2,270 research outputs found

    An Examination of Actual Fraud Cases With a Focus on the Auditor’s Responsibility

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    The purpose of this paper is to contribute to an understanding of the intricate relationship between audit regulation and developments in audit practice in relation to the fraud issue. The extent and exact nature of the responsibilities of the auditor to detect fraud in relation to audit engagements has been widely discussed over the years. In this paper we classify actual cases, where the responsibilities of auditors have been established by the court system and/or by the auditors own professional organizations in Denmark. The dataset includes all publicized cases raised against Danish auditors within the time period 1909-2006. The information provided in the cases provides a basis for identifying the actual responsibilities pertaining to fraud during the audit. The overall finding of the historical analysis is that the responsibilities of the auditor in relation to fraud should be interpreted not as a group of its own, but in line with the development of what constitutes a good audit in general.Fraud; auditor responsibility; intentional misstatements; misappropriation; fraudulent reporting; embezzlement;

    Barrier loci and progress towards evolutionary generalities

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    Genetic architecture of adaptive radiation across two trophic levels

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    Evolution of trophic diversity is a hallmark of adaptive radiation. Yet, transitions between carnivory and herbivory are rare in young adaptive radiations. Haplochromine cichlid fish of the African Great Lakes are exceptional in this regard. Lake Victoria was colonized by an insectivorous generalist and in less than 20 000 years, several clades of specialized herbivores evolved. Carnivorous versus herbivorous lifestyles in cichlids require many different adaptations in functional morphology, physiology and behaviour. Ecological transitions in either direction thus require many traits to change in a concerted fashion, which could be facilitated if genomic regions underlying these traits were physically linked or pleiotropic. However, linkage/pleiotropy could also constrain evolvability. To investigate components of the genetic architecture of a suite of traits that distinguish invertivores from algae scrapers, we performed quantitative trait locus (QTL) mapping using a second-generation hybrid cross. While we found indications of linkage/pleiotropy within trait complexes, QTLs for distinct traits were distributed across several unlinked genomic regions. Thus, a mixture of independently segregating variation and some pleiotropy may underpin the rapid trophic transitions. We argue that the emergence and maintenance of associations between the different genomic regions underpinning co-adapted traits that evolved and persist against some gene flow required reproductive isolation

    Genomic insights into the vulnerability of sympatric whitefish species flocks

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    The erosion of habitat heterogeneity can reduce species diversity directly but can also lead to the loss of distinctiveness of sympatric species through speciation reversal. We know little about changes in genomic differentiation during the early stages of these processes, which can be mediated by anthropogenic perturbation. Here, we analyse three sympatric whitefish species (Coregonus spp) sampled across two neighbouring and connected Swiss pre‐alpine lakes, which have been differentially affected by anthropogenic eutrophication. Our data set comprises 16,173 loci genotyped across 138 whitefish using restriction‐site associated DNA sequencing (RADseq). Our analysis suggests that in each of the two lakes the population of a different, but ecologically similar, whitefish species declined following a recent period of eutrophication. Genomic signatures consistent with hybridisation are more pronounced in the more severely impacted lake. Comparisons between sympatric pairs of whitefish species with contrasting ecology, where one is shallow benthic and the other one more profundal pelagic, reveal genomic differentiation that is largely correlated along the genome, while differentiation is uncorrelated between pairs of allopatric provenance with similar ecology. We identify four genomic loci that provide evidence of parallel divergent adaptation between the shallow benthic species and the two different more profundal species. Functional annotations available for two of those loci are consistent with divergent ecological adaptation. Our genomic analysis indicates the action of divergent natural selection between sympatric whitefish species in pre‐alpine lakes and reveals the vulnerability of these species to anthropogenic alterations of the environment and associated adaptive landscape

    Rediscovery of a presumed extinct species, Salvelinus profundus, after re-oligotrophication

