of time, the length of the period in which hatching occurs tends to be much shorter than the period in which pupation occurs.     

Module-based construction of plasmids for chromosomal integration of the fission yeast Schizosaccharomyces pombe

Integration of an external gene into a fission yeast chromosome is useful to investigate the effect of the gene product. An easy way to knock-in a gene construct is use of an integration plasmid, which can be targeted and inserted to a chromosome through homologous recombination. Despite the advantage of integration, construction of integration plasmids is energy- and time-consuming, because there is no systematic library of integration plasmids with various promoters, fluorescent protein tags, terminators and selection markers; therefore, researchers are often forced to make appropriate ones through multiple rounds of cloning procedures. Here, we establish materials and methods to easily construct integration plasmids. We introduce a convenient cloning system based on Golden Gate DNA shuffling, which enables the connection of multiple DNA fragments at once: any kind of promoters and terminators, the gene of interest, in combination with any fluorescent protein tag genes and any selection markers. Each of those DNA fragments, called a ‘module’, can be tandemly ligated in the order we desire in a single reaction, which yields a circular plasmid in a one-step manner. The resulting plasmids can be integrated through standard methods for transformation. Thus, these materials and methods help easy construction of knock-in strains, and this will further increase the value of fission yeast as a model organism.     

Dynamic information and host acceptance by a tephritid fruit fly

Abstract. 1. Female apple maggot (Rhagoletis pomonella Walsh) flies held in field cages usually oviposited in an unparasitized (non-pheromone marked) fruit when it was encountered.
2. Oviposition in a previously parasitized (pheromone marked) fruit depended upon the time since the last oviposition (TSLO) and the percentage of infested fruit encountered during search for oviposition sites.
3. Previous theories of host acceptance suggest that the acceptance or rejection of a host should depend dichotomously on time since last oviposition and the fraction of marked hosts in the last five encounters. The experiments, however, show considerable variability and are thus not consistent with the theory.
4. A new theory for the experiments is introduced. This model involves physiological (egg complement) and informational state variables and leads to intuitive understanding of the experimental results. In particular, the model shows how the plasticity in oviposition site selection may arise from fitness maximizing behaviour. Alternative models are also discussed. All of the models stress the importance of physiological and informational states.