As microbiology undergoes a renaissance, fuelled in part by developments in new sequencing technologies, the massive diversity and abundance of microbes becomes yet more obvious. The Archaea have traditionally been perceived as a minor group of organisms forced to evolve into environmental niches not occupied by their more 'successful' and 'vigorous' counterparts, the bacteria. Here we outline some of the evidence gathered by an increasingly large and productive group of scientists that demonstrates not only that the Archaea contribute significantly to global nutrient cycling, but also that they compete successfully in 'mainstream' environments. Recent data suggest that the Archaea provide the major routes for ammonia oxidation in the environment. Archaea also have huge economic potential that to date has only been fully realized in the production of thermostable polymerases. Archaea have furnished us with key paradigms for understanding fundamentally conserved processes across all domains of life. In addition, they have provided numerous exemplars of novel biological mechanisms that provide us with a much broader view of the forms that life can take and the way in which micro-organisms can interact with other species. That this information has been garnered in a relatively short period of time, and appears to represent only a small proportion of what the Archaea have to offer, should provide further incentives to microbiologists to investigate the underlying biology of this fascinating domain. IntroductionWhen Carl Woese first proposed that the tree of life encompassed three distinct lineages, including a new prokaryotic one initially designated Archaebacteria (later Archaea), it would have been hard to imagine the broad spectrum of novel findings that study of these remarkable organisms would bring to light. Indeed, in their groundbreaking paper, in which Woese & Fox (1977) proposed the third Kingdom [later Domain (Woese et al., 1990)] of Archaebacteria, they were represented solely by the methanogens. These were quickly supplemented by the addition of extreme halophiles and thermoacidophiles Woese et al., 1978), but at that time one of the characteristics of archaebacteria was 'their occurrence only in unusual habitats'. By the 1980s, many new hyperthermophilic organisms that grew optimally above 80 u C, and often optimally above 100 uC, had been isolated and shown also to be archaea (Tu et al., 1982;Zillig et al., 1981). Later studies showed by molecular rather than culture methods that archaea are cosmopolitan, and in certain habitats, such as the oceans, are significant contributors to the biomass (DeLong & Pace, 2001;Olsen et al., 1986;Robertson et al., 2005). Over the years, archaea have gone from microbial extremophilic oddities to organisms of universal importance and have been used to elucidate fundamental biological questions. Studies of archaea have proven to be enormously fruitful: unique traits found nowhere else in nature have been revealed in archaea, and there are many instances of archaeal pro...

We examined responses of songbirds breeding in high-elevation Engelmann spruce – subalpine fir (Picea englemannii Parry ex Engelm. – Abies lasiocarpa (Hook.) Nutt.) forests to four perforation harvest patterns near Sicamous, British Columbia. Each treatment removed approximately 30% of the timber volume but varied the size of openings from 10-ha clearcuts to small gaps (<0.01 ha), where individual trees were removed. Abundance and diversity of breeding songbirds were monitored over a 4-year period, including 2 years each of pre- and post-harvest conditions. Two-thirds of the original songbird assemblage consisted of mature forest species that showed only modest changes in relative abundance following harvest. Two species showed significant responses to harvesting: golden-crowned kinglet (Regulus satrapa Lichtensteins) declined significantly postharvest, with the largest declines occurring in single-tree and 10-ha treatments; and dark-eyed junco (Junco hyemalis L.) responded positively to harvest. At high elevations, 30% volume removal allowed much of the songbird community to be accommodated immediately after harvest. Future research should address whether the apparent short-term accommodation of high-elevation birds persists across time and as more of the continuous forest cover is removed.

A parasitic flatworm ( Ribeiroia ondatrae Price, 1931) is known to cause severe limb abnormalities and high mortality levels in American amphibian populations. The distributional pattern of this parasite—its main dispersal agent being birds—correlates with the boundaries of migratory flyways in the USA. Yet thus far, R. ondatrae have not been found in Canadian amphibians, which is surprising, considering that said flyways extend well into northern Canada. In this study, we report on a lake in British Columbia that is known to support amphibians with abnormalities similar to those induced by R. ondatrae. To determine if the parasite was present and if it was the cause of the abnormalities, we collected and necropsied metamorphs of the Columbia Spotted Frog ( Rana luteiventris Thompson, 1913) and the Pacific Chorus Frog ( Pseudacris regilla (Baird and Girard, 1852)), and we set up field enclosures to protect larvae from R. ondatrae. Abnormality levels were high in both species (>20%), with the vast majority being found in close proximity to the metacercariae of R. ondatrae. Moreover, the types of abnormalities closely matched those previously recorded in field and laboratory exposures of amphibians to R. ondatrae. Finally, larvae that developed in the same lake, but were protected from R. ondatrae by an enclosure, did not develop abnormalities. Collectively, these results demonstrate that R. ondatrae are both present in an amphibian community in Canada and responsible for causing limb abnormalities.

No abstract

The nesting ecology of western meadowlarks (Sturnella neglecta) in southern Manitoba is strongly influenced by the timing of breeding. Physical characteristics of nests change, apparently in response to seasonally altered thermal demands. The largest eggs and the largest clutches are produced in the middle portion of the breeding season, and nests initiated at that time produce the greatest number of young. Nevertheless, nesting productivity is highest for females that begin nesting earlier in the season and that can therefore renest if their initial attempt fails. Females breeding with already-mated males have, on average, as high a reproductive success as do primary females. Nevertheless, nestlings of secondary females frequently starve if they do not receive a male's parental care. Asynchronous hatching and facultative brood reduction may decrease the total losses incurred through nestling starvation, and may be adaptations that allow successful polygyny in this species. Aggressive interactions between resident and unmated females may protect a primary female's "preferred" status and may affect a male's ability to breed bigamously.