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    Lake Constance (47° 38’ N, 9° 22’ E) is a deep (max. depth 251m) and large (surface area 536 km2) postglacial lake in Central Europe. Originally, it harboured two charr species – Salvelinus umbla and S. profundus. The first is a medium-sized, colourful, winter spawning charr, which is widespread across Central European lakes, the second a small, pale, summer spawning, deepwater charr, which is endemic to Lake Constance (Schillinger 1901, Kottelat and Freyhof 2007). S. profundus has exceptionally large eyes and the upper jaw strongly overlaps the lower jaw. These traits are both considered adaptations to its life in the deep where it mostly feeds on profundal benthos (Schillinger 1901). During the second half of the last century, Lake Constance became eutrophic, resulting in oxygen-depletion in deep waters (IGKB 2004). The anoxic conditions harmed the development of eggs by profundal spawning fish (Baer et al. 2017). Thanks to strict management interventions, the lake has returned to an oligotrophic state, and oxygen is again available in the water column down to the greatest depth (IGKB 2004)

    A taxonomic revision of ten whitefish species from the lakes Lucerne, Sarnen, Sempach and Zug, Switzerland, with descriptions of seven new species (Teleostei, Coregonidae)

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    The taxonomy of the endemic whitefish of the lakes of the Reuss River system (Lucerne, Sarnen, Zug) and Lake Sempach, Switzerland, is reviewed and revised. Lake Lucerne harbours five species. Coregonus intermundia sp. nov. and C. suspensus sp. nov., are described. Coregonus nobilis Haack, 1882, C. suidteri Fatio, 1885, and C. zugensis NĂŒsslin, 1882, are redescribed. Genetic studies have shown that C. suidteri and C. zugensis are composed of several distinct species endemic to different lakes. The names C. suidteri and C. zugensis are restricted to the species of lakes Sempach and Zug, respectively. The whitefish populations previously referred to as C. suidteri and C. zugensis from Lake Lucerne are described as C. litoralis sp. nov. and C. muelleri sp. nov., respectively. Furthermore, the whitefish from Lake Zug that were previously referred to as C. suidteri are described as C. supersum sp. nov. A holotype is designated for C. supersum that was previously one of two syntypes of C. zugensis. The other syntype is retained for C. zugensis. Coregonus obliterus sp. nov. is described from Lake Zug, and C. obliterus and C. zugensis from Lake Zug are extinct. Finally, we describe C. sarnensis sp. nov. from lakes Sarnen and Alpnach. Coregonus suidteri from Lake Sempach shows strong signals of introgression from deliberately translocated non-native whitefish species, which questions if the extant population still carries a genetic legacy from the original species and thus may need to be considered extinct. Coregonus suspensus is genetically partially of allochthonous origin, closely related to the radiation of Lake Constance. It is therefore compared to all known and described species of Lake Constance: C. wartmanni Bloch, 1784, C. macrophthalmus NĂŒsslin, 1882, C. arenicolus Kottelat,1997, and C. gutturosus Gmelin, 1818

    Competition among small individuals hinders adaptive radiation despite ecological opportunity.

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    Ontogenetic diet shifts, where individuals change their resource use during development, are the rule rather than the exception in the animal world. Here, we aim to understand how such changes in diet during development affect the conditions for an adaptive radiation in the presence of ecological opportunity. We use a size-structured consumer-resource model and the adaptive dynamics approach to study the ecological conditions for speciation. We assume that small individuals all feed on a shared resource. Large individuals, on the other hand, have access to multiple food sources on which they can specialize. We find that competition among small individuals can hinder an adaptive radiation to unfold, despite plenty of ecological opportunity for large individuals. When small individuals experience strong competition for food, they grow slowly and only a few individuals are recruited to the larger size classes. Hence, competition for food among large individuals is weak and there is therefore no disruptive selection. In addition, initial conditions determine if an adaptive radiation occurs or not. A consumer population initially dominated by small individuals will not radiate. On the other hand, a population initially dominated by large individuals may undergo adaptive radiation and diversify into multiple species

