North American Host Research Articles

Parasitism of Ground Beetles (Coleoptera: Carabidae) by a New Species of Hairworm (Nematomorpha: Gordiida) in Arctic Canada.

The host-parasite associations between ground beetles (Coleoptera: Carabidae) and hairworms (Nematomorpha: Gordiida) collected from the Arctic (an understudied and ecologically important region) is described. Carabids and their parasites were collected from 12 sites spanning the 3 northernmost ecoclimatic zones of Canada (north boreal, subarctic, and high Arctic) using standardized methods. The beetles and hairworms were identified using traditional morphological approaches. Seven beetle species are recorded as hosts: Amara alpina, Pterostichus caribou, Pterostichus brevicornis, Pterostichus tareumiut, Pterostichus haematopus, Patrobus septentrionis, and Notiophilus borealis. All represent new host records (increasing the known North American host list from 14 to 21), and this is the first record of hairworm infection in the genus Notiophilus. Beetles from Banks Island, Northwest Territory, were infected in high numbers (11-19% per sampling period) and were used as an ecological case study. There was no significant relationship between infection status and host species, body size, or sex. Beetles collected in yellow pan traps and in wet habitats were more likely to be infected, likely due to water-seeking behavior induced by the parasites. Morphological examinations indicate that the hairworms collected from all locations represent a single, new species of Gordionus, making it only the sixth hairworm species and the third species of that genus found in Canada. Hosts are unknown for all other Canadian (and 1 Alaskan) Gordionus species.

Population-Level Immune-Mediated Adaptation in HIV-1 Polymerase during the North American Epidemic.

Human leukocyte antigen (HLA) class I-associated polymorphisms in HIV-1 that persist upon transmission to HLA-mismatched hosts may spread in the population as the epidemic progresses. Transmission of HIV-1 sequences containing such adaptations may undermine cellular immune responses to the incoming virus in future hosts. Building upon previous work, we investigated the extent of HLA-associated polymorphism accumulation in HIV-1 polymerase (Pol) through comparative analysis of linked HIV-1/HLA class I genotypes sampled during historic (1979 to 1989; n = 338) and modern (2001 to 2011; n = 278) eras from across North America (Vancouver, BC, Canada; Boston, MA; New York, NY; and San Francisco, CA). Phylogenies inferred from historic and modern HIV-1 Pol sequences were star-like in shape, with an inferred most recent common ancestor (epidemic founder virus) sequence nearly identical to the modern North American subtype B consensus sequence. Nevertheless, modern HIV-1 Pol sequences exhibited roughly 2-fold-higher patristic (tip-to-tip) genetic distances than historic sequences, with HLA pressures likely driving ongoing diversification. Moreover, the frequencies of published HLA-associated polymorphisms in individuals lacking the selecting HLA class I allele was on average ∼2.5-fold higher in the modern than in the historic era, supporting their spread in circulation, though some remained stable in frequency during this time. Notably, polymorphisms restricted by protective HLA alleles appear to be spreading to a greater relative extent than others, though these increases are generally of modest absolute magnitude. However, despite evidence of polymorphism spread, North American hosts generally remain at relatively low risk of acquiring an HIV-1 polymerase sequence substantially preadapted to their HLA profiles, even in the present era. HLA class I-restricted cytotoxic T-lymphocyte (CTL) escape mutations in HIV-1 that persist upon transmission may accumulate in circulation over time, potentially undermining host antiviral immunity to the transmitted viral strain. We studied >600 experimentally collected HIV-1 polymerase sequences linked to host HLA information dating back to 1979, along with phylogenetically reconstructed HIV-1 sequences dating back to the virus' introduction into North America. Overall, our results support the gradual spread of many-though not all-HIV-1 polymerase immune escape mutations in circulation over time. This is consistent with recent observations from other global regions, though the extent of polymorphism accumulation in North America appears to be lower than in populations with high seroprevalence, older epidemics, and/or limited HLA diversity. Importantly, the risk of acquiring an HIV-1 polymerase sequence at transmission that is substantially preadapted to one's HLA profile remains relatively low in North America, even in the present era.

Characterization, distribution, biology and impact on Italian walnut orchards of the invasive North-American leafminer Coptodisca lucifluella (Lepidoptera: Heliozelidae).

