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61.
Felipe Dargent Marilyn E. Scott Andrew P. Hendry Gregor F. Fussmann 《Proceedings. Biological sciences / The Royal Society》2013,280(1773)
A reduction in the strength of selection is expected to cause the evolution of reduced trait expression. Elimination of a parasite should thus cause the evolution of reduced resistance to that parasite. To test this prediction in nature, we studied the fourth- and eighth-generation descendants of guppies (Poecilia reticulata) introduced into four natural streams following experimental elimination of a common and deleterious parasite (Gyrodactylus spp.). After two generations of laboratory rearing to control for plasticity and maternal effects, we infected individual fish to assess their resistance to the parasite. Contrary to theoretical expectations, the introduced guppy populations had rapidly and repeatably evolved increased resistance to the now-absent parasite. This evolution was not owing to a resistance-tolerance trade-off, nor to differences in productivity among the sites. Instead, a leading candidate hypothesis is that the rapid life-history evolution typical in such introductions pleiotropically increases parasite resistance. Our study adds a new dimension to the growing evidence for contemporary evolution in the wild, and also points to the need for a re-consideration of simple expectations from host–parasite theory. In particular, our results highlight the need for increased consideration of multiple sources of selection and pleiotropy when studying evolution in natural contexts. 相似文献
62.
Yoshichika Takamura Tomiko Takamura Masami Soejima Teijiro Uemura 《Bioscience, biotechnology, and biochemistry》2013,77(5):718-728
Maleate cis-trans isomerase in Alcaligenes faecalis IB–14 was induced by malonate and purified about 100-fold over the crude cell-free extract by treatments of ammonium sulfate fractionation, Sephadex G–100 gel filtration, DEAE-cellulose and DEAE-Sephadex A–50 column chromatography. The preparation was shown to be monodisperse on ultracentrifugal analysis and Svedberg value was found to be 3.84 S.The enzyme was most active at pH value around 8.3 and was stable over the range of pH 5.0 to 7.0 in the presence of dithiothreitol (DTT) for a few weeks, but in the absence of it, the enzyme activity was markedly decreased, especially in the alkaline region. The enzyme activity was inhibited by various sulfhydryl reagents and oxidizing agents, whereas it was not affected by metal chelating agents. The inhibition by Hg2+ and PCMB was overcome by the addition of sulfhydryl compounds such as DTT, 2-mercaptoethanol, l-cysteine and glutathione. It was observed that the enzyme did not require co-factor for its function.Kinetic studies showed that Michaelis constant for maleate was 2.8×10?3 m and the enzyme did not catalyze the reverse reaction. 相似文献
63.
Lee A. Rollins Angela T. Moles Serena Lam Robert Buitenwerf Joanna M. Buswell Claire R. Brandenburger Habacuc Flores‐Moreno Knud B. Nielsen Ellen Couchman Gordon S. Brown Fiona J. Thomson Frank Hemmings Richard Frankham William B. Sherwin 《Ecology and evolution》2013,3(13):4501-4517
Some introduced populations thrive and evolve despite the presumed loss of diversity at introduction. We aimed to quantify the amount of genetic diversity retained at introduction in species that have shown evidence of adaptation to their introduced environments. Samples were taken from native and introduced ranges of Arctotheca populifolia and Petrorhagia nanteuilii. Using microsatellite data, we identified the source for each introduction, estimated genetic diversity in native and introduced populations, and calculated the amount of diversity retained in introduced populations. These values were compared to those from a literature review of diversity in native, confamilial populations and to estimates of genetic diversity retained at introduction. Gene diversity in the native range of both species was significantly lower than for confamilials. We found that, on average, introduced populations showing evidence of adaptation to their new environments retained 81% of the genetic diversity from the native range. Introduced populations of P. nanteuilii had higher genetic diversity than found in the native source populations, whereas introduced populations of A. populifolia retained only 14% of its native diversity in one introduction and 1% in another. Our literature review has shown that most introductions demonstrating adaptive ability have lost diversity upon introduction. The two species studied here had exceptionally low native range genetic diversity. Further, the two introductions of A. populifolia represent the largest percentage loss of genetic diversity in a species showing evidence of substantial morphological change in the introduced range. While high genetic diversity may increase the likelihood of invasion success, the species examined here adapted to their new environments with very little neutral genetic diversity. This finding suggests that even introductions founded by small numbers of individuals have the potential to become invasive. 相似文献
64.
David P. Dimmock Michelle M. Clark Mary Gaughran Julie A. Cakici Sara A. Caylor Christina Clarke Michele Feddock Shimul Chowdhury Lisa Salz Cynthia Cheung Lynne M. Bird Charlotte Hobbs Kristen Wigby Lauge Farnaes Cinnamon S. Bloss Stephen F. Kingsmore the RCIGM Investigators 《American journal of human genetics》2020,107(5):942
65.
