The current distribution of signal and native crayfish in the Broadmead Brook, Wiltshire

Signal crayfish (Pacifastacus leniusculus) have existed in the upper reaches of Broadmead Brook in Wiltshire since 200 individuals were introduced at West Kington in 1981. The population has expanded upstream and downstream since this introduction, however, giving rise to concerns that it may potentially threaten the native crayfish population further downstream. Signal crayfish can act as a vector of crayfish plague - a disease caused by the fungus Aphanomyces astaci Schikora which results in almost complete mortality to the native, white-clawed crayfish Austropotamobius pallipes. The native crayfish in Broadmead Brook have not yet succumbed to crayfish plague and are currently free of the disease. However, as signal crayfish appear to out-compete the native species, the native population could still be under threat. In this article, we highlight the findings of previous crayfish surveys on Broadmead Brook and describe work undertaken in summer 2001 to map the current distribution of native and signal crayfish. Finally, options for controlling the spread of signal crayfish are discussed

Ecological and genetic effects of introduced species on their native competitors

Species introductions to new habitats can cause a decline in the population size of competing native species and consequently also in their genetic diversity. We are interested in why these adverse effects are weak in some cases whereas in others the native species declines to the point of extinction. While the introduction rate and the growth rate of the introduced species in the new environment clearly have a positive relationship with invasion success and impact, the influence of competition is poorly understood. Here, we investigate how the intensity of interspecific competition influences the persistence time of a native species in the face of repeated and ongoing introductions of the nonnative species. We analyze two stochastic models: a model for the population dynamics of both species and a model that additionally includes the population genetics of the native species at a locus involved in its adaptation to a changing environment. Counterintuitively, both models predict that the persistence time of the native species is lowest for an intermediate intensity of competition. This phenomenon results from the opposing effects of competition at different stages of the invasion process: With increasing competition intensity more introduction events are needed until a new species can establish, but increasing competition also speeds up the exclusion of the native species by an established nonnative competitor. By comparing the ecological and the eco-genetic model, we detect and quantify a synergistic feedback between ecological and genetic effects.Comment: version accepted at Theoretical Population Biolog

Text and Context: Teaching Native American Literature

Silence is a major value in Native American culture, for silence is the token of acceptance, the symbol of peace and serenity, and the outward expression of harmony between the human and natural worlds. The result of this tradition of silence, however, is a limited written record, a limited number of texts produced by Native Americans themselves. This situation allowed the Anglo to step into the void and speak for Native Americans themselves, or more accurately, to claim to speak as their interpreters. The implication that white culture drew from the lack of a written language in any of the Native American tribes was that these people had nothing of value to say to themselves or to others. It was not until the past twenty years that Native Americans have begun to produce their own literary works written in English with an eye toward communicating with the American population as a whole. Until the publication of Scott Momaday\u27s House Made of Dawn (1968), the general population had not heard actual Native Americans speak in their own voices-the white culture had been speaking for them. During the past twenty years, however, there has been a veritable explosion of texts coming from the Native American community, and we now have a substantial corpus to use in teaching contemporary Native American literature

Kirramyces destructans in Australia: biosecurity threat or elusive native pathogen?

Kirramyces destructans was first described in 1996 from north Sumatra, Indonesia, where it caused severe leaf and shoot blight on Eucalyptus grandis in nurseries and young plantations. Since then it has been reported in nurseries and plantations in Vietnam, Thailand and China, with its host range extending to include E. camaldulensis and E. urophylla. K. destructans has also been reported from native E. urophylla in East Timor and was considered a significant biosecurity threat to Australia’s native eucalypt forests and plantations. A study on the population diversity of K. destructans isolates throughout south-east Asia in which 8 gene regions were sequenced (four nuclear genes, one mitochondrial gene and three microsatellite markers) detected very low nucleotide polymorphism. This genetic uniformity is indicative of an introduced population which has subsequently spread throughout Asia via human-mediated movement of germplasm. Surveys of sentinel plantings in northern Australia revealed a complex of Kirramyces spp. among which K. destructans was detected. The same gene regions and markers were sequenced as for the Asian study and diversity among the K. destructans isolates in Australia was found to be much greater than that in Asia. We believe that K. destructans is native to Australia where is resides symptomlessly within the native vegetation. The disease is only expressed when non-endemic eucalypts are planted. As such the pathogen is a major encumbrance to the establishment of commercial eucalypt plantations in Northern Australia. The disease has not been observed in native ecosystems, but the effect of inoculum build up within plantations on adjacent native eucalypt remnants is not known

Diversity of HLA Class I and Class II blocks and conserved extended haplotypes in Lacandon Mayans.

Here we studied HLA blocks and haplotypes in a group of 218 Lacandon Maya Native American using a high-resolution next generation sequencing (NGS) method. We assessed the genetic diversity of HLA class I and class II in this population, and determined the most probable ancestry of Lacandon Maya HLA class I and class II haplotypes. Importantly, this Native American group showed a high degree of both HLA homozygosity and linkage disequilibrium across the HLA region and also lower class II HLA allelic diversity than most previously reported populations (including other Native American groups). Distinctive alleles present in the Lacandon population include HLA-A*24:14 and HLA-B*40:08. Furthermore, in Lacandons we observed a high frequency of haplotypes containing the allele HLA-DRB1*04:11, a relatively frequent allele in comparison with other neighboring indigenous groups. The specific demographic history of the Lacandon population including inbreeding, as well as pathogen selection, may have elevated the frequencies of a small number of HLA class II alleles and DNA blocks. To assess the possible role of different selective pressures in determining Native American HLA diversity, we evaluated the relationship between genetic diversity at HLA-A, HLA-B and HLA-DRB1 and pathogen richness for a global dataset and for Native American populations alone. In keeping with previous studies of such relationships we included distance from Africa as a covariate. After correction for multiple comparisons we did not find any significant relationship between pathogen diversity and HLA genetic diversity (as measured by polymorphism information content) in either our global dataset or the Native American subset of the dataset. We found the expected negative relationship between genetic diversity and distance from Africa in the global dataset, but no relationship between HLA genetic diversity and distance from Africa when Native American populations were considered alone

Ethnic minority immigrants and their children in Britain

According to the 2001 UK Census ethnic minority groups account for 4.6 million or 7.9 percent of the total UK population. The 2001 British Labour Force Survey indicates that the descendants of Britain’s ethnic minority immigrants form an important part of the British population (2.8 percent) and of the labour force (2.1 percent). In this paper, we use data from the British Labour Force Survey over the period 1979-2005 to investigate educational attainment and economic behaviour of ethnic minority immigrants and their children in Britain. We compare different ethnic minority groups born in Britain to their parent’s generation and to equivalent groups of white native born individuals. Intergenerational comparisons suggest that British born ethnic minorities are on average more educated than their parents as well more educated than their white native born peers. Despite their strong educational achievements, we find that ethnic minority immigrants and their British born children exhibit lower employment probabilities than their white native born peers. However, significant differences exist across immigrant/ethnic groups and genders. British born ethnic minorities appear to have slightly higher wages than their white native born peers. But if British born ethnic minorities were to face the white native regional distribution and were attributed white native characteristics, their wages would be considerably lower. The substantial employment gap between British born ethnic minorities and white natives cannot be explained by observable differences. We suggest some possible explanations for these gaps

Admixture in the Hispanics of the San Luis Valley, Colorado, and its implications for complex trait gene mapping.

Hispanic populations are a valuable resource that can and should facilitate the identification of complex trait genes by means of admixture mapping (AM). In this paper we focus on a particular Hispanic population living in the San Luis Valley (SLV) in Southern Colorado. We used a set of 22 Ancestry Informative Markers (AIMs) to describe the admixture process and dynamics in this population. AIMs are defined as genetic markers that exhibit allele frequency differences between parental populations >or=30%, and are more informative for studying admixed populations than random markers. The ancestral proportions of the SLV Hispanic population are estimated as 62.7 +/- 2.1% European, 34.1 +/- 1.9% Native American and 3.2 +/- 1.5% West African. We also estimated the ancestral proportions of individuals using these AIMs. Population structure was demonstrated by the excess association of unlinked markers, the correlation between estimates of admixture based on unlinked marker sets, and by a highly significant correlation between individual Native American ancestry and skin pigmentation (R2= 0.082, p < 0.001). We discuss the implications of these findings in disease gene mapping efforts

Parasite spill-back from domestic hosts may induce an Allee effect in wildlife hosts

The exchange of native pathogens between wild and domesticated animals can lead to novel disease dynamics. A simple model reveals that the spill-back of native parasites\ud from domestic to wild hosts may cause a demographic Allee effect. Because parasite spill-over and spill-back decouples the abundance of parasite infectious stages from the abundance of the wild host population, parasitism and mortality of the wild host population increases non-linearly as host abundance decreases. Analogous to the effects of satiation of generalist predators, parasite spill-back can produce an unstable equilibrium in the abundance of the host population above which the host population persists and below which it is at risk of extirpation. These effects are likely to be most pronounced in systems where the parasite has a high efficiency of transmission from domestic to wild host populations due to prolonged sympatry, disease vectors, or proximity of domesticated populations to wildlife migratory corridors

Hawaiian Picture‐Winged Drosophila Exhibit Adaptive Population Divergence along a Narrow Climatic Gradient on Hawaii Island

1. Anthropogenic influences on global processes and climatic conditions are increasingly affecting ecosystems throughout the world. 2. Hawaii Island’s native ecosystems are well studied and local long‐term climatic trends well documented, making these ecosystems ideal for evaluating how native taxa may respond to a warming environment. 3.This study documents adaptive divergence of populations of a Hawaiian picture‐winged Drosophila, D. sproati, that are separated by only 7 km and 365 m in elevation. 4.Representative laboratory populations show divergent behavioral and physiological responses to an experimental low‐intensity increase in ambient temperature during maturation. The significant interaction of source population by temperature treatment for behavioral and physiological measurements indicates differential adaptation to temperature for the two populations. 5.Significant differences in gene expression among males were mostly explained by the source population, with eleven genes in males also showing a significant interaction of source population by temperature treatment. 6.The combined behavior, physiology, and gene expression differences between populations illustrate the potential for local adaptation to occur over a fine spatial scale and exemplify nuanced response to climate change