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71.
SOME ASPECTS OF THE MICROBIOLOGY OF FROZEN PEAS 总被引:2,自引:2,他引:0
72.
LINK E. OLSON STEVEN M. GOODMAN ANNE D. YODER 《Biological journal of the Linnean Society. Linnean Society of London》2004,83(1):1-22
The increasing use of mitochondrial DNA (mtDNA) to explore and test species limits among morphologically similar species is potentially compromised by phenomena poorly reflective of organismal history and speciation, including (but not limited to) stochastic lineage sorting and gene flow. In situations where molecular data are only available from a single gene or linkage partition (e.g. mtDNA), corroboration of suspected species boundaries should be sought from independent lines of evidence, such as morphology. Recent attempts to delimit species using mtDNA and morphology have either implicitly or explicitly ignored the possibility that distinct species can occur in direct sympatry throughout much of their range, presumably because such situations are believed to be rare. We examined phylogenetic relationships within the long‐tailed shrew tenrecs (Mammalia: Tenrecidae; Microgale spp.) from Madagascar. Current taxonomy recognizes two broadly sympatric species, though as many as six have been described. Given that alpha taxonomy within shrew tenrecs has been controversial, and that patterns of morphological variation can be especially difficult to assess for this group, some authors have suggested that additional cryptic species may exist. To examine this possibility, we conducted a phylogenetic study using the mitochondrial NADH dehydrogenase subunit 2 gene and a morphometric analysis of 29 craniodental, postcranial, and external measurements from a broad geographical sample of long‐tailed shrew tenrecs. The two data sets were nearly perfectly congruent in identifying four groups that can be classified as species, thereby doubling the currently recognized number of species. We present previously unrecognized distributional evidence consistent with our conclusions and provide an empirical example of how a revised understanding of species limits alters inferences of geographic variation and species coexistence, particularly with respect to fine‐scale habitat partitioning. The results of this study suggest that certain species pairs, previously assumed to be single species occupying broad elevational ranges, are actually reproductively isolated units that are partitioning their environment along elevational lines. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 83 , 1–22. 相似文献
73.
ATTILA HETTYEY FRANZISKA RÖLLI NINA THÜRLIMANN ANNE‐CATHERINE ZÜRCHER JOSH VAN BUSKIRK 《Biological journal of the Linnean Society. Linnean Society of London》2012,106(4):820-827
The ability of prey to detect predators directly affects their probability of survival. Chemical cues are known to be important for predator detection in aquatic environments, but the role of other potential cues is controversial. We tested for changes in behaviour of Rana temporaria tadpoles in response to chemical, visual, acoustic, and hydraulic cues originating from dragonfly larvae (Aeshna cyanea) and fish (Gasterosteus aculeatus). The greatest reduction in tadpole activity occurred when all cues were available, but activity was also significantly reduced by visual cues only. We did not find evidence for tadpoles lowering their activity in response to acoustic and hydraulic cues. There was no spatial avoidance of predators in our small experimental containers. The results show that anuran larvae indeed use vision for predator detection, while acoustic and hydraulic cues may be less important. Future studies of predator‐induced responses of tadpoles should not only concentrate on chemical cues but also consider visual stimuli. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ??, ??–??. 相似文献
74.
ANNE DONCHIN 《Bioethics》2009,23(1):28-38
The recent case of the UK woman who lost her legal struggle to be impregnated with her own frozen embryos, raises critical issues about the meaning of reproductive autonomy and the scope of regulatory practices. I revisit this case within the context of contemporary debate about the moral and legal dimensions of assisted reproduction. I argue that the gender neutral context that frames discussion of regulatory practices is unjust unless it gives appropriate consideration to the different positions women and men occupy in relation to reproductive processes and their options for autonomous choice. First, I consider relevant legal rulings, media debate, and scholarly commentary. Then I discuss the concept of reproductive autonomy imbedded in this debate. I argue that this concept conflates informed consent and reproductive autonomy, thereby providing an excessively narrow reading of autonomy that fails to give due regard to relations among individuals or the social, political and economic environment that shapes their options. I contrast this notion of autonomy with feminist formulations that seek to preserve respect for the agency of individuals without severing them from the conditions of their embodiment, their surrounding social relationships, or the political contexts that shape their options. Taking these considerations into account I weigh the advantages of regulation over the commercial market arrangement that prevails in some countries and suggest general guidelines for a regulatory policy that would more equitably resolve conflicting claims to reproductive autonomy. 相似文献
75.
ANNE PETERS 《Ibis》2007,149(1):121-127
When selection strongly favours a testosterone-dependent trait in males, and this trait is not beneficial to females, a correlated response to selection in females, which also circulate some testosterone, could slow the rate of evolution in males. Here I investigate whether experimental testosterone treatment in female Superb Fairy-wrens Malurus cyaneus can induce the testosterone-dependent sexually selected moult into nuptial plumage, as it does in males. Silastic testosterone implants in females rapidly induced a moult akin to the male prenuptial moult, involving all body areas that are colourful in nuptial males (head, upper back, ear tufts, breast). Moreover, the newly moulted feathers had a similar glistening appearance and morphology as male nuptial feathers. However, the treatment failed to induce production of the blue and black structural colours, and the breast and ear tufts were lighter than the normal grey-brown feathers of females and males in eclipse plumage. Microscopic and ultrastructural analyses of these unusual feathers could further our understanding of structural colour production. 相似文献
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79.
MARION A. WATSON G. D. HEATHCOTE F. B. LAUCKNER † P. ANNE SOWRAY † 《The Annals of applied biology》1975,81(2):181-198
Partial regression equations were calculated that relate the mean percentage of plants infected with yellowing viruses (beet yellows and beet mild yellowing viruses) in sugar-beet crops at the end of August to the number of days during January, February and March when temperatures fell below – 0.3 °C (31-5 °F) and the mean temperatures in April, for the 21 yr, 1951–71, using weather records from Rothamsted Experimental Station. Regression analyses were also made to find the effect of other factors including mean and minimum temperatures for the same months, and also mean counts of ‘green aphids’, mainly of the vector Myzus persicae, on sugar-beet plants during May and June. Significant relationships were established with all factors, but ‘frost-days’ and April mean temperatures accounted for the greatest percentage of the variance in yellows incidence. The calculations were made separately for the years from 1951 to 1958, when no routine advice was given to farmers about aphid control, and 1959–71 when a ‘spray-warning scheme’ was in operation, and many crops were sprayed at critical times to prevent aphid- and virus-spread. Weather factors had the same effects in both periods, but for any particular weather less virus was spread in the second period than in the first, although there were sufficient aphids, i.e. the numbers expected from the prevailing weather conditions. There was no evidence that insecticide treatment used in any one year affected aphid-incidence in subsequent years. Regression analyses on weather variables were also calculated separately for each of seventeen beet-sugar factory collection-areas, using weather records from local weather stations, and also the Rothamsted weather records. Unexpectedly, the fit of the regressions was always better with Rothamsted weather data than with local weather records. Mean yellows-incidence for the different factory areas declined from south to north, and there was a linear relationship with the square root of the latitude above 50 °C. At the same time the correlation coefficients relating yellows-incidence to ‘frost-days’ became smaller and less significant, and those showing dependence 相似文献
80.
ANNE P. BONNY 《The New phytologist》1972,71(2):393-405