The leafminer Coptodisca sp. (Lepidoptera: Heliozelidae), recently recorded for the first time in Europe on Italian black and common walnut trees, is shown to be the North-American Coptodisca lucifluella (Clemens) based on morphological (forewing pattern) and molecular (cytochrome oxidase c subunit I sequence) evidence. The phylogenetic relatedness of three species feeding on Juglandaceae suggests that C. lucifluella has likely shifted, within the same host plant family, from its original North-American hosts Carya spp. to Juglans spp. Over the few years since its detection, it has established in many regions in Italy and has become a widespread and dominant invasive species. The leafminer completes three to four generations per year, with the first adults emerging in April-May and mature larvae of the last generation starting hibernation in September-October. Although a high larval mortality was recorded in field observations (up to 74%), the impact of the pest was substantial with all leaves infested at the end of the last generation in all 3 years tested. The distribution of the leafminer in the canopy was homogeneous. The species is redescribed and illustrated, a lectotype is designated and a new synonymy is established.

A Summary of EPRI's Engineering and Economic Studies of Post Combustion Capture Retrofit Applied at Various North American Host Sites

With more than 300 GW of installed coal-fired plants in the US alone, and with many coal plants being currently built in China and India, it is conceivable that CO2 will need to be removed from these existing coal-fired plant assets to significantly reduce green house gas emissions to acceptable levels. The Electric Power Research Institute (EPRI) recently completed a series of detailed economic and engineering studies examining the feasibility of retrofitting post combustion capture (PCC) to existing pulverized coal (PC) and/or circulating fluidized-bed (CFB) power plants, for five different North American “host” sites. Whilst studies have previously considered optimized retrofit on theoretical plants, the current work focused on retrofitting existing “real world” assets. This paper provides a number of performance and costs results from the extensive retrofit evaluation, as well as providing additional insight on the technical results and economic comparisons that emerged.

Sudden oak death: interactions of the exotic oomycete Phytophthora ramorum with naïve North American hosts.

Ten years after a threatening and previously unknown disease of oaks and tanoaks appeared in coastal California, a significant amount of progress has been made toward the understanding of its causal agent Phytophthora ramorum and of the novel pathosystems associated with this exotic organism. However, a complete understanding of the ecology and epidemiology of this species still eludes us. In part, our inability to fully understand this organism is due to its phylogenetic, phylogeographic, phenotypic, and epidemiological complexities, all reviewed in this paper. Most lines of evidence suggest that the high degree of disease severity reported in California is not simply due to a generalized lack of resistance or tolerance in naïve hosts but also to an innate ability of the pathogen to survive in unfavorable climatic conditions and to reproduce rapidly when conditions become once again favorable.

Epidemiology of a Daphnia-multiparasite system and its implications for the red queen.

The Red Queen hypothesis can explain the maintenance of host and parasite diversity. However, the Red Queen requires genetic specificity for infection risk (i.e., that infection depends on the exact combination of host and parasite genotypes) and strongly virulent effects of infection on host fitness. A European crustacean (Daphnia magna) – bacterium (Pasteuria ramosa) system typifies such specificity and high virulence. We studied the North American host Daphnia dentifera and its natural parasite Pasteuria ramosa, and also found strong genetic specificity for infection success and high virulence. These results suggest that Pasteuria could promote Red Queen dynamics with D. dentifera populations as well. However, the Red Queen might be undermined in this system by selection from a more common yeast parasite (Metschnikowia bicuspidata). Resistance to the yeast did not correlate with resistance to Pasteuria among host genotypes, suggesting that selection by Metschnikowia should proceed relatively independently of selection by Pasteuria.

Molecular characterization reveals distinct genospecies of Anaplasma phagocytophilum from diverse North American hosts

Anaplasma phagocytophilum is an emerging tick-borne pathogen that infects humans, domestic animals and wildlife throughout the Holarctic. In the far-western United States, multiple rodent species have been implicated as natural reservoirs for A. phagocytophilum. However, the presence of multiple A. phagocytophilum strains has made it difficult to determine which reservoir hosts pose the greatest risk to humans and domestic animals. Here we characterized three genetic markers (23S-5S rRNA intergenic spacer, ank and groESL) from 73 real-time TaqMan PCR-positive A. phagocytophilum strains infecting multiple rodent and reptile species, as well as a dog and a horse, from California. Bayesian and maximum-likelihood phylogenetic analyses of all three genetic markers consistently identified two major clades, one of which consisted of A. phagocytophilum strains infecting woodrats and the other consisting of strains infecting sciurids (chipmunks and squirrels) as well as the dog and horse strains. In addition, analysis of the 23S-5S rRNA spacer region identified two unique and highly dissimilar clades of A. phagocytophilum strains infecting several lizard species. Our findings indicate that multiple unique strains of A. phagocytophilum with distinct host tropisms exist in California. Future epidemiological studies evaluating human and domestic animal risk should incorporate these distinctions.

