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Hilary S. Callahan Massimo Pigliucci Carl D. Schlichting 《BioEssays : news and reviews in molecular, cellular and developmental biology》1997,19(6):519-525
The plastic response of phenotypic traits to environmental change is a common research focus in several disciplines - from ecology and evolutionary biology to physiology and molecular genetics. The use of model systems such as the flowering plant Arabidopsis thaliana has facilitated a dialogue between developmental biologists asking how plasticity is controlled (proximate causes) and organismal biologists asking why plasticity exists (ultimate causes). Researchers studying ultimate causes and consequences are increasingly compelled to reject simplistic, ‘black box’ models, while those studying proximate causes and mechanisms are increasingly obliged to subject their interpretations to ecological ‘reality checks.’ We review the successful multidisciplinary efforts to understand the phytochrome-mediated shade-avoidance and light-seeking responses of flowering plants as a pertinent example of convergence between evolutionary and molecular biology. In this example, the two-way exchange between reductionist and holist camps has been essential to rapid and sustained progress. This should serve as a model for future collaborative efforts towards understanding the responses of organisms to their constantly changing environments. 相似文献
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Future uses of pollen analysis must include plant macrofossils 总被引:8,自引:0,他引:8
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While the life history traits of animals usually exhibit substantial phenotypic plasticity, such plasticity might reflect
either a simple alteration in the level of energy accrual and use or a genuine shift in energy allocation tactics between
environmental conditions. The latter would represent genuine plasticity in the life history itself, and thus it is important
to distinguish which of these two processes underlies the observed plasticity of life history traits. We investigated this
issue by examining the effects of temperature and salinity variation during ontogeny on the allocation of biomass and lipid
storage in male sailfin mollies, Poecilia latipinna. We raised males from four natural populations from birth to maturity in controlled laboratory conditions. Neither distinct
temperatures (23 or 29°C) nor different salinity regimes (2, 12, or 20 parts per thousand) affected body mass, although males
from different populations differed substantially in body mass. However, males raised at the higher temperature had a greater
allocation of biomass to testis and a lower allocation to viscera mass. The amount of stored lipid was altered by temperature
variation but the direction and magnitude of the effect varied substantially among males from the different populations. Salinity
variation affected neither biomass allocation nor the level of lipid storage. These results indicate that male mollies possess
a flexible developmental program with respect to temperature that canalizes body size and alters the allocation of biomass
among competing demands for reproductive readiness and capacity for energy storage.
Received: 25 November 1996 / Accepted: 1 December 1997 相似文献
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Hilary E. Kahn 《American anthropologist》1998,100(1):230-231
Tlie Two Milpas of Chan Kom:. Study of Socioeconomic and Political Transformations in. Maya Community. Alicia Re Cruz. Albany: State University of New York Press, 1996. 203 pp. 相似文献
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Plasma oxytocin levels were measured serially in 22 women receiving prostaglandin E2 or F2α intravenously for the induction of labour. Oxytocin was detected in the plasma of 19 of the 22 women; positive levels were found in 60 (43%) of 139 plasma samples, an incidence similar to that in the late first stage of spontaneous labour. Oxytocin was found in the maternal plasma even when the fetus was dead, and in the plasma of two men receiving prostaglandin infusions. This indicates that prostaglandins stimulate the pituitary directly and suggests that this mechanism may play a part in the oxytocic action of infused prostaglandins. 相似文献
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Necropsy of a stranded adult leatherback turtle (Dermochelys coriacea) determined that the animal died as a result of valvular endocarditis and septicemia. Vibrio damsela was isolated from the endocardial thrombus. The route of entry for infection probably was through the gastrointestinal tract. 相似文献
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Applicants to St Mary''s Hospital Medical School were asked to comment freely on the process of selection. They were particularly concerned about the role of interviews, excessive emphasis on academic achievement, the problem of rank-ordering choices on the UCCA form, and possible biases in selection. These concerns and the results of our survey suggest that candidates should not be asked to rank their choices in order of preference, that UCCA applications for medicine should be subject to an early closing date, that as many applicants as possible should be interviewed, that applicants should be encouraged to apply after taking A levels, that educational opportunity should be taken into account in assessing A level grades, and that mature students should be encouraged, not least by providing mandatory awards for a second degree in medicine. 相似文献