Intrasexual competition among females and the stabilization of a conspicuous colour polymorphism in a Lake Victoria cichlid fish

The maintenance of colour polymorphisms within populations has been a long-standing interest in evolutionary ecology. African cichlid fish contain some of the most striking known cases of this phenomenon. Intrasexual selection can be negative frequency dependent when males bias aggression towards phenotypically similar rivals, stabilizing male colour polymorphisms. We propose that where females are territorial and competitive, aggression biases in females may also promote coexistence of female morphs. We studied a polymorphic population of the cichlid fish Neochromis omnicaeruleus from Lake Victoria, in which three distinct female colour morphs coexist: one plain brown and two blotched morphs. Using simulated intruder choice tests in the laboratory, we show that wild-caught females of each morph bias aggression towards females of their own morph, suggesting that females of all three morphs may have an advantage when their morph is locally the least abundant. This mechanism may contribute to the establishment and stabilization of colour polymorphisms. Next, by crossing the morphs, we generated sisters belonging to different colour morphs. We find no sign of aggression bias in these sisters, making pleiotropy unlikely to explain the association between colour and aggression bias in wild fish, which is maintained in the face of gene flow. We conclude that female-female aggression may be one important force for stabilizing colour polymorphism in cichlid fish.

Diversity of the basic defect of homozygous CFTR mutation genotypes in humans

BACKGROUND: Knowledge of how CFTR mutations other than F508del translate into the basic defect in cystic fibrosis (CF) is scarce due to the low incidence of homozygous index cases. METHODS: 17 individuals who are homozygous for deletions, missense, stop or splice site mutations in the CFTR gene were investigated for clinical symptoms of CF and assessed in CFTR function by sweat test, nasal potential difference and intestinal current measurement. RESULTS: CFTR activity in sweat gland, upper airways and distal intestine was normal for homozygous carriers of G314E or L997F and in the range of F508del homozygotes for homozygous carriers of E92K, W1098L, R553X, R1162X, CFTRdele2(ins186) or CFTRdele2,3(21 kb). Homozygotes for M1101K, 1898+3 A-G or 3849+10 kb C-T were not consistent CF or non-CF in the three bioassays. 14 individuals exhibited some chloride conductance in the airways and/or in the intestine which was identified by the differential response to cAMP and DIDS as being caused by CFTR or at least two other chloride conductances. DISCUSSION: CFTR mutations may lead to unusual electrophysiological or clinical manifestations. In vivo and ex vivo functional assessment of CFTR function and in-depth clinical examination of the index cases are indicated to classify yet uncharacterised CFTR mutations as either disease-causing lesions, risk factors, modifiers or neutral variants.

Compensatory growth in moose and its relationship to sex, longevity, intraspecific competition, and senescence

Individual life history theory is largely focused on understanding the extent to which various phenotypes of an organism are adaptive and whether they represent life history trade-offs. Compensatory growth (CG) is increasingly appreciated as a phenotype of interest to evolutionary ecologists. CG or catch-up growth involves the ability of an organism to grow at a faster-than-normal rate following periods of under-nutrition once conditions subsequently improve. Here, I examine CG in a population of moose (Alces alces) living on Isle Royale, a remote island in Lake Superior, North America. I gained insights about CG from measurements of skeletal remains of 841 moose born throughout a 52-year period. In particular, I compared the length of the metatarsal bone (ML) with several skull measurements. While ML is an index of growth while the moose is in utero and during the first year or two of life, a moose skull continues to grow until a moose is approximately 5 years of age. Because of these differences, the strength of correlation between ML and skull measurements, for a group of moose (say female moose) is an indication of that group’s capacity for CG. Using this logic, I conducted analyses whose results suggest that the capacity for CG did not differ between sexes, between individuals born during periods of high and low population densities, or between individuals exhibiting signs of senescence and those that do not. The analysis did however suggest that long-lived individuals had a greater capacity for CG than short-lived individuals. These results suggest that CG in moose is an adaptive trait and might not be associated with life history trade-offs.

EC Electronic Communications and Competition Law

Telecommunications have developed at an incredible speed over the last couple of decades. The decreasing size of our phones and the increasing number of ways in which we can communicate are barely the only result of this (r)evolutionary development. The latter has indeed multiple implications. The change of paradigm for telecommunications regulation, epitomised by the processes of liberalisation and reregulation, was not sufficient to answer all regulatory questions pertinent to communications. Today, after the transition from monopoly to competition, we are faced perhaps with an even harder regulatory puzzle, since we must figure out how to regulate a sector that is as dynamic and as unpredictable as electronic communications have proven to be, and as vital and fundamental to the economy and to society at large. The present book addresses the regulatory puzzle of contemporary electronic communications and suggests the outlines of a coherent model for their regulation. The search for such a model involves essentially deliberations on the question "Can competition law do it all?", since generic competition rules are largely seen as the appropriate regulatory tool for the communications domain. The latter perception has been the gist of the 2002 reform of the European Community (EC) telecommunications regime, which envisages a withdrawal of sectoral regulation, as communications markets become effectively competitive and ultimately bestows the regulation of the sector upon competition law only. The book argues that the question of whether competition law is the appropriate tool needs to be examined not in the conventional contexts of sector specific rules versus competition rules or deregulation versus regulation but in a broader governance context. Consequently, the reader is provided with an insight into the workings and specific characteristics of the communications sector as network-bound, converging, dynamic and endowed with a special societal role and function. A thorough evaluation of the regulatory objectives in the communications environment contributes further to the comprehensive picture of the communications industry. Upon this carefully prepared basis, the book analyses the communications regulatory toolkit. It explores the interplay between sectoral communications regulation, competition rules (in particular Article 82 of the EC Treaty) and the rules of the World Trade Organization (WTO) relevant to telecommunications services. The in-depth analysis of multilevel construct of EC communications law is up-to-date and takes into account important recent developments in the EC competition law in practice, in particular in the field of refusal to supply and tying, of the reform of the EC electronic communications framework and new decisions of the WTO dispute settlement body, such as notably the Mexico-Telecommunications Services Panel Report. Upon these building elements, an assessment of the regulatory potential of the EC competition rules is made. The conclusions drawn are beyond the scope of the current situation of EC electronic communications and the applicable law and explore the possible contours of an optimal regulatory framework for modern communications. The book is of particular interest to communications and antitrust law experts, as well as policy makers, government agencies, consultancies and think-tanks active in the field. Experts on other network industries (such as electricity or postal communications) can also profit from the substantial experience gathered in the communications sector as the most advanced one in terms of liberalisation and reregulation.

Divergent adaptation of hepatitis C virus genotypes 1 and 3 to human leukocyte antigen-restricted immune pressure

Many hepatitis C virus (HCV) infections worldwide are with the genotype 1 and 3 strains of the virus. Cellular immune responses are known to be important in the containment of HCV genotype 1 infection, and many genotype 1 T cell targets (epitopes) that are presented by host human leukocyte antigens (HLAs) have been identified. In contrast, there is almost no information known about the equivalent responses to genotype 3. Immune escape mechanisms used by HCV include the evolution of viral polymorphisms (adaptations) that abrogate this host-viral interaction. Evidence of HCV adaptation to HLA-restricted immune pressure on HCV can be observed at the population level as viral polymorphisms associated with specific HLA types. To evaluate the escape patterns of HCV genotypes 1 and 3, we assessed the associations between viral polymorphisms and specific HLA types from 187 individuals with genotype 1a and 136 individuals with genotype 3a infection. We identified 51 HLA-associated viral polymorphisms (32 for genotype 1a and 19 for genotype 3a). Of these putative viral adaptation sites, six fell within previously published epitopes. Only two HLA-associated viral polymorphisms were common to both genotypes. In the remaining sites with HLA-associated polymorphisms, there was either complete conservation or no significant HLA association with viral polymorphism in the alternative genotype. This study also highlights the diverse mechanisms by which viral evasion of immune responses may be achieved and the role of genotype variation in these processes. CONCLUSION: There is little overlap in HLA-associated polymorphisms in the nonstructural proteins of HCV for the two genotypes, implying differences in the cellular immune pressures acting on these viruses and different escape profiles. These findings have implications for future therapeutic strategies to combat HCV infection, including vaccine design.

Color polymorphism and intrasexual competition in assemblages of cichlid fish

The origin and maintenance of phenotypic polymorphisms is a classical problem in evolutionary ecology. Aggressive male-male competition can be a source of negative frequency-dependent selection stabilizing phenotypic polymorphisms when aggression is biased toward the own morph. We studied experimental assemblages of red and blue color morphs of the Lake Victoria cichlid fish Pundamilia. Aggression was investigated in mixed-color and single-color assemblages. We found that aggression was indeed biased toward males of the same color, which could in theory reduce aggression levels in mixed-color assemblages and promote coexistence. However, previous studies showed high aggression levels in red and dominance of red over blue males in dyadic interactions, which could hinder coexistence. We found that coexistence in mixed-color assemblages reduced the level of aggression in red males but not in blue males. Red and blue males were equally dominant in mixed-color assemblages, suggesting that predictions derived from dyadic interactions may not be valid for an assemblage situation. The results are consistent with field data: the geographic range of red is nested within that of blue, suggesting that red cannot displace blue. Our study suggests that male-male competition may be a significant force for maintaining phenotypic diversity.

What Price Social and Health Care? Commodities, Competition and Consumers

In this paper we explore some important disputes and problems surrounding the legal status and social purpose of Health