Phosphorus nutrition of ectomycorrhizal and arbuscular mycorrhizal tree seedlings from a lowland tropical rain forest in Korup National Park, Cameroon

The relationship between mycorrhizal colonisation and phosphorus acquired by seedlings of the arbuscular mycorrhizal tree Oubanguia alata Bak f. (Scytopetalaceae) and the ectomycorrhizal tree Tetraberlinia moreliana Aubr. (Caesalpiniodeae) was evaluated at low and high inorganic phosphorus availability. AM colonisation was positively correlated with phosphorus uptake by O. alata at low, but not at high phosphorus availability. Seedlings growth was positively related to arbuscular mycorrhizal colonisation at both low and high phosphorus availability, suggesting that growth promotion by arbuscular mycorrhizas is not simply related to an increase of phosphorus uptake. In contrast, phosphorus uptake by T. moreliana was correlated with EM colonisation at both low and high phosphorus availability, but there was no relationship between growth and ectomycorrhizal colonisation. Promotion of phosphorus uptake by arbuscular mycorrhizas and ectomycorrhizas at low phosphorus availability is consistent with the co-occurrence of the two types of mycorrhiza in tropical rain forests where available soil phosphorus is low. However, ectomycorrhizal colonisation may also be of advantage where inputs of phosphorus rich litter raise the phosphorus status of the soil, as seen in the groves of ectomycorrhizal trees in Korup National Park, and may be one of the factors reinforcing local dominance by these trees

Virulence as a Model for Interplanetary and Interstellar Colonisation - Parasitism or Mutualism

In the light of current scientific assessments of human-induced climate change, we investigate an experimental model to inform how resource-use strategies may influence interplanetary and interstellar colonisation by intelligent civilisations. In doing so, we seek to provide an additional aspect for refining the famed Fermi Paradox. The model described is necessarily simplistic, and the intent is to simply obtain some general insights to inform and inspire additional models. We model the relationship between an intelligent civilisation and its host planet as symbiotic, where the the relationship between the symbiont and the host species (the civilisation and the planets ecology, respectively) determines the fitness and ultimate survival of both organisms. We perform a series of Monte Carlo Realisation simulations, where civilisations pursue a variety of different relationships/strategies with their host planet, from mutualism to parasitism, and can consequently 'infect' other planets/hosts. We find that parasitic civilisations are generally less effective at survival than mutualist civilisations, provided that interstellar colonisation is inefficient (the maximum velocity of colonisation/infection is low). However, as the colonisation velocity is increased, the strategy of parasitism becomes more successful, until they dominate the 'population'. This is in accordance with predictions based on island biogeography and r/K selection theory. While heavily assumption dependent, we contend that this provides a fertile approach for further application of insights from theoretical ecology for extraterrestrial colonisation - while also potentially offering insights for understanding the human-Earth relationship and the potential for extraterrestrial human colonisation.Comment: 18 pages, 7 figures, published in the International Journal of Astrobiolog

Isolation mediates persistent founder effects on zooplankton colonisation in new temporary ponds

Understanding the colonisation process in zooplankton is crucial for successful restoration of aquatic ecosystems. Here, we analyzed the clonal and genetic structure of the cyclical parthenogenetic rotifer Brachionus plicatilis by following populations established in new temporary ponds during the first three hydroperiods. Rotifer populations established rapidly after first flooding, although colonisation was ongoing throughout the study. Multilocus genotypes from 7 microsatellite loci suggested that most populations (10 of 14) were founded by few clones. The exception was one of the four populations that persisted throughout the studied hydroperiods, where high genetic diversity in the first hydroperiod suggested colonisation from a historical egg bank and, no increase in allelic diversity was detected with time. In contrast, in another of these four populations, we observed a progressive increase of allelic diversity. This population became less differentiated from the other populations suggesting effective gene flow soon after its foundation. Allelic diversity and richness remained low in the remaining two, more isolated, populations, suggesting little gene flow. Our results highlight the complexity of colonisation dynamics, with evidence for persistent founder effects in some ponds, but not in others, and with early immigration both from external source populations, and from residual, historical diapausing egg banks

