27 resultados para diversification


Relevância:

20.00% 20.00%

Publicador:

Resumo:

The Northern Ireland conflict has been described as one of the most over-researched conflicts in the world. However, this is a relatively recent development. For many years, when the conflict was most intense, social scientists in Northern Ireland were silent and not vocal. The sectarian violence that dominated the life in Northern Ireland as well as the fact that the country was a fundamentally unjust society contributed to this silence. However, since the peace process began in the mid 1990s, a growing number of qualitative studies have been published, utilising one-to-one interviews and focus group discussions, in order to "make people's voices heard" and deal with the consequences of the so-called "Troubles". This paper looks into the emergence of a qualitative social research landscape in Northern Ireland beyond the conflict and explores issues so far neglected. It is argued that a number of factors have contributed to this, among them the availability of research funding to voluntary and community sector organisations that use their data to influence policy-making and equality legislation in a country which is still deeply divided along socio-religious lines.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

For US credit unions, revenue from non-interest sources has increased significantly in recent years. We investigate the impact of revenue diversification on financial performance for the period 1993–2004. The impact of a change in strategy that alters the share of non-interest income is decomposed into a direct exposure effect, reflecting the difference between interest and non-interest bearing activities, and an indirect exposure effect which reflects the effect of the institution’s own degree of diversification. On both risk-adjusted and unadjusted returns measures, a positive direct exposure effect is outweighed by a negative indirect exposure effect for all but the largest credit unions. This may imply that similar diversification strategies are not appropriate for large and small credit unions. Small credit unions should eschew diversification and continue to operate as simple savings and loan institutions, while large credit unions should be encouraged to exploit new product opportunities around their core expertise.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Venom has only been recently discovered to be a basal trait of the Anguimorpha lizards. Consequently, very little is known about the timings of toxin recruitment events, venom protein molecular evolution, or even the relative physical diversifications of the venom system itself. A multidisciplinary approach was used to examine the evolution across the full taxonomical range of this similar to 130 million-year-old clade. Analysis of cDNA libraries revealed complex venom transcriptomes. Most notably, three new cardioactive peptide toxin types were discovered (celestoxin, cholecystokinin, and YY peptides). The latter two represent additional examples of convergent use of genes in toxic arsenals, both having previously been documented as components of frog skin defensive chemical secretions. Two other novel venom gland-overexpressed modified versions of other protein frameworks were also recovered from the libraries (epididymal secretory protein and ribonuclease). Lectin, hyaluronidase, and veficolin toxin types were sequenced for the first time from lizard venoms and shown to be homologous to the snake venom forms. In contrast, phylogenetic analyses demonstrated that the lizard natriuretic peptide toxins were recruited independently of the form in snake venoms. The de novo evolution of helokinestatin peptide toxin encoding do-mains within the lizard venom natriuretic gene was revealed to be exclusive to the helodermatid/anguid subclade. New isoforms were sequenced for cysteine-rich secretory protein, kallikrein, and phospholipase A 2 toxins. Venom gland morphological analysis revealed extensive evolutionary tinkering. Anguid glands are characterized by thin capsules and mixed glands, serous at the bottom of the lobule and mucous toward the apex. Twice, independently this arrangement was segregated into specialized serous protein-secreting glands with thick capsules with the mucous lobules now distinct (Heloderma and the Lanthanotus/Varanus clade). The results obtained highlight the importance of utilizing evolution-based search strategies for biodiscovery and emphasize the largely untapped drug design and development potential of lizard venoms. Molecular & Cellular Proteomics 9:2369-2390, 2010.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

