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41.
Although individuals in many fish species move to shallow waters to spawn, the California grunion (Leuresthes tenuis) is almost unique in its constitutive display of synchronous full-emergence beach spawning. During a spawning event, fish
ride large waves onshore to spawn on beach land, where their eggs incubate terrestrially. Here, we employ molecular markers
to ascertain how this unusual reproductive behavior impacts genetic parentage. We developed and utilized four highly polymorphic
microsatellite markers to assess maternal and paternal contributions in a total of 682 progeny from 17 nests of a natural
population of L. tenuis. Alleles deduced to be of paternal origin in progeny were used to determine the minimum number of sires per nest and to estimate
the true number of sires per nest via Bayesian analysis. We document the following: (a) no instances of multiple maternity
for progeny within a nest; (b) a high frequency of nests (88%) with multiple paternity; and (c) an appreciable fraction of
nests (18%) in which the estimated number of genetic sires (as many as nine) proved to be greater than the observed number
of male attendants, thus implicating occasional extra-group fertilization events. From these and other observations, we also
conclude that spawning behavior in grunions may involve site choice but not explicit mate choice. In addition to providing
the first analysis of molecular parentage in a beach-spawning fish, we compare our findings to those reported previously for
a beach-spawning arthropod, and we discuss the forces that may be maintaining this peculiar reproductive behavior. 相似文献
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Rosemary Lyster 《环境政策》2017,26(3):438-458
A Capability Approach is adopted to critically analyse, in the interests of Climate Justice, whether the Paris Agreement is likely to adequately protect human and non-human Capabilities from the worst impacts of climate disasters. The mitigation, adaptation, and loss and damage provisions of the Paris Agreement are not convincing. Adaptation offers only a modest response to climate change, compared with mitigation, and current financial commitments to fund adaptation in developing countries are far too low. Consequently, the Parties to the United Nations Framework Convention on Climate Change have a long way to go in their negotiations before they have any hope of meeting their agreed temperature goals, and protecting human and non-human Capabilities from climate disasters. 相似文献
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Kopittke PM Asher CJ Kopittke RA Menzies NW 《Environmental pollution (Barking, Essex : 1987)》2007,150(2):280-287
A concentration as low as 1 microM lead (Pb) is highly toxic to plants, but previous studies have typically related plant growth to the total amount of Pb added to a solution. In the present experiment, the relative fresh mass of cowpea (Vigna unguiculata) was reduced by 10% at a Pb2+ activity of 0.2 microM for the shoots and at a Pb2+ activity of 0.06 microM for the roots. The primary site of Pb2+ toxicity was the root, causing severe reductions in root growth, loss of apical dominance (shown by an increase in branching per unit root length), the formation of localized swellings behind the root tips (due to the initiation of lateral roots), and the bending of some root tips. In the root, Pb was found to accumulate primarily within the cell walls and intercellular spaces. 相似文献
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