Phylogenetic and phenotypic divergence of an insular radiation of birds

Evolutionary divergence of lineages is one of the key mechanisms underpinning large scale patterns in biogeography and biodiversity. Island systems have been highly influential in shaping theories of evolutionary diversification and here I use the insular Zosteropidae of the south west Pacific to investigate the roles of ecology and biogeography in promoting evolutionary divergence. Initially I build a phylogenetic tree of the study group and use it to reveal the pattern of colonisation and diversification. My results suggest a complex history of dispersal with the observed pattern most likely a result of repeated bouts of colonisation and extinction. I then use the new phylogeny to quantify the diversification rates of the Zosteropidae. I find a very high rate of lineage divergence and suggest the most likely explanation relates to extensive niche availability in the south west Pacific. I also find evidence for an overall slowdown in diversification combined with repeated bursts of accelerated speciation, consistent with a model of taxon cycles. I do not find evidence for sympatric speciation, however. Finally I combine morphological and phylogenetic data to investigate the mode of evolution, evidence for character displacement and influence of biogeography on trait evolution. I find little support for the traditional theory of character displacement in sympatric species. I do, however, find some support for biogeographic theories. Taken together my results do not support traditional theories on the ecological and biogeographical basis of divergence, even in those cases where Zosterops have been used as exemplars. This appears to be because those theories assume rather simple patterns of colonisation and a static ecological system. Instead, my results suggest that evolutionary diversification is dominated by recurrent waves of colonisation and extinction, which, viewed at any particular moment, tend to obscure any underlying ecological rules

The effect of multiple paternity on genetic diversity during and after colonisation

In metapopulations, genetic variation of local populations is influenced by the genetic content of the founders, and of migrants following establishment. We analyse the effect of multiple paternity on genetic diversity using a model in which the highly promiscuous marine snail Littorina saxatilis expands from a mainland to colonise initially empty islands of an archipelago. Migrant females carry a large number of eggs fertilised by 1 - 10 mates. We quantify the genetic diversity of the population in terms of its heterozygosity: initially during the transient colonisation process, and at long times when the population has reached an equilibrium state with migration. During colonisation, multiple paternity increases the heterozygosity by 10 - 300 % in comparison with the case of single paternity. The equilibrium state, by contrast, is less strongly affected: multiple paternity gives rise to 10 - 50 % higher heterozygosity compared with single paternity. Further we find that far from the mainland, new mutations spreading from the mainland cause bursts of high genetic diversity separated by long periods of low diversity. This effect is boosted by multiple paternity. We conclude that multiple paternity facilitates colonisation and maintenance of small populations, whether or not this is the main cause for the evolution of extreme promiscuity in Littorina saxatilis.Comment: 7 pages, 5 figures, electronic supplementary materia

Bio-Communication of Bacteria and its Evolutionary Interrelations to Natural Genome Editing Competences of Viruses

Communicative competences enable bacteria to develop, organise and coordinate rich social life with a great variety of behavioral patterns even in which they organise themselves like multicellular organisms. They have existed for almost four billion years and still survive, being part of the most dramatic changes in evolutionary history such as DNA invention, cellular life, invention of nearly all protein types, partial constitution of eukaryotic cells, vertical colonisation of all eukaryotes, high adaptability through horizontal gene transfer and co-operative multispecies colonisation of all ecological niches. Recent research demonstrates that these bacterial competences derive from the aptitude of viruses for natural genome editing. 
	In contrast to a book which would be the appropriate space to outline in depth all communicative pathways inherent in bacterial life in this current article I want to give an overview for a broader readership over the great variety of bacterial bio-communication: In a first step I describe how they interpret and coordinate, what semiochemical vocabulary they share and which goals they try to reach. In a second stage I describe the main categories of sign-mediated interactions between bacterial and non-bacterial organisms, and between bacteria of the same or related species. In a third stage I will focus on the relationship between bacteria and their obligate settlers, i.e. viruses. We will see that bacteria are important hosts for multiviral colonisation and virally-determined order of nucleic acid sequences.