We previously described a Multilocus Sequence Typing (MLST) scheme based on eight genes that facilitates population genetic and evolutionary analysis of P. acnes. While MLST is a portable method for unambiguous typing of bacteria, it is expensive and labour intensive. Against this background, we now describe a refined version of this scheme based on two housekeeping (aroE; guaA) and two putative virulence (tly; camp2) genes (MLST) that correctly predicted the phylogroup (IA, IA, IB, IC, II, III), clonal complex (CC) and sequence type (ST) (novel or described) status for 91% isolates (n = 372) via cross-referencing of the four gene allelic profiles to the full eight gene versions available in the MLST database (http://pubmlst.org/pacnes/). Even in the small number of cases where specific STs were not completely resolved, the MLST method still correctly determined phylogroup and CC membership. Examination of nucleotide changes within all the MLST loci provides evidence that point mutations generate new alleles approximately 1.5 times as frequently as recombination; although the latter still plays an important role in the bacterium's evolution. The secreted/cell-associated 'virulence' factors tly and camp2 show no clear evidence of episodic or pervasive positive selection and have diversified at a rate similar to housekeeping loci. The co-evolution of these genes with the core genome might also indicate a role in commensal/normal existence constraining their diversity and preventing their loss from the P. acnes population. The possibility that members of the expanded CAMP factor protein family, including camp2, may have been lost from other propionibacteria, but not P. acnes, would further argue for a possible role in niche/host adaption leading to their retention within the genome. These evolutionary insights may prove important for discussions surrounding camp2 as an immunotherapy target for acne, and the effect such treatments may have on commensal lineages. © 2013 McDowell et al.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Question: How parallel is adaptive evolution when it occurs from different genetic backgrounds? Background: Divergent evolutionary lineages of several post-glacial fish species including the threespine stickleback are found together in Ireland. Goals: To investigate the morphological diversity of stickleback populations in Ireland and assess whether morphology evolved in parallel between evolutionary lineages. Methods: We sampled stickleback from lake, river, and coastal habitats across Ireland. Microsatellite and mitochondrial DNA data revealed evolutionary history. Geometric morphometrics and linear trait measurements characterized morphology. We used a multivariate approach to quantify parallel and non-parallel divergence within and between lineages. Results: Repeated evolution of similar morphologies in similar habitats occurred across Ireland, concordant with patterns observed elsewhere in the stickleback distribution. A strong pattern of habitat-specific morphology existed even among divergent lineages. Furthermore, a strong signal of shared morphological divergence occurred along a marine-freshwater axis. Evidently, deterministic natural selection played a more important role in driving freshwater adaptation than independent evolutionary history. © 2013 Mark Ravinet.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Question: How parallel is adaptive evolution when it occurs from different genetic backgrounds?
Background: Divergent evolutionary lineages of several post-glacial fish species including the threespine stickleback are found together in Ireland.
Goals: To investigate the morphological diversity of stickleback populations in Ireland and assess whether morphology evolved in parallel between evolutionary lineages.
Methods: We sampled stickleback from lake, river, and coastal habitats across Ireland. Microsatellite and mitochondrial DNA data revealed evolutionary history. Geometric morphometrics and linear trait measurements characterized morphology. We used a multivariate approach to quantify parallel and non-parallel divergence within and between lineages.
Results: Repeated evolution of similar morphologies in similar habitats occurred across Ireland, concordant with patterns observed elsewhere in the stickleback distribution. A strong pattern of habitat-specific morphology existed even among divergent lineages. Furthermore, a strong signal of shared morphological divergence occurred along a marine–freshwater axis. Evidently, deterministic natural selection played a more important role in driving freshwater adaptation than independent evolutionary history.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Throughout Earth's history there have been temporal and spatial variations in the amount of visible and ultraviolet radiation received by ecosystems. This paper examines if temporal changes in these forms of energy receipt could have influenced the tempo and mode of plant diversity and speciation, focusing in particular upon Cenozoic time-scales. Evidence for changing patterns of plant diversity and speciation apparent in various fossil records and molecular phylogenies are considered alongside calculated changes in thermal and solar ultraviolet energy (specifically UV-B) over the past 50 Myr. We suggest that changes in thermal energy influx (amount and variability) affected the tempo of evolution through its influence upon community dynamics (e.g. population size, diversity, turnover, extinctions). It was not only the amount of thermal energy but also variability in its flux that may have influenced these processes, and ultimately the rate of diversification. We suggest that variations in UV-B would have influenced the mode and tempo of speciation through changes to genome stability during intervals of elevated UV-B. We argue, therefore, that although variability in thermal energy and UV-B fluxes through time may lead to the same end-point (changing the rate of diversification), the processes responsible are very different and both need to be considered when linking evolutionary processes to energy flux.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The capital approach is frequently used to model sustainability. A development is deemed to be sustainable when capital is not reduced. There are different definitions of sustainability, based on whether or not they allow that different forms of capital may be substituted for each other. A development that allows for the substitution of different forms of capital is called weakly sustainable. This article shows that in a risky world and a risk-averse society even under the assumptions of weak sustainability the circumstances under which different forms of capital may be substituted are limited. This is due to the risk-reducing effect of diversification. Using Modern Portfolio Theory this article shows under which conditions substitution of different forms of capital increases risk for future generations.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Genes, species and ecosystems are often considered to be assets. The need to ensure a sufficient diversity of this asset is being increasingly recognised today. Asset managers in banks and insurance companies face a similar challenge. They are asked to manage the assets of their investors by constructing efficient portfolios. They deliberately make use of a phenomenon observed in the formation of portfolios: returns are additive, while risks diversify. This phenomenon and its implications are at the heart of portfolio theory. Portfolio theory, like few other economic theories, has dramatically transformed the practical work of banks and insurance companies. Before portfolio theory was developed about 50 years ago, asset managers were confronted with a situation similar to the situation the research on biodiversity faces today. While the need for diversification was generally accepted, a concept that linked risk and return on a portfolio level and showed the value of diversification was missing. Portfolio theory has closed this gap. This article first explains the fundamentals of portfolio theory and transfers it to biodiversity. A large part of this article is then dedicated to some of the implications portfolio theory has for the valuation and management of biodiversity. The last section introduces three development openings for further research.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A basic operational objective of any environmental organisation is to raise awareness among the public on issues of environmental protection, through the dissemination of knowledge and experience to local communities, so that the conservation and ecologically sound management of natural resources can acquire a local dimension. This can be achieved either through interventions directed at the State, mainly in relation to its legislative function, or by encouraging citizens to change or improve their attitude regarding environmental matters. In order to ensure a successful outcome and the efficient functioning of any organisation, a feeling of mutual trust and understanding should exist between the latter and its various audiences, i.e. the State and society. A basic ingredient of this balance between the organisation, the broader public and the State is effective communication and activity planning. As a way of contributing to the exploration of this process, this paper describes the means of communication used by Greek environmental organisations, and presents, through a non-linear model, the differentiation amongst them, in conjunction with aspects of the profile of those running each organisation and other indicators, such as the years in operation and the membership figures in each sampled organisation. The paper concludes by arguing that the diversification of communication means is related to the head person's years as a member of the organisation and the extent of its total membership. Another important finding is that the more the involvement in activities within the organisation, the less differentiation we observe amongst the employed means of communication.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Background: After a volcano erupts, a lake may form in the cooled crater and become an isolated aquatic ecosystem. This makes fishes in crater lakes informative for understanding sympatric evolution and ecological diversification in barren environments. From a geological and limnological perspective, such research offers insight about the process of crater lake ecosystem establishment and speciation. In the present study we use genetic and coalescence approaches to infer the colonization history of Midas cichlid fishes (Amphilophus cf. citrinellus) that inhabit a very young crater lake in Nicaragua-the ca. 1800 year-old Lake Apoyeque. This lake holds two sympatric, endemic morphs of Midas cichlid: one with large, hypertrophied lips (~20% of the total population) and another with thin lips. Here we test the associated ecological, morphological and genetic diversification of these two morphs and their potential to represent incipient speciation.
Results: Gene coalescence analyses [11 microsatellite loci and mitochondrial DNA (mtDNA) sequences] suggest that crater lake Apoyeque was colonized in a single event from the large neighbouring great lake Managua only about 100 years ago. This founding in historic times is also reflected in the extremely low nuclear and mitochondrial genetic diversity in Apoyeque. We found that sympatric adult thin- and thick-lipped fishes occupy distinct ecological trophic niches. Diet, body shape, head width, pharyngeal jaw size and shape and stable isotope values all differ significantly between the two lip-morphs. The eco-morphological features pharyngeal jaw shape, body shape, stomach contents and stable isotopes (d15N) all show a bimodal distribution of traits, which is compatible with the expectations of an initial stage of ecological speciation under disruptive selection. Genetic differentiation between the thin- and thick-lipped population is weak at mtDNA sequence (FST = 0.018) and absent at nuclear microsatellite loci (FST < 0.001).
Conclusions: This study provides empirical evidence of eco-morphological differentiation occurring very quickly after the colonization of a new and vacant habitat. Exceptionally low levels of neutral genetic diversity and inference from coalescence indicates that the Midas cichlid population in Apoyeque is much younger (ca. 100 years or generations old) than the crater itself (ca. 1 800 years old). This suggests either that the crater remained empty for many hundreds of years after its formation or that remnant volcanic activity prevented the establishment of a stable fish population during the early life of the crater lake. Based on our findings of eco-morphological variation in the Apoyeque Midas cichlids, and known patterns of adaptation in Midas cichlids in general, we suggest that this population may be in a very early stage of speciation (incipient species), promoted by disruptive selection and ecological diversification.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Madagascar is home to numerous endemic species and lineages, but the processes that have contributed to its endangered diversity are still poorly understood. Evidence is accumulating to demonstrate the importance of Tertiary dispersal across varying distances of oceanic barriers, supplementing vicariance relationships dating back to the Cretaceous, but these hypotheses remain tentative in the absence of well-supported phylogenies. In the Papilio demoleus group of swallowtail butterflies, three of the five recognized species are restricted to Madagascar, whereas the remaining two species range across the Afrotropical zone and southern Asia plus Australia. We reconstructed phylogenetic relationships for all species in the P. demoleus group, as well as 11 outgroup Papilio species, using 60 morphological characters and about 4 kb of nucleotide sequences from two mitochondrial (cytochrome oxidase I and II) and two nuclear (wg and EF-1a) genes. Of the three endemic Malagasy species, the two that are formally listed as endangered or at risk represented the most basal divergences in the group, while the more common third endemic was clearly related to African P. demodocus. The fifth species, P. demoleus, showed little differentiation across southern Asia, but showed divergence from its subspecies sthenelus in Australia. Dispersal-vicariance analysis using cladograms derived from morphology and three independent genes indicated a Malagasy diversification of lime swallowtails in the middle Miocene. Thus, diversification processes on the island of Madagascar may have contributed to the origin of common butterflies that now occur throughout much of the Old World tropical and subtemperate regions. An alternative hypothesis, that Madagascar is a refuge for ancient lineages resulting from successive colonizations from Africa, is less parsimonious and does not explain the relatively low continental diversity of the group.