    Contemporary ecotypic divergence during a recent range expansion was facilitated by adaptive introgression

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    Although rapid phenotypic evolution during range expansion associated with colonization of contrasting habitats has been documented in several taxa, the evolutionary mechanisms that underlie such phenotypic divergence have less often been investigated. A strong candidate for rapid ecotype formation within an invaded range is the three-spine stickleback in the Lake Geneva region of central Europe. Since its introduction only about 140 years ago, it has undergone a significant expansion of its range and its niche, now forming phenotypically differentiated parapatric ecotypes that occupy either the pelagic zone of the large lake or small inlet streams, respectively. By comparing museum collections from different times with contemporary population samples, we here reconstruct the evolution of parapatric phenotypic divergence through time. Using genetic data from modern samples, we infer the underlying invasion history. We find that parapatric habitat-dependent phenotypic divergence between the lake and stream was already present in the first half of the twentieth century, but the magnitude of differentiation increased through time, particularly in antipredator defence traits. This suggests that divergent selection between the habitats occurred and was stable through much of the time since colonization. Recently, increased phenotypic differentiation in antipredator defence traits likely results from habitat-dependent selection on alleles that arrived through introgression from a distantly related lineage from outside the Lake Geneva region. This illustrates how hybridization can quickly promote phenotypic divergence in a system where adaptation from standing genetic variation was constrained

    Transgressive segregation in mating traits drives hybrid speciation.

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    Hybridization can rapidly generate novel genetic variation, which can promote ecological speciation by creating novel adaptive phenotypes. However, it remains unclear how hybridization, creating novel mating phenotypes (e.g., mating season, genitalia shapes, sexual displays, mate preferences), affects speciation especially when the phenotypes do not confer adaptive advantages. Here, based on individual-based evolutionary simulations, we propose that transgressive segregation of mating traits can drive incipient hybrid speciation. Simulations demonstrated that incipient hybrid speciation occurred most frequently when the hybrid population received moderate continued immigration from parental lineages causing recurrent episodes of hybridization. Recurrent hybridization constantly generated genetic variation, which promoted the rapid stochastic evolution of mating phenotypes in a hybrid population. The stochastic evolution continued until a novel mating phenotype came to dominate the hybrid population, which reproductively isolates the hybrid population from parental lineages. However, too frequent hybridization rather hindered the evolution of reproductive isolation by inflating the variation of mating phenotypes to produce phenotypes allowing mating with parental lineages. Simulations also revealed conditions for long-term persistence of hybrid species after their incipient emergence. Our results suggest that recurrent transgressive segregation of mating phenotypes can offer a plausible explanation for hybrid speciation and radiations that involved little adaptive ecological divergence

    Sexual dimorphism dominates divergent host plant use in stick insect trophic morphology

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    Background: Clear examples of ecological speciation exist, often involving divergence in trophic morphology. However, substantial variation also exists in how far the ecological speciation process proceeds, potentially linked to the number of ecological axes, traits, or genes subject to divergent selection. In addition, recent studies highlight how differentiation might occur between the sexes, rather than between populations. We examine variation in trophic morphology in two host-plant ecotypes of walking-stick insects (Timema cristinae), known to have diverged in morphological traits related to crypsis and predator avoidance, and to have reached an intermediate point in the ecological speciation process. Here we test how host plant use, sex, and rearing environment affect variation in trophic morphology in this species using traditional multivariate, novel kernel density based and Bayesian morphometric analyses. Results: Contrary to expectations, we find limited host-associated divergence in mandible shape. Instead, the main predictor of shape variation is sex, with secondary roles of population of origin and rearing environment. Conclusion: Our results show that trophic morphology does not strongly contribute to host-adapted ecotype divergence in T. cristinae and that traits can respond to complex selection regimes by diverging along different intraspecific lines, thereby impeding progress toward speciation
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