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Enumeration, identification and characterisation of methanogens colonising pre-ruminant calves : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science at Massey University, Palmerston North, New Zealand

Methane-producing archaea, methanogens, in ruminant animals are a major source of anthropogenic methane. With a global warming potential 23 times greater than carbon dioxide, methane has been targeted for reduction under the Kyoto protocol. In New Zealand methane emissions from ruminant animals are major contributor to the national greenhouse gas inventory. For this reason agricultural industries are challenged with reducing methane emissions from ruminants. This investigation on methanogens in young dairy calves was carried out to obtain information on methanogen colonisation and establishment in the rumen because little is known about this process. In this study, methanogen colonisation occurred within two days after birth in four calves that were raised in the absence of cows. Anaerobic culture techniques were used to enumerate methanogens in gut samples and showed that methanogen numbers increased over time, but dropped below detection limits in two of four calves between six and 11 days after birth. Methanogens in these two calves then reappeared at day 13. By three weeks of age methanogen densities in all four calves were approximately 108 cells ml -1. These densities are similar to those found by other workers for 3-week old and mature ruminants. Colonies picked from anaerobic agar roll-tubes prepared from enumeration cultures yielded 31 methanogenic isolates and 28 isolates that utilised hydrogen but did not produce methane. Eleven of the 31 methanogenic isolates were selected for purification. Despite extensive efforts only four methanogens were able to be purified from the eleven isolates because of persistent non-methanogenic eubacteria also present in cultures. A phylogenetic analysis of 16S rRNA gene sequences from purified and partially-purified methanogen isolates was carried out and dendograms constructed to identify methanogens. Some phenotypic characteristics of purified methanogens were determined. This revealed a number of methanogen species previously not found in the rumen. The results showed Methanofollis liminatans (three isolates), Methanoculleus palmolei (three isolates) or Methanosarcina barkeri (one isolate) were the predominant culturable methanogens colonising the rumen two days after birth. The three isolates identified as M. liminatans were only 96.0% identical at the 16S rRNA gene level to the M. liminatans type strain, DSM 4140, and appear to be a new methanogen species. In gut samples collected 3-5 days after birth, Methanobacterium bryantii (three isolates) was found to be a predominant methanogen in some calves apparently replacing the first methanogens colonising the developing rumen. Twenty two days after birth Methanobrevibacter thaueri (one isolate) was identified as a predominant methanogen in one calf. These results are the first to suggest that there is a successional change in the methanogen populations as the rumen develops in young ruminants. Consideration of the colonising species showed that Mcl. palmolei were obtained from only two calves (calves 10 and 12) and that Mfl. liminatans-like isolates were obtained only from a different cohort of calves penned separately to calves 10 and 12. These methanogens, previously found only in terrestrial or aquatic environments, are probably the primary colonising methanogens because there were no mature ruminants to provide alternative inocula. It appears that the developing rumen of young calves provides a niche suitable for opportunistic hydrogenotrophic methanogens. A PCR investigation using targeted primers specific for seven groupings of methanogens was carried out on all rumen samples to obtain information not dependant on culturing. This analysis on DNA extracts showed methanogens belonging to the Methanobacteriales were present in almost every sample. Methanogens belonging to the Methanosarcinales and Methanomicrobiales were not detected in any sample. At the end of the trial (22 days), PCR analysis showed the presence of Methanobacterium spp. and Methanobrevibacter spp. in all four calves. Although there were some disagreements with results for isolates cultured, overall, PCR results confirmed the concept of successional changes in methanogen populations in pre-ruminant calves

A colonisation-inhibition culture consisting of Salmonella Enteritidis and Typhimurium ΔhilAssrAfliG strains protects against infection by strains of both serotypes in broilers

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Placement and displacement : the fallen woman in discourse : a thesis presented in partial fulfilment of the requirements for the degree of Master of Arts in English at Massey University

This thesis is an invitation to reconsider the process of reading and representing the fallen woman. It combines an eclectic theoretical approach, drawing on works by Foucault, Derrida and Kristeva, with the metaphor of colonisation and the palimpsest. Using this construction, the thesis examines the placement of the fallen woman in discourse. The first section discusses how she falls in discourse, and uses textual and visual examples (predominantly Esther Barton from Gaskell's Mary Barton, Monica Widdowson and Rhoda Nunn from Gissing's The Odd Women). The reading of these figures uncovers three characteristic issues in the fallen woman's representation: her construction as murderer, the 'justice' of her death, and her pornographic interaction with the reader. This examination of the placement of the fallen woman continues in the second section. Here, the thesis explores how representations of her placement in discourse also suggest a displacement--that is, how her fall in discourse is a fall from discourse. Reading her site as a palimpsest of colonising representations uncovers the placement and displacement of the fallen woman in discourse