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Climate change is expected to affect natural populations in many ways. One way of getting an understanding of the effects of a changing climate is to analyze time series of natural populations. Therefore, we analyzed time series of 25 and 20 years, respectively, in two populations of the citril finch (Carduelis citrinella) to understand the background of a dramatic increase in wing length in this species over this period, ranging between 1.3 and 2.9 phenotypic standard deviations. We found that the increase in wing length is closely correlated to warmer winters and in one case to rain in relation to temperature in the summer. In order to understand the process of change, we implemented seven simulation models, ranging from two nonadaptive models (drift and sampling), and five adaptive models with selection and/or phenotypic plasticity involved and tested these models against the time series of males and females from the two population separately. The nonadaptive models were rejected in each case, but the results were mixed when it comes to the adaptive models. The difference in fit of the models was sometimes not significant indicating that the models were not different enough. In conclusion, the dramatic change in mean wing length can best be explained as an adaptive response to a changing climate. 相似文献
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Martin Chalfie 《Developmental neurobiology》1993,24(10):1433-1441
Mutations causing a touch-insensitive phenotype in the nematode Caenorhabditis elegans have been the basis of studies on the specification of neuronal cell fate, inherited neurodegeneration, and the molecular nature of mechanosensory transduction. © 1993 John Wiley & Sons, Inc. 相似文献
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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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Plants from a sun and shade population were grown in two environments differing in the ratio of red to far-red light (R/FR
ratio). A low R/FR ratio, simulating vegetation shade, promoted the formation of long, upright-growing leaves and allocation
towards shoot growth, whereas a high R/FR ratio had the opposite effects. The increase in plant height under the low R/FR
ratio was accompanied by a reduction in the number of leaves. Population differences in growth form resembled the differences
between plants grown in different light environments: plants from the shade population had rosettes with long erect leaves,
whereas plants from the sun population formed prostrate rosettes with short leaves. Plants from the shade population were
more responsive to the R/FR ratio than plants from the sun population: the increases in leaf length, plant height, and leaf
area ratio under a low R/FR ratio were larger in the shade population. However, differences in plasticity were small compared
to the population difference in growth form itself. We argue that plants do not respond optimally to shading and that developmental
constraints might have limited the evolution of an optimal response.
Received: 8 December 1996 / Accepted: 31 March 1997 相似文献