John P. DeLong Valery E. Forbes Nika Galic Jean P. Gibert Robert G. Laport Joseph S. Phillips Janna M. Vavra 《Ecology and evolution》2016,6(2):573-581
It is increasingly recognized that evolution may occur in ecological time. It is not clear, however, how fast evolution – or phenotypic change more generally – may be in comparison with the associated ecology, or whether systems with fast ecological dynamics generally have relatively fast rates of phenotypic change. We developed a new dataset on standardized rates of change in population size and phenotypic traits for a wide range of species and taxonomic groups. We show that rates of change in phenotypes are generally no more than 2/3, and on average about 1/4, the concurrent rates of change in population size. There was no relationship between rates of population change and rates of phenotypic change across systems. We also found that the variance of both phenotypic and ecological rates increased with the mean across studies following a power law with an exponent of two, while temporal variation in phenotypic rates was lower than in ecological rates. Our results are consistent with the view that ecology and evolution may occur at similar time scales, but clarify that only rarely do populations change as fast in traits as they do in abundance. 相似文献
66.
67.
Frequency‐dependent selection for rare genotypes promotes genetic diversity of a tropical palm 下载免费PDF全文
Negative frequency‐dependent selection among species is a key driver of community diversity in natural systems, but the degree to which negative frequency‐dependent selection shapes patterns of survival and genetic diversity within species is poorly understood. In a 5‐year field experiment, we show that seedlings of a tropical palm with rare genotypes had a pronounced survival advantage over seedlings with common genotypes, with effect sizes comparable to that of light availability. This ‘rare genotype advantage’ led to an increase in population‐wide genetic diversity among seedlings compared to null expectations, as predicted by negative frequency‐dependent selection, and increased reproductive success in adult trees with rare genotypes. These results suggest that within‐species negative frequency‐dependent selection of genotypes can shape genetic variation on ecologically relevant timescales in natural systems and may be a key, overlooked source of non‐random mortality for tropical plants. 相似文献
68.
Phylogeography of Arabis serrata (Brassicaceae) in the Japanese Archipelago based on chloroplast DNA variations 下载免费PDF全文
Arabis serrata (Brassicaceae), a perennial plant widely distributed along the Japanese Archipelago, occurs in various habitats: for example, limestone zones, serpentine barrens, volcanic soils, and roadsides. It likely survived by adapting to its surrounding environment, resulting in great morphological and ecological variation. In this study, we performed a phylogeographic analysis to examine past changes in the distribution of A. serrata following climate oscillations during the Pleistocene. To cover most of A. serrata's range, leaves were collected from eight to ten individuals randomly selected from each of 37 populations in the Japanese Archipelago. Two chloroplast noncoding regions of the samples were amplified and sequenced: trnT(GGU)‐psbD and trnH(GUG)‐psbA spacers. Twenty‐five haplotypes were detected and distinguished by 31 substitutions. Four main haplotypes were observed in many populations distributed throughout the Japanese Archipelago. According to the genetic boundaries detected using the Monmonier algorithm, A. serrata is clustered into four groups, each including several populations: Hokkaido Island, northern mainland Honshu, central Japan, and western Japan. The boundaries, however, were not robust because all genetic parameters did not support the differentiation among groups. These results indicate the absence of an obvious geographic structure in the distribution of A. serrata, suggesting that this species has experienced a rapid range expansion in postglacial times. 相似文献
69.
该研究利用RACE ( Rapid amplification of cDNA ends)技术从小蓬中成功分离编码金属硫蛋白( Metal-lothionein,MT)的cDNA序列,命名为NeMT2,在GenBank中登录号为KT835290。该基因全长590 bp,开放阅读框为237 bp,编码78个氨基酸,编码的氨基酸序列中含有14个半胱氨酸残基( Cys,C),呈C-C,C-X-C,C-X-X-C排列,集中分布在肽链的N端和C端,基因编码蛋白的分子量为7.6036 kD,等电点为4.71。系统发育分析表明,小蓬金属硫蛋白NeMT2与藜科的海蓬子( AEF01492)和盐穗木( AHI62953)同源性最高,其次是甜菜( XP 010667708.1)。生物信息学分析表明,金属硫蛋白NeMT2无信号肽结构,属于非跨膜亲水性蛋白;疏水性分析表明,NeMT2蛋白的35~45个氨基酸之间有较强的疏水性,其中第41位Asp具最强的疏水性(1.444);结构预测分析该蛋白质二级结构的主要元件是无规则卷曲。通过RT-PCR对NeMT2基因的表达分析发现, NeMT2基因在铜矿区和非铜矿区的小蓬叶片中均有表达,但该基因在铜矿区小蓬叶片的表达量明显高于非铜矿区。将小蓬NeMT2基因定向克隆到植物表达载体pCAMBIA1300的35S 启动子下游,构建该基因的植物超表达载体pCAMBIA1300+NeMT2。该研究结果为进一步研究该基因的功能和小蓬响应重金属胁迫的分子机制提供了一定基础。 相似文献
70.