Linking Larvae and Adults of Apharyngostrigea cornu, Hysteromorpha triloba, and Alaria mustelae (Diplostomoidea: Digenea) Using Molecular Data

Because the taxonomy of trematodes is based on adults, the larval stages of most digeneans cannot be identified to species based on morphology alone. Molecular data provide a means of linking larval stages to known adults. We obtained sequences from the barcode region of cytochrome oxidase I (CO1) from adult and larval parasites of fish, frogs, birds, and mammals across North America. Sequences from adult Apharyngostrigea cornu, Hysteromorpha triloba, and Alaria mustelae (Diplostomoidea: Digenea) from definitive hosts matched those of meta- and mesocercariae from fish and frogs. These data provided new information on the distributions of all 3 parasite species. Metacercariae of A. cornu, which have not been previously reported in North American hosts, were found in Notemigonus crysoleucas, Pimephales notatus, and Catostomus commersonii in the St. Lawrence River. Metacercariae of H. triloba are reported in Canadian waters and in N. hudsonius for the first time. Alaria mustelae is reported for the first time in frogs from Quebec, Canada, and an additional species of Alaria was detected in California. Sequences of internal transcribed spacer rDNA from a subset of specimens support the same species boundaries indicated by CO1 divergence. There was little divergence in CO1 sequences from an unidentified diplostomid species sampled at a large spatial scale.

The Asian black truffle Tuber indicum can form ectomycorrhizas with North American host plants and complete its life cycle in non-native soils

The Asian black truffle Tuber indicum is morphologically and phylogenetically similar to the European black truffle Tuber melanosporum. T. indicum is considered a threat to T. melanosporum trufficulture due to its presumed competitiveness and broad host compatibility. Recently, in independent events, T. indicum was found fruiting in a forest in Oregon, USA, and was detected as ectomycorrhizas within a truffle orchard established with trees believed to have been inoculated with T. melanosporum. We used haplotype networking to assess intraspecific ITS rDNA diversity among Asian and North American T. indicum group B isolates. To further assess the potential of T. indicum to spread onto native host plants it was inoculated onto seedlings of loblolly pine (Pinus taeda) and pecan (Carya illinoinensis, Juglandaceae), species endemic to North America. T. indicum formed ectomycorrhizas on both host species examined. This supports previous studies from Europe and Asia that indicate T. indicum has a broad host spectrum, an ecological trait that may be important to its invasion ecology. This is the first report of T. indicum introductions in North America and of this species fruiting outside of its native range. To help prevent further unintended truffle introductions we recommend that fruitbodies used by the truffle industry for inoculating seedlings first be identified with DNA methods.

Molecular and biometric assessment of Myzodium mimulicola (Hemiptera: Aphididae), with new synonymy and host and distributional data

AbstractA molecular and biometric assessment and redescription of Myzodium mimulicola (Drews and Sampson) are provided. New North American host and distributional data are presented, including the first record from Alaska. Myzodium knowltoni (Smith and Robinson) is a junior subjective synonym of M. mimulicola, based on molecular-sequence and morphological evidence. A key to the known Myzodium species (apterae and alatae) is included.

The placement of Gyrodactylus salmonis (Yin & Sproston) in the molecular phylogeny of studied members of the Gyrodactylus wageneri‐group parasitizing salmonids

The molecular phylogeny of Gyrodactylus salmonis from brook charr, Salvelinus fontinalis, rainbow trout, Oncorhynchus mykiss, cutthroat trout, O. clarkii, and Atlantic salmon, Salmo salar, in Canada is presented using sequences from ITS-rDNA and the mitochondrial COX 1 gene. Sequence variation among G. salmonis specimens from the different North American hosts was consistent with within-species variation reported for other Gyrodactylus. Sequence data are compared to those from other members of the wageneri group parasitizing salmoniform fishes in northern Europe (G. derjavini, G. derjavinoides, G. lavareti, G. salaris, G. salvelini, G. teuchis and G. truttae) and Asia (G. brachymystacis). Sequence divergence between G. salmonis and the recently described G. salvelini on Arctic charr, Salvelinus alpinus, in Finland was consistent with within-species levels of variation in Gyrodactylus; however, phylogenetic analyses and morphological comparisons provided evidence of their distinctiveness such that they appear to be sister species. They grouped with G. lavareti (a parasite of a coregonid) to form a clade separate from European and Asian species of the wageneri lineage known from salmonid fish. Further study of gyrodactylids from across salmonid, coregonid and thymallid fish in the northern hemisphere would shed more light on the phylogeography of these parasites and serves as an important backdrop to understanding the evolution of their emergent virulence.

Release from foliar and floral fungal pathogen species does not explain the geographic spread of naturalized North American plants in Europe

Summary During the last centuries many alien species have established and spread in new regions, where some of them cause large ecological and economic problems. As one of the main explanations of the spread of alien species, the enemy‐release hypothesis is widely accepted and frequently serves as justification for biological control. We used a global fungus–plant host distribution data set for 140 North American plant species naturalized in Europe to test whether alien plants are generally released from foliar and floral pathogens, whether they are mainly released from pathogens that are rare in the native range, and whether geographic spread of the North American plant species in Europe is associated with release from fungal pathogens. We show that the 140 North American plant species naturalized in Europe were released from 58% of their foliar and floral fungal pathogen species. However, when we also consider fungal pathogens of the native North American host range that in Europe so far have only been reported on other plant species, the estimated release is reduced to 10.3%. Moreover, in Europe North American plants have mainly escaped their rare, pathogens, of which the impact is restricted to few populations. Most importantly and directly opposing the enemy‐release hypothesis, geographic spread of the alien plants in Europe was negatively associated with their release from fungal pathogens. Synthesis. North American plants may have escaped particular fungal species that control them in their native range, but based on total loads of fungal species, release from foliar and floral fungal pathogens does not explain the geographic spread of North American plant species in Europe. To test whether enemy release is the major driver of plant invasiveness, we urgently require more studies comparing release of invasive and non‐invasive alien species from enemies of different guilds, and studies that assess the actual impact of the enemies.

Begging and cowbirds: brood parasites make hosts scream louder

Avian brood parasites have evolved striking begging ability that often allows them to prevail over the host progeny in competition for parental resources. Host young are therefore selected by brood parasites to evolve behavioral strategies that reduce the cost of parasitism. We tested the prediction that the intensity of nestling begging displays functioning to attract parental care increases across species with the frequency of parasitism by the brown-headed cowbird (Molothrus ater). This was expected because host young should try to prevail over highly competitive parasitic broodmates in scramble interactions, act more selfishly when frequency of parasitism is high because brood parasites often affect more severely host condition than conspecific broodmates, and discount the kin selection costs of subtracting resources to unrelated parasites. Across 31 North American host species, begging loudness positively covaried with parasitism rate in Passerines, and such effect was stronger in species with small compared with large clutches. Begging loudness increased with brood parasitism and nest predation among the most suitable host species. These results held after controlling for concomitant ecological factors and for common ancestry effects. Our results support the hypothesis that avian brood parasitism has played a role in the evolution of begging behavior of host young.

Elective Divinities: Exile and Religious Conversion in Alfred Döblin'sSchicksalsreise (Destiny's Journey), Karl Jakob Hirsch'sHeimkehr zu Gott (Return to God), and Karl Stern'sthe Pillar of Fire

But paradise is sealed and the cherub stands behind us; we must make the journey around the world and see if it is open somewhere from behind ... --Heinrich von Kleist, On the Marionette Theater (342) (1) While escaping from the advancing German army in 1940 and trying to find his family in the south of France, the exiled German author and psychologist Alfred Doblin (1878-1957) had a powerful religious experience that eventually led to his conversion from Judaism to Christianity in 1941. At his own sixty-fifth birthday party in California in 1943, Doblin announced to a group of his fellow exiles and friends that he had been baptized and become a member of the Catholic Church (Emde 15). Although Doblin considered his conversion to be an integral part of his intellectual and artistic progression, his announcement earned him the scorn of his fellow in exile. Bertolt Brecht memorialized the announcement in his vindictive poem Peinlicher Vorfall (Embarrassing Incident) by painting a snide picture of Doblin decked out in a moth-eaten priest's hat and defiling the platform that belongs to the artists (Brecht 91). (2) A devout convert could not possibly be at the same time a serious artist and intellectual, only a ridiculous caricature. Doblin's announcement of his conversion separated him from the secular political movements championed by many of his fellow exiled intellectuals. This secularism was so integral to the projects of the most influential members of the exile community that, as Wolfgang Fruhwald puts it, every step from the path of this ideal was seen as betrayal and was subsequently stigmatized (240). (3) Criticized by Jewish Nationalists and Marxists (Fruhwald 240-41, Emde 15-17, Muller-Salget 153-54) and scrutinized by their North American hosts, (4) Doblin and other emigres who converted to another religion (5) followed a conviction that exile was best explained and experienced in tandem with a deeply personal spiritual quest. Those whose quests led to conversion from Judaism to Christianity not only provoked their secular colleagues in exile, they purposefully withdrew themselves from a religious and cultural community that was reeling from the incomprehensible scope and brutality of the Holocaust. These individual conversions had enormous ramifications for the larger group of traumatized and crisis-weary European exiles: How could the converts appropriately address the political, aesthetical and ethical dilemmas caused by their highly personal spiritual experiences? In this article, I will investigate three conversion narratives written by Jewish intellectuals who converted to Christianity while in exile in North America: Alfred Doblin's Schicksalsreise: Bericht und Bekenntnis (published in English as Destiny's Journey: Flight from the Nazis), Karl Jakob Hirsch's Heimkehr zu Gott: Briefe an meinen Sohn (Returning Home to God: Letters To My Son), and Karl Stern's The Pillar of Fire. The authors of these texts, I will demonstrate, use their conversion narratives to infuse their own brand of spirituality into the aesthetic and political doctrines that surround them. In order to do so, Doblin, Hirsch, and Stern employ similar strategies to minimize the potential ethical problems of their conversions. By portraying their processes of Christianization as a natural outgrowth of the suffering of the exile experience or from their spiritual rediscoveries of Judaism, these authors attempt to create an ethically unencumbered viewpoint from which to criticize the secularized aesthetics of the European exile community. After Hitler seized political power in 1933, many German and Austrian artists, writers and intellectuals were forced to seek refuge in other countries. (6) In spite of their common situation and common enemy, those driven into exile represented a diverse collection of different political and aesthetic ideologies. (7) The situations and locations of those in exile also varied greatly, from relative economic comfort to intense poverty and political insecurity (Moore). …

Host Records for <I>Ornithonyssus sylviarum</I> (Mesostigmata: Macronyssidae) from Birds of North America (Canada, United States, and Mexico)

The northern fowl mite, Ornithonyssus sylviarum (Canestrini and Fanzago, 1877) (Mesostigmata: Macronyssidae) is a broadly distributed blood-feeding parasite that has been collected from many birds of temperate regions. Previously, the most complete host list was published in 1938, and it included 15 North American (Canada, United States, and Mexico) host species. In the process of a general survey of bird-associated mites in Alberta, Canada, we recovered many O. sylviarum specimens. Herein, we update the previous host list with these observations and records published since 1938. We collected mites by washing the bodies of salvaged birds and examining the filtrate. Northern fowl mites were collected from 26 host species, with 16 of these species being the first host records for North America. Including results from the current study, O. sylviarum has been reported from 72 species of North American birds from 26 families. This updated host list will be useful to anyone interested in the role of O. sylviarum in transmission of avian disease.

Host usage and seasonal activity patterns of Ixodes kingi and I. sculptus (Acari: Ixodidae) nymphs in a Colorado prairie landscape, with a summary of published North American host records for all life stages

We examined host usage and seasonal activity patterns of the nymphal stage of the ticks Ixodes kingi and I. sculptus within a prairie rodent community in north-central Colorado. Ixodes kingi was commonly encountered on both northern grasshopper mice (Onychomys leucogaster) and thirteen-lined ground squirrels (Spermophilus tridecemlineatus), whereas I. sculptus frequently infested S. tridecemlineatus but was absent from O. leucogaster. Low numbers of ticks of both species were collected from deer mice (Peromyscus maniculatus) and Ord's kangaroo rats (Dipodomys ordii). Nymphal loads of I. kingi and I. sculptus increased dramatically on commonly infested rodent species from spring (May-June) to summer (July-August). Further, rodents trapped on prairie-dog towns tended to experience increased nymphal loads of I. kingi (O. leucogaster, S. tridecemlineatus) but decreased loads of I. sculptus (S. tridecemlineatus) following plague epizootics among prairie dog populations. A summary of published North American host records revealed that I. kingi has been recorded from humans, domestic animals (cat, dog), 17 species of carnivores, 40 species of rodents, and four species of lagomorphs, and that I. sculptus has been recorded from humans, domestic animals (cat, dog, goat), 13 species of carnivores, 34 species of rodents, and three species of lagomorphs. In accordance with our observations from Colorado, I. kingi commonly has been found to infest heteromyid and murid rodents (such as grasshopper mice), whereas I. sculptus most frequently has been collected from ground-dwelling sciurid rodents, especially Spermophilus ground squirrels. The potential roles of I. kingi and I. sculptus as enzootic vectors of human pathogens, particularly the agents of tularemia (Francisella tularensis), Q fever (Coxiella burnetii), and Colorado tick fever (CTF virus), are discussed.

Resistance breeding against nonnative pathogens in forest trees — current successes in North America

Nonnative invasive pathogens have decimated North American forests for over 100 years, and additional pathogens continue to arrive. These pathogens are destined to be permanent fixtures in the ecosystem. In many cases, management activities have been unsuccessful in slowing the spread of these pathogens or in restoring forests. Genetic resistance potentially provides an invaluable management tool for restoring these species or using them in plantations. Although native tree species are highly susceptible to some nonnative pathogens, a low frequency of resistance is present in even those North American host species most affected. Classical breeding methods can produce genetically diverse and resistant populations for reforestation or restoration of natural forests. However, any operational program for developing resistant populations of forest trees must contend with relatively long generation times, as well as the long-lived nature of trees and the potential of the pathogen to evolve. Western white pine (Pinus monticola), Port-Orford-cedar (Chamaecyparis lawsoniana), American chestnut (Castanea dentata), and American elm (Ulmus americana) are examples of species for which there are successful breeding programs for disease resistance. Examples from these species, with a particular focus on western white pine and white pine blister rust [Cronartium ribicola] resistance, will be used to illustrate some of the successes in operational programs, as well as to discuss some of the research needs and current unknowns in developing durable resistance. Some of these programs have been ongoing for 50 years, while the Port-Orford-cedar program began only in the last decade. Resistant seedlings from several programs are now being used in reforestation and restoration.

Isolates of Microbotryum violaceum from North American host species are phylogenetically distinct from their European host-derived counterparts

Microbotryum violaceum is a basidiomycete that infects the anthers of its Caryophyllaceae host species. Individual fungal isolates are host limited, though they are not morphologically distinct. This study used variable regions of the highly conserved gamma-tubulin, beta-tubulin, and ribosomal RNA-encoding genes to determine the relationships among M. violaceum fungal isolates from different host species and different geographical locations. Phylogenetic trees from intron nucleotide sequences in two protein-coding genes were compared to trees produced from internal transcribed spacers (ITS) of rDNA. Phylogenetic analyses suggested that there are two clades, one from North America and one from Europe. Isolates from both clades grouped according to host species, although in some analyses isolates from closely related host species were placed together. These results are consistent with the view that M. violaceum has experienced cospeciation with its hosts.

Obligate brood parasites as selective agents for evolution of egg appearance in passerine birds.

Many passerine host species have counteracted the parasite egg mimicry in their coevolutionary arms race with the common cuckoo (Cuculus canorus) by evolving increased interclutch and reduced intraclutch variation in egg appearance. Such variations make it easier for hosts to recognize a foreign egg, reduce the possibility of making recognition errors, and reduce the ability of the cuckoo to mimic the eggs of a particular host. Here, we investigate if such clutch characteristics have evolved among North American passerines. We predict that due to the absence of brood parasites with egg mimicry on this continent, these passerines should (1) not show any relationship between rejection rates and intra- or interclutch variation, and (2) intraclutch variation should be lower and interclutch variation higher in European hosts exposed to cuckoo parasitism as compared to North American hosts parasitized by cowbirds. Here we present data that show support for most of these and other predictions, as well as when controlling statistically for effects of common descent. However, the effect of continent on intraclutch variation was less than predicted and we discuss a possible reason for this. All things considered, the results demonstrate that parasitism by a specialist brood parasite with egg mimicry is a powerful selective force regarding the evolution of egg characteristics in passerine birds.

The Indochinese Refugees

Cambodian, Laotian and Vietnamese refugees who have come to North American host countries via the South Asian camps have been exposed to many potentially traumatic events and have been submitted to an alienating migration process. A comprehensive analysis of their experience both in refugee camps and North American host countries is facilitated by the use of various stress theories. The stressors of change, acculturation, bereavement and trauma are identified with regard to the migration process of the Indochinese refugees as well as to the pre- and post-migration period. Some implications for practice in social, physical and mental health settings are underlined: in particular a sensitivity to the meaning of physical illness within this population, to the cultural reticence towards mental health consultation, to the possibility of longterm vulnerability to post-traumatic stress disorders and to increasing value conflicts within the family. Intervention experiences both in the South Asian